Self-aligned source/drain contact for vertical field effect transistor
A method for manufacturing a semiconductor device includes forming a fin on a semiconductor substrate. In the method, a bottom source/drain region is formed between the fin and the semiconductor substrate, and a top source/drain region is formed on the fin. The method further includes forming a cap layer covering part of a top surface of the top source/drain region. A portion of the top source/drain region and an underlying portion of the fin not covered by the cap layer are removed. The removal exposes a portion of the bottom source/drain region. A dielectric spacer is formed on a side of the fin adjacent the exposed portion of the bottom source/drain region, and extends onto a side of the top source/drain region. A bottom source/drain contact is formed on the exposed portion of the bottom source/drain region and on the dielectric spacer.
1. A method for manufacturing a semiconductor device, comprising:
forming a fin on a semiconductor substrate;
forming a bottom source/drain region between the fin and the semiconductor substrate;
forming a top source/drain region on the fin;
forming a cap layer covering part of a top surface of the top source/drain region;
removing a portion of the top source/drain region and an underlying portion of the fin not covered by the cap layer, wherein the removal exposes a portion of the bottom source/drain region;
forming a dielectric spacer on a side of the fin adjacent the exposed portion of the bottom source/drain region, wherein the dielectric spacer extends onto a side of the top source/drain region; and
forming a bottom source/drain contact on the exposed portion of the bottom source/drain region and on the dielectric spacer.
2. The method according to claim 1 , wherein the removal of the portion of the top source/drain region and the underlying portion of the fin reduces a length of the fin in a direction parallel to a top surface of the substrate.
3. The method according to claim 1 , further comprising, following the removal of the portion of the top source/drain region and the underlying portion of the fin, laterally recessing a remaining portion of the top source/drain region and a remaining portion of the fin with respect to a side surface of the cap layer.
4. The method according to claim 1 , further comprising:
forming a gate structure on an end side of the fin; and
forming a top spacer on the gate structure on the end side of the fin and an end side of the top source/drain region.
5. The method according to claim 4 , further comprising forming one or more dielectric layers to fill in an area on the end sides on the fin and the top source/drain region and on the top surface of the top source/drain region.
6. The method according to claim 5 , further comprising:
forming an opening in a dielectric layer of the one or more dielectric layers on the top surface of the top source/drain region, wherein forming a cap layer comprising filling the opening with a dielectric material.
7. The method according to claim 5 , further comprising forming an opening in the one or more dielectric layers to expose the gate structure and the top spacer.
8. The method according to claim 7 , wherein the bottom source/drain contact is formed in at least part of the opening.
9. The method according to claim 7 , further comprising removing the exposed gate structure and top spacer, wherein the removal of the exposed gate structure and top spacer exposes the end sides on the fin and the top source/drain region.
10. The method according to claim 9 , wherein the end sides on the fin and the top source/drain region comprise part of the portion of the top source/drain region and the underlying portion of the fin not covered by the cap layer.
11. The method according to claim 9 , wherein the gate structure is formed on a bottom spacer on the end side of the fin.
12. The method according to claim 11 , wherein the opening exposes a portion of the bottom spacer.
13. The method according to claim 12 , further comprising removing the exposed portion of the bottom spacer.
14. The method according to claim 1 , further comprising removing an end of the fin and an end of the bottom source/drain region underlying the end of the fin prior to forming the top source/drain region.
15. A method for manufacturing a vertical transistor device, comprising:
forming a vertical channel region on a semiconductor substrate;
forming a bottom source/drain region between the vertical channel region and the semiconductor substrate;
forming a top source/drain region on the vertical channel region;
forming a cap layer masking part of a top surface of the top source/drain region;
removing an unmasked portion of the top source/drain region and an underlying portion of the vertical channel region, wherein the removal exposes a portion of the bottom source/drain region;
forming a dielectric spacer on a side of the vertical channel region adjacent the exposed portion of the bottom source/drain region, wherein the dielectric spacer extends onto a side of the top source/drain region; and
forming a bottom source/drain contact on the exposed portion of the bottom source/drain region and on the dielectric spacer.