A technique for creating phase shift photolithography masks for use with a stepper or mask aligner, as well as how to achieve sub-150 nm features of different aspect ratios is described. The mask utilizes two different regions, one transparent region of only the mask material, and another transparent region of SiO2, which are overlapped to create the pattern. Patterning was done by use of a Canon Stepper. By adjusting the angle between the two mask regions, the aspect ratio, which is defined as the length:width, of features was controlled. Features below 100 nm were patterned, and aspect ratios were controllably tuned between 1.1 and 2.6. The feature size was also shown to be able to be reduced by 25-30 nm with the use of reactive ion etching.
Bibliographical noteFunding Information:
This work was supported partially by the MRSEC Program of the National Science Foundation under Award Number DMR-0212302, NSF ECCS (0702264) and NSF NEB program.
- Mask fabrication
- Nanoscale patterning
- Phase-shift lithography