Patent US6143629A successfully refreshed from Google Patents.
US6143629A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing semiconductor substrate
Assignee: Canon Inc
•
Filing: 1999-09-03
•
Granted: 2000-11-07
•
Expires: 2019-09-03
Abstract
Abstract In a process for producing a semiconductor substrate, comprising sealing surface pores of a porous silicon layer and thereafter forming a single-crystal layer on the porous silicon layer by epitaxial growth, intermediate heat treatment is carried out after the sealing and before the epitaxial growth and at a temperature higher than the temperature at the time of the sealing. This process improves crystal quality of the semiconductor substrate having the single-crystal layer formed by epitaxial growth and improves smoothness at the bonding interface when applied to bonded wafers this process enables the detection of the smaller particles on the surface by a laser light scattering method.
Inventors
- 👤 Nobuhiko Sato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:46
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/20; H10P90/00; H10P90/19; H10P90/1904; H10P90/1906; H10P90/1912; H10P14/24; H10P14/29; H10P14/2901; H10P14/2902; H10P14/2905; H10P14/32; H10P14/3202; H10P14/3204; H10P14/3211; H10P14/3242; H10P14/3256; H10P14/34; H10P14/3402; H10P14/3404; H10P14/3411; H10P14/36; H10P14/3602; H10W; H10W10/00; H10W10/10; H10W10/181; H10P50/00; H10P50/60; H10P50/61; H10P50/613
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
74 words
A process for producing a semiconductor substrate having a non-porous single-crystal layer on a surface of a porous silicon layer comprising, in the listed order, the steps of: sealing surface pores of the porous silicon layer to lower its surface pore density; heat treating the porous silicon layer at a temperature higher than the temperature in the sealing step; and epitaxially growing the non-porous single-crystal layer on the surface of the porous silicon layer.
Claim 2
Dependent Claim
74 words
A process for producing a semiconductor substrate having a non-porous single-crystal layer on a surface of a porous silicon layer comprising, in the listed order, the steps of: sealing surface pores of the porous silicon layer to lower its surface pore density; heat treating the porous silicon layer at a temperature higher than the temperature in the sealing step; and epitaxially growing the non-porous single-crystal layer on the surface of the porous silicon layer.
Claim 3
Dependent Claim
51 words
The process according to claim 1, wherein the sealing step comprises at least one step selected from baking in an atmosphere of ultrahigh vacuum and baking in a reducing atmosphere containing hydrogen, and the step of imparting silicon atoms to the surface of the porous silicon layer after the baking step.
Claim 4
Dependent Claim
24 words
The process according to claim 2, wherein in the baking step the porous silicon is etched to a death of 2 nm or less.
Claim 5
Dependent Claim
22 words
The process according to claim 1, wherein the heat treating step is carried out in an atmosphere containing no silicon source gas.
Claim 6
Dependent Claim
22 words
The process according to claim 1, wherein the heat treating step is carried out at a temperature of 1,000° C. or above.
Claim 7
Dependent Claim
20 words
The process according to claim 3, wherein the porous silicon is etched to a depth of 1 nm or less.
Claim 8
Dependent Claim
28 words
The process according to claim 1, wherein the sealing step is carried out after a preoxidation step wherein pore wall surfaces of the porous silicon layer are oxidized.
Claim 9
Dependent Claim
29 words
The process according to claim 7, which further comprises the step of removing an oxide film formed on the surface of the porous silicon layer by the preoxidation step.
Claim 10
Dependent Claim
31 words
The process according to claim 1, wherein the sealing step, the heat treating step and the growth step are carried out in a reaction chamber connected to a load lock chamber.
Claim 11
Dependent Claim
23 words
The process according to claim 1, wherein the sealing step is carried out at a pressure higher than that in the growth step.
Claim 12
Dependent Claim
18 words
The process according to claim 1, wherein the non-porous single-crystal layer is a layer formed by heteroepitaxial growth.
Claim 13
Dependent Claim
18 words
The process according to claim 1, wherein the porous silicon layer is formed by anodizing a single-crystal silicon.
Claim 14
Dependent Claim
22 words
The process according to claim 12, wherein the single-crystal silicon is anodized in a solution containing hydrofluoric acid, water and an alcohol.
Claim 15
Dependent Claim
23 words
The process according to claim 12, wherein the single-crystal silicon to be anodized is doped with an impurity to the level of degeneracy.
Claim 16
Dependent Claim
20 words
The process according to claim 1, wherein the heat treating step is carried out in a reducing atmosphere containing hydrogen.
