Silicon gas injector and method of making
A gas injector tube usable in a batch thermal treatment oven including two silicon shells joined together with an adhesive formed of a fine silicon powder and a curable silica-forming agent, such as a spin-on glass, which is ultrasonically homogenized. The tube may have a gas outlet on its distal end or be sealed with a silicon cap and have side outlet holes formed along its side. The silicon injector tube may be used in combination with a silicon tower and a silicon liner so that all bulk parts within the furnace hot zone are formed of silicon.
1 . A silicon gas injector comprising an injector tube formed of two shells comprising substantially pure silicon bonded together with an adhesive formed of silicon powder and a silica-forming agent and forming a first central bore therebetween.
2 . The injector of claim 1 , further comprising a second silicon tube assembly bonded to the two shells with an adhesive formed of silicon powder and a silica-form agent and including a supply tube extending perpendicularly to the injector tube and including a second central bore communicating with the first central bore.
3 . The injector of claim 1 , wherein the silicon powder has a size distribution with 99% of all particles having diameters of less than 75 μm.
4 . The injector of claim 3 , wherein size distribution has 99% of all the particles having diameters of less than 10 μm
5 . The injector of claim 4 , wherein the size distribution has 99% of all the particles having diameters of less than 100 nm.
6 . The injector of claim 2 , wherein the second silicon tube assembly includes the supply tube and an elbow formed as an integral unit.
7 . The injector of claim 1 , wherein the two shells are formed of virgin polysilicon.
8 . The injector of claim 1 , wherein the two shells comprise mating tongues and grooves at interfaces therebetween.
9 . The injector of claim 1 , wherein the two shells comprises mating steps at interfaces therebetween.
10 . The injector of claim 1 , wherein the two shells comprise mating stepped surfaces at interfaces therebetween.
11 . The injector of claim 1 , further comprising a cap sealed to an end of the bonded shells and further comprising at least one holes formed in an axially extending side of one of the shells and extending to a bore of the tube.
12 . The injector of claim 11 , wherein there are a plurality of the holes axially spaced along the axially extending side.
13 . The injector of claim 12 , wherein diameters of the holes or spacings between at least three of the holes varies along the axially extending side.
14 . A method of assembling a gas injector, comprising the steps of:
providing two shells comprising substantially pure silicon and forming an axial bore therebetween when assembled together;
applying an adhesive comprising silicon powder and a curable silica-forming agent to at least some mating faces of the two shells;
assembling the two shells by juxtaposing respective mating faces of the two shells; and
annealing the assembled shells at a temperature of at a temperature sufficient to glassify adhesive.
15 . The method of claim 14 , wherein the temperature is least 400° C.
16 . The method of claim 15 , wherein the temperature is between 850 and 1000° C.
17 . The method of claim 14 , wherein the providing step includes:
machining the shells from at least one annealed virgin polysilicon member.
18 . The method of claim 14 , further comprising applying a powder-free wetting agent to at least some of the mating faces prior to applying the adhesive.
19 . The method of claim 18 , wherein the wetting agent comprises a curable silica-forming agent.
20 . The method of claim 14 , further comprising:
mixture the silica-forming agent and the silicon powder into a mixture; and
ultrasonically agitating the mixture to form the adhesive.
21 . A method of bonding together two silicon parts, comprising the steps of:
mixing together silicon powder and a silica-forming agent;
ultrasonically agitating the mixture;
applying the agitated mixture to at least one of two mating surface of two respective silicon members; and
joining the silicon members along the two mating surfaces with the agitated mixture therebetween.
22 . The method of claim 21 , further comprising annealing the joined silicon members to thereby cure the silica-forming agent.
23 . A method of thermally treating silicon wafers, comprising:
supporting silicon production wafers on a silicon tower;
disposing the silicon tower and the wafers supported thereupon in a furnace including a silicon liner surrounding the tower; and
flowing a process gas through at least one silicon injector having an outlet disposed between the tower and the liner to treat the production wafers in a hot zone of the furnace within the liner;
wherein all bulk portions of the tower, the liner, and the injector disposed within the hot zone are substantially free of material other than silicon and excluding any lead-based adhesive for the injector.
24 . The method of claim 23 , wherein the injector comprises a tube formed of two substantially pure silicon shells bonded together with an adhesive formed of silicon powder and a silica-forming agent and forming a central axial bore therebetween.