US7118973B1
Expired / Lapsed
US
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Method of forming a transistor with a channel region in a layer of composite material
Assignee: National Semiconductor Corp
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Filing: 2004-06-16
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Granted: 2006-10-10
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Expires: 2024-06-16
Abstract
Abstract The vertical diffusion of dopants from the gate and the bulk material into the channel region, and the lateral diffusion of dopants from the source and drain regions into the channel region resulting from thermal cycling during the fabrication of a MOS transistor is minimized by forming the source and drain regions in a layer of composite material that includes silicon, germanium, and carbon.
Inventors
- 👤 Abdalla Aly Naem
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:33
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0223; H10D30/0227; H10D30/60; H10D30/601; H10D30/751
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
203 words
A method of forming a MOS transistor on a semiconductor material of a first conductivity type, the method comprising: forming a layer of composite material of the first conductivity type on the semiconductor material, the layer of composite material including a first layer, a second layer that contacts a top surface of the first layer, a third layer that contacts a top surface of the second layer, and a fourth layer that contacts a top surface of the third layer, the first layer including silicon and carbon, the second layer including silicon and being substantially free of carbon, the third layer including silicon and carbon, the fourth layer including silicon and being substantially free of carbon; forming an insulation layer on the layer of composite material; forming a layer of conductive material on the insulation layer; etching the layer of conductive material to form a gate; and forming spaced-apart source and drain regions of a second conductivity type in the layer of composite material on opposite sides of the gate, an isolation region adjoining the semiconductor material, the isolation region having a top surface, the semiconductor material having a top surface that is substantially coplanar with the top surface of the isolation region.
Claim 2
Independent Claim
203 words
A method of forming a MOS transistor on a semiconductor material of a first conductivity type, the method comprising: forming a layer of composite material of the first conductivity type on the semiconductor material, the layer of composite material including a first layer, a second layer that contacts a top surface of the first layer, a third layer that contacts a top surface of the second layer, and a fourth layer that contacts a top surface of the third layer, the first layer including silicon and carbon, the second layer including silicon and being substantially free of carbon, the third layer including silicon and carbon, the fourth layer including silicon and being substantially free of carbon; forming an insulation layer on the layer of composite material; forming a layer of conductive material on the insulation layer; etching the layer of conductive material to form a gate; and forming spaced-apart source and drain regions of a second conductivity type in the layer of composite material on opposite sides of the gate, an isolation region adjoining the semiconductor material, the isolation region having a top surface, the semiconductor material having a top surface that is substantially coplanar with the top surface of the isolation region.
Claim 3
Independent Claim
147 words
A method of forming a MOS transistor on a semiconductor material of a first conductivity type, the method comprising: forming a layer of composite material of the first conductivity type on the semiconductor material, the layer of composite material including a first layer, a second layer that contacts a top surface of the first layer, and a third layer that contacts a top surface of the second layer, the first layer including silicon and carbon, the second layer including silicon and being substantially free of carbon, the third layer including silicon and carbon; forming an insulation layer on the layer of composite material; forming a layer of conductive material on the insulation layer; etching the layer of conductive material to form a gate; and forming spaced-apart source and drain regions of a second conductivity type in the layer of composite material on opposite sides of the gate.
Claim 4
Independent Claim
147 words
A method of forming a MOS transistor on a semiconductor material of a first conductivity type, the method comprising: forming a layer of composite material of the first conductivity type on the semiconductor material, the layer of composite material including a first layer, a second layer that contacts a top surface of the first layer, and a third layer that contacts a top surface of the second layer, the first layer including silicon and carbon, the second layer including silicon and being substantially free of carbon, the third layer including silicon and carbon; forming an insulation layer on the layer of composite material; forming a layer of conductive material on the insulation layer; etching the layer of conductive material to form a gate; and forming spaced-apart source and drain regions of a second conductivity type in the layer of composite material on opposite sides of the gate.
Claim 5
Dependent Claim
86 words
The method of claim 2 and further comprising: forming a first material on a top surface of the semiconductor material before the layer of composite material is formed; and removing a portion of the first material to expose a region of the top surface of the semiconductor material and leave a remaining portion of the first material on the top surface of the semiconductor material, the layer of composite material being formed on the top surface of the semiconductor material and surrounded by the first material.
