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Patent US5348905A successfully refreshed from Google Patents.
US5348905A
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Method of making diffused buried plate trench DRAM cell array
Assignee: International Business Machines Corp
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Filing: 1993-08-26
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Granted: 1994-09-20
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Expires: 2013-08-26
Abstract
Abstract A high density substrate plate DRAM cell memory device and process are described in which a buried plate region is formed adjacent to deep trench capacitors such that the substrate region of DRAM transfer FETs can be electrically isolated from other FETs on a semiconductor substrate. The buried region is partially formed by lateral outdiffusion from the sidewalls of the deep trenches and partially formed by an N-well surface diffusion which entirely surrounds the DRAM array region.
Inventors
- 👤 Donald M. Kenney
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:29
CPC Classifications
H; H10; H10B; H10B12/00; H10B12/30; H10B12/37
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
175 words
The method of making a dynamic random access memory device comprising the steps of: providing a semiconductor substrate of a first conductivity type; forming a plurality of deep trenches in a matrix pattern on a top surface of said substrate; diffusing a second conductivity type impurity from the lower portion of the depth of said deep trenches into said substrate to form a continuous buried diffused region of a second conductivity type across the entire extent of the matrix pattern; forming a dielectric layer on the inside of said deep trenches and filling said trenches with a conductive electrode material; forming around the perimeter of said matrix pattern a diffused surface region of said second conductivity type having a depth so as to physically and electrically isolate a portion of the substrate within the matrix pattern above said continuous buried diffused region; and forming within the isolated portion of the matrix pattern a plurality of semiconductor devices for coupling signals to and from said conductive electrode material within at least some of said deep trenches.
Claim 2
Independent Claim
175 words
The method of making a dynamic random access memory device comprising the steps of: providing a semiconductor substrate of a first conductivity type; forming a plurality of deep trenches in a matrix pattern on a top surface of said substrate; diffusing a second conductivity type impurity from the lower portion of the depth of said deep trenches into said substrate to form a continuous buried diffused region of a second conductivity type across the entire extent of the matrix pattern; forming a dielectric layer on the inside of said deep trenches and filling said trenches with a conductive electrode material; forming around the perimeter of said matrix pattern a diffused surface region of said second conductivity type having a depth so as to physically and electrically isolate a portion of the substrate within the matrix pattern above said continuous buried diffused region; and forming within the isolated portion of the matrix pattern a plurality of semiconductor devices for coupling signals to and from said conductive electrode material within at least some of said deep trenches.
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein a diffusion barrier collar is provided in the upper portion of said deep trenches.
Claim 4
Dependent Claim
44 words
The method of making a dynamic random access memory device of claim 1 wherein the step of forming a dielectric layer on the inside of said deep trenches includes the step of forming a thick dielectric collar at the top of said deep trenches.
Claim 5
Dependent Claim
25 words
The method of claim 2 wherein the diffusion barrier collar is removed prior to the forming of a dielectric layer inside of said deep trenches.
Claim 6
Dependent Claim
81 words
The method of making a dynamic random access memory device of claim 3 wherein the step of forming a plurality of deep trenches includes the steps of forming a plurality of shallow trenches in said substrate, forming a sidewall protecting layer on the sidewalls of said shallow trenches, extending the depth of said shallow trenches to form said deep trenches, placing a source of impurity dopant material at least on the lower portion of the sidewalls of the extended deep trenches.
Claim 7
Dependent Claim
29 words
The method of making a dynamic random access memory device of claim 5 wherein the source of dopant material used to form the continuous buried diffused region is arsenic.
Claim 8
Dependent Claim
33 words
The method of making a dynamic random access memory device of claim 5 wherein the source of dopant material used to form the continuous buried diffused region is an arsenic containing glass layer.
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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) | 1997-09-19 | 1998-03-21 | 1998-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-09-19 | 2002-03-21 | 2002-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-09-19 | 2006-03-21 | 2006-09-20 | $7700.00 | Window Closed / Lapsed |