US5393687A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making buried contact module with multiple poly si layers
Assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
•
Filing: 1993-12-16
•
Granted: 1995-02-28
•
Expires: 2013-12-16
Abstract
Abstract A new method of forming source/drain buried contact junctions is described. The method of forming a buried contact to a source/drain junction or other active device region in a silicon substrate is described. A first polysilicon layer is deposited over the surface of a silicon substrate. A second layer of polysilicon is deposited over the first layer of polysilicon wherein the polysilicon grain boundaries of the first and second polysilicon layers will be mismatched. The second polysilicon layer is doped. The grain boundary mismatch will slow the diffusion of the dopant into the silicon substrate. The dopant is driven in to form the buried contact with a shallow junction.
Inventors
- 👤 Mong-Song Liang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:25
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0113; Y; Y10; Y10S; Y10S148/00; Y10S148/035
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
118 words
The method of forming a buried contact with a shallow junction in a silicon substrate comprising: depositing a first polysilicon layer over the surface of said silicon substrate; cooling said silicon substrate after said deposition of said first polysilicon layer to a temperature lower than the deposition temperature; depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been cooled wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched; doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate; and driving in said dopant to form said buried contact with a shallow junction.
Claim 2
Independent Claim
118 words
The method of forming a buried contact with a shallow junction in a silicon substrate comprising: depositing a first polysilicon layer over the surface of said silicon substrate; cooling said silicon substrate after said deposition of said first polysilicon layer to a temperature lower than the deposition temperature; depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been cooled wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched; doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate; and driving in said dopant to form said buried contact with a shallow junction.
Claim 3
Dependent Claim
51 words
The method of claim 1 wherein a third polysilicon layer is deposited overlying said second polysilicon layer wherein said substrate is cooled after the deposition of said second polysilicon layer and before deposition of said third polysilicon layer and wherein said third polysilicon layer is doped to form said buried contact.
Claim 4
Dependent Claim
20 words
The method of claim 1 wherein the thickness of said first polysilicon layer is between about 50 to 2500 Angstroms.
Claim 5
Dependent Claim
20 words
The method of claim 1 wherein the thickness of said second polysilicon layer is between about 100 to 2500 Angstroms.
Claim 6
Dependent Claim
18 words
The method of claim 1 wherein said second polysilicon layer is doped by diffusion of POCl 3 .
Claim 7
Dependent Claim
33 words
The method of claim 1 wherein said second polysilicon layer is doped by ion implant of phosphorus with a dosage of between about 5 E 14 to 5 E 16 atoms/cm 2 .
Claim 8
Dependent Claim
33 words
The method of claim 1 wherein said second polysilicon layer is doped by ion implant of arsenic with a dosage of between about 5 E 14 to 5 E 16 atoms/cm 2 .
Claim 9
Dependent Claim
27 words
The method of claim 1 wherein said drive-in of said buried contact is performed at between about 800° to 1000° C. in a nitrogen or oxygen ambient.
Claim 10
Independent Claim
134 words
The method of forming a buried contact with a shallow junction in the formation of a static random access memory (SRAM) integrated circuit comprising: depositing a first polysilicon layer over the surface of a silicon substrate; cooling said silicon substrate after said deposition of said first polysilicon layer to a temperature lower than the deposition temperature; depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been cooled wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched; doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate; and driving in said dopant to form said buried contact with a shallow junction in the formation of said SRAM integrated circuit.
Claim 11
Independent Claim
134 words
The method of forming a buried contact with a shallow junction in the formation of a static random access memory (SRAM) integrated circuit comprising: depositing a first polysilicon layer over the surface of a silicon substrate; cooling said silicon substrate after said deposition of said first polysilicon layer to a temperature lower than the deposition temperature; depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been cooled wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched; doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate; and driving in said dopant to form said buried contact with a shallow junction in the formation of said SRAM integrated circuit.
Claim 12
Dependent Claim
51 words
The method of claim 9 wherein a third polysilicon layer is deposited overlying said second polysilicon layer wherein said substrate is cooled after the deposition of said second polysilicon layer and before deposition of said third polysilicon layer and wherein said third polysilicon layer is doped to form said buried contact.
Claim 13
Dependent Claim
20 words
The method of claim 9 wherein the thickness of said first polysilicon layer is between about 50 to 2500 Angstroms.
Claim 14
Dependent Claim
20 words
The method of claim 9 wherein the thickness of said second polysilicon layer is between about 100 to 2500 Angstroms.
Claim 15
Dependent Claim
18 words
The method of claim 9 wherein said second polysilicon layer is doped by diffusion of POCl 3 .
Claim 16
Dependent Claim
33 words
The method of claim 9 wherein said second polysilicon layer is doped by ion implant of phosphorus with a dosage of between about 5 E 14 to 5 E 16 atoms/cm 2 .
Claim 17
Dependent Claim
33 words
The method of claim 9 wherein said second polysilicon layer is doped by ion implant of arsenic with a dosage of between about 5 E 14 to 5 E 16 atoms/cm 2 .
Claim 18
Dependent Claim
27 words
The method of claim 9 wherein said drive-in of said buried contact is performed at between about 800° to 1000° C. in a nitrogen or oxygen ambient.
