US5432129A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming low resistance contacts at the junction between regions having different conductivity types
Assignee: STMicroelectronics lnc USA
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Filing: 1993-04-29
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Granted: 1995-07-11
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Expires: 2013-04-29
Abstract
Abstract A thin film transistor structure having a first and a second polycrystalline silicon layer of different conductivity types (P and N) has a high resistance contact at the resultant P-N junction. This contact resistance is reduced by forming TiSi 2 (titanium disilicide) or other refractory metal silicides such as cobalt or molybdenum in specific regions, namely the P-N junction contact. Titanium disilicide consumes the portion of the second polycrystalline silicon layer in the P-N contact junction and at the same time consumes a small portion of the underlying first polycrystalline silicon layer, such that the high resistance P-N junction now no longer exists.
Inventors
- 👤 Robert L. Hodges
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:35
CPC Classifications
H; H10; H10B; H10B10/00; H10D; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0113; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/064; H10W20/066; Y; Y10; Y10S; Y10S148/00; Y10S148/019
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
197 words
A method of forming a portion of an integrated circuit, comprising: forming a first polycrystalline silicon layer having a first conductivity type, wherein a first insulating layer is formed over a portion of the first polycrystalline silicon layer and is patterned and etched to expose a portion of the first polycrystalline silicon layer; forming a second polycrystalline silicon layer having a second conductivity type and having a contact region with the first polycrystalline silicon layer, wherein the second polycrystalline silicon layer makes contact with the first polycrystalline silicon layer through the exposed portion of the first polycrystalline silicon layer; forming a second insulating layer over the second polycrystalline silicon layer in the contact region so as to confine the converting step to the contact region; and converting the second polycrystalline silicon layer in the contact region, and a portion of the first polycrystalline silicon layer in the contact region, to a silicide; wherein the step of converting the second polycrystalline silicon layer to silicide comprises the further steps of: forming a refractory metal layer over the second polycrystalline silicon layer; and annealing the refractory metal layer so as to form the metal silicide in the contact region.
Claim 2
Independent Claim
197 words
A method of forming a portion of an integrated circuit, comprising: forming a first polycrystalline silicon layer having a first conductivity type, wherein a first insulating layer is formed over a portion of the first polycrystalline silicon layer and is patterned and etched to expose a portion of the first polycrystalline silicon layer; forming a second polycrystalline silicon layer having a second conductivity type and having a contact region with the first polycrystalline silicon layer, wherein the second polycrystalline silicon layer makes contact with the first polycrystalline silicon layer through the exposed portion of the first polycrystalline silicon layer; forming a second insulating layer over the second polycrystalline silicon layer in the contact region so as to confine the converting step to the contact region; and converting the second polycrystalline silicon layer in the contact region, and a portion of the first polycrystalline silicon layer in the contact region, to a silicide; wherein the step of converting the second polycrystalline silicon layer to silicide comprises the further steps of: forming a refractory metal layer over the second polycrystalline silicon layer; and annealing the refractory metal layer so as to form the metal silicide in the contact region.
Claim 3
Independent Claim
165 words
A method of forming a portion of an integrated circuit, comprising: forming a first polycrystalline silicon layer having a first conductivity type; forming a first insulating layer over the first polycrystalline silicon layer; patterning and etching the first insulating layer to expose a portion of the first polycrystalline silicon layer in a contact region; forming a second polycrystalline silicon layer having a second conductivity type which makes electrical contact with the first polycrystalline silicon layer in the contact region; patterning and etching the second polycrystalline silicon layer; forming a second insulating layer over the second polycrystalline silicon layer; etching an opening through the second insulating layer to create a salicide mask opening over the contact region; forming a first metal containing layer over the second polycrystalline silicon layer; and annealing the first metal containing layer so as to form metal silicide which consumes the second polycrystalline silicon layer in the contact region and a portion of the first polycrystalline silicon layer in the contact region.
