A method for determining parameters of an imaging transfer function (point spread function) is presented. With regard to a model that describes the imaging transfer function including a number of model parameters, a test substrate is exposed and developed using a test pattern which comprises multiple sub-patterns that are based on the same sub-pattern template but with varying control width of a feature in the template, such as the width of a line or a distance between lines. On the test substrate, isofocal dose measurements are performed using the structures thus formed on a test substrate with varying control and imaging parameters. The isofocal dose thus determined are utilized to determine the model parameters of the imaging transfer function.
G03F 7/00 - Production par voie photomécanique, p. ex. photolithographique, de surfaces texturées, p. ex. surfaces impriméesMatériaux à cet effet, p. ex. comportant des photoréservesAppareillages spécialement adaptés à cet effet
2.
Method for Determining Focal Properties in a Target Beam Field of a Multi-Beam Charged-Particle Processing Apparatus
A method for determining focal properties in a target beam field of a charged-particle multi-beam processing apparatus is presented, where the focal properties relate to aperture images formed by the beamlets at or near the target within this apparatus, such as height of focus, astigmatic length, or size of blur. By modifying an electrostatic voltage of a lens or another suitable operating parameter of the projection optics, the landing angles of the beamlets are tilted by a small tilting angle, causing a small displacement of the positions where the beamlets hit the target surface. Using the amounts of displacement and the change of landing angles a map is generated that describes a mapping from the change of landing angles to the amounts of displacement as a function of the position, for instance by using a best fit to a predefined model; this map is then used to extract the focal properties, which in turn can be used to correct for imaging errors in the processing apparatus.
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
H01J 37/153 - Dispositions électronoptiques ou ionoptiques pour la correction de défauts d'images, p. ex. stigmateurs
3.
Device and Method for Calibrating a Charged-Particle Beam
A beam calibration device is presented for calibrating a charged-particle beam in a charged-particle processing apparatus in relation to a positioning of the beam with respect to a target. The beam calibration device includes a detector for the charged particles that are arriving at a registering structure of said device. The beam is deflected from a designated target position towards the device, by means of a lateral initial deflection, thus allowing the beam to impinge on at least one of the registering structures. The beam is scanned over the beam calibration device, thus covering a pre-defined region on this device including the registering structure, and using the detector, an electric current is measured as a current signal and is evaluated, to determine a central relative position of the beam with respect to an optimal position predefined on the beam calibration device surface. Using this optimal position, the beam is deflected back to the designated target position by a reverse lateral deflection which is an inverse of said initial deflection combined with a deflection correction, which represents a correction of the lateral beam position to compensate the central relative position.
H01J 37/147 - Dispositions pour diriger ou dévier la décharge le long d'une trajectoire déterminée
H01J 37/244 - DétecteursComposants ou circuits associés
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
4.
Optimizing Image Distortion in a Multi Beam Charged Particle Processing Apparatus
The invention proposes adjusting the optical imaging system of a charged-particle multi-beam processing apparatus with regard to spatial and angular image distortion of the beam field, which describes the deviation of landing positions and landing angles of beamlets from respective nominal values within the beam field. Starting from a determination of the image distortion, so-called fingerprints are determined, which represent the change of image distortion effected by a unit change of a respective operating parameter of a component of the projection optics; then values of operating parameters are obtained which optimize a corrected distortion obtained from a superposition of the image distortion and a change of operating parameters that causes a variation of the image distortion, as expressed by a linear combination of said fingerprints. The optimizing values thus obtained are applied to the respective optical elements of the projection optics. The procedure may suitable be iterated until the distortion is suitably optimized.
H01J 37/304 - Commande des tubes par une information en provenance des objets, p. ex. signaux de correction
H01J 37/04 - Dispositions des électrodes et organes associés en vue de produire ou de commander la décharge, p. ex. dispositif électronoptique, dispositif ionoptique
H01J 37/153 - Dispositions électronoptiques ou ionoptiques pour la correction de défauts d'images, p. ex. stigmateurs
H01J 37/22 - Dispositifs optiques ou photographiques associés au tube
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
5.
Adjustable Magnetic Lens Having Permanent-Magnetic and Electromagnetic Components
A fine-adjustable charged particle lens comprises a magnetic circuit assembly including permanent magnets and a yoke body, surrounding a beam passage extending along the longitudinal axis. The permanent magnet is arranged between an inner yoke component and an outer yoke component so as to form a magnetic circuit having at least two gaps, generating a magnetic field reaching inwards into the beam passage, into which a sleeve insert having electrostatic electrodes can be inserted, which may also generate an electric field spatially overlapping said magnetic field. An electromagnetic adjustment coil is located between the inner and outer yoke shell. This electromagnetic adjustment coil is driven by an adjustable supply current running primarily along a circumferential direction and modifies the magnetic flux in the magnetic circuit to cause a variation in the magnetic flux density in the gaps.
An electron beam lithography apparatus-includes: a density set storage unit that stores, for each of pieces of figure information, a set of pieces of first density information corresponding to areas occupied by a figure in first small regions divided from a figure region specified by the piece of figure information; a density set acquisition unit that acquires first density sets respectively corresponding to the pieces of figure information from the density set storage unit; a correction amount acquisition unit that acquires correction amounts corresponding to the first density sets for each of the pieces of figure information, and are for the second small regions; an emission amount acquisition unit that acquires, for the second small regions, emission amounts of an electron beam with intensities corresponding to the correction amounts for the second small regions; and a drawing unit that emits an electron beam according to the emission amounts.