Claim 19
Dependent Claim
21 words
The method of claim 9 wherein the junction depth of said buried contact junction is between about 0.5 to 0.8 microns.
Claim 20
Independent Claim
134 words
The method of forming a buried contact with a shallow junction in the formation of a dynamic random access memory (DRAM) integrated circuit comprising: depositing a first polysilicon layer over the surface of a silicon substrate; cooling said silicon substrate after said deposition of said first polysilicon layer to a temperature lower than the deposition temperature; depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been cooled wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched; doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate; and driving in said dopant to form said buried contact with a shallow junction in the formation of said DRAM integrated circuit.
Claim 21
Independent Claim
134 words
The method of forming a buried contact with a shallow junction in the formation of a dynamic random access memory (DRAM) integrated circuit comprising: depositing a first polysilicon layer over the surface of a silicon substrate; cooling said silicon substrate after said deposition of said first polysilicon layer to a temperature lower than the deposition temperature; depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been cooled wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched; doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate; and driving in said dopant to form said buried contact with a shallow junction in the formation of said DRAM integrated circuit.
Claim 22
Dependent Claim
50 words
The method of claim 18 wherein a third polysilicon layer is deposited overlying said second polysilicon-layer wherein said substrate is cooled after the deposition of said second polysilicon layer and before deposition of said third polysilicon layer and wherein said third polysilicon layer is doped to form said buried contact.
Claim 23
Dependent Claim
20 words
The method of claim 18 wherein the thickness of said first polysilicon layer is between about 50 to 2500 Angstroms.
Claim 24
Dependent Claim
20 words
The method of claim 18 wherein the thickness of said second polysilicon layer is between about 100 to 2500 Angstroms.
Claim 25
Dependent Claim
18 words
The method of claim 18 wherein said second polysilicon layer is doped by diffusion of POCl 3 .
Claim 26
Dependent Claim
33 words
The method of claim 18 wherein said second polysilicon layer is doped by ion implant of phosphorus with a dosage of between about 5 E 14 to 5 E 16 atoms/cm 2 .
Claim 27
Dependent Claim
33 words
The method of claim 18 wherein said second polysilicon layer is doped by ion implant of arsenic with a dosage of between about 5 E 14 to 5 E 16 atoms/cm 2 .
Claim 28
Dependent Claim
27 words
The method of claim 18 wherein said drive-in of said buried contact is performed at between about 800° to 1000° C. in a nitrogen or oxygen ambient.
Claim 29
Dependent Claim
26 words
The method of claim 18 wherein for a 4 Megabit DRAM, the junction depth of said buried contact junction is between about 0.4 to 0.6 microns.
Claim 30
Dependent Claim
26 words
The method of claim 18 wherein for a 16 Megabit DRAM, the junction depth of said buried contact junction is between about 0.1 to 0.3 microns.
Claim 31
Independent Claim
118 words
The method of forming a buried contact with a shallow junction in a silicon substrate comprising: depositing a first polysilicon layer over the surface of said silicon substrate; dipping said silicon substrate in dilute hydrofluoric acid after said deposition of said first polysilicon layer; depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been dipped in said hydrofluoric acid wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched; doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate; and driving in said dopant to form said buried contact with a shallow junction.
Claim 32
Independent Claim
118 words
The method of forming a buried contact with a shallow junction in a silicon substrate comprising: depositing a first polysilicon layer over the surface of said silicon substrate; dipping said silicon substrate in dilute hydrofluoric acid after said deposition of said first polysilicon layer; depositing a second layer of polysilicon on said first layer of polysilicon after said silicon substrate has been dipped in said hydrofluoric acid wherein the polysilicon grain boundaries of said first and second polysilicon layers will be mismatched; doping said second polysilicon layer wherein the said grain boundary mismatch will slow the diffusion of the dopant into said silicon substrate; and driving in said dopant to form said buried contact with a shallow junction.
Claim 33
Dependent Claim
55 words
The method of claim 28 wherein a third polysilicon layer is deposited overlying said second polysilicon layer wherein said substrate is dipped in dilute hydrofluoric acid after the deposition of said second polysilicon layer and before deposition of said third polysilicon layer and wherein said third polysilicon layer is doped to form said buried contact.
Claim 34
Dependent Claim
27 words
The method of claim 28 wherein said buried contact with a shallow junction is formed in the fabrication of a static random access memory (SRAM) integrated circuit.
Claim 35
Dependent Claim
27 words
The method of claim 28 wherein said buried contact with a shallow junction is formed in the fabrication of a dynamic random access memory (DRAM) integrated circuit.
References Cited (Backward Citations)
US4407060A
Cited
JPS61208829A
Cited
US4950617A
Cited
US4978629A
Cited
US5030584A
Cited
US5049514A
Cited
US4945070A
Cited
JPH04349617A
Cited
JPH0547703A
Cited
JPH05129215A
Cited
US5323022A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-02-27 | 1998-08-29 | 1999-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-02-27 | 2002-08-29 | 2003-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-02-27 | 2006-08-29 | 2007-02-28 | $7700.00 | Window Closed / Lapsed |