Method using disposable and permanent films for diffusion and implant doping
First Claim
1. A method for making a transistor on a substrate of a semiconductor wafer, the method comprising the steps of:
- a) forming a gate oxide over the substrate;
b) forming at least one gate layer over the gate oxide;
c) patterning the at least one gate layer and the gate oxide to create a gate, the patterning creating two exposed substrate regions on opposing sides of the gate;
d) forming and patterning a conforming layer to form decomposable sidewall spacers on sidewalls of the gate;
e) implanting exposed portions of the semiconductor wafer with a dopant of a first type to implant source/drain regions in the substrate;
f) heating the substrate sufficiently to anneal and activate the dopant to further form the source/drain regions;
g) removing the decomposable sidewall spacers;
h) forming a second conforming layer over the gate and source/drain regions;
i) doping the second conforming layer with a dopant of the first type;
j) beating the substrate at a temperature high enough to cause diffusion of the dopant of the first type from the conforming layer and into underlying layers, thereby creating extensions in the source/drain regions; and
k) removing at least a portion of the second conforming layer to expose at least the source/drain regions; and
wherein the step of doping the second conforming layer with a dopant of the first type comprises the step of implanting the second conforming layer with a dopant of the first type having an energy, wherein a higher dopant energy is chosen with a thicker second conforming layer and a lower dopant energy is chosen with a thinner second conforming layer, the step of implanting performed wherein the dopant impinges a surface of he semiconductor at angles ranging between 45 and 60 degrees.
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Abstract
Methods are provided that use disposable and permanent films to dope underlying layers through diffusion. Additionally, methods are provided that use disposable films during implantation doping and that provide a surface from which to dope underlying materials. Some of these disposable films can be created from a traditionally non-disposable film and made disposable. In this manner, solvents may be used that do not etch underlying layers of silicon-based materials. Preferably, deep implantation is performed to form source/drain regions, then an anneal step is performed to activate the dopants. A conformal layer is deposited and implanted with dopants. One or more anneal steps are performed to create very shallow extensions in the source/drain regions.
45 Citations
26 Claims
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1. A method for making a transistor on a substrate of a semiconductor wafer, the method comprising the steps of:
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a) forming a gate oxide over the substrate;
b) forming at least one gate layer over the gate oxide;
c) patterning the at least one gate layer and the gate oxide to create a gate, the patterning creating two exposed substrate regions on opposing sides of the gate;
d) forming and patterning a conforming layer to form decomposable sidewall spacers on sidewalls of the gate;
e) implanting exposed portions of the semiconductor wafer with a dopant of a first type to implant source/drain regions in the substrate;
f) heating the substrate sufficiently to anneal and activate the dopant to further form the source/drain regions;
g) removing the decomposable sidewall spacers;
h) forming a second conforming layer over the gate and source/drain regions;
i) doping the second conforming layer with a dopant of the first type;
j) beating the substrate at a temperature high enough to cause diffusion of the dopant of the first type from the conforming layer and into underlying layers, thereby creating extensions in the source/drain regions; and
k) removing at least a portion of the second conforming layer to expose at least the source/drain regions; and
wherein the step of doping the second conforming layer with a dopant of the first type comprises the step of implanting the second conforming layer with a dopant of the first type having an energy, wherein a higher dopant energy is chosen with a thicker second conforming layer and a lower dopant energy is chosen with a thinner second conforming layer, the step of implanting performed wherein the dopant impinges a surface of he semiconductor at angles ranging between 45 and 60 degrees. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
I) depositing germanium dioxide or SixGe(1−
x), wherein x is less than or equal to 0.3, through chemical vapor deposition; and
II) anisotropically etching the conforming layer.
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11. The method of claim 8 wherein:
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the method further comprises, after the step of forming and patterning a conforming layer to form decomposable sidewall spacers on sidewalls of the gate, the steps of;
I) forming a protective layer over the gate and its two exposed substrate regions on opposing sides of the gate; and
II) forming and patterning a photoresist layer on the substrate that exposes the gate and its two exposed substrate regions on opposing sides of the gate; and
the step of implanting exposed portions of the semiconductor wafer with a dopant of a first type to implant source/drain regions in the substrate further comprises the steps of;
I) removing the photoresist layer; and
II) removing the protective layer.
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12. The method of claim 11 wherein the protective layer is selected from the group consisting essentially of anti-reflective coating, silicon dioxide, silicon oxynitride, or Parylene.
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13. The method of claim 1, wherein the second conforming layer comprises germanium dioxide or SixGe(1−
- x), wherein x is less than or equal to 0.3.
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14. The method of claim 13 wherein the step of removing at least a portion of the second conforming layer to expose at least the source/drain regions comprises the step of removing the second conforming layer by placing the substrate in water.
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15. The method of claim 13 wherein:
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the method further comprises, after the step of forming a second conforming layer over the gate and source/drain regions, the steps of;
I) forming a protective layer over the portion of the second conforming layer that covers gate and its two exposed substrate regions on opposing sides of the gate; and
II) forming and patterning a photoresist layer on the substrate that exposes the portion of the second conforming layer that covers the gate and its two exposed substrate regions on opposing sides of the gate; and
the step of implanting the second conforming layer with a dopant of the first type further comprises the steps of;
I) removing the photoresist layer; and
II) removing the protective layer.
