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US 5,294,286 AGranted
Process for forming a thin film of silicon
AssigneesResearch Development Corporation of Japan, Junichi Nishizawa, Oki Electric Industry Co., Ltd., Soubei Suzuki
InventorsJunichi Nishizawa, Hitoshi Abe, Soubei Suzuki
Life of this patent
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Abstract
The thickness of a thin film of an element semiconductor may be determined by counting the number of cycles of gaseous component introductions within a crystal growth vessel. Each cycle permits at most one monolayer of growth since the pressure in the vessel during gaseous component introduction is maintained under a saturation condition. The temperature to which a substrate in the vessel is heated is that for which epitaxial growth results.
Claims34
A process for forming a monocrystalline thin film of silicon on a silicon substrate located in a crystal growth vessel, comprising the steps of:
- (a) evacuating the interior of the crystal growth vessel to an evacuation pressure;
- (b) heating the substrate to, and maintaining the substrate at, a temperature within a range of from about 700 to 900 degrees C;
- (c) introducing a first supply of gaseous molecules of SiH.sub.2 Cl.sub.2 onto the substrate disposed in the growth vessel for a first period of time of from about 0.5 to 200 seconds while maintaining the internal pressure of the growth vessel under a saturation condition within the range of from about 3.times.10.sup.-3 to 10.sup.-1 Pascal to form a single molecular ad-layer of a second compound dissociated from the gaseous molecules of SiH.sub.2 Cl.sub.2 on the substrate, said second compound containing silicon;
- (d) evacuating the interior of said crystal growth vessel to remove molecules other than those which form said single molecular ad-layer;
- (e) introducing a second supply of gaseous molecules reactable with said single molecular ad-layer for a second time period of from about 0.5 to 200 seconds, while maintaining the internal pressure of the growth vessel under the saturation condition within the range of from about 3.times.10.sup.-3 to 10.sup.-1 Pascal so as to chemically react with said single molecular ad-layer to form gaseous molecules of a reactant compound;
- (f) evacuating said growth vessel to remove the gaseous molecules of said second supply and said reactant compound so as to leave a monocrystalline thin film with the thickness of a single molecular layer of silicon;
- (g) cyclically repeating the sequence of steps (c) to (f) and maintaining the substrate at said temperature to grow the monocrystalline thin film of silicon on the substrate to a desired thickness which is dimensionally as precise as that for a single molecular layer, the desired thickness being attained by cycling the sequence of steps (c) to (f) by a plurality of times equivalent to an integral result of a division of the desired thickness of the monocrystalline thin film of silicon by a thickness of the single molecular monolayer of silicon;
- and
- (h) continuously evacuating the crystal growth chamber during steps (c) to (g) at a substantially constant rate of evacuation, the gaseous molecules being introduced during steps (c) and (e) including a respective amount which is in excess of that necessary for forming just the single molecular layer of silicon during each cycle even taking into account a removal rate of the gaseous molecules caused by the evacuation taking place during steps (c) and (e).
6 more elements
A process for forming a monocrystalline thin film of silicon on a silicon substrate located in a crystal growth vessel, comprising the steps of:
- (a) evacuating the interior of the crystal growth vessel to an evacuation pressure;
- (b) heating the substrate to, and maintaining the substrate at, a temperature within a range of from about 700 to 900 degrees C;
- (c) introducing a first supply of gaseous molecules of SiH.sub.2 Cl.sub.2 onto the substrate disposed in the growth vessel for a first period of time of from 0.5 to 200 seconds while maintaining the internal pressure of the growth vessel under a saturation condition within the range of from about 10.sup.-1 to 1 Pascal to form a multiple molecular ad-layer of a second compound dissociated from the gaseous molecules of SiH.sub.2 Cl.sub.2 on the substrate, said second compound containing silicon;
- (d) evacuating the interior of said crystal growth vessel to remove molecules other than those which form said multiple molecular ad-layer;
- (e) introducing a second supply of gaseous molecules reactable with said multiple molecular ad-layer for a second time period of from about 0.5 to 200 seconds, while maintaining the internal pressure of the growth vessel under the saturation condition within the range of from about 10.sup.-1 to 1 Pascal so as to chemically react with said multiple molecular ad-layer to form gaseous molecules of a reactant compound;
- (f) evacuating said growth vessel to remove the gaseous molecules of said second supply and said reactant compound so as to leave a monocrystalline thin film with the thickness of a multiple molecular layer of silicon;
- (g) cyclically repeating the sequence of steps (c) to (f) and maintaining the substrate at said temperature to grow the monocrystalline thin film of silicon on the substrate to a desired thickness which is dimensionally as precise as that for a multiple molecular layer, the desired thickness being attained by cycling the sequence of steps (c) to (f) by a plurality of times equivalent to an integral result of a division of the desired thickness of the monocrystalline thin film of silicon by a thickness of the multiple molecular monolayer of silicon;
- and
- (h) continuously evacuating the crystal growth chamber during steps (c) to (g) at a substantially constant rate of evacuation, the gaseous molecules being introduced during steps (c) and (e) including a respective amount which is in excess of that necessary for forming just the multiple molecular layer of silicon during each cycle even taking into account a removal rate of the gaseous molecules caused by the evacuation taking place during steps (c) and (e).
6 more elements
Dependencies are inferred from the claim text.