Pitch multiplication spacers and methods of forming the same
Spacers in a pitch multiplication process are formed without performing a spacer etch. Rather, the mandrels are formed over a substrate and then the sides of the mandrels are reacted, e.g., in an oxidization, nitridation, or silicidation step, to form a material that can be selectively removed relative to the unreacted portions of the mandrel. The unreacted portions are selectively removed to leave a pattern of free-standing spacers. The free-standing spacers can serve as a mask for subsequent processing steps, such as etching the substrate.
1. A method for forming an integrated circuit, comprising:
defining a pattern in a selectively definable layer over a substrate;
transferring the pattern from the selectively definable layer to an underlying layer of temporary material to form a plurality of temporary placeholders in the layer of temporary material across a region over the substrate;
providing a cap layer on a top horizontal surface of the temporary placeholders, wherein the cap layer inhibits reactions on the top horizontal surface and exposes sidewalls of the temporary placeholders;
blanket depositing a layer comprising a solid phase reactant over the cap layer and the temporary placeholders;
converting some of the temporary material into an other material to form a plurality of spacers underneath the cap layer, the spacers forming a plurality of mask features, wherein converting some of the temporary material comprises selectively reacting sidewalls of the temporary placeholders with the solid phase reactant, wherein at least part of the spacers are formed directly under the cap layer, the cap layer and the spacers formed of different materials;
selectively removing the cap layer relative to the spacers;
selectively removing unconverted temporary material between the spacers after removing the cap layer; and
subsequently etching the substrate through a mask pattern defined by the plurality of spacers.
2. The method of claim 1 , wherein the blanket deposition comprises a chemical vapor deposition.
3. The method of claim 1 , wherein the blanket deposition comprises an atomic layer deposition.
4. The method of claim 1 , wherein converting some of the temporary material comprises reacting a portion of the layer comprising the solid phase reactant with the temporary material.
5. The method of claim 4 , further comprising preferentially removing an unreacted remainder of the layer.
6. The method of claim 1 , wherein the solid phase reactant comprises a metal and the other material comprises a metal silicide.
7. The method of claim 6 , wherein the metal is selected from the group consisting of tantalum, hafnium, and nickel.
8. The method of claim 1 , wherein selectively reacting sidewalls of the temporary placeholders comprises exposing the sidewalls to a gas phase reactant.
9. The method of claim 8 , wherein the gas phase reactant is selected from the group consisting of a nitrogen and an oxygen-containing species.
10. The method of claim 1 , wherein defining the pattern comprises performing photolithography.
11. The method of claim 10 , wherein defining the pattern comprises performing photolithography utilizing 193 nm or 248 nm wavelength light.
12. The method of claim 1 , wherein transferring the pattern comprises performing an anisotropic etch.
13. The method of claim 1 , wherein selectively removing unconverted temporary material comprises performing a wet etch.
14. The method of claim 1 , wherein the spacers extend in spaced, generally parallel relation to one another at least between first and second spaced planes extending perpendicular to the spacers.
15. The method of claim 1 , wherein the temporary placeholders comprise silicon.