Preserving TEOS hard mask using COR for raised source-drain including removable/disposable spacer
First Claim
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1. A method of forming a complementary metal oxide semiconductor (CMOS) device comprising the steps of:
- (a) providing a material stack atop a surface of a semiconductor substrate, said material stack comprising an oxide hard mask located atop a gate conductor, which is located atop a gate dielectric;
(b) patterning said oxide hard mask and said gate conductor of said material stack;
(c) performing a post etch cleaning step utilizing a first chemical oxide removal (COR) step;
(d) forming a disposable spacer on at least each sidewall of said patterned gate conductor;
(e) removing portions of said gate dielectric not protected by said disposable spacers and said patterned gate conductor to expose portions of said semiconductor substrate wherein said removing comprises a second chemical oxide removal step;
(f) forming raised source/drain regions in said exposed portions of the semiconductor substrate; and
(g) removing said disposable spacers to expose portions of said semiconductor substrate abutting the patterned gate coductor.
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Abstract
The present invention provides a method for preserving an oxide hard mask for the purpose of avoiding growth of epi Si on the gate stack during raised source/drain formation. The oxide hard mask is preserved in the present invention by utilizing a method which includes a chemical oxide removal processing step instead of an aqueous HF etchant.
119 Citations
23 Claims
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1. A method of forming a complementary metal oxide semiconductor (CMOS) device comprising the steps of:
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(a) providing a material stack atop a surface of a semiconductor substrate, said material stack comprising an oxide hard mask located atop a gate conductor, which is located atop a gate dielectric;
(b) patterning said oxide hard mask and said gate conductor of said material stack;
(c) performing a post etch cleaning step utilizing a first chemical oxide removal (COR) step;
(d) forming a disposable spacer on at least each sidewall of said patterned gate conductor;
(e) removing portions of said gate dielectric not protected by said disposable spacers and said patterned gate conductor to expose portions of said semiconductor substrate wherein said removing comprises a second chemical oxide removal step;
(f) forming raised source/drain regions in said exposed portions of the semiconductor substrate; and
(g) removing said disposable spacers to expose portions of said semiconductor substrate abutting the patterned gate coductor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
forming source/drain extension regions in portions of said semiconductor substrate that are left exposed after removing step g; and
forming source/drain regions in at least said raised source/drain regions.
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3. The method of claim 1 wherein said oxide hard mask is comprised of an oxide formed by chemical vapor deposition of tetraethylorthosilicate.
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4. The method of claim 1 wherein said first COR process comprises a gaseous mixture of HF and ammonia.
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5. The method of claim 4 wherein said gaseous mixture of HF and ammonia comprises a ratio of 2 parts HF and 1 part ammonia.
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6. The method of claim 1 wherein said first COR process is performed at a pressure between 1 mTorr and at a temperature of about 25°
- C.
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7. The method of claim 1 wherein said disposable spacers are comprised of SiO2.
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8. The method of claim 1 wherein said second COR process comprises a gaseous mixture of HF and ammonia.
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9. The method of claim 8 wherein said gaseous mixture of HF and ammonia comprises a ratio of 2 parts HF and 1 part ammonia.
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10. The method of claim 1 wherein said second COR process is performed at a pressure between 1 mTorr and at a temperature of about 25°
- C.
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11. The method of claim 10 wherein said second COR process results in the formation of a solid reaction product.
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12. The method of claim 11 wherein said solid reaction product is removed by heating to a temperature of about 100°
- C., rinsing in water, or an aqueous solution.
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13. The method of claim 11 wherein said solid reaction product is removed by heating to a temperature of about 100°
- C. and with an aqueous HF solution.
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14. The method of claim 1 wherein step (f) comprises an epi Si growth process.
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15. The method of claim 1 further comprising forming source/drain regions prior to the removing of the disposable spacers.
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16. The method of claim 1 wherein said removing of the disposable spacers further comprises the removing of the oxide hard mask and the removing of the gate dielectric underlying the disposable spacers.
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17. The method of claim 1 wherein said removing of the disposable spacers does not remove the oxide hard mask and the underlying gate dielectric.
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18. The method of claim 17 wherein the disposable spacers are removed by hot phosphoric acid.
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19. A method of forming a complementary metal oxide semiconductor (CMOS) device comprising the steps of:
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(a) providing a material stack atop a surface of a semiconductor substrate, said material stack comprising an oxide hard mask located atop a gate conductor, which is located atop a gate dielectric;
(b) patterning said oxide hard mask and said gate conductor of said material stack;
(c) performing a post etch cleaning step utilizing a first chemical oxide removal (COR) step;
(d) forming a disposable spacer comprising SiO2 on at least each sidewall of said patterned gate conductor;
(e) removing portions of said gate dielectric not protected by said disposable spacers and said patterned gate conductor to expose portion of said semiconductor, wherein said removing comprising a second COR step;
(f) forming raised source/drain regions in said exposed portions of the semiconductor substrate; and
(g) removing said disposable spacers to expose portions of said semiconductor substrate abutting the patterned gate conductor. - View Dependent Claims (20, 21, 22, 23)
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Specification