US4597160A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating a polysilicon transistor with a high carrier mobility
Assignee: RCA Corp
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Filing: 1985-08-09
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Granted: 1986-07-01
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Expires: 2005-08-09
Abstract
Abstract A method for making a TFT comprises forming an amorphous silicon layer having a smooth upper surface. An insulating layer is then formed on the smooth surface at or below the critical temperature for the instantaneous crystallization of amorphous. This slowly converts the amorphous silicon to polycrystalline silicon while retaining the smooth surface. TFTs incorporating the invention have a relatively high field effect (surface) mobility.
Inventors
- 👤 Alfred C. Ipri
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:36
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/031; H10D30/0312; H10D30/0314; H10D30/0321; H10D30/60; H10D30/67; H10D30/6729; H10D30/673; H10D30/6731; H10D30/674; H10D30/6741; H10D30/6743; H10D30/6745; H10P; H10P14/00; H10P14/20; H10P14/24; H10P14/29; H10P14/2901; H10P14/2922; H10P14/32; H10P14/3202; H10P14/3204; H10P14/3211; H10P14/34; H10P14/3402; H10P14/3404; H10P14/3411; Y; Y10; Y10S; Y10S148/00; Y10S148/118
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
88 words
A method for making a transistor comprising: forming a first amorphous silicon layer on a substrate to obtain a smooth surface on said layer; heating said amorphous silicon layer in an oxidizing ambient at or slightly below the critical temperature of silicon to form an insulating layer on said smooth surface and to convert said amorphous silicon layer to a polycrystalline silicon layer while retaining said smooth surface; forming a gate on said insulating layer; and forming source and drain regions in said silicon layer adjacent said gate.
Claim 2
Independent Claim
88 words
A method for making a transistor comprising: forming a first amorphous silicon layer on a substrate to obtain a smooth surface on said layer; heating said amorphous silicon layer in an oxidizing ambient at or slightly below the critical temperature of silicon to form an insulating layer on said smooth surface and to convert said amorphous silicon layer to a polycrystalline silicon layer while retaining said smooth surface; forming a gate on said insulating layer; and forming source and drain regions in said silicon layer adjacent said gate.
Claim 3
Dependent Claim
34 words
The method of claim 1, wherein said first recited forming step comprises depositing said amorphous silicon layer by low pressure chemical vapor deposition at a substrate temperature of about 550° C. to 570° C.
Claim 4
Dependent Claim
19 words
The method of claim 2, wherein said depositing step comprises depositing at a substrate temperature of about 560° C.
Claim 5
Dependent Claim
26 words
The method of claim 1, wherein said first recited forming step comprises forming said silicon layer with a thickness of about 100 nm to 500 nm.
Claim 6
Dependent Claim
25 words
The method of claim 1, wherein said heating step comprises growing said insulating layer at a substrate temperature between about 580° C. and 620° C.
Claim 7
Dependent Claim
19 words
The method of claim 5, wherein said growing step comprises growing at a substrate temperature of about 600° C.
Claim 8
Dependent Claim
22 words
The method of claim 6, wherein said growing step has a duration of about 120 hours and said oxidizing ambient comprises steam.
Claim 9
Dependent Claim
21 words
The method of claim 1, wherein said step of forming said gate comprises depositing and defining a second amorphous silicon layer.
Claim 10
Dependent Claim
18 words
The method of claim 8, further comprising converting said second amorphous silicon layer to a polycrystalline silicon layer.
Claim 11
Dependent Claim
26 words
The method of claim 9, wherein said step of converting said second amorphous layer comprises heating said layer to about 600° C. for about 4 hours.
Claim 12
Dependent Claim
21 words
The method of claim 1, wherein said step of forming source and drain regions comprises ion implanting a conductivity modifying dopant.
Claim 13
Dependent Claim
24 words
The method of claim 11, wherein said ion implanting step comprises implanting boron with an areal density of about 8×10 15 ions/cm 2 .
References Cited (Backward Citations)
US3093507A
Cited
US3396052A
Cited
US3911168A
Cited
US3900345A
Cited
US3900597A
Cited
US4376657A
Cited
US4358326A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-06-30 | 1989-12-30 | 1990-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-30 | 1993-12-30 | 1994-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-30 | 1997-12-30 | 1998-07-01 | $7700.00 | Window Closed / Lapsed |