H01J 37/153 - Dispositions électronoptiques ou ionoptiques pour la correction de défauts d'images, p. ex. stigmateurs
G03F 7/00 - Production par voie photomécanique, p. ex. photolithographique, de surfaces texturées, p. ex. surfaces impriméesMatériaux à cet effet, p. ex. comportant des photoréservesAppareillages spécialement adaptés à cet effet
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
7.
Adjustable Permanent Magnetic Lens Having Thermal Control Device
A fine-adjustable charged particle lens comprises a magnetic circuit assembly including permanent magnets and a yoke body, surrounding a beam passage extending along the longitudinal axis. The permanent magnet is arranged between an inner yoke component and an outer yoke component so as to form a magnetic circuit having at least two gaps, generating a magnetic field reaching inwards into the beam passage, into which a sleeve insert having electrostatic electrodes can be inserted, which may also generate an electric field spatially overlapping said magnetic field. In order to modify the magnetic flux and thus the magnetic field in the gaps, a thermal control element located in the yoke body introduces or extracts heat to or from components of the of the magnetic circuit assembly so as to thermally control or modulate the magnetic behavior of said components.
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
The invention relates to a multi-beam pattern definition device for use in a particle-beam processing or inspection apparatus, said device being adapted to be irradiated with a beam of electrically charged particles and allow passage of the beam through a plurality of apertures thus forming a corresponding number of beamlets, said device comprising an aperture array device in which at least two sets of apertures are realized, an opening array device located downstream of the aperture array device having a plurality of openings configured for the passage of beamlets, said opening array device comprises impact regions, wherein charged impinge upon said impact regions.
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
H01J 37/147 - Dispositions pour diriger ou dévier la décharge le long d'une trajectoire déterminée
H01J 37/04 - Dispositions des électrodes et organes associés en vue de produire ou de commander la décharge, p. ex. dispositif électronoptique, dispositif ionoptique
9.
Adjustable Permanent Magnetic Lens Having Shunting Device
A fine-adjustable charged particle lens comprises a magnetic circuit assembly including permanent magnets, a yoke body, and a shunting device comprising a shunting component, and this assembly surrounds a beam passage extending along the longitudinal axis (cx). The shunting device is placed in the yoke body besides the permanent magnets and may be composed of several sector components, comprising different high magnetically permeable materials. The permanent magnet and the yoke body form a magnetic circuit having at least two gaps, in order to generate a magnetic field reaching inwards into the beam passage, into which a sleeve insert having electrostatic electrodes can be inserted, which may also generate an electric field spatially overlapping said magnetic field. The shunting device partially bypasses the magnetic flux of said circuit assembly and thus reduces the magnetic field to a desired value.
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
Semiconductor manufacturing machines and apparatus and
machines and apparatus for producing in relation to the
following goods: semiconductor devices, electronic
components and prototypes of semiconductors, semiconductor
devices and electronic components.
Semiconductor manufacturing machines and apparatus; machines and apparatus for the production of semiconductor devices, electronic components and prototypes of semiconductors, and semiconductor devices and electronic components
semiconductor manufacturing machines and apparatus and Machines and apparatus for producing in relation to the following goods: Semiconductor devices, electronic components and prototypes of semiconductors, semiconductor devices and electronic components.
13.
Beam pattern device having beam absorber structure
A multi-beam pattern definition device for use in a particle-beam processing or inspection apparatus, which is irradiated with a beam of electrically charged particles through a plurality of apertures to form corresponding beamlets, comprises an aperture array device in which said apertures are realized according to several sets of apertures arranged in respective aperture arrangements, and an absorber array device having openings configured for the passage of at least a subset of beamlets that are formed by the apertures. The absorber array device comprises openings corresponding to one of the aperture arrangement sets, whereas it includes a charged-particle absorbing structure comprising absorbing regions surrounded by elevated regions and configured to absorb charged particles impinging thereupon at locations corresponding to apertures of the other aperture arrangements of the aperture array device, effectively confining the effects of irradiated particles and electric charge therein.
A fine-adjustable electromagnetic lens for a charged-particle optical apparatus comprises a magnetic circuit assembly including one or more ring magnets, and a sleeve insert of generally rotational symmetry around a longitudinal axis. The sleeve insert surrounds a passage opening extending along the longitudinal axis, and comprises several electrically conductive electrode elements configured to generate an electrostatic field within the passage opening. The ring magnets are arranged circumferentially around an inner yoke shell and surrounded by an outer yoke shell; the inner yoke shell in turn surrounds a central portion of the sleeve insert. The ring magnets are magnetized such that the two magnetic poles are oriented towards the inner and outer yoke shell, respectively. The inner and outer yoke shell together with the ring magnets form a magnetic circuit having at least one gap, in order to generate a magnetic field reaching inwards into the passage opening and spatially overlapping with the electrostatic field generated by the sleeve insert.
[Problem] It has not conventionally been possible for an appropriate radiation amount when rendering a shape using an electron beam to be acquired rapidly. [Solution] An appropriate radiation amount when rendering a shape using an electron beam can be acquired rapidly by means of an electron beam rendering device comprising: a density set storage unit for storing, for each of one or more items of shape information, a set of first density information corresponding to a surface area in which shapes are included in each of two or more first small regions obtained by splitting a shape region specified by the shape information; a density set acquiring unit 33 for acquiring from the density set storage unit a first density set corresponding to each of the one or more items of shape information; a correction amount acquiring unit for acquiring correction amounts for each of two or more second small regions, the correction amounts corresponding to the one or more first density sets for each of the one or more items of shape information; a radiation amount acquiring unit for acquiring, for each of the two or more second small regions, a radiation amount of an electron beam having an intensity corresponding to the correction amounts of each of the two or more second small regions; and a rendering unit for radiating the electron beam onto each of the two or more second small regions in accordance with the radiation amount for each of the two or more second small regions.
