Automated CD-error compensation for negative-tone chemically amplified resists by zone-controlled post-exposure bake

Lothar Berger; Peter Dress; Thomas Gairing; J. J. Chen; Ren-Guey Hsieh; Hsin-Chang Lee; Hung-Chang Hsieh

doi:10.1117/12.517202

17 December 2003 Automated CD-error compensation for negative-tone chemically amplified resists by zone-controlled post-exposure bake

Lothar Berger, Peter Dress, Thomas Gairing, J. J. Chen, Ren-Guey Hsieh, Hsin-Chang Lee, Hung-Chang Hsieh

Author Affiliations +

Proceedings Volume 5256, 23rd Annual BACUS Symposium on Photomask Technology; (2003) https://doi.org/10.1117/12.517202
Event: Photomask Technology, 2003, Monterey, California, United States

Abstract

Negative-tone chemically amplified resists (nCARs), like NEB22 are promising candidates for next-generation lithography, e.g. 90 nm and 65 nm technology node and next-generation lithography. For these resists, e-beam exposure and post-exposure bake (PEB) are most critical processes, since these resists show a strong sensitivity to post-exposure delay (PED) in vacuum during e-beam writing of about 0.5 nm/h, and in air while waiting for PEB. Further, such resists show a strong PEB temperature sensitivity of up to 8 nm/K. The multi-zone hotplate approach of the APB AFB 5500 bake system with its use prior temperature uniformity results in excellent global CD-uniformity already. However, all kinds of systematic large area effects of processes, e.g. blank coat/bake, exposure, PED, the PEB itself, etch loading, etc. may transfer in additional systematic CD-errors. Such systematic, repeatable errors can be reduced during PEB by superimposing an appropriate non-uniform temperature profile onto the regular, optimized uniform bake temperature profile, thereby compensating for such CD-non-uniformities. The required temperature profile can automatically be calculated from a suitable gobal CD measurement, determined in a typical process flow. The compensation of CD-errors resulting from vacuum PED and hotplate temperature characteristics is demonstrated here, by using automated temperature profile calculation. The global CD uniformity was improved significantly, the achieved results show a typical reduction of about 20-30%, from a total global range of about 9nm to about 6-7nm on leading-edge production photomasks.

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Lothar Berger, Peter Dress, Thomas Gairing, J. J. Chen, Ren-Guey Hsieh, Hsin-Chang Lee, and Hung-Chang Hsieh "Automated CD-error compensation for negative-tone chemically amplified resists by zone-controlled post-exposure bake", Proc. SPIE 5256, 23rd Annual BACUS Symposium on Photomask Technology, (17 December 2003); https://doi.org/10.1117/12.517202

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