Nanosheet devices with CMOS epitaxy and method of forming
This disclosure relates to a method of forming nanosheet devices including: forming a first and second nanosheet stack on a substrate, the first and the second nanosheet stacks including a plurality of vertically spaced nanosheets disposed on the substrate and separated by a plurality of spacing members, each of the plurality of spacing members including a sacrificial layer and a pair of inner spacers formed on lateral ends of the sacrificial layer; growing a pair of epitaxial regions adjacent to the first and second nanosheet stacks from each of the plurality of nanosheets such that each of the plurality of inner spacers is enveloped by one of the epitaxial regions; covering the first nanosheet stack with a mask; and forming a pair of p-type source/drain regions on the second nanosheet stack, each of the pair of p-type source/drain regions being adjacent to the epitaxial regions on the second nanosheet stack.
1. A method comprising:
forming a first and second nanosheet stack on a substrate, the first and the second nanosheet stacks each including a plurality of vertically spaced nanosheets disposed on the substrate and separated by a plurality of spacing members, each of the plurality of spacing members including a sacrificial layer and a pair of inner spacers formed on lateral ends of the sacrificial layer;
growing a pair of epitaxial regions adjacent to each of the first and the second nanosheet stacks from each of the plurality of nanosheets such that each of the plurality of inner spacers is enveloped by one of the epitaxial regions;
covering the first nanosheet stack with a mask; and
forming a pair of p-type source/drain regions on the second nanosheet stack, each of the pair of p-type source/drain regions being adjacent to one of the epitaxial regions on the second nanosheet stack.
2. The method of claim 1 , wherein the pair of epitaxial regions is formed on each of the plurality of nanosheet stacks prior to the covering of the first nanosheet stack with the mask.
3. The method of claim 1 , further comprising: prior to forming the pair of p-type source/drain regions, partially removing the pair of epitaxial regions on the second nanosheet stack such that each of the plurality of inner spacers of the second nanosheet stack remains enveloped by a remaining portion of one of the pair of epitaxial regions on the second nanosheet stack.
4. The method of claim 1 , further comprising:
covering the second nanosheet stack with a mask; and
forming a pair of n-type source/drain regions on the pair of epitaxial regions on the first nanosheet stack.
5. The method of claim 1 , wherein the pair of epitaxial regions on each of the first and second nanosheet stacks includes undoped silicon.
6. The method of claim 1 , wherein the first nanosheet stack is formed adjacent to the second nanosheet stack on the substrate.
7. The method of claim 3 , wherein the covering of the first nanosheet stack includes:
forming a liner over the first and the second nanosheet stacks;
forming a soft mask over the liner on the first nanosheet stack; and
removing a horizontal portion of the liner over the pair of epitaxial regions on the second nanosheet stack and leaving a vertical portion of the liner on sidewalls of the second nanosheet stack.
8. The method of claim 7 , further comprising etching the pair of epitaxial regions on the second nanosheet stack with an anisotropic etch selective to the substrate and the vertical portion of the liner to reduce a width of the pair of epitaxial regions on the second nanosheet stack such that each of the plurality of inner spacers of the second nanosheet stack remains enveloped by one of the pair of epitaxial regions on the second nanosheet stack.
9. The method of claim 7 , wherein the pair of epitaxial regions on each of the first nanosheet stack and the second nanosheet stack is an n-type doped material.
10. The method of claim 9 , further comprising removing all of the pair of epitaxial regions from the second nanosheet stack, selective to the nanosheets of the second nanosheet stack, the inner spacers, and the substrate.
11. A method comprising:
forming a first and second nanosheet stack on a substrate such that the first nanosheet stack is adjacent to the second nanosheet stack, the first and the second nanosheet stacks each including a plurality of vertically spaced nanosheets disposed on the substrate and separated by a plurality of spacing members, each of the plurality of spacing members including a sacrificial layer and a pair of inner spacers formed on lateral ends of the sacrificial layer;
growing a pair of epitaxial regions adjacent to each of the first and the second nanosheet stacks from each of the plurality of nanosheets such that each of the plurality of inner spacers is enveloped by one of the epitaxial regions, the pair of epitaxial regions on each of the first and second nanosheet stacks includes undoped silicon;
covering the first nanosheet stack with a first mask;
forming a pair of p-type source/drain regions on the second nanosheet stack, each of the pair of p-type source/drain regions being adjacent to one of the epitaxial regions on the second nanosheet stack;
removing the first mask covering the first nanosheet stack after the forming of the pair of p-type source/drain regions on the second nanosheet stack;
covering the second nanosheet stack with a second mask; and
forming a pair of n-type source/drain regions on the pair of epitaxial regions on the first nanosheet stack.
12. The method of claim 11 , further comprising: prior to the forming of the pair of n-type source/drain regions on the first nanosheet stack, partially removing the pair of epitaxial regions on the first nanosheet stack such that each of the plurality of inner spacers of the first nanosheet stack remains enveloped by a remaining portion of one of the pair of epitaxial regions on the first nanosheet stack.
13. The method of claim 12 , wherein the covering of the second nanosheet stack includes:
forming a second liner over the first and the second nanosheet stacks;
forming a second soft mask over the second liner on the second nanosheet stack; and
removing a horizontal portion of the second liner over the pair of epitaxial regions on the first nanosheet stack and leaving a vertical portion of the second liner on sidewalls of the first nanosheet stack.
14. The method of claim 11 , further comprising: prior to the forming of the pair of p-type source/drain regions on the second nanosheet stack, partially removing the pair of epitaxial regions on the second nanosheet stack such that each of the plurality of inner spacers of the second nanosheet stack remains enveloped by a remaining portion of one of the pair of epitaxial regions on the second nano sheet stack.
15. The method of claim 14 , wherein the covering of the first nanosheet stack includes:
forming a first liner over the first and the second nanosheet stacks;
forming a first soft mask over the first liner on the first nanosheet stack; and
removing a horizontal portion of the first liner over the pair of epitaxial regions on the second nanosheet stack and leaving a vertical portion of the first liner on sidewalls of the second nanosheet stack.