In a writing process in a charged-particle multi-beam apparatus, a desired pattern is written onto a target wherein said desired pattern is provided as input pattern data (INPDAT) in a vector format and processed through a pattern data processing flow. A data preprocessing system receives the input pattern data (INPDAT) and preprocesses the input pattern data independently of the writing process, preferably in advance to it, using writing parameter data provided to the data preprocessing system, and writes the intermediate pattern data (IMDAT) thus obtained to a data storage. When a writing process is carried out using the apparatus, its writing control system reads the intermediate pattern data from the data storage, converts them into pattern streaming data (SBUF), and streams the pattern streaming data to the apparatus for writing the pattern to the target.
H01J 37/147 - Dispositions pour diriger ou dévier la décharge le long d'une trajectoire déterminée
H01J 37/30 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
A charged-particle source for generating a charged-particle comprises a sequence of electrodes, including an emitter electrode with an emitter surface, a counter electrode held at an electrostatic voltage with respect to the emitter electrode at a sign opposite to that of the electrically charged particles, and one or more adjustment electrodes surrounding the source space between the emitter electrode and the counter electrode. These electrodes have a basic overall rotational symmetry along a central axis, with the exception of one or more steering electrodes which is an electrode which interrupts the radial axial-symmetry of the electric potential of the source, for instance tilted or shifted to an eccentric position or orientation, configured to force unintended, secondary charged particles away from the emission surface.
H01J 37/063 - Disposition géométrique des électrodes pour la formation du faisceau
H01J 37/04 - Dispositions des électrodes et organes associés en vue de produire ou de commander la décharge, p. ex. dispositif électronoptique, dispositif ionoptique
H01J 37/147 - Dispositions pour diriger ou dévier la décharge le long d'une trajectoire déterminée
18.
Correction of Blur Variation in a Multi-Beam Writer
In order to compensate for undesired effects of varying elevation of a target with respect to a nominal target plane, during writing a desired pattern on the target in a charged-particle beam apparatus, the pattern is re-calculated in each of a number of segments of the target plane by: determining an elevation of the target in the segment from the nominal target plane; determining a local blur value which represents the actual value of blur corresponding to the elevation, with regard to a dependence of the blur upon the elevation of the target; calculating a convolution kernel which represents a point spreading function realizing a local blur value; and re-calculating a nominal exposure pattern by applying the kernel to the pattern. The convolution kernel corresponds to introducing an additional blur into the pattern in the segment, increasing the blur to a given target blur value which is uniform to all segments.
G03F 1/74 - Réparation ou correction des défauts dans un masque par un faisceau de particules chargées [CPB charged particle beam], p. ex. réparation ou correction de défauts par un faisceau d'ions focalisé
G03F 1/70 - Adaptation du tracé ou de la conception de base du masque aux exigences du procédé lithographique, p. ex. correction par deuxième itération d'un motif de masque pour l'imagerie
(iii) calculating durations for the contributing exposure slots thus determined such that the sum of the durations over said contributing exposure slots is an actual effective exposure time which approximates said desired duration of the effective pixel exposure time.
The durations in step (iii) are calculated in accordance with a predetermined set of allowed durations, wherein at least one of the durations thus calculated is different from the other durations selected for said set of exposure slots.
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
G03F 7/213 - Exposition simultanée avec le même motif lumineux de différentes zones de la même surface
20.
Charged-particle source and method for cleaning a charged-particle source using back-sputtering
A charged-particle source for emission of electrons or other electrically charged particles comprises, located between the emitter electrode having an emitter surface and a counter electrode, at least two adjustment electrodes; a pressure regulator device is configured to control the gas pressure in the source space at a pre-defined pressure value. In a first cleaning mode of the particle source, applying a voltage between the emitter and counter electrodes directs gas particles towards the counter electrode, generating secondary electrons which ionize particles of the gas in the source space, and electrostatic potentials are applied to at least some of the adjustment electrodes, generating an electric field directing the ionized gas particles onto the emitter surface.
A rasterized exposure method implementing a position correction for edge positions to correct for a non-linear relationship between the position of a feature edge (dCD) of a pattern element boundary and the nominal position of the boundary as expressed through the dose of exposure (d) of the edge pixel is provided. The position correction includes: determining a position value of the edge position, determining a corrected position value based on the position value using a predefined non linear function, and modifying the pattern to effectively shift the pattern element boundary in accordance with the corrected position value. The non linear function describes the inverse of the relationship between a nominal position value (d), which is used as input value during exposure of the pattern, and a resulting position (dCD) of the pattern element boundary generated when exposed with the nominal position value.
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
22.
Method for irradiating a target using restricted placement grids
A method for irradiating a target with a beam of energetic electrically charged particles, wherein the target comprises an exposure region where an exposure by said beam is to be performed, and the exposure of a desired pattern is done employing a multitude of exposure positions on the target. Each exposure position represents the location of one of a multitude of exposure spots of uniform size and shape, with each exposure spot covering at least one pattern pixel of the desired pattern. The exposure positions are located within a number of mutually separate cluster areas which are defined at respective fixed locations on the target. In each cluster area the exposure position are within a given neighboring distance to a next neighboring exposure position, while the cluster areas are separated from each other by spaces free of exposure positions, which space has a width, which is at least the double of the neighboring distance.
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
Machines and apparatus for the production of semiconductors
and semiconductor devices, of electronic components and of
prototypes of semiconductors, semiconductor devices and
electronic components.
24.