Claim 6
Dependent Claim
45 words
The method of claim 2 wherein the forming a layer of composite material includes: removing a portion of the semiconductor material to expose an etched surface of the semiconductor material; and growing the layer of composite material on the etched surface of the semiconductor material.
Claim 7
Dependent Claim
14 words
The method of claim 4 and further comprising planarizing the layer of composite material.
Claim 8
Dependent Claim
35 words
The method of claim 2 wherein the layer of composite material includes a fourth layer that contacts a top surface of the third layer, the fourth layer including silicon and being substantially free of carbon.
Claim 9
Dependent Claim
39 words
The method of claim 6 wherein an isolation region adjoins the semiconductor material, the isolation region having a top surface, the layer of composite material having a top surface that lies above the top surface of the isolation region.
Claim 10
Dependent Claim
13 words
The method of claim 6 wherein the second and third layers include germanium.
Claim 11
Dependent Claim
14 words
The method of claim 8 wherein the fourth layer is substantially free of germanium.
Claim 12
Dependent Claim
20 words
The method of claim 6 wherein an isolation region adjoins the semiconductor material, the isolation region having a top surface.
Claim 13
Dependent Claim
60 words
The method of claim 10 wherein the forming a layer of composite material includes: removing a portion of the semiconductor material to expose an etched surface of the semiconductor material, the etched surface of the semiconductor material lying below the top surface of the isolation region; and growing the layer of material on the etched surface of the semiconductor material.
Claim 14
Dependent Claim
36 words
The method of claim 11 and further comprising planarizing the layer of composite material so that the top surface of the layer of composite material and the top surface of the isolation region are substantially coplanar.
Claim 15
Independent Claim
246 words
A method of forming a MOS transistor on a semiconductor material of a first conductivity type, the method comprising: forming a layer of composite material of the first conductivity type on the semiconductor material, the layer of composite material including a first layer, a second layer that contacts a top surface of the first layer, and a third layer that contacts a top surface of the second layer, the first layer including silicon and carbon, the second layer including silicon and being substantially free of carbon, the third layer including silicon and carbon; forming an insulation layer on the layer of composite material; forming a layer of conductive material on the insulation layer; etching the layer of conductive material to form a gate; forming spaced-apart source and drain regions of a second conductivity type in the layer of composite material on opposite sides of the gate; forming a first material on a top surface of the semiconductor material before the layer of composite material is formed; removing a portion of the first material to expose a region of the top surface of the semiconductor material and leave a remaining portion of the first material on the top surface of the semiconductor material, the layer of composite material being formed on the top surface of the semiconductor material and surrounded by the first material; and removing the remaining portion of the first material from the top surface of the semiconductor material before the insulation layer is formed.
Claim 16
Independent Claim
246 words
A method of forming a MOS transistor on a semiconductor material of a first conductivity type, the method comprising: forming a layer of composite material of the first conductivity type on the semiconductor material, the layer of composite material including a first layer, a second layer that contacts a top surface of the first layer, and a third layer that contacts a top surface of the second layer, the first layer including silicon and carbon, the second layer including silicon and being substantially free of carbon, the third layer including silicon and carbon; forming an insulation layer on the layer of composite material; forming a layer of conductive material on the insulation layer; etching the layer of conductive material to form a gate; forming spaced-apart source and drain regions of a second conductivity type in the layer of composite material on opposite sides of the gate; forming a first material on a top surface of the semiconductor material before the layer of composite material is formed; removing a portion of the first material to expose a region of the top surface of the semiconductor material and leave a remaining portion of the first material on the top surface of the semiconductor material, the layer of composite material being formed on the top surface of the semiconductor material and surrounded by the first material; and removing the remaining portion of the first material from the top surface of the semiconductor material before the insulation layer is formed.
Claim 17
Dependent Claim
32 words
The method of claim 13 wherein an isolation region adjoins the semiconductor material, the layer of composite material having a top surface that lies above a top surface of the isolation region.
Claim 18
Dependent Claim
13 words
The method of claim 14 wherein the second and third layers include germanium.
Claim 19
Dependent Claim
35 words
The method of claim 15 wherein the layer of composite material includes a fourth layer that contacts a top surface of the third layer, the fourth layer including silicon and being substantially free of carbon.
Claim 20
Dependent Claim
14 words
The method of claim 16 wherein the fourth layer is substantially free of germanium.
Claim 21
Dependent Claim
13 words
The method of claim 17 wherein the composite layer is selectively epitaxially grown.
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