Simplified pitch doubling process flow
A method for fabricating a semiconductor device comprises patterning a layer of photoresist material to form a plurality of mandrels. The method further comprises depositing an oxide material over the plurality of mandrels by an atomic layer deposition (ALD) process. The method further comprises anisotropically etching the oxide material from exposed horizontal surfaces. The method further comprises selectively etching photoresist material.
1. A method for fabricating a semiconductor device, the method comprising:
patterning a layer of photoresist material to form a plurality of photoresist mandrels over a hard mask layer, the photoresist mandrels having a pitch of about 150 nm or less;
using an atomic layer deposition technique to blanket deposit an oxide material onto the plurality of mandrels;
depositing another layer of photoresist material on the blanket deposited oxide material;
patterning the other layer of photoresist material;
anisotropically etching the oxide material to form spacers on sidewalls of mandrels and to pattern oxide under the patterned other layer of photoresist material;
etching the photoresist material of the layer of photoresist material and the other layer of photoresist material selectively with respect to the oxide material, thereby forming a plurality of free-standing oxide spacers over the hard mask layer;
transferring a pattern defined by the spacers and the patterned oxide to the hard mask layer; and
transferring the pattern to a substrate underlying the hard mask layer.
2. The method of claim 1 , wherein the oxide material is deposited using a precursor selected from the group consisting of Si 2 Cl 6 , H 2 O and C 5 H 5 N.
3. The method of claim 1 , wherein:
the plurality of mandrels are formed in a device array region; and
the oxide material is also deposited over a device peripheral region.
4. The method of claim 1 , further comprising isotropically etching the plurality of mandrels to form a plurality of modified mandrels before depositing the oxide material.
5. The method of claim 4 , wherein isotropically etching the plurality of mandrels comprises using an oxygen-containing plasma selected from the group consisting of a SO 2 /O 2 /N 2 /Ar plasma, a Cl 2 /O 2 /He plasma, and a HBr/O 2 /N 2 plasma.
6. The method of claim 4 , wherein the modified mandrels have a width between about 35 nm and about 70 nm.
7. The method of claim 1 , wherein patterning the layer of photoresist comprises using nano-imprint lithography.
8. The method of claim 1 , wherein anisotropically etching the oxide material comprises using a HBr/Cl 2 -containing plasma.
9. The method of claim 1 , wherein the oxide material is deposited at a temperature less than about 100° C.
10. The method of claim 1 , wherein the oxide material is deposited at a temperature less than about 80° C.
11. The method of claim 1 , wherein the layer of photoresist material is patterned over a silicon oxynitride layer that is positioned over a carbon layer.
12. The method of claim 1 , wherein the plurality of mandrels have a height between about 50 nm and about 300 nm.
13. The method of claim 1 , wherein the layer of photoresist material comprises a material selected from the group consisting of argon fluoride photoresist, and krypton fluoride photoresist.