Active hardmask for lithographic patterning
In an implementation, energy reaching the lower surface of a photoresist may be redirected back into the photoresist material. This may be done by, for example, reflecting and/or fluorescing the energy from a hardmask provided on the wafer surface back into the photoresist.
1. A method comprising:
directing extreme ultraviolet electromagnetic energy from an energy source toward a photoresist, the photoresist having a first surface closer to the energy source than a second surface; and
redirecting a portion of the electromagnetic energy reaching the second surface back into the photoresist, wherein the redirecting causes sidewall angles of a channel in the photoresist to be greater than or equal to approximately eighty degrees and less than or equal to approximately eighty-five degrees and wherein the redirecting comprises fluorescing the portion of the electromagnetic energy.
2. The method of claim 1 , wherein the redirecting further comprises reflecting the portion of the electromagnetic energy.
3. The method of claim 2 , wherein the reflecting comprises reflecting with a Bragg reflector.
4. The method of claim 2 , wherein reflecting comprises reflecting with a reflector comprising multiple layers.
5. The method of claim 4 , wherein the multiple layers comprise molybdenum and silicon.
6. The method of claim 4 , wherein the multiple layers comprise ruthenium and silicon.
7. The method of claim 1 , wherein said redirecting comprises redirecting at least 33% of the electromagnetic energy reaching the second surface.
8. A method for transferring a pattern to a semiconductor substrate, the method comprising:
applying a reflective hardmask above a surface of the semiconductor substrate; applying a photoresist to a surface of the reflective material;
directing extreme ultraviolet energy toward the photoresist;
reflecting at least a portion of the radiation back into the photoresist; and
fluorescing radiation into the photoresist, wherein the reflecting causes sidewall angles of a channel in the photoresist to be greater than or equal to approximately eighty degrees and less than or equal to approximately eighty-five degrees.
9. The method of claim 8 , wherein the applying the reflective hardmask comprises applying a Bragg reflector.
10. The method of claim 8 , wherein the applying the reflective hardmask comprises applying a plurality of layers, the plurality of layers including layers of different materials.
11. The method of claim 10 , wherein the plurality of layers of materials comprise molybdenum and silicon.
12. The method of claim 10 , wherein the plurality of layers of materials comprise ruthenium and silicon.