Claim 17
Dependent Claim
29 words
The process according to claim 1, wherein the heat treatment is made after the surface of the non-porous single-crystal layer begins to decrease in haze during the sealing step.
Claim 18
Dependent Claim
29 words
The process according to claim 1, wherein the heat treatment is made after the surface of the non-porous single-crystal layer begins to decrease in roughness during the sealing step.
Claim 19
Dependent Claim
19 words
The process according to claim 1, wherein the sealing step is carried out at a temperature below 1,000° C.
Claim 20
Dependent Claim
25 words
The process according to claim 1, wherein the growth step is carried out at a temperature lower than the temperature in the heat treating step.
Claim 21
Dependent Claim
35 words
The process according to claim 1, wherein conditions are so set that a thickness of a non-porous portion formed on the porous silicon layer in the sealing step does not become larger than 50 nm.
Claim 22
Dependent Claim
31 words
The process according to claim 2, wherein the step of imparting silicon atoms is begun before all the surface pores of the porous silicon layer are sealed in the baking step.
Claim 23
Dependent Claim
37 words
The process according to claim 1, wherein the heat treating step is begun once the porous silicon layer has a surface pore density of 1×10 8 cm -2 or less as a result of the sealing step.
Claim 24
Dependent Claim
36 words
The process according to claim 1, wherein the sealing step and the heat treating step are carried out under the same pressure and the growth step is carried out under a pressure different from that pressure.
Claim 25
Dependent Claim
24 words
The process according to claim 1, wherein the growth step is carried out at a temperature lower than the temperature in the sealing step.
Claim 26
Dependent Claim
107 words
A process for producing a semiconductor substrate comprising, in the listed order, the steps of: providing a first substrate having a porous silicon layer on a non-porous silicon substrate; sealing surface pores of the porous silicon layer to lower its surface pore density; heat treating the porous silicon layer whose surface pores have been sealed at a temperature higher than the temperature in the sealing step; epitaxially growing a non-porous single-crystal layer on the surface of the porous silicon layer; bonding the non-porous single-crystal layer to a second substrate; and removing the porous silicon layer so as to leave the non-porous single-crystal layer on the second substrate.
Claim 27
Dependent Claim
107 words
A process for producing a semiconductor substrate comprising, in the listed order, the steps of: providing a first substrate having a porous silicon layer on a non-porous silicon substrate; sealing surface pores of the porous silicon layer to lower its surface pore density; heat treating the porous silicon layer whose surface pores have been sealed at a temperature higher than the temperature in the sealing step; epitaxially growing a non-porous single-crystal layer on the surface of the porous silicon layer; bonding the non-porous single-crystal layer to a second substrate; and removing the porous silicon layer so as to leave the non-porous single-crystal layer on the second substrate.
Claim 28
Dependent Claim
51 words
The process according to claim 25, wherein the sealing step comprises at least one step selected from baking in an atmosphere of ultrahigh vacuum and baking in a reducing atmosphere containing hydrogen, and the step of imparting silicon atoms to the surface of the porous silicon layer after the baking step.
Claim 29
Dependent Claim
28 words
The process according to claim 25, wherein the sealing step is carried out after a preoxidation step wherein pore wall surfaces of the porous silicon layer are oxidized.
Claim 30
Dependent Claim
29 words
The process according to claim 27, which further comprises the step of removing an oxide film formed on the surface of the porous silicon layer by the preoxidation step.
Claim 31
Dependent Claim
28 words
The process according to claim 25, wherein the bonding step comprises the step of bonding an oxide film formed on the non-porous single-crystal layer to the second substrate.
Claim 32
Dependent Claim
35 words
The process according to claim 25, wherein the bonding step comprises the step of bonding a first insulating film formed on the non-porous single-crystal layer to a second insulating film formed on the second substrate.
Claim 33
Dependent Claim
26 words
The process according to claim 25 which further comprises, before the step of removing the porous silicon layer, the step of removing the non-porous silicon substrate.
Claim 34
Dependent Claim
33 words
The process according to claim 25, wherein the step of removing the porous silicon layer comprises the step of separating a multi-layer structure formed in the bonding step at the porous silicon layer.
References Cited (Backward Citations)
US4933255A
Cited
JPH0521338A
Cited
US5371037A
Cited
US5869387A
Cited
US5492859A
Cited
US5536361A
Cited
US5670411A
Cited
US5980633A
Cited
EP0755068A2
Cited
JPH09100197A
Cited
US6008540A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-11-07 | 2004-05-08 | 2004-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-11-07 | 2008-05-08 | 2008-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-11-07 | 2012-05-08 | 2012-11-07 | $7700.00 | Window Closed / Lapsed |