US4640004A
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Method and structure for inhibiting dopant out-diffusion
Assignee: National Semiconductor Corp
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Filing: 1984-04-13
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Granted: 1987-02-03
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Expires: 2004-04-13
Abstract
Abstract A method for inhibiting out-diffusion of dopants from polycrystalline or single crystal silicon substrates of high speed semiconductor devices into metal silicide conductive layers disposed on the substrate comprises interposing a refractory metal nitride layer between the doped silicon substrate and the refractory metal silicide conductive layer. Dopant out-diffusion is further retarded, and contact resistance lowered, by adding a thin layer of refractory metal between the refractory metal nitride layer and the silicon substrate.
Inventors
- 👤 Michael E. Thomas
- 👤 Madhukar B. Vora
- 👤 Ashok K. Kapoor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 02:09
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0112; H10D62/00; H10D62/80; H10D62/83; H10D64/013; H10D64/01302; H10D64/01304; H10D64/01306; H10D64/01308; H10D64/01312; H10D64/60; H10D64/62; H10D64/66; H10D64/661; H10D64/662; H10D64/664; H10W; H10W20/00; H10W20/40; H10W20/41; H10W20/44; H10W20/4403; H10W20/4437; H10W20/4441; Y; Y10; Y10S; Y10S148/00; Y10S148/034; Y10S438/00; Y10S438/909
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
58 words
A method of inhibiting dopant out-diffusion in a semiconductor device including a silicon substrate containing a dopant and having a refractory metal silicide layer disposed on at least a portion of one surface thereof, said method comprising the step of disposing a refractory metal nitride barrier layer between said doped silicon substrate and said refractory metal silicide layer.
Claim 2
Independent Claim
58 words
A method of inhibiting dopant out-diffusion in a semiconductor device including a silicon substrate containing a dopant and having a refractory metal silicide layer disposed on at least a portion of one surface thereof, said method comprising the step of disposing a refractory metal nitride barrier layer between said doped silicon substrate and said refractory metal silicide layer.
Claim 3
Dependent Claim
28 words
The method in accordance with claim 1 wherein said barrier layer includes a refractory metal selected from the group consisting of tantalum, niobium, titanium, zirconium, chromium and hafnium.
Claim 4
Dependent Claim
22 words
The method in accordance with claim 2 wherein said dopant is selected from the group consisting of boron, phosphorus, arsenic and antimony.
Claim 5
Dependent Claim
26 words
The method in accordance with claim 3 comprising an additional step of disposing a layer of refractory metal between said barrier layer and said silicon substrate.
Claim 6
Dependent Claim
29 words
The method in accordance with claim 4 wherein said refractory metal layer comprises a refractory metal selected from the group consisting of tantalum, niobium, titanium, zirconium, chromium and hafnium.
Claim 7
Dependent Claim
17 words
The method in accordance with claim 5 wherein the refractory metal of said barrier layer comprises tantalum.
Claim 8
Dependent Claim
12 words
The method in accordance with claim 5 wherein said dopant comprises boron.
Claim 9
Dependent Claim
18 words
The method in accordance with claim 5 wherein the refractory metal of said refractory metal layer comprises titanium.
Claim 10
Dependent Claim
32 words
The method in accordance with claim 5 wherein the refractory metal of said barrier layer comprises tantalum, the dopant comprises boron and the refractory metal of said refractory metal layer comprises titanium.
Claim 11
Independent Claim
149 words
A method of inhibiting dopant diffusion in a high speed semiconductor device, said method comprising the steps of: (a) providing a silicon substrate containing a dopant and having a first surface; (b) disposing a first layer of a first refractory metal over the first surface of said substrate, said first layer having a predetermined thickness; (c) depositing a second refractory metal on said first layer in an ambient environment having a predetermined concentration of nitrogen in order to form a blanket layer of a refractory metallic nitride having a predetermined thickness; (d) placing an amorphous, co-deposited third refractory metal: silicon layer, having a predetermined thickness and a predetermined atomic ratio of silicon to refractory metal, on said blanket layer; and (e) transforming said co-deposited layer to a refractory metallic dicilicide layer by heating at a predetermined temperature for a predetermined amount of time in a second predetermined ambient environment.
