US5830538A
Expired / Lapsed
US
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Method to form a polycrystalline film on a substrate
Assignee: Videocon Global Ltd
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Filing: 1996-05-02
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Granted: 1998-11-03
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Expires: 2016-05-02
Abstract
Abstract A semiconductor processing method is provided for growing a polycrystalline film by preferably chemical vapor deposition (CVD) from a suitable precursor gas or gases on a substrate which has been coated with seeds, preferably of nanocrystal size, of the semiconductor material. The structure of the nanocrystal seeds (not the substrate) serves as a template for the structure of the final polycrystalline film. The density of the seeds and the thickness of the grown polycrystalline film determine the grain size of the polycrystalline film at the surface of said film. Epitaxial CVD onto the seeds to produce the polycrystalline film avoids the recrystallization step generally necessary for the formation of a polycrystalline film, and thus allows for the growth of polycrystalline films at reduced temperatures.
Inventors
- 👤 Stephen McConnell Gates
- 👤 James Richard Heath
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 08:54
CPC Classifications
C; C23; C23C; C23C16/00; C23C16/22; C23C16/30; C23C16/32; C23C16/325; C23C16/02; C23C16/0272; C23C16/24; C30; C30B; C30B25/00; C30B25/02; C30B25/18
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
196 words
A method comprising the steps of: providing a substrate; said substrate having a surface; placing said substrate in a chamber having a first atmosphere and having an input part and an output part; said substrate being unheated; introducing at said input part a combination of a precursor gas and a buffer gas; exposing said combination to an energy to dissociate said precursor gas to nanocrystals of seeds containing particles of a first material, said nanocrystals being suspended in a second atmosphere; causing said nanocrystals to flow in a flow direction from said input port to said output port; said substrate being disposed substantially parallel to said flow direction so that said nanocrystal seeds are transported over said surface of said substrate; a fraction of said nanocrystal seeds being falled out from said second atmosphere onto said surface as said second atmosphere passes over said surface to form a seeded surface; exposing said surface to said second atmosphere containing a second material raising on said surface to an elevated temperature less than about 580° C. to grow crystallites of said second material on said seeds to form a polycrystalline layer of said second material on said surface.
Claim 2
Independent Claim
196 words
A method comprising the steps of: providing a substrate; said substrate having a surface; placing said substrate in a chamber having a first atmosphere and having an input part and an output part; said substrate being unheated; introducing at said input part a combination of a precursor gas and a buffer gas; exposing said combination to an energy to dissociate said precursor gas to nanocrystals of seeds containing particles of a first material, said nanocrystals being suspended in a second atmosphere; causing said nanocrystals to flow in a flow direction from said input port to said output port; said substrate being disposed substantially parallel to said flow direction so that said nanocrystal seeds are transported over said surface of said substrate; a fraction of said nanocrystal seeds being falled out from said second atmosphere onto said surface as said second atmosphere passes over said surface to form a seeded surface; exposing said surface to said second atmosphere containing a second material raising on said surface to an elevated temperature less than about 580° C. to grow crystallites of said second material on said seeds to form a polycrystalline layer of said second material on said surface.
Claim 3
Dependent Claim
46 words
A method according to claim 1 wherein said step of providing on said surface said crystalline seeds comprises: exposing said surface to a second atmosphere containing constituents of said crystalline seeds; and exposing said atmosphere to an energy to transform said constituents into said crystalline seeds.
Claim 4
Dependent Claim
43 words
A method according to claim 1 wherein said substrate has a substrate melting and/or softening temperature, and wherein there is a temperature suitable for epitaxial CVD on the seeds, and said epitaxial CVD temperature is less than said substrate melting and/or softening temperature.
Claim 5
Dependent Claim
23 words
A method according to claim 2 wherein step of exposing said atmosphere to an energy comprises exposing said atmosphere to an electromagnetic beam.
Claim 6
Dependent Claim
22 words
A method according to claim 2 wherein step of exposing said atmosphere to an energy comprises exposing said atmosphere to thermal energy.
Claim 7
Dependent Claim
14 words
A method according to claim 4 wherein said electromagnetic beam is a light beam.
Claim 8
Dependent Claim
15 words
A method according to claim 4 wherein said electromagnetic beam is a radio-frequency plasma source.
Claim 9
Dependent Claim
15 words
A method according to claim 1 wherein said seeds are formed from a precursor material.
Claim 10
Dependent Claim
25 words
A method according to claim 8 wherein said precursor material is selected from the group consisting of silanes, germanes and a combination thereof with hydrocarbons.
Claim 11
Dependent Claim
22 words
A method according to claim 2 wherein said second material is selected from the group consisting of silicon, germanium and silicon carbide.
Claim 12
Dependent Claim
21 words
A method according to claim 4 wherein said step of exposing said atmosphere to an energy is done at ambient temperature.
Claim 13
Dependent Claim
13 words
A method according to claim 4 wherein said second atmosphere is photolytically active.
Claim 14
Dependent Claim
18 words
A method according to claim 4 wherein said second atmosphere is activated in an RF or microwave plasma.
Claim 15
Dependent Claim
13 words
A method according to claim 5 wherein said second atmosphere is pyrolytically active.
Claim 16
Dependent Claim
19 words
A method according to claim 6 wherein said seeds are crystallized by irradiating said second atmosphere with photolysis-activation radiation.
Claim 17
Dependent Claim
14 words
A method according to claim 5 wherein said seeds are crystallized by thermal energy.
Claim 18
Dependent Claim
16 words
A method according to claim 7 wherein said seeds are crystallized by exposure to a plasma.
Claim 19
Dependent Claim
12 words
A method according to claim 2 wherein said seeds are single crystalline.
Claim 20
Dependent Claim
22 words
A method according to claim 1 wherein said seeds have dimensions in a range of from about 2 to about 30 nanometers.
Claim 21
Dependent Claim
26 words
A method according to claim 1 wherein coverage of said seeds on said surface is in a range of from about 0.01 to about 1 monolayer.
Claim 22
Dependent Claim
16 words
A method according to claim 1 wherein said first atmosphere is a chemical vapor deposition atmosphere.
Claim 23
Dependent Claim
23 words
A method according to claim 21 wherein said first atmosphere epitaxially deposits said second material on said seeds to form said polycrystalline layer.
Claim 24
Dependent Claim
27 words
A method according to claim 20 wherein said polycrystalline layer has grains having an average grain size, which has substantially an inverse relationship to said average coverage.
Claim 25
Dependent Claim
19 words
A method according to claim 1 wherein said seeds grow together as said material to form said polycrystalline layer.
Claim 26
Dependent Claim
17 words
A method according to claim 1, wherein said first material is the same as the second material.
Claim 27
Dependent Claim
19 words
A method according to claim 1, wherein said first material has a similar crystalline lattice to the second material.
Claim 28
Dependent Claim
13 words
A method according to claim 23, wherein said inverse relationship is approximately linear.
Claim 29
Dependent Claim
20 words
A method according to claim 8 wherein said precursor material is a germane and said seeds are of germanium seeds.
Claim 30
Dependent Claim
22 words
A method according to claim 8 wherein said precursor material is a silane hydrocarbon mixture and said seeds are silicon carbide seeds.
Claim 31
Dependent Claim
19 words
A method according to claim 8 wherein said precursor material is a silane and said seeds are silicon seeds.
Claim 32
Dependent Claim
12 words
A method according to claim 1, wherein said substrate is a glass.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-11-02 | 2002-05-04 | 2002-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-02 | 2006-05-04 | 2006-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-02 | 2010-05-04 | 2010-11-03 | $7700.00 | Window Closed / Lapsed |