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16. The method of claim 15 wherein the protective layer is selected from the group consisting essentially of anti-reflective coating, silicon dioxide, silicon oxynitride, or parylene.
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17. The method of claim 1, wherein the step of forming a second conforming layer over the gate and source/drain regions comprises the step of depositing a second conformal layer that comprises geranium.
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18. The method of claim 17 wherein the germanium is deposited through chemical vapor deposition.
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19. A method for making a transistor on a substrate of a semiconductor wafer, the method comprising the steps of:
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a) forming a gate oxide over the substrate;
b) forming at least one gate layer over the gate oxide;
c) patterning the at least one gate layer and the gate oxide to create a gate, the patterning creating two exposed substrate regions on opposing sides of the gate;
d) forming and patterning a conforming layer to form decomposable sidewall spacers on sidewalls of the gate;
e) implanting exposed portions of the semiconductor wafer with a dopant of a first type to implant source/drain regions in the substrate;
f) heating the substrate sufficiently to anneal and activate the dopant to further form the source/drain regions;
g) removing the decomposable sidewall spacers;
h) forming a second conforming layer over the gate and source/drain regions;
i) doping the second conforming layer with a dopant of the firs type;
j) healing the substrate at a temperature high enough to cause diffusion of the dopant of the first type from the conforming layer and into underlying layers, thereby creating extensions in the source/drain regions; and
k) removing at least a portion of the second conforming layer to expose at least the source/drain regions; and
wherein the step of form and patterning a conforming layer to form decomposable sidewall spacers on sidewalls of the gate comprises the step of depositing the conformal layer comprising germanium; and
wherein the step of removing the decomposable sidewall spacers comprises the steps of;
I) heating the substrate in an oxygen atmosphere at a temperature above 500 degrees centigrade wherein the germanium in the decomposable sidewall spacers is converted into water-soluble germanium dioxide; and
II) removing the decomposable sidewall spacers by placing the substrate in water. - View Dependent Claims (20)
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21. A method for making a transistor on a substrate of a semiconductor wafer, the method comprising the steps of:
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a) forming a gate oxide over the substrate;
b) forming at least one gate layer over the gate oxide;
c) patterning the at least one gate layer and the gate oxide to create a gate, the patterning creating two exposed substrate regions on opposing sides of the gate;
d) forming and patterning a conforming layer to form decomposable sidewall spacers on sidewalls of the gate;
e) implanting exposed portions of the semiconductor wafer with a dopant of a first type to implant source/drain regions in the substrate;
f) heating the substrate sufficiently to anneal and activate the dopant to further form the source/drain regions;
g) removing the decomposable sidewall spacers;
h) forming a second conforming layer over the gate and source/drain regions;
i) doping the second conforming layer with a dopant of the first type;
j) heating the substrate at a temperature high enough to cause diffusion of the dopant of the first type from the conforming layer and into underlying layers thereby creating extensions in the source/drain regions; and
k) removing at least a portion of the second conforming layer to expose at least the source/drain regions, and wherein the step of forming and patterning a conforming layer to form decomposable sidewall spacers on sidewalls of the gate comprises the step of depositing a conformal layer that comprises SixGe(1−
x), where in x is less than or equal to 0.3.- View Dependent Claims (22, 23)
I) heating the substrate in an oxygen atmosphere at a temperature above 500 degrees centigrade wherein the germanium in the decomposable sidewall spacers is converted into water-soluble germanium dioxide; and
II) removing the decomposable sidewall spacers by placing the substrate in water.
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24. A method for making a transistor on a substrate of a semiconductor wafer, the method comprising the steps of:
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a) forming a gate oxide over the substrate;
b) forming at least one gate layer over the gate oxide;
c) patterning the at least one gate layer and the gate oxide to create a gate, the patterning creating two exposed substrate regions on opposing sides of the gate;
d) forming and patterning a conforming layer to form decomposable sidewall spacers on sidewalls of the gate;
e) implanting exposed potfons of the semiconductor wafer with a dopant of a first to implant second drain regions in the substrate;
f) heating the substrate sufficiently to anneal and active the dopant to further form the source/drain regions;
g) removing the decomposable sidewall spacers;
h) forming a second conforming layer over the gate and source/drain regions;
i) doping the second conforming layer with a dopant of the first type;
j) heating the substrate at a temperature high enough to cause diffusion of the dopant of the first type from the conforming layer and into underlying layer, thereby creating extensions in the source/drain regions, and k) removing at least a portion of the second conforming layer to expose at least the source/drain region; and
wherein the step of forming a second conforming layer over the gate and source/drain regions comprises the step of depositing a second conformal layer that comprises germanium; and
wherein the step of removing at least a portion of the second conforming layer to expose at least the source/drain regions comprises the steps of;
I) heating the substrate in an oxygen atmosphere at a temperature above 500 degrees centigrade wherein the germanium in the second conformal layer is converted into water-soluble germanium dioxide; and
II) removing the germanium dioxide and the second conformal layer by placing the substrate in water. - View Dependent Claims (25, 26)
l) forming a third conforming layer of silicon dioxide over the gate and source/drain regions; and
m) anisotropically patterning the third conforming layer to form sidewall spacers on sidewalls of the gate.
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Specification