US6177699B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
DRAM cell having a verticle transistor and a capacitor formed on the sidewalls of a trench isolation
Assignee: Adeia Semiconductor Technologies LLC
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Filing: 1998-05-21
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Granted: 2001-01-23
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Expires: 2018-05-21
Abstract
Abstract A DRAM cell capacitor and access transistor are described. Capacitor formation, access transistor fabrication and cell isolation methods are integrated by using isolation trench sidewalls to form DRAM capacitors and access transistors. A doped silicon substrate adjacent to the vertical sidewalls of the isolation trench provides one DRAM cell capacitor plate. The DRAM capacitor also contains a dielectric material that partially covers the interior vertical sidewalls of the isolation trench. A conductive layer covering the dielectric material on the vertical sidewalls of the isolation trench forms the second capacitor plate and completes the DRAM capacitor. A vertically oriented access transistor is formed over top of the capacitor. To accomplish this, an isolation dielectric is deposited and patterned to provide a support structure for gate electrodes of the vertical access transistor above the trench sidewall capacitors. After gate structure formation the support layer is replaced with selectively doped epitaxial silicon in which the transistor's channel, source, and drain are formed.
Inventors
- 👤 Dung-Ching Perng
- 👤 Yauh-Ching Liu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:51
CPC Classifications
H; H10; H10B; H10B12/00; H10B12/01; H10B12/02; H10B12/03; H10B12/038; H10D; H10D1/00; H10D1/01; H10D1/045; H10D1/047; H10D1/60; H10D1/68; H10D1/682; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/014; H10W10/0148; H10W10/10; H10W10/17; H10B12/0387
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
132 words
A DRAM cell formed on an active region of an semiconductor substrate, the DRAM cell comprising: an isolation trench in the semiconductor substrate, wherein said isolation trench electrically isolates said DRAM cell from one or more adjacent DRAM cells; at least two capacitors disposed on a sidewall of the isolation trench and each capacitor including first and second capacitor plates separated by a dielectric layer; and a vertically oriented access transistor disposed over and electrically coupled with the capacitor, whereby said isolation trench is substantially filled with an isolation dielectric, such that said isolation trench includes (i) the dielectric layer forming part of at least one of the capacitors and (ii) the isolation dielectric which occupies a portion of the isolation trench which is not occupied by the at least two capacitors.
Claim 2
Dependent Claim
132 words
A DRAM cell formed on an active region of an semiconductor substrate, the DRAM cell comprising: an isolation trench in the semiconductor substrate, wherein said isolation trench electrically isolates said DRAM cell from one or more adjacent DRAM cells; at least two capacitors disposed on a sidewall of the isolation trench and each capacitor including first and second capacitor plates separated by a dielectric layer; and a vertically oriented access transistor disposed over and electrically coupled with the capacitor, whereby said isolation trench is substantially filled with an isolation dielectric, such that said isolation trench includes (i) the dielectric layer forming part of at least one of the capacitors and (ii) the isolation dielectric which occupies a portion of the isolation trench which is not occupied by the at least two capacitors.
Claim 3
Dependent Claim
43 words
The DRAM cell of claim 1 wherein said first capacitor plate is defined by said semiconductor substrate at a section of the wall of said isolation trench, and wherein said second capacitor plate is defined by a conductive layer within said isolation trench.
Claim 4
Dependent Claim
26 words
The DRAM cell of claim 2 wherein said access transistor is an MOS device having a drain that is electrically connected to the second capacitor plate.
Claim 5
Dependent Claim
44 words
The DRAM cell of claim 2 wherein said first capacitor plate has a first dopant concentration and the semiconductor substrate adjacent to said first capacitor plate has a second dopant concentration wherein said first dopant concentration is substantially greater than said second dopant concentration.
Claim 6
Dependent Claim
25 words
The DRAM cell of claim 2 wherein said conductive layer of said second capacitor plate is between about 200 Å and about 2000 Å thick.
Claim 7
Dependent Claim
19 words
The DRAM cell of claim 1 wherein said isolation trench is at least partially filled with a dielectric material.
Claim 8
Dependent Claim
18 words
The DRAM cell claim 1 wherein said isolation trench has a depth of at least about 0.1 μm.
Claim 9
Dependent Claim
18 words
The DRAM cell claim 1 wherein said isolation trench has a width of at most about 2 μm.
Claim 10
Dependent Claim
45 words
The DRAM cell of claim 1 wherein said dielectric layer includes at least one of SiO 2 , Si 3 N x , silicon oxynitride, sandwich layers of SiO 2 /Si 3 N x /SiO 2 , Ta 2 O 5 , BST and PZT.
Claim 11
Dependent Claim
19 words
The DRAM cell of claim 1 wherein said dielectric layer has a dielectric constant of at least about 9.
Claim 12
Dependent Claim
16 words
The DRAM cell of claim 9 wherein said dielectric layer includes Ta 2 O 5 .
Claim 13
Dependent Claim
20 words
The DRAM cell of claim 1 wherein said dielectric layer is between about 30 Å and about 200 Å thick.
Claim 14
Dependent Claim
29 words
The DRAM cell of claim 1 wherein said access transistor is oriented substantially parallel to the vertical sidewalls of said isolation trench and substantially perpendicular to said semiconductor substrate.
Claim 15
Dependent Claim
24 words
The DRAM cell of claim 1 wherein the portion of said isolation trench adjacent to said capacitor is filled with a first isolation dielectric.
Claim 16
Dependent Claim
29 words
The DRAM cell of claim 14 further comprising a second isolation dielectric provided over said first isolation dielectric and isolating the access transistor from access transistors of adjacent cells.
Claim 17
Dependent Claim
41 words
The DRAM cell of claim 1 wherein said access transistor comprises: a semiconductor bulk section; a gate dielectric provided on a vertical surface of the bulk semiconductor section; a gate electrode is provided over said gate dielectric; and a source region.
Claim 18
Dependent Claim
27 words
The DRAM cell of claim 16 wherein the semiconductor bulk section is an epitaxial silicon layer is provided over said semiconductor substrate at regions outside trench isolation.
Claim 19
Dependent Claim
33 words
The DRAM cell of claim 17 wherein the electrical connection between the second capacitor plate and the drain of the access transistor is provided in said semiconductor substrate and said epitaxial silicon layer.
Claim 20
Dependent Claim
21 words
The DRAM cell of claim 17 wherein said source region of said access transistor is provided in said epitaxial silicon layer.
Claim 21
Dependent Claim
29 words
The DRAM cell of claim 16 wherein a first silicide layer is provided over said gate electrode and a second layer of silicide is provided over said source region.
Claim 22
Dependent Claim
36 words
The DRAM cell of claim 16 wherein said gate electrode is oriented substantially perpendicular to the surface of said semiconductor substrate and the source region is oriented substantially parallel to the surface of said semiconductor substrate.
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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) | 2004-01-23 | 2004-07-24 | 2005-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-01-23 | 2008-07-24 | 2009-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-01-23 | 2012-07-24 | 2013-01-23 | $7700.00 | Window Closed / Lapsed |