Dose-related feature reshaping in an exposure pattern to be exposed in a multi beam writing apparatus
A method for re-calculating a pattern to be exposed on a target by means of a charged-particle multi-beam writing apparatus is presented. The pattern elements of a pattern, initially associated with a respective assigned dose, are recalculated in view of obtaining reshaped pattern elements which have a nominal dose as assigned dose. The nominal dose represents a predefined standard value of exposure dose to be exposed for pixels during a scanning stripe exposure within the multi-beam apparatus. For the pattern elements associated with an assigned dose deviating from the nominal dose, the pattern element is reshaped by determining a reshape distance from the value of the assigned dose using a predefined dose slope function forming a reshaped pattern element, whose boundary is offset with regard to boundary of the initial pattern element by an offset distance equaling said reshape distance, assigning the nominal dose to the reshaped pattern element, and replacing the pattern element by the reshaped pattern element.
H01J 37/00 - Tubes à décharge pourvus de moyens permettant l'introduction d'objets ou d'un matériau à exposer à la décharge, p. ex. pour y subir un examen ou un traitement
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
Machines and apparatus for the production of semiconductors and semiconductor devices, of electronic components and of prototypes of semiconductors, semiconductor devices and electronic components
26.
Advanced dose-level quantization of multibeam-writers
In a charged-particle multi-beam writing method a desired pattern is written on a target using a beam of energetic electrically charged particles, by imaging apertures of a pattern definition device onto the target, as a pattern image which is moved over the target. Thus, exposure stripes are formed which cover the region to be exposed in sequential exposures, and the exposure stripes are mutually overlapping, such that each area of said region is exposed by at least two different areas of the pattern image at different transversal offsets (Y1). For each pixel, a corrected dose amount is calculated by dividing the value of the nominal dose amount by a correction factor (q), wherein the same correction factor (q) is used with pixels located at positions which differ only by said transversal offsets (Y1) of overlapping stripes.
H01J 37/09 - DiaphragmesÉcrans associés aux dispositifs électronoptiques ou ionoptiquesCompensation des champs perturbateurs
H01J 37/31 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour couper ou perforer
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
27.
Method for compensating pattern placement errors caused by variation of pattern exposure density in a multi-beam writer
A method for compensating pattern placement errors during writing a pattern on a target in a charged-particle multi-beam exposure apparatus including a layout generated by exposing a plurality of beam field frames using a beam of electrically charged particles, wherein each beam field frame has a respective local pattern density, corresponding to exposure doses imparted to the target when exposing the respective beam field frames. During writing the beam field frames, the positions deviate from respective nominal positions because of build-up effects within said exposure apparatus, depending on the local pattern density evolution during writing the beam field frames. To compensate, a displacement behavior model is employed to predict displacements; a local pattern density evolution is determined, displacements of the beam field frames are predicted based on the local pattern density evolution and the displacement behavior model, and the beam field frames are repositioned accordingly based on the predicted values.
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
G03F 1/78 - Création des motifs d'un masque par imagerie par un faisceau de particules chargées [CPB charged particle beam], p. ex. création des motifs d'un masque par un faisceau d'électrons
28.
Multi-beam writing using inclined exposure stripes
To irradiate a target with a beam of energetic electrically charged particles, the beam is formed and imaged onto a target, where it generates a pattern image composed of pixels. The pattern image is moved along a path on the target over a region of exposure, and this movement defines a number of stripes covering said region in sequential exposures and having respective widths. The number of stripes are written parallel to each other along a general direction, which is at a small angle to a principal pattern direction of structures to be written within the region of exposure.
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
29.
Multi-beam writing of pattern areas of relaxed critical dimension
To irradiate a target with a beam of energetic electrically charged particles, the beam is formed and imaged onto a target, where it generates a pattern image composed of pixels. For a pattern which comprises a primary pattern region to be written with a predetermined primary feature size and a secondary pattern region which is composed of structure features capable of being written with a secondary feature size, larger than the primary feature size. The structure features of the primary pattern region are written by exposing a plurality of exposure spots on grid positions of a first exposure grid; the structure features in the secondary pattern region are written by exposing a plurality of exposure spots on grid positions of a second exposure grid according to a second arrangement which is coarser that the regular arrangement of the first exposure grid.
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
To irradiate a target with a beam of energetic electrically charged particles, the beam is formed and imaged onto a target, where it generates a pattern image composed of pixels. The pattern image is moved along a path on the target over a region to be exposed, and this movement defines a number of stripes covering said region in sequential exposures and having respective widths. The number of stripes is written in at least two sweeps which each have a respective general direction, but the general direction is different for different sweeps, e.g. perpendicular to each other. Each stripe belongs to exactly one sweep and runs substantially parallel to the other stripes of the same sweep, namely, along the respective general direction. For each sweep the widths, as measured across said main direction, of the stripes of one sweep combine into a cover of the total width of the region.
H01J 37/20 - Moyens de support ou de mise en position de l'objet ou du matériauMoyens de réglage de diaphragmes ou de lentilles associées au support
G21K 5/04 - Dispositifs d'irradiation avec des moyens de formation du faisceau
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
31.
Correction of short-range dislocations in a multi-beam writer
Method for computing an exposure pattern for exposing a desired pattern on a target in a charged-particle lithography apparatus, in which a particle beam is directed to and illuminates a pattern definition device comprising an aperture array composed of a plurality of blanking apertures through which said particle beam penetrates for writing said desired pattern by exposing a multitude of pixels within an exposure area on the target, said method taking into account a spatially dependent distortion of the target within the exposure area, with respect to dislocations transversal to the direction of the particle beam.
