Abstract

Doped silicon particles, including powder suitable for plasma spraying semiconductor devices, is formed by liquid doping applied to larger particles, which are then milled to a smaller size. Doped or undoped silicon may be milled by a roller mill including silicon rollers (12, 14) and advantageously having feed (70) and collection (92) systems formed of silicon and operated in a nitrogen ambient (100). A two-stage system includes sieving the rolled product for further size reduction in a jet mill.

IPC Classes  ?

• H01L 31/18 - Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
• H01L 31/042 - PV modules or arrays of single PV cells
• H01J 7/24 - Cooling arrangementsHeating arrangementsMeans for circulating gas or vapour within the discharge space

Abstract

A hybrid nozzle (50) for use in a plasma spray gun (8), especially for plasma spraying silicon to form semiconductor devices such as solar cell. The outlet of the gun includes a two-piece annular electrode against which the plasma is ignited and through which the plasma plume exits the gun together with entrained silicon. In one embodiment, the upstream part (16) is composed of graphite to allow ignition of the plasma and the downstream part (52) is composed of pure silicon. In another aspect, the silicon feedstock is injected into the plasma plume through ports (56) formed through the silicon part.

IPC Classes  ?

• B05B 7/22 - Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating the material to be sprayed electrically, e.g. by arc
• B05B 5/06 - Electrostatic spraying apparatusSpraying apparatus with means for charging the spray electricallyApparatus for spraying liquids or other fluent materials by other electric means using electric arc