CHEMICAL VAPOR DEPOSITION METHOD AND APPARATUS
A method of forming a filament assembly of a chemical vapor deposition (CVD) reactor, comprising at least one filament structure connected by a bridge, is disclosed. The filament structure comprises a hollow silicon filament integral with a silicon seed. Various embodiments of this invention are described, along with a CVD system comprising this filament assembly as well as a method of depositing silicon onto this filament assembly.
1 . A method of forming a filament assembly of a chemical vapor deposition system, comprising the steps of:
i) providing an electrically conductive bridge comprising at least one filament contact;
ii) providing a silicon seed having a first end comprising a protrusion configured to grow a hollow silicon filament thereon and a second end configured to mate with the filament contact of the bridge;
iii) contacting the protrusion on the first end of the silicon seed with molten silicon in a shaping dye of a crystal growth apparatus, the protrusion of the silicon seed and the shaping dye having substantially similar cross-sectional shapes;
iv) forming a filament structure comprising the hollow silicon filament on the first end of the silicon seed; and
v) connecting the filament structure to the electrically conductive bridge by mating the second end of the silicon seed with the filament contact of the bridge.
2 . The method of claim 1 , wherein the method further comprises the steps of providing a second silicon seed having a first end comprising a protrusion configured to grow a second hollow silicon filament thereon and a second end configured to mate with a second filament contact of the bridge; contacting the protrusion on the first end of the second silicon seed with molten silicon in a shaping dye of a crystal growth apparatus, the protrusion second silicon seed and the shaping dye having substantially similar cross-sectional shapes; forming a second filament structure comprising the second hollow silicon filament on the second silicon seed; and connecting the second filament structure to the electrically conductive bridge by mating the second surface of the second silicon seed with the second filament contact of the bridge.
3 . The method of claim 1 , wherein the bridge is a silicon bridge.
4 . The method of claim 1 , wherein the filament contact is a hole through the bridge.
5 . The method of claim 4 , wherein the second end of the silicon seed fits through the hole, electrically connecting the filament structure to the bridge.
6 . The method of claim 5 , wherein the second end of the silicon seed is tapered, having a decreasing width in a direction away from the hollow silicon filament.
7 . The method of claim 6 , wherein the second end is frustoconical.
8 . The method of claim 1 , wherein the second end of the silicon seed is configured to lock onto the filament contact of the bridge.
9 . The method of claim 8 , wherein the filament contact and the second end of the silicon seed comprise mating screw threads.
10 . The method of claim 1 , wherein the hollow silicon filament is cylindrical.
11 . The method of claim 10 , wherein the cross-sectional shapes of the shaping dye and the protrusion are substantially circular.
12 . The method of claim 1 , wherein the protrusion is a raised lip around a perimeter of the first end of the silicon seed.
13 . The method of claim 1 , wherein the second end of the silicon seed further comprises a vent hole.
14 . The method of claim 1 , wherein the hollow silicon filament is integral with the silicon seed.
15 . The method of claim 1 , wherein the crystal growth apparatus is an EFG crystal growth apparatus.
16 . A chemical vapor deposition system comprising at least one filament assembly having a pair of vertical filament structures electrically connected by a horizontal electrically conductive bridge, the bridge comprising a pair of filament contacts and the filament structures comprising a hollow silicon filament on a silicon seed,
wherein the silicon seed has a first end comprising a protrusion configured to grow the hollow silicon filament thereon and a second end configured to mate with the filament contacts of the bridge;
17 . The chemical vapor deposition system of claim 16 , wherein the hollow silicon filaments are integral with the silicon seeds.
18 . A method of depositing silicon onto a filament assembly in a chemical vapor deposition system comprising the steps of introducing gaseous silicon precursor reagents into the chemical vapor deposition system and promoting conversion of the gaseous silicon precursors reagents to silicon on the filament assembly, wherein the filament assembly is formed by a method comprising the steps of:
i) providing an electrically conductive bridge comprising at least one filament contact;
ii) providing a silicon seed having a first end comprising a protrusion configured to grow a hollow silicon filament thereon and a second end configured to mate with the filament contact of the bridge;
iii) contacting the protrusion on the first end of the silicon seed with molten silicon in a shaping dye of a crystal growth apparatus, the protrusion of the silicon seed and the shaping dye having substantially similar cross-sectional shapes;
iv) forming a filament structure comprising the hollow silicon filament on the first end of the silicon seed; and
v) connecting the filament structure to the electrically conductive bridge by mating the second end of the silicon seed with the filament contact of the bridge.