G21K 5/04 - Dispositifs d'irradiation avec des moyens de formation du faisceau
G05B 19/402 - Commande numérique [CN], c.-à-d. machines fonctionnant automatiquement, en particulier machines-outils, p. ex. dans un milieu de fabrication industriel, afin d'effectuer un positionnement, un mouvement ou des actions coordonnées au moyen de données d'un programme sous forme numérique caractérisée par des dispositions de commande pour le positionnement, p. ex. centrage d'un outil par rapport à un trou dans la pièce à usiner, moyens de détection additionnels pour corriger la position
H01J 37/304 - Commande des tubes par une information en provenance des objets, p. ex. signaux de correction
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
32.
Customizing a particle-beam writer using a convolution kernel
An exposure pattern is computed which is used for exposing a desired pattern on a target in a charged-particle multi-beam processing apparatus so as to match a reference writing tool, possible of different type: The desired pattern is provided as a graphical representation suitable for the reference tool, such as a raster graphics, on the image area on the target. A convolution kernel is used which describes a mapping from an element of the graphical representation to a group of pixels which is centered around a nominal position of said element. A nominal exposure pattern is calculated by convolution of the graphical representation with the convolution kernel, said nominal exposure pattern being suitable to create a nominal dose distribution on the target when exposed with the processing apparatus.
H01J 3/14 - Dispositifs pour la focalisation ou la réflexion du rayon ou du faisceau
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
H01J 37/09 - DiaphragmesÉcrans associés aux dispositifs électronoptiques ou ionoptiquesCompensation des champs perturbateurs
H01J 37/04 - Dispositions des électrodes et organes associés en vue de produire ou de commander la décharge, p. ex. dispositif électronoptique, dispositif ionoptique
33.
Compensation of imaging deviations in a particle-beam writer using a convolution kernel
An exposure pattern is computed for exposing a desired pattern on a target in a charged-particle multi-beam processing apparatus to match a reference writing tool, and/or for compensating a deviation of the imaging from a pattern definition device onto the target from a desired value of critical dimension along at least one direction in the image area on the target: The desired pattern is provided as a graphical representation suitable for the reference tool, on the image area on the target. A convolution kernel is used which describes a mapping from an element of the graphical representation to a group of pixels which is centered around a nominal position of said element. A nominal exposure pattern is calculated by convolution of the graphical representation with the convolution kernel, said nominal exposure pattern being suitable to create a nominal dose distribution on the target when exposed with the processing apparatus.
G21K 5/04 - Dispositifs d'irradiation avec des moyens de formation du faisceau
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
H01J 37/09 - DiaphragmesÉcrans associés aux dispositifs électronoptiques ou ionoptiquesCompensation des champs perturbateurs
H01J 37/04 - Dispositions des électrodes et organes associés en vue de produire ou de commander la décharge, p. ex. dispositif électronoptique, dispositif ionoptique
34.
Compensation of dose inhomogeneity using overlapping exposure spots
An exposure pattern is computed which is used for exposing a desired pattern on a target by means of a particle beam and a blanking aperture array in a particle-optical lithography apparatus, taking into account a non-uniform current dose distribution as generated by the beam over the positions of the apertures of the blanking aperture array: From the desired pattern a nominal exposure pattern is calculated as a raster graphics comprising nominal dose values for the pixels of the raster graphics; based on a map of the current dose distribution, which correlates each aperture with a current factor describing the current dose of the beam at the location of the aperture, a compensated dose value is calculated for each pixel; and for each pixel, a discrete value is determined by selecting a value from a discrete gray scale so as to approximate the compensated dose value.
H01J 37/304 - Commande des tubes par une information en provenance des objets, p. ex. signaux de correction
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
In a charged-particle multi-beam processing apparatus for exposure of a target with a plurality of parallel particle-optical columns, each column has a beam shaping device forming the shape of the illuminating beam into a desired pattern composed of a multitude of sub-beams, by means of an aperture array device, which defines the shape of a respective sub-beam by means of an array of apertures, and a deflection array device selectively deflecting sub-beams off their nominal paths; thus, only the non-selected sub-beams can reach the target. According to many embodiments of the invention each beam shaping device is provided with a first field-boundary device and a second field-boundary device, which are the first and last plate elements traversed by the beam. One of the first and second field-boundary devices defines a field-free space interval so as to accommodate feeding lines for controlling the deflection array device.
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
H01J 37/09 - DiaphragmesÉcrans associés aux dispositifs électronoptiques ou ionoptiquesCompensation des champs perturbateurs
H01J 37/04 - Dispositions des électrodes et organes associés en vue de produire ou de commander la décharge, p. ex. dispositif électronoptique, dispositif ionoptique
H01J 37/147 - Dispositions pour diriger ou dévier la décharge le long d'une trajectoire déterminée
36.
Compensation of defective beamlets in a charged-particle multi-beam exposure tool
An exposure pattern is computed which is used for exposing a desired pattern on a target by means of a blanking aperture array in a particle-optical lithography apparatus which has a finite number of defects, said desired pattern being composed of a multitude of image elements within an image area on the target: A list of defective blanking apertures is provided, comprising information about the type of defect of the defective blanking apertures; from the desired pattern a nominal exposure pattern is calculated as a raster graphics over the image elements disregarding the defective blanking apertures; the “compromised” image elements (1105) are determined which are exposed by aperture images of defective blanking apertures; for each compromised element (1105), a set of neighboring image elements is selected as “correction elements” (1104); for each compromised element, corrected dose values are calculated for the correction elements, said corrected dose values minimizing an error functional of the deviation of the dose distribution including the defects from the nominal dose distribution, under the constraint that each of the corrected dose values falls within the allowed doses; and a corrected exposure pattern (1103) is generated by substituting the corrected dose values for the nominal dose values at the correction elements.
