US4906590A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming a trench capacitor on a semiconductor substrate
Assignee: Mitsubishi Electric Corp
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Filing: 1989-04-24
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Granted: 1990-03-06
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Expires: 2009-04-24
Abstract
Abstract The disclosed method of forming a capacitor on a semiconductor substrate includes the steps of filling a trench in the semiconductor substrate with a photoresist, a step of exposing the photoresist in situ to a standing wave of light intensity which is created by interference between incident light directed to the bottom of the trench and reflected light from the bottom of the trench, developing and exposed photoresist in situ to leave periodic photoresist regions along the side wall of the trench in the direction of its depth, and etching the side wall using the residual periodic photoresist as a mask to create periodic hollows along the side wall of the trench.
Inventors
- 👤 Yukimichi Kanetaki
- 👤 Yasuo Kinoshita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 05:55
CPC Classifications
H; H10; H10B; H10B12/00; H10B12/01; H10B12/02; H10B12/03; H10B12/038; H10B12/30; H10B12/37; H10D; H10D1/00; H10D1/01; H10D1/045; H10D1/047; H10P; H10P50/00; H10P50/69; H10P50/691; H10P76/00; H10P76/20; H10P76/204; H10P76/2041; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/948; Y10S438/949; Y10S438/964
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
187 words
A method of forming a capacitor on a semiconductor substrate, comprising the steps of: forming a mask layer having an opening on a major surface of said substrate, forming a trench having a bottom wall and a side wall in said substrate by anisotropic etching through said opening, filling said trench with a photoresist, exposing the photoresist in the trench to a standing wave of light intensity which is created by interference between incident light directed to the bottom of the trench and reflected light from the bottom of the trench, developing the photoresist exposed to said standing wave of light intensity to leave periodic regions of photoresist along the side wall of the trench in the direction of its depth, etching the side wall of the trench using the residual periodic photoresist as a mask to create periodic hollows along the side wall of the trench, removing the residual periodic photoresist and forming an insulation layer on the side wall and bottom wall of the trench, and forming a conductive layer on the insulation layer formed on the side wall and bottom wall of the trench.
Claim 2
Independent Claim
187 words
A method of forming a capacitor on a semiconductor substrate, comprising the steps of: forming a mask layer having an opening on a major surface of said substrate, forming a trench having a bottom wall and a side wall in said substrate by anisotropic etching through said opening, filling said trench with a photoresist, exposing the photoresist in the trench to a standing wave of light intensity which is created by interference between incident light directed to the bottom of the trench and reflected light from the bottom of the trench, developing the photoresist exposed to said standing wave of light intensity to leave periodic regions of photoresist along the side wall of the trench in the direction of its depth, etching the side wall of the trench using the residual periodic photoresist as a mask to create periodic hollows along the side wall of the trench, removing the residual periodic photoresist and forming an insulation layer on the side wall and bottom wall of the trench, and forming a conductive layer on the insulation layer formed on the side wall and bottom wall of the trench.
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein said semiconductor substrate is a silicon substrate.
Claim 4
Dependent Claim
28 words
The method of claim 2 wherein said mask layer having the opening is a silicon oxide layer created by thermal oxidation and said opening is created by photoetching.
Claim 5
Dependent Claim
17 words
The method of claim 3 wherein said anisotropic etching is reactive ion etching with CCl 4 gas.
Claim 6
Dependent Claim
12 words
The method of claim 1 wherein said photoresist is a positive-acting photoresist.
Claim 7
Dependent Claim
27 words
The method of claim 1 wherein the periodic hollows along the side wall of the trench are created by dry etching with CF 4 +O 2 gas.
Claim 8
Dependent Claim
18 words
The method of claim 1 wherein said residual periodic photoresist is removed by means of a plasma asher.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-05 | 1993-09-04 | 1994-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-05 | 1997-09-04 | 1998-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-05 | 2001-09-04 | 2002-03-06 | $7700.00 | Window Closed / Lapsed |