Forming a hybrid channel nanosheet semiconductor structure

1. A method for fabricating a nanosheet semiconductor structure, the method comprising:

forming a first nanosheet field effect transistor (FET) structure having a first inner spacer comprised of a first material and a second nanosheet FET structure having a second inner spacer comprised of a second material; wherein forming the first nanosheet FET structure and the second nanosheet FET structure comprises:

creating a first inner spacer formation within a first silicon germanium (SiGe) channel, wherein the first SiGe channel is comprised in a first channel region of a first FET region; and

creating a second inner spacer formation within a second SiGe channel, wherein the second SiGe channel is comprised in a second channel region of a second FET region; wherein creating the first inner spacer formation comprises forming a first divot within the first SiGe channel and filling the first divot with a first ceramic material, wherein creating the second inner spacer formation comprises forming a second divot within the second SiGe channel and filling the second divot with a second ceramic material;

wherein the first material is different than the second material.

2. The method of claim 1 , where in the first nanosheet FET structure is an n-type FET structure and the second nanosheet FET structure is a p-type FET structure.

3. The method of claim 1 , wherein the first SiGe channel is formed from one or more first SiGe nanosheets, and wherein the second SiGe channel is formed from one or more second SiGe nanosheets.

4. The method of claim 1 , wherein at least one of the first and second channel regions is formed via etching.

5. The method of claim 1 , wherein at least one of the first and second divots is formed via etching.

6. The method of claim 1 , wherein at least one of the first and second ceramic materials is comprised of silicon-boron-carbide-nitride (SiBCN).

7. A method for fabricating a nanosheet semiconductor structure, the method comprising:

forming a first nanosheet field effect transistor (FET) structure having a first inner spacer comprised of a first material and a second nanosheet FET structure having a second inner spacer comprised of a second material; wherein forming the first nanosheet FET structure and the second nanosheet FET structure comprises:

creating a first inner spacer formation within a first silicon germanium (SiGe) channel, wherein the first SiGe channel is comprised in a first channel region of a first FET region; and

creating a second inner spacer formation within a second SiGe channel, wherein the second SiGe channel is comprised in a second channel region of a second FET region;

forming a first stack on the first FET region and a second stack on the second FET region, wherein the first stack comprises a first substrate, the one or more first Si nanosheets, and the one or more first SiGe nanosheets, and wherein the second stack comprises the second substrate, the one or more second Si nanosheets, and the one or more second SiGe nanosheets;

forming a first pad insulator on the first channel region and a second pad insulator on the second channel region;

forming a first gate on the first pad insulator and a second gate on the second pad insulator;

forming a first hard mask on the first gate and a second hard mask on the second gate;

forming a first spacer on the first channel region, the first gate, and the first hard mask, and a second spacer on the second channel region, the second gate, and the second hard mask, wherein each spacer comprises silicon mononitride (SiN); and

forming the first channel region from the first stack and the second channel region from the second stack.

8. The method of claim 7 , wherein at least one of the first and second substrates is comprised of Si.

9. A method for fabricating a nanosheet semiconductor structure, the method comprising:

forming a first nanosheet field effect transistor (FET) structure having a first inner spacer comprised of a first material and a second nanosheet FET structure having a second inner spacer comprised of a second material; wherein forming the first nanosheet FET structure and the second nanosheet FET structure comprises:

creating a first inner spacer formation within a first silicon germanium (SiGe) channel, wherein the first SiGe channel is comprised in a first channel region of a first FET region; and

creating a second inner spacer formation within a second SiGe channel, wherein the second SiGe channel is comprised in a second channel region of a second FET region;

depositing a first sacrificial liner on the first FET region and a second sacrificial liner on the second FET region;

forming a mask on the second sacrificial liner;

forming a first source/drain region on a first silicon (Si) channel of the first channel region, wherein the first Si channel is formed from one or more first Si nanosheets;

removing the mask and the first and second sacrificial liners;

creating a third inner spacer formation within a second Si channel, wherein the second Si channel is comprised in the second channel region, and wherein the second Si channel is formed from one or more second Si nanosheets; and

forming a second source/drain region on the second SiGe channel.

10. The method of claim 9 , wherein creating the third inner spacer region comprises forming a divot within the second Si channel and filling the divot with a silicate glass.

11. The method of claim 10 , wherein the silicate glass is silicon oxycarbide (SiCO).

12. The method of claim 9 , wherein at least one of the first and second source/drain regions is formed via an epitaxial growth process.

13. The method of claim 9 , wherein forming the first nanosheet FET structure and the second nanosheet FET structure further comprises filling the first source/drain region with a first oxide and the second source/drain region with a second oxide.

14. The method of claim 13 , wherein forming the first nanosheet FET structure and the second nanosheet FET structure further comprises:

replacing a first gate of the first FET region with a first metal and the first SiGe channel with a first work function metal; and

replacing a second gate of the second FET region with a second metal and the second Si channel with a second work function metal.

15. The method of claim 14 , wherein the first and second gates are comprised of polysilicon, and wherein replacing the first and second gates comprises removing the first and second gates via a polysilicon pull process.

16. The method of claim 14 , wherein replacing the first Si channel comprises performing a Si channel release, and wherein replacing the second SiGe channel comprises performing a SiGe channel release.

17. The method of claim 14 , wherein at least one of the first and second metals is comprised of tungsten (W).

18. The method of claim 14 , further comprising performing a first chemical mechanical planarization (CMP) process after replacing the first gate and the first Si channel, and a second CMP process after replacing the second gate and the second SiGe channel.