US4763179A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semiconductor memory device
Assignee: Mitsubishi Electric Corp
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Filing: 1987-06-24
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Granted: 1988-08-09
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Expires: 2007-06-24
Abstract
Abstract A semiconductor memory device such as a MOS dynamic RAM comprises transistor portions (2, 3 and 5) for writing and reading a signal and capacitor portions (1, 2, 6 and 9) by pn junction for storing a signal. The capacitor portions have preferably as large a capacitance as possible. For this purpose, a capacitor hole (7) is formed in a p type semiconductor substrate (6) and an n type semiconductor region (9) is provided along the capacitor hole (7) so that the pn junction area therebetween is increased and the capacitance is made large.
Inventors
- 👤 Natsuro Tsubouchi
- 👤 Masafumi Kimata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:35
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/60; H10D1/62; H10B; H10B12/00; H10B12/30; H10B12/37; Y; Y10; Y10S; Y10S148/00; Y10S148/014; Y10S438/00; Y10S438/901
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
163 words
A semiconductor memory device using a capacitor as a memory device, comprising: a substrate (6) of a first conductive type formed with a generally vertical hole (21) extending substantially vertically to an upper surface thereof and including an enlarged buried well formed within the substrate at a lower end of the generally vertical hole, a semiconductor region (9) of a second conductive type formed in said substrate (6) of the first conductive type, said semiconductor region (9) extending along said generally vertical hole (21) and along said enlarged buried well, and said enlarged buried well establishing a capacitor region between said substrate (6) of the first conductive type and said semiconductor region (9) of the second conductive type, said buried well being an isotropically etched well thereby having a generally flat bottom surface and including a curved surface region (8) extending continuously between said bottom to the lower end of the generally vertical hole, said well being wider than the generally vertical hole.
Claim 2
Dependent Claim
163 words
A semiconductor memory device using a capacitor as a memory device, comprising: a substrate (6) of a first conductive type formed with a generally vertical hole (21) extending substantially vertically to an upper surface thereof and including an enlarged buried well formed within the substrate at a lower end of the generally vertical hole, a semiconductor region (9) of a second conductive type formed in said substrate (6) of the first conductive type, said semiconductor region (9) extending along said generally vertical hole (21) and along said enlarged buried well, and said enlarged buried well establishing a capacitor region between said substrate (6) of the first conductive type and said semiconductor region (9) of the second conductive type, said buried well being an isotropically etched well thereby having a generally flat bottom surface and including a curved surface region (8) extending continuously between said bottom to the lower end of the generally vertical hole, said well being wider than the generally vertical hole.
Claim 3
Dependent Claim
16 words
A semiconductor memory device in accordance with claim 1, wherein said curved surface region is concave.
Claim 4
Dependent Claim
26 words
A semiconductor memory device in accordance with claim 2, wherein the bottom surface of said well extends within said substrate generally parallel to said upper surface.
References Cited (Backward Citations)
JPS53130178A
Cited
GB2075752A
Cited
EP0044400A2
Cited
JPS583269A
Cited
EP0085988A2
Cited
EP0088451A1
Cited
EP0108390A1
Cited
GB2138207A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-08-09 | 1992-02-08 | 1992-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-09 | 1996-02-08 | 1996-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-09 | 2000-02-08 | 2000-08-09 | $7700.00 | Window Closed / Lapsed |