Optical Lithography For Half-Micron And Sub-Half-Micron Resolution

F. A. Vollenbroek; M. J. H. J. Geomini

doi:10.1117/12.968343

1 January 1988 Optical Lithography For Half-Micron And Sub-Half-Micron Resolution

F. A. Vollenbroek, M. J. H. J. Geomini

Proceedings Volume 0920, Advances in Resist Technology and Processing V; (1988) https://doi.org/10.1117/12.968343
Event: Santa Clara Symposium on Microlithography, 1988, Santa Clara, CA, United States

Abstract

The lithographic requirements for half-micron and sub-half-micron design rules are discussed in terms of the resolution capability of 436 nm, 365 nm and 248 nm reduction steppers, the depth of focus, bulk and reflection effects and the impact of using advanced single-layer resist systems instead of conventional positive photoresists. Using the simulation model SLIM (Simulation of Latent Image Manipulations) the distribution of the product of photolysis in the latent image is calculated as resulting from patternwise exposures and resolution enhancing procedures as Image Reversal (ImRe) and Built In Mask (BIM). On the basis of the concentrations and gradients arising from patterning with 365 nm in a 1.5 μm thick resist layer it is shown that, using an i-line lens with 0.42 NA, the patterning of 0.5 μm lines and spaces will be possible. For sub-half-micron dimensions a shorter wavelength (e.g. 248 nm) is required to ensure a sufficient image contrast. A difficulty that arises at this wavelength is that novolak-based photoresists exhibit a very low transparency, thus hampering the penetration of UV-light in the resist layer. It is shown that, in order to image these resists in the positive mode either the absorptivity of the resin or the thickness of the resist layer has to be reduced considerably. Alternatively a 'top-imaging' procedure, as for instance BIM and DESIRE could be used. In this case a penetration depth of the imaging UV-light of 0.3 μm may be sufficient. An additional advantage of these procedures is that both the problem of limited focus depth and the detrimental effects caused by reflection of UV-light at the substrate are alleviated.

Citation Download Citation

F. A. Vollenbroek and M. J. H. J. Geomini "Optical Lithography For Half-Micron And Sub-Half-Micron Resolution", Proc. SPIE 0920, Advances in Resist Technology and Processing V, (1 January 1988); https://doi.org/10.1117/12.968343

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