G21K 5/04 - Dispositifs d'irradiation avec des moyens de formation du faisceau
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
H01J 37/04 - Dispositions des électrodes et organes associés en vue de produire ou de commander la décharge, p. ex. dispositif électronoptique, dispositif ionoptique
To irradiate a target with a beam of energetic radiation formed by electrically charged particles, the beam is formed and imaged onto a target, where it generates a pattern image composed of pixels. The pattern image is moved along a path on the target over a region to be exposed, and this movement defines a number of stripes covering said region in sequential exposures and having respective widths. The number of stripes is written in at least two subsequent passes such that for each pass, the widths of the stripes of one pass combine into a cover of the total width of the region to be exposed; and each pass is associated with one of a number of partial grids of pattern pixels which are exposable during the respective pass. The mutually different partial grids combine to the complete plurality of pattern pixels which compose the region to be exposed.
H01J 37/302 - Commande des tubes par une information d'origine externe, p. ex. commande par programme
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
38.
Pattern definition device having multiple blanking arrays
A pattern definition (PD) device for use in a charged-particle multi-beam processing or inspection apparatus includes at least two deflection array devices positioned in a stacked arrangement. A particle beam (Ib) traversing the PD device is formed into a plurality of beamlets, which can be deflected or blanked by the two deflection array devices. Each deflection array device comprises a plurality of blanking openings allowing passage of beamlets, and a plurality of deflecting devices, each deflecting device being associated with a respective blanking opening and comprising an electrostatic electrode. The deflecting devices are selectively activatable and configured to influence, when activated, the beamlets traversing said respective blanking openings so as to deflect said beamlets off their nominal paths. Each deflection array device is configured to act on only respective subsets of beamlets by selectively deflecting them, while allowing the other beamlets to traverse the respective deflection array device without deflection.
H01J 37/04 - Dispositions des électrodes et organes associés en vue de produire ou de commander la décharge, p. ex. dispositif électronoptique, dispositif ionoptique
H01J 37/147 - Dispositions pour diriger ou dévier la décharge le long d'une trajectoire déterminée
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
39.
High-voltage insulation device for charged-particle optical apparatus
A high-voltage insulation device (300) for use in a charged-particle optical apparatus comprises a plurality of rigid pillars (320) made of electrically insulating material. These pillars (320) are arranged around a central passage (310) which traverses the insulating device along its longitudinal axis (L), and the two ends of each pillar are configured to be respectively fixed to two separate electrostatic housings (221, 231) of the charged-particle optical apparatus by means of two respective end plates (311, 312), with the pillars (320) being oriented at an angle so as to be inclined with regard to said longitudinal axis (L). Advantageously, the pillars are mechanically adjustable with regard to their effective length, and each pillar (320) is arranged outside the central passage with its two ends at either of the first and second end plates (311, 312), preferably in a zig-zag arrangement.
H01J 37/147 - Dispositions pour diriger ou dévier la décharge le long d'une trajectoire déterminée
H01J 37/02 - Tubes à décharge pourvus de moyens permettant l'introduction d'objets ou d'un matériau à exposer à la décharge, p. ex. pour y subir un examen ou un traitement Détails
H01J 37/04 - Dispositions des électrodes et organes associés en vue de produire ou de commander la décharge, p. ex. dispositif électronoptique, dispositif ionoptique
H01J 37/15 - Réglage mécanique externe de composants électronoptiques ou ionoptiques
H01J 37/317 - Tubes à faisceau électronique ou ionique destinés aux traitements localisés d'objets pour modifier les propriétés des objets ou pour leur appliquer des revêtements en couche mince, p. ex. implantation d'ions
B82Y 10/00 - Nanotechnologie pour le traitement, le stockage ou la transmission d’informations, p. ex. calcul quantique ou logique à un électron
B82Y 40/00 - Fabrication ou traitement des nanostructures
2), possibly a complementary subset with respect to a desired pattern, are not exposed; contrariwise, during the exposure of the corresponding overlap margin (m12), image pixels corresponding to image pixels in the first subset are not exposed, but those corresponding to image pixels in the second subset are.
A multi-beam pattern definition device (102) for use in a particle-beam processing or inspection apparatus is configured to be irradiated with a beam (lp,bp) of electrically charged particles so as to form a number of beamlets to be imaged to a target. An aperture array means (202) comprises at least two sets of apertures (221, 222) for defining respective beamlets (b1-b5), wherein the sets of apertures comprise a plurality of apertures arranged in interlacing arrangements and the apertures of different sets are offset to each other by a common displacement vector (d12). An opening array means (201) has a plurality of openings (210) configured for the passage of a subset of beamlets corresponding to one of the sets of apertures but lacking openings (being opaque to the beam) at locations corresponding to the other sets of apertures. A positioning means shifts the aperture array means relative to the opening array means in order to selectively bring one of the sets of apertures into alignment with the openings in the opening array means.
The invention relates to a multi-beam deflector array means for use in a particle-beam exposure apparatus employing a beam of charged particles, said multi-beam deflector array means having an overall plate-like shape with a membrane region and a buried CMOS-layer, said membrane region comprising a first side facing towards the incoming beam of particles and a second side opposite to the first side, an array of apertures, each aperture allowing passage of a corresponding beam element formed out of said beam of particles, and an array of electrodes, each aperture being associated with at least one of said electrodes and the electrodes being controlled via said CMOS layer, wherein the electrodes are pillared, standing proud of the main body of the multi-beam deflector array means, the electrodes being connected to one side of the main body of the multi-beam deflector array means by means of bonding connections.
For maskless irradiating a target with a beam of energetic electrically charged particles using a pattern definition means with a plurality of apertures and imaging the apertures in the pattern definition means onto a target which moves (v) relative to the pattern definition means laterally to the axis, the location of the image is moved along with the target, for a pixel exposure period within which a distance of relative movement of the target is covered which is at least a multiple of the width (w) of the aperture images as measured on the target, and after said pixel exposure period the location of the beam image is changed, which change of location generally compensates the overall movement of the location of the beam image.
