Method for forming pattern
View Patent ↗In an exposure step, a combination of a first photomask and a second mask is used. The first mask has a real pattern corresponding to the pattern actually formed on the film to be processed, and a dummy pattern added for controlling pattern pitch in the first photomask within a prescribed range; and the second photomask has a pattern isolating a real-pattern-formed region from a dummy-pattern-formed region. In forming the pattern, after forming a film to be processed on a substrate, a first mask is formed on the film to be processed, by lithography, using the first photomask, and a second mask is formed on the film to be processed, by lithography, using the second photomask. Thereafter, the film to be processed is etched and removed using the first and second masks as masks to form the pattern.
1. A method for forming patterns comprising:
forming a film on a substrate;
forming a first hard mask over said film, by lithography, using a first photomask, wherein forming said first hard mask includes
forming said first hard mask over said film,
forming a first resist pattern by transferring the pattern of said first photomask over said first hard mask using photolithography, said first photomask having a real pattern, which is an actual pattern over said film, and a dummy pattern added to control pattern pitch in said first photomask, and
etching said first hard mask using said first resist pattern as an etching mask;
forming a second hard mask over said film and on said first hard mask, by lithography, using a second photomask, wherein forming said second hard mask includes
forming said second hard mask over said film and on said first hard mask,
forming a second resist pattern by transferring the pattern of said second photomask over said second hard mask, using photolithography, said second photomask having a pattern isolating a region in which said dummy pattern is formed from a region in which said real pattern is formed, and
etching said second hard mask using said second resist pattern as an etching mask; and
etching said film using said first hard mask and said second hard mask as masks.
2. The method for forming patterns according to claim 1 , wherein said first hard mask is a silicon nitride film and said second hard mask is a silicon oxide film.
3. The method for forming patterns according to claim 1 , including using a quadrapole illumination source for exposure in the lithography used in forming said first hard mask.
4. The method for forming patterns according to claim 1 , including using a dipole illumination source for exposure in the lithography used in forming said first hard mask.
5. The method for forming patterns according to claim 1 , including using a circular illumination source for exposure in the lithography used in forming said first hard mask.
6. The method for forming patterns according to claim 1 , wherein said first photomask is an attenuated phase shifting mask.
7. The method for forming patterns according to claim 1 , wherein said first photomask is an alternating phase shifting mask.