Reducing intralevel capacitance in semiconductor devices
Methods of forming air gaps in hole and trench structures are disclosed. The methods may be used to form buried voids, i.e., voids for which the top is below the top of the adjacent features. The methods include inhibition of the hole or trench structures and selective deposition at the top of the structure forming an air gap within the structures. In some embodiments, the methods are to reduce intra-level capacitance in semiconductor devices.
1. A method comprising:
providing a structure comprising features and an open gap between the features, the open gap including sidewall and bottom surfaces and having a depth; and
performing one or more inhibition blocks, each inhibition block comprising:
a) exposing the structure to an inhibition treatment to inhibit dielectric deposition on the sidewall and bottom surfaces of the gap, and
b) selectively depositing dielectric film near the top of the gap without significant deposition near the bottom surface of the gap.
2. The method of claim 1 , further comprising closing the gap with deposited dielectric material, thereby forming a closed air gap between the features.
3. The method of claim 2 , wherein the gap is closed during an inhibition block.
4. The method of claim 2 , further comprising, after the performing the one or more inhibition blocks, performing a deposition to close the gap.
5. The method of claim 2 , wherein the gap is closed with surface inhibition species remaining in the closed air gap.
6. The method of claim 2 , wherein the top of the closed gap is below the top of the features.
7. The method of claim 1 , further comprising performing a passivation operation to remove surface inhibition species from the sidewall and/or bottom surfaces prior to closing the gap.
8. The method of claim 7 , wherein at least one inhibition block comprises a passivation operation.
9. The method of claim 7 , wherein the passivation operation is performed after performing one or more inhibition blocks.
10. The method of claim 7 , wherein the passivation operation comprises exposing the structure to an oxygen plasma.
11. The method claim 1 , wherein (b) is performed without significant deposition within most of the gap.
12. The method of claim 1 , wherein the inhibition treatment includes halogen species.
13. The method of claim 1 , further comprising depositing a conformal dielectric layer on the sidewall and bottom surfaces prior to performing the one or more inhibition blocks.
14. The method of claim 13 , wherein exposure to the inhibition treatment results in treating the conformal dielectric layer such that inhibition species are adsorbed onto or react with the conformal dielectric layer.
15. The method of claim 13 , further comprising, after closing the gap, depositing a dielectric cap layer over the features and gap by chemical vapor deposition.
16. The method of claim 15 , wherein the dielectric cap layer is deposited in the same chamber as the inhibition blocks are performed.
17. The method of claim 1 , wherein the features are metal lines.
18. The method of claim 1 , wherein the inhibition block further comprises selectively removing inhibition from the top of the gap between (a) and (b).
19. A method comprising:
providing a structure comprising features and an open gap between the features, the open gap including sidewall and bottom surfaces and having a depth; and
and performing one or more inhibition blocks, each inhibition block comprising:
(a) exposing the structure to an inhibition treatment to inhibit dielectric deposition on the sidewall and bottom surfaces of the gap, and
(b) performing one or more atomic layer deposition (ALD) cycles to selectively deposit dielectric film near the top of the gap without significant deposition near the bottom surface of the gap.
20. A method comprising:
providing a structure comprising features and an open gap between the features, the open gap including sidewall and bottom surfaces and having a depth; and
performing one or more inhibition blocks, each inhibition block comprising:
(a) exposing the structure to an inhibition treatment to inhibit dielectric deposition on the sidewall and bottom surfaces of the gap, and
(b) performing a chemical vapor deposition (CVD) operation to selectively deposit dielectric film near the top of the gap without significant deposition near the bottom surface of the gap.