Contact structure for semiconductor device
A method of forming a semiconductor device includes forming a source/drain region on a substrate and forming a first interlayer dielectric (ILD) layer over the source/drain region. The method further includes forming a second ILD layer over the first ILD layer, forming a source/drain contact structure within the first ILD layer and the second ILD layer, and selectively removing a portion of the source/drain contact structure to form a concave top surface of the source/drain contact structure.
1. A method of forming a semiconductor device, comprising:
forming a source/drain region on a substrate, comprising:
forming a fin structure on the substrate;
etching a portion of the fin structure to form a recessed fin region; and
epitaxially growing the source/drain region on the recessed fin region;
forming a first interlayer dielectric (ILD) layer over the source/drain region;
forming a second ILI) layer over the first ILD layer;
forming a source/drain contact structure within the first and second ILD layers; and
selectively removing a portion of the source/drain contact structure to form a concave top surface of the source/drain contact structure.
2. The method of claim 1 , further comprising:
forming a third ILD layer over the second ILD layer; and
forming an interconnect extending through the third ILD layer and in contact with the source/drain contact structure, wherein the interconnect comprises a dual-damascene interconnect structure.
3. The method of claim 1 , wherein the selectively removing the portion of the source/drain contact structure comprises:
treating the portion of the source/drain contact structure in an oxygen plasma; and
wet etching the oxygen plasma treated portion to form the concave top surface.
4. The method of claim 3 , wherein the treating the portion of the source/drain contact structure in the oxygen plasma comprises:
maintaining an oxygen gas flow rate at a range from about 100 standard cubic centimeters per minute (sccm) to about 500 sccm; and
maintaining a temperature of about 10° C. to about 100° C.
5. The method of claim 3 , wherein the wet etching the oxygen plasma treated portion comprises using a solution of deionized water and ozone, dilute hydrofluoric acid, and carbonated deionized water.
6. The method of claim 1 , wherein the selectively removing the portion of the source/drain contact structure comprises:
oxidizing the portion of the source/drain contact structure in an oxygen plasma; and
wet etching the oxidized portion of the source/drain contact structure to form the concave top surface.
7. The method of claim 1 , further comprising forming insulating spacers positioned within the second ILD layer and along sidewalk of the second ILD layer.
8. The method of claim 1 , wherein the forming the source/drain contact structure within the first and the second ILD layers comprises etching portions of the first and the second ILD layers over the source/drain region, the etching comprising:
etching a first portion at a first etch rate; and
etching a second portion at a second etch rate slower than the first etch rate.
9. The method of claim 1 ; further comprising:
forming a metal gate structure on the fin structure; and
forming a gate contact structure over the metal gate structure.
10. The method of claim 1 , wherein the epitaxially growing the source/drain region comprises epitaxially growing the source/drain contact structure in contact with the source/drain region.
11. The method of claim 1 , wherein the selectively removing the portion of the source/drain contact structure comprises:
oxidizing the portion of the source/drain contact structure; and
removing the oxidized portion of the source/drain contact structure to form the concave top surface.
12. A method of forming a semiconductor device, comprising:
forming a source/drain region on a substrate, comprising:
forming a fin structure on the substrate;
etching a portion of the fin structure to form a recessed fin region; and
epitaxially growing the source/drain region on the recessed fin region;
forming a source/drain contact structure on the source/drain region;
forming a concavely-curved surface at the source/drain contact structure; and
forming insulating spacers on sidewalls of the source/drain contact structure.
13. The method of claim 12 , wherein the forming the concavely-curved surface comprises selectively removing a portion of the source/drain contact structure to form a concave top surface of the source/drain contact structure.
14. The method of claim 13 , wherein the selectively removing the portion of the source/drain contact structure comprises:
treating the portion of the source/drain contact structure in an oxygen plasma; and
wet etching the oxygen plasma treated portion to form the concave top surface.
15. The method of claim 13 , wherein the selectively removing the portion of the source/drain contact structure comprises:
oxidizing the portion of the source/drain contact structure in oxygen plasma; and
wet etching the oxidized portion of the source/drain contact structure to form the concave top surface.
16. A method of forming an electrical connection between a source/drain region and a metal interconnect in a semiconductor structure, comprising:
forming a first interlayer dielectric (ILD) layer over the source/drain region;
forming a second II D layer over the first ILD layer, wherein the second ILD layer includes a dual-damascene interconnect structure; and
forming a source/drain contact structure within the first and second ilLD layers and between the source/drain region and the metal interconnect, wherein forming the source/drain contact structure comprises forming a concavely-curved interface between the source/drain contact structure and the metal interconnect.
17. The method of claim 16 ; wherein the forming the concavely-curved interface comprises selectively removing a portion of the source/drain contact structure to form a concave top surface of the source/drain contact structure.
18. The method of claim 17 , wherein the selectively removing the portion of the source/drain contact structure comprises:
treating the portion of the source/drain contact structure in an oxygen plasma; and
wet etching the oxygen plasma treated portion to form the concave top surface.
19. The method of claim 17 ; wherein the selectively removing the portion of the source/drain contact structure comprises:
oxidizing the portion of the source/drain contact structure in an oxygen plasma; and
wet etching the oxidized portion of the source/drain contact structure to form the concave top surface.
20. The method of claim 16 , further comprising:
forming a third ILD layer over the second H D layer; and
forming the metal interconnect extending through the third ILD layer and in contact with the source/drain contact structure, wherein the metal interconnect comprises an other dual-damascene interconnect structure.