In a particle multi-beam structuring apparatus for forming a pattern on a target's surface using a beam of electrically charged particles, during exposure steps the particle beam is produced, directed through a pattern definition means producing a patterned particle beam composed of multiple beamlets, and projected by an optical column including a controllable deflection means onto the target surface to form, at a nominal location on the target, a beam image comprising the image of defining structures in the pattern definition means. The beam image's nominal location relative to the target is changed between exposure steps. The actual location of the beam image is varied within each exposure step around the nominal location, through a set of locations realizing a distribution of locations within the image plane around a mean location coinciding with the nominal location, thus introducing an additional blur which is homogenous over the entire beam image.
The disclosure relates to a method for producing a multi-beam deflector array device with a plurality of openings for use in a particle-beam exposure apparatus, in particular a projection lithography system, said method starting from a CMOS wafer and comprising the steps of generating at least one pair of parallel trenches on the first side of the wafer blank at the edges of an area where the circuitry layer below is non-functional, the trenches reaching into the layer of bulk material; passivating the sidewalls and bottom of the trenches; depositing a conducting filling material into the trenches, thus creating columns of filling material serving as electrodes; attaching metallic contact means to the top of the electrodes; structuring of an opening between the electrodes, said opening stretching across abovementioned area so that the columns are arranged opposite of each other on the sidewalls of the opening.
In a maskless particle multibeam processing apparatus, a particle beam is projected through a pattern definition system producing a regular array of beamlets according to a desired pattern, which is projected onto a target which moves at continuous speed along a scanning direction with respect to the pattern definition system. During a sequence of uniformly timed exposure steps the beam image is moved along with the target along the scanning direction, and between exposure steps the location of the beam image is changed with respect to the target. During each exposure step the target covers a distance greater than the mutual distance of neighboring image elements on the target. The location of the beam image at consecutive exposure steps corresponds to a sequence of interlacing placement grids, and after each exposure step the beam image is shifted to a position associated with a different placement grid, with a change of location generally including a component across the scanning direction, thus cycling through the set of placement grids.
The invention relates to a method for forming a pattern on a substrate surface of a target by means of a beam of electrically charged particles in a number of exposure steps, where the beam is split into a patterned beam and there is a relative motion between the substrate and the pattern definition means. This results in an effective overall motion of the patterned particle beam over the substrate surface and exposition of image elements on the substrate surface in each exposure step, wherein the image elements on the target are exposed to the beamlets multiply, namely several times during a number of exposure steps according to a specific sequence. The sequence of exposure steps of the image elements is arranged in a non-linear manner according to a specific rule from one exposure step to the subsequent exposure step in order to reduce the current variations in the optical column of the multi-beam exposure apparatus during the exposure of the pattern.
G03F 9/00 - Mise en registre ou positionnement d'originaux, de masques, de trames, de feuilles photographiques, de surfaces texturées, p. ex. automatique
G03C 5/00 - Procédés photographiques ou agents à cet effetRégénération de tels agents de traitement
48.
Compensation of dose inhomogeneity and image distortion
An improved aperture arrangement in a device for defining a pattern on a target, for use in a particle-beam exposure apparatus, by being irradiated with a beam of electrically charged particles and allowing passage of the beam only through a plurality of apertures. The device includes an aperture array having a plurality of apertures of identical shape defining the shape and relative position of beamlets permeating the apertures. A blanking device switches off the passage of selected beamlets permeating the apertures and defined by them. The apertures are arranged on the aperture array according to an arrangement deviating from a regular arrangement by small deviations, adjusting for distortions caused by the particle-beam exposure apparatus, and the size of the apertures of the aperture array differs across the aperture array in order to allow for an adjustment of the current radiated on the target through the apertures and the corresponding openings.
In a charged-particle exposure apparatus for exposure of a target with a beam of electrically charged particles, the illumination system includes a deflector device adapted to vary the direction of incidence of the illuminating beam upon the pattern definition device, the pattern definition device forms the shape of the illuminating beam into a desired pattern, and the projection optics system projects an image of the beam shape defined in the pattern definition device onto the target; the projection optics system includes a blocking aperture device having an opening and being adapted to block passage of beams traversing outside the opening, namely when the deflector device is activated to tilt the beamlet by a sufficient angle from its non-deflected path, e.g., for blanking out during the process of loading a pattern into the pattern definition device.
In a pattern-lock system of particle-beam apparatus wherein the imaging of the pattern is done by means of at least two consecutive projector stages of the projecting system, reference marks are imaged upon registering means to determine the position of the particle-beam, at the location of an intermediary image of the reference marks produced by a non-final projector stage, with the registering means being positioned at locations of nominal positions of an intermediary imaging plane. Furthermore, to produce a scanning movement over the registering means the reference beamlets are shifted laterally by means of deflector means provided in the pattern defining means in dependence of a time-dependent electric voltage.
A multi-beam source for generating a plurality of beamlets of energetic electrically charged particles. The multi-beam source includes an illumination system generating an illuminating beam of charged particles and a beam-forming system being arranged after the illumination system as seen in the direction of the beam, adapted to form a plurality of telecentric or homocentric beamlets out of the illuminating beam. The beam forming system includes a beam-splitter and an electrical zone device, the electrical zone having a composite electrode composed of a plurality of substantially planar partial electrodes, adapted to be applied different electrostatic potentials and thus influencing the beamlets.