Claim 12
Independent Claim
149 words
A method of inhibiting dopant diffusion in a high speed semiconductor device, said method comprising the steps of: (a) providing a silicon substrate containing a dopant and having a first surface; (b) disposing a first layer of a first refractory metal over the first surface of said substrate, said first layer having a predetermined thickness; (c) depositing a second refractory metal on said first layer in an ambient environment having a predetermined concentration of nitrogen in order to form a blanket layer of a refractory metallic nitride having a predetermined thickness; (d) placing an amorphous, co-deposited third refractory metal: silicon layer, having a predetermined thickness and a predetermined atomic ratio of silicon to refractory metal, on said blanket layer; and (e) transforming said co-deposited layer to a refractory metallic dicilicide layer by heating at a predetermined temperature for a predetermined amount of time in a second predetermined ambient environment.
Claim 13
Dependent Claim
20 words
The method of claim 10 wherein said dopant is selected from the group consisting of boron, phosphorous, arsenic and antimony.
Claim 14
Dependent Claim
10 words
The method of claim 11 wherein said dopant is boron.
Claim 15
Dependent Claim
27 words
The method of claim 10 wherein said first, second and third refractory metals are selected from the group consisting of tantalum, titanium, niobium, zirconium, chromium and hafnium.
Claim 16
Dependent Claim
14 words
The method in accordance with claim 13, wherein said first refractory metal comprises titanium.
Claim 17
Dependent Claim
14 words
The method in accordance with claim 13 wherein said second refractory metal comprises tantalum.
Claim 18
Dependent Claim
14 words
The method in accordance with claim 13 wherein said third refractory metal comprises tantalum.
Claim 19
Dependent Claim
18 words
The method of claim 16 wherein the thickness of said co-deposited layer is substantially equal to 2500 Å.
Claim 20
Dependent Claim
19 words
The method of claim 17 wherein said predetermined atomic ratio of silicon to tantalum is substantially equal to 2.5:1.
Claim 21
Dependent Claim
40 words
The method of claim 18 wherein said amorphous tantalum: silicon layer is transformed to tantalum disilicide by heating at a temperature substantially equal to 950° C. for a time substantially equal to 30 minutes in an ambient environment of hydrogen.
Claim 22
Dependent Claim
20 words
The method of claim 10 wherein the thickness of said first refractory metal layer is substantially equal to 50 Å.
Claim 23
Dependent Claim
24 words
The method of claim 10 wherein the thickness of said blanket layer is in a range of from approximately 200 Å to 1000 Å.
Claim 24
Dependent Claim
24 words
The method of claim 10 wherein the concentration of nitrogen is in a range of from approximately 1×10 -6 torr to 1×10 -2 torr.
Claim 25
Dependent Claim
69 words
The method of claim 10 comprising the additional steps of: (a) etching through said metallic disilicide, blanket and first refractory metal layers to said silicon substrate surface in predetermined locations on said first surface; (b) disposing a layer of silicon dioxide over said etched and non-etched portions; (c) covering said layer of silicon dioxide with a layer of glass; and (d) reflowing said glass layer at a predetermined temperature.
Claim 26
Dependent Claim
26 words
The method in accordance with claim 17 wherein said glass is reflowed at a temperature in the range of from approximately 825° C. to 1000° C.
Claim 27
Dependent Claim
63 words
In a semiconductor device including a silicon substrate containing a dopant and having a first refractory metal layer disposed on at least one portion of one surface thereof, a method of blocking silicon transport from said substrate to said first refractory metal layer comprising the step of disposing a refractory metal nitride barrier layer between said substrate and said first refractory metal layer.
Claim 28
Dependent Claim
63 words
In a semiconductor device including a silicon substrate containing a dopant and having a first refractory metal layer disposed on at least one portion of one surface thereof, a method of blocking silicon transport from said substrate to said first refractory metal layer comprising the step of disposing a refractory metal nitride barrier layer between said substrate and said first refractory metal layer.
Claim 29
Dependent Claim
28 words
The method in accordance with claim 25 wherein said barrier layer includes a refractory metal selected from the group consisting of tantalum, niobium, titanium, zirconium, chromium and hafnium.
Claim 30
Dependent Claim
27 words
The method in accordance with claim 26 wherein said first refractory metal layer comprises a refractory metel selected from the group consisting of molybdenum, tungsten and tantalum.
Claim 31
Dependent Claim
27 words
The method in accordance with claim 27 comprising an additional step of disposing a second layer of refractory metal between said barrier layer and said silicon substrate.
Claim 32
Dependent Claim
30 words
The method in accordance with claim 28 wherein said second refractory metal layer comprises a refractory metal selected from the group consisting of tantalum, niobium, titanium, zirconium, chromium and hafnium.
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