Claim 4
Independent Claim
165 words
A method of forming a portion of an integrated circuit, comprising: forming a first polycrystalline silicon layer having a first conductivity type; forming a first insulating layer over the first polycrystalline silicon layer; patterning and etching the first insulating layer to expose a portion of the first polycrystalline silicon layer in a contact region; forming a second polycrystalline silicon layer having a second conductivity type which makes electrical contact with the first polycrystalline silicon layer in the contact region; patterning and etching the second polycrystalline silicon layer; forming a second insulating layer over the second polycrystalline silicon layer; etching an opening through the second insulating layer to create a salicide mask opening over the contact region; forming a first metal containing layer over the second polycrystalline silicon layer; and annealing the first metal containing layer so as to form metal silicide which consumes the second polycrystalline silicon layer in the contact region and a portion of the first polycrystalline silicon layer in the contact region.
Claim 5
Dependent Claim
19 words
The method of claim 2, wherein the first conductivity type is P+ and the second conductivity type is N+.
Claim 6
Dependent Claim
19 words
The method of claim 2, wherein the first conductivity type is N+ and the second conductivity type is P+.
Claim 7
Dependent Claim
66 words
The method of claim 5, wherein before the step of forming the first polycrystalline silicon layer, the following, additional steps are performed: forming a lower insulating layer over a substrate such that the first polycrystalline silicon layer is formed over the lower insulating layer; and patterning and etching the lower insulating layer to expose a portion of the source/drain region of a first field effect device.
Claim 8
Dependent Claim
29 words
The method of claim 5, wherein the lower insulating layer is patterned and etched to expose a portion of a second gate electrode of a second field effect device.
Claim 9
Dependent Claim
20 words
The method of claim 6, wherein the lower insulating layer has a thickness of between approximately 300 to 2000 Angstroms.
Claim 10
Dependent Claim
47 words
The method of claim 2, wherein after the step of forming a second insulating layer over the second polycrystalline silicon layer, an implant of the second polycrystalline silicon layer and an implant of a thin film transistor source/drain region of a first field effect device is performed.
Claim 11
Dependent Claim
47 words
The method of claim 2, wherein before the step of forming a second insulating layer over the second polycrystalline silicon layer, an implant of the second polycrystalline silicon layer and an implant of a thin film transistor source/drain region of a first field effect device is performed.
Claim 12
Dependent Claim
26 words
The method of claim 2, wherein the first polycrystalline silicon layer is implanted with N+ phosphorous at a concentration of approximately 1×10 18 /cm 3 .
Claim 13
Dependent Claim
16 words
The method of claim 2, wherein the first polycrystalline silicon layer is implanted with N+ arsenic.
Claim 14
Dependent Claim
25 words
The method of claim 2, wherein the first insulating layer is densified by dilution in O 2 , N 2 , or H 2 O.
Claim 15
Dependent Claim
44 words
The method of claim 2, wherein the step of forming the second polycrystalline silicon layer comprises the steps of: depositing amorphous silicon at a temperature of less than approximately 600 degrees Celsius; and annealing the amorphous silicon to form the second polycrystalline silicon layer.
Claim 16
Dependent Claim
26 words
The method of claim 2, wherein the second polycrystalline silicon layer has a large grain size characteristic of amorphous silicon having been deposited, recrystallized and annealed.
Claim 17
Dependent Claim
13 words
The method of claim 2, wherein the second insulating layer is silicon nitride.
Claim 18
Dependent Claim
13 words
The method of claim 2, wherein the second insulating layer is silicon dioxide.
Claim 19
Dependent Claim
15 words
The method of claim 2, wherein the first metal containing layer is a refractory metal.
Claim 20
Dependent Claim
13 words
The method of claim 17, wherein the first metal containing layer is titanium.
Claim 21
Dependent Claim
40 words
The method of claim 18, wherein, during the annealing step, the first metal containing layer is heated in a nitrogen atmosphere to produce titanium disilicide in the contact region and titanium nitride elsewhere, and the titanium nitride is subsequently stripped.
Claim 22
Dependent Claim
13 words
The method of claim 17, wherein the first metal containing layer is cobalt.
Claim 23
Dependent Claim
13 words
The method of claim 17, wherein the first metal containing layer is molybdenum.
Claim 24
Dependent Claim
21 words
The method of claim 2, wherein the annealing step creates a second metal containing layer over the first metal containing layer.
Claim 25
Dependent Claim
13 words
The method of claim 22, wherein the second metal containing layer is removed.
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| 3.5 Years (Year 4) | 1998-07-10 | 1999-01-09 | 1999-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-07-10 | 2003-01-09 | 2003-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-07-10 | 2007-01-09 | 2007-07-11 | $7700.00 | Window Closed / Lapsed |