A multi-beam pattern definition device for use in a particle-beam processing or inspection apparatus, which is set up to be irradiated with a beam of electrically charged particles and allow passage of the beam through a plurality of apertures thus forming beamlets, which are imaged onto a target. A deflection array has a plurality of electrostatic deflector electrodes for each beamlet. Each deflector electrode can be applied an electrostatic potential individually. Counter electrodes are electrically connected to a counter potential independently of the deflection array through a counter-electrode array. The counter potentials may be a common ground potential or individual potentials in order to improve system reliability. In conjunction with an associated counter electrode, each deflector electrode deflects its beamlet sufficiently to deflect the beamlet off its nominal path when applied an activating voltage against the respective counter electrode.
A particle-beam projection processing apparatus for irradiating a target, with an illumination system for forming a wide-area illuminating beam of energetic electrically charged particles; a pattern definition means for positioning an aperture pattern in the path of the illuminating beam; and a projection system for projecting the beam thus patterned onto a target to be positioned after the projection system. A foil located across the path of the patterned beam is positioned between the pattern definition means and the position of the target at a location close to an image of the aperture pattern formed by the projection system.
For maskless irradiating a target with a beam of energetic electrically charged particles using a pattern definition means with a plurality of apertures and imaging the apertures in the pattern definition means onto a target which moves (v) relative to the pattern definition means laterally to the axis, the location of the image is moved along with the target, for a pixel exposure period within which a distance of relative movement of the target is covered which is at least a multiple of the width (w) of the aperture images as measured on the target, and after said pixel exposure period the location of the beam image is changed, which change of location generally compensates the overall movement of the location of the beam image.
In a particle-beam projection processing apparatus for irradiating a target by a beam of energetic electrically charged particles, including an illumination system, a pattern definition system for positioning an aperture arrangement composed of apertures transparent to the energetic particles in the path of the illuminating beam, and a projection system to project the beam onto a target, there is provided at least one plate electrode device, which has openings corresponding to the apertures of the pattern definition system and including a composite electrode composed of a number of partial electrodes being arranged non-overlapping and adjoining to each other, the total lateral dimensions of the composite electrode covering the aperture arrangement of the pattern definition system. The partial electrodes can be applied different electrostatic potentials.
The invention relates to a multi-beam deflector array device for use in a particle-beam exposure apparatus employing a beam of charged particles, the multi-beam deflector array device having a plate-like shape with a membrane region, the membrane region including a first side facing towards the incoming beam of particles, an array of apertures, each aperture allowing passage of a corresponding beamlet formed out of the beam of particles, a plurality of depressions, each depression being associated with at least one aperture, and an array of electrodes, each aperture being associated with at least one electrode and each electrode being located in a depression, the electrodes being configured to realize a non-deflecting state, wherein the particles that pass through the apertures are allowed to travel along a desired path, and a deflecting state, wherein the particles are deflected off the desired path.
In a particle-beam apparatus for irradiating a target, a pattern defined in a pattern definer is projected onto the target through a projection system by a beam of energetic electrically charged particles of, largely, a species of a nominal mass having a nominal kinetic energy. To generate the beam, a particle source, a velocity-dependent deflector and an illumination optics system are provided. The velocity-dependent deflector includes a transversal dipole electrical field and/or a transversal dipole magnetic field, which act upon the particles so as to causing a deviation of the path of the particles with regard to the paths of the nominal species which is dependent on the velocity of the particles. A delimiter is provided as a component of the pattern definer or, preferably, the projection system, serving to remove particles whose paths are deviating from the nominal path.
G21K 1/08 - Déviation, concentration ou focalisation du faisceau par des moyens électriques ou magnétiques
G01N 23/00 - Recherche ou analyse des matériaux par l'utilisation de rayonnement [ondes ou particules], p. ex. rayons X ou neutrons, non couvertes par les groupes , ou
In a particle-beam projection processing apparatus a target (41) is irradiated by means of a beam (pb) of energetic electrically charged particles, using a projection system (103) to image a pattern presented in a pattern definition means (102) onto the target (41) held at position by means of a target stage; no elements—other than the target itself—obstruct the path of the beam after the optical elements of the projection system. In order to reduce contaminations from the target space into the projection system, a protective diaphragm (15) is provided between the projection system and the target stage, having a central aperture surrounding the path of the patterned beam, wherein at least the portions of the diaphragm defining the central aperture are located within a field-free space after the projection system (103).
In a pattern definition device for use in a particle-beam processing apparatus a plurality of apertures (21) are arranged within a pattern definition field (pf) wherein the positions of the apertures (21) in the pattern definition field (pf) taken with respect to a direction (X, Y) perpendicular, or parallel, to the scanning direction are offset to each other by not only multiple integers of the effective width (w) of an aperture taken along said direction, but also multiple integers of an integer fraction of said effective width. The pattern definition field (pf) may be segmented into several domains (D) composed of a many staggered lines (pl) of apertures; along the direction perpendicular to the scanning direction, the apertures of a domain are offset to each other by multiple integers of the effective width (w), whereas the offsets of apertures of different domains are integer fractions of that width.
For compensation of a magnetic field in an operating region a number of magnetic field sensors (S1, S2) and an arrangement of compensation coils (Hh) surrounding said operating region is used. The magnetic field is measured by at least two sensors (S1, S2) located at different positions outside the operating region, preferably at opposing positions with respect to a symmetry axis of the operating region, generating respective sensor signals (s1, s2), the sensor signals of said sensors are superposed to a feedback signal (ms, fs), which is converted by a controlling means to a driving signal (d1), and the driving signal is used to steer at least one compensation coil (Hh). To further enhance the compensation, the driving signal is also used to derive an additional input signal (cs) for the superposing step to generate the feedback signal (fs).
