Low-k feature formation processes and structures formed thereby
Semiconductor device structures having low-k features and methods of forming low-k features are described herein. Some examples relate to a surface modification layer, which may protect a low-k feature during subsequent processing. Some examples relate to gate spacers that include a low-k feature. Some examples relate to a low-k contact etch stop layer. Example methods are described for forming such features.
1. A method of manufacturing a semiconductor device, the method comprising:
flowing a first precursor into a deposition chamber, the first precursor comprising silicon, carbon, and an H functional group;
purging the first precursor from the deposition chamber;
flowing a second precursor into the deposition chamber, the second precursor comprising oxygen, wherein the flowing the first precursor and the flowing the second precursor are part of a first cycle and wherein each reagent within the first cycle is either the first precursor or the second precursor;
repeating the first cycle one or more times, to form a low-k layer along a sidewall of a gate stack;
forming a gate spacer along the sidewall of the gate stack comprising anisotropically etching the low-k layer; and
forming a surface modification layer along the sidewall of the gate stack, the low-k layer being formed on the surface modification layer, the surface modification layer being disposed between the gate stack and the low-k layer, a concentration of nitrogen in the surface modification layer increasing in a direction from the gate stack to the low-k layer, wherein forming the gate spacer further comprises anisotropically etching the surface modification layer, the gate spacer comprising respective portions of the low-k layer and the surface modification layer.
2. The method of claim 1 , wherein the method deposits a layer of SiOC.
3. The method of claim 2 , wherein the layer of SiOC is low-k gate spacer layer.
4. The method of claim 3 , wherein the repeating the first cycle one or more times comprises repeating the cycle between one time and one hundred and fifty times.
5. The method of claim 1 , wherein the first precursor is silated methane.
6. The method of claim 1 , wherein the method does not include a precursor that includes nitrogen.
7. A method comprising:
forming a low-k layer using an Atomic Layer Deposition (ALD), process, wherein the low-k layer is formed along a sidewall of a gate stack, the ALD process comprising:
for a cycle, flowing a silicon and carbon source precursor having an H functional group, wherein each reagent within the cycle is either the silicon and carbon source precursor or a second precursor; and
repeating the cycle a number of times; and
forming a gate spacer along the sidewall of the gate stack comprising anisotropically etching the low-k layer; and
forming a surface modification layer along the sidewall of the gate stack, the low-k layer being formed on the surface modification layer, the surface modification layer being disposed between the gate stack and the low-k layer, a concentration of nitrogen in the surface modification layer increasing in a direction from the gate stack to the low-k layer, wherein forming the gate spacer further comprises anisotropically etching the surface modification layer, the gate spacer comprising respective portions of the low-k layer and the surface modification layer.
8. The method of claim 7 wherein the low-k layer has a concentration of nitrogen less than 5 atomic percent of the low-k layer.
9. The method of claim 7 , wherein the ALD process does not include a precursor that includes nitrogen.
10. The method of claim 7 , wherein the silicon and carbon source precursor includes a silicon atom and a leaving group.
11. The method of claim 7 , wherein the second precursor is an oxygen source precursor.
12. The method of claim 11 , wherein:
the silicon and carbon source precursor is (SiCl 3 ) 2 CH 2 ,
and the oxygen source precursor is H 2 O.
13. A method comprising:
forming a low-k layer using an Atomic Layer Deposition (ALD) process along a sidewall of a gate stack, the ALD process comprising:
for a cycle, flowing (SiCl 3 ) 2 CH 2 and then flowing H 2 O; and
repeating the cycle a number of times; and
forming a gate spacer along the sidewall of the gate stack comprising etching the low-k layer; and
forming a surface modification layer along the sidewall of the gate stack, the forming the low-k layer forming the low-k layer on the surface modification layer, the surface modification layer being disposed between the gate stack and the low-k layer, a concentration of nitrogen in the surface modification layer increasing in a direction from the gate stack to the low-k layer, wherein forming the gate spacer further comprises anisotropically etching the surface modification layer, the gate spacer comprising respective portions of the low-k layer and the surface modification layer.
14. The method of claim 13 , wherein the low-k layer has a concentration of nitrogen less than 5 atomic percent of the low-k layer.
15. The method of claim 13 , wherein the ALD process does not include a precursor that includes nitrogen.
16. The method of claim 15 , wherein the etching the low-k layer comprises anisotropically etching the low-k layer.
17. The method of claim 16 , wherein the forming the low-k layer forms a layer of SiOC.
18. The method of claim 13 , wherein the forming the low-k layer forms a layer of SiOC.
19. The method of claim 1 wherein the low-k layer has a concentration of nitrogen less than 5 atomic percent of the low-k layer.