MAIN SPACER TRIM-BACK METHOD FOR REPLACEMENT GATE PROCESS
First Claim
1. A method of trimming back main spacers of replacement gate structures on a substrate, comprising:
- forming main spacers for replacement gate structures on the substrate, wherein the replacement gate structures have a dielectric layer, a dummy layer over the dielectric layer, and a hard mask over the dummy layer;
performing source and drain implants, wherein source and drain patterns are formed to allow source and drain implants to be performed on desired regions of the substrate and the source and drain patterns are removed from the substrate after the source and drain implants are performed;
trimming back the main spacers to increase a space between two adjacent replacement gate structures on the substrate to allow proper formation of metal silicide by subsequent processing;
after said trimming back, performing source and drain anneal; and
forming the metal silicide on the substrate.
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Abstract
The embodiments of methods described in this disclosure for trimming back nitride spacers for replacement gates allows the hard mask layers (or hard mask) to protect the polysilicon above the high-K dielectric during trim back process. The process sequence also allows determining the trim-back amount based on the process uniformity (or control) of nitride deposition and nitride etchback (or trimming) processes. Nitride spacer trim-back process integration is critical to avoid creating undesirable consequences, such as silicided polyisicon on top of high-K dielectric described above. The integrated process also allows widening the space between the gate structures to allow formation of silicide with good quality and allow contact plugs to have sufficient contact with the silicide regions. The silicide with good quality and good contact between the contact plugs and the silicide regions increase the yield of contact and allows the contact resistance to be in acceptable and workable ranges.
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Citations
21 Claims
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1. A method of trimming back main spacers of replacement gate structures on a substrate, comprising:
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forming main spacers for replacement gate structures on the substrate, wherein the replacement gate structures have a dielectric layer, a dummy layer over the dielectric layer, and a hard mask over the dummy layer; performing source and drain implants, wherein source and drain patterns are formed to allow source and drain implants to be performed on desired regions of the substrate and the source and drain patterns are removed from the substrate after the source and drain implants are performed; trimming back the main spacers to increase a space between two adjacent replacement gate structures on the substrate to allow proper formation of metal silicide by subsequent processing; after said trimming back, performing source and drain anneal; and forming the metal silicide on the substrate. - View Dependent Claims (3, 4, 5, 6, 7, 9, 10, 11, 21)
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2. A method of trimming back main nitride spacers of replacement gate structures on a substrate, comprising:
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forming main nitride spacers for replacement gate structures on the substrate, wherein the replacement gate structures have a high dielectric constant (high-K) dielectric layer, a dummy polysilicon layer over the high-K dielectric layer, and a hard mask with an oxide layer over a nitride layer; performing source and drain implants, wherein source and drain patterns are formed to allow source and drain implants to be performed on desired regions of the substrate and the source and drain patterns are removed from the substrate after the source and drain implants are performed; trimming back the main nitride spacers to increase a space between two adjacent replacement gate structures on the substrate to allow proper formation of metal silicide by subsequent processing and to increase contact yield; performing source and drain anneal; and forming the metal silicide on the substrate; wherein a thin oxide layer formed on the substrate as a result of the removal of the source and drain patterns, and the method further comprises removing the thin oxide layer before the main nitride spacers are trimmed back. - View Dependent Claims (8)
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12. A method of trimming back main nitride spacers of replacement gate structures on a substrate, comprising:
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forming main nitride spacers for replacement gate structures on the substrate, wherein the replacement gate structures have a high dielectric constant (high-K) dielectric layer and a dummy polysilicon layer over the high-K dielectric layer, and a hard mask with an oxide layer over a nitride layer; performing source and drain implants, wherein source and drain patterns are formed to allow source and drain implants to be performed on desired regions of the substrate and the source and drain patterns are removed from the substrate after the source and drain implants are performed; performing first trim-back of the main nitride spacers to increase a space between two adjacent replacement gate structures on the substrate to allow proper formation of metal silicide by subsequent processing and to increase contact yield; performing source and drain anneal; implanting polysilicon on the substrate before the forming of the metal silicide, wherein the implanted polysilicon improves the quality of the metal silicide formed, and wherein the first trim-back of the main nitride spacers reduces shadowing effect of polysilicon implant; forming the metal silicide on the substrate; and performing second trim-back of the main nitride spacers to increase the space between two adjacent replacement gate structures on the substrate to further increase the contact yield. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A method of trimming back main nitride spacers of replacement gate structures on a substrate, comprising:
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forming main nitride spacers for replacement gate structures on the substrate, wherein the replacement gate structures have a high dielectric constant (high-K) dielectric layer, a dummy polysilicon layer over the high-K dielectric layer, and a hard mask with an oxide layer over a nitride layer; performing source and drain implants, wherein source and drain patterns are formed to allow source and drain implants to be performed on desired regions of the substrate and the source and drain patterns are removed from the substrate after the source and drain implants are performed; performing first trim-back of the main nitride spacers to increase a space between two adjacent replacement gate structures on the substrate to allow proper formation of metal silicide by subsequent processing; performing source and drain anneal; forming the metal silicide on the substrate; and performing second trim-back of the main nitride spacers to increase the space between two adjacent replacement gate structures on the substrate.
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Specification