FinFETs with controllable and adjustable channel doping
A method of forming features of a finFET structure includes forming fins on a surface of a substrate. A first liner is formed around each fin and a shallow trench isolation region is formed around each fin. A dopant layer is implanted in each fin. A portion of the shallow trench isolation region is etched from each fin. A first portion of the structure is blocked and the first liner replaced with a second liner in a second portion of the structure.
1. A method of forming features of a finFET structure, comprising:
forming fins on a surface of a substrate;
forming a first liner on a sidewall of each fin and on a surface of the substrate;
forming a shallow trench isolation region around each fin and on a surface of the first liner;
implanting a dopant layer in each fin;
recessing a portion of the shallow trench isolation region to expose a top portion of the first liner;
blocking a first fin in a first region of the substrate;
removing the top portion of the first liner in a second region of the substrate to expose a top portion of each fin in the second region of the substrate; and
forming a second liner on the exposed top portion of each fin in the second region of the substrate such that the second liner contacts a top portion of the sidewall of each fin and the first liner contacts a bottom portion of the sidewall of each fin.
2. The method of claim 1 , wherein the first liner and the second liner comprise a different material.
3. The method of claim 1 , wherein the first liner comprises a material selected from nitride, nitride oxide, or a combination comprising at least one of the foregoing.
4. The method of claim 1 , wherein the second liner comprises an oxide.
5. The method of claim 4 , wherein the second liner comprises silicon dioxide.
6. The method of claim 1 , wherein the second liner is formed onto the structure with by a method selected from chemical vapor deposition, plasma deposition, physical vapor deposition, atomic layer deposition or a combination comprising at least one of the foregoing.
7. The method of claim 6 , wherein the method is plasma enhanced chemical vapor deposition.
8. The method of claim 1 , wherein the second liner is used to control and adjust channel doping for the fin.
9. The method of claim 1 , wherein the first region comprises a high threshold voltage region of the structure.
10. The method of claim 1 , wherein the second region comprises a low threshold voltage region of the structure.
11. A method of forming features of a finFET structure, comprising:
forming fins on a surface of a substrate;
forming a first liner comprising a nitride on a sidewall of each fin and on a surface of the substrate;
forming a shallow trench isolation region around each fin and on a surface of the first liner;
removing a fin from the structure;
implanting a dopant layer in each fin;
recessing a portion of the shallow trench isolation region to expose a top portion of the first liner;
blocking a high threshold voltage region of the structure;
removing the top portion of the first liner in a low threshold voltage region of the structure to expose a top portion of each fin in the low threshold voltage region of the structure; and
forming a second liner on the exposed top portion of each fin in the low threshold voltage region of the structure such that the second liner contacts a top portion of the sidewall of each fin and the first liner contacts a bottom portion of the sidewall of each fin;
forming a dummy gate and spacers over a fin; and
performing a source/drain epitaxy to form the finFET structure.
12. The method of claim 11 , wherein the second liner is used to control and adjust channel doping for the fin.