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Digital Approximation of Soft Apodized Masks for Photolithography Generated by Vector Scanned Electron Beam Lithograph

IP.com Disclosure Number: IPCOM000053167D
Original Publication Date: 1981-Sep-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Levenson, MD: AUTHOR

Abstract

Improved resolution for proximity printing is obtained by using soft apodized photolithography masks. The soft apodized masks are formed by using vector scanned electron beam techniques to write an appropriate pattern of small (

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Digital Approximation of Soft Apodized Masks for Photolithography Generated by Vector Scanned Electron Beam Lithograph

Improved resolution for proximity printing is obtained by using soft apodized photolithography masks. The soft apodized masks are formed by using vector scanned electron beam techniques to write an appropriate pattern of small (<lambda/4) apertures and obstacles on the mask. Such a pattern has the effect of roughening the edges of the apertures which in turn tends to suppress the undesirable Fourier components which are usually introduced by sharp changes in the electric field at the aperture edges. The holes and islands left behind would be comparable in size to grains of photographic emulsion. The nonlinear response of high contrast photoresist would recover the sharp boundaries between the exposed and unexposed regions. Suitable patterns must have the average transmission of areas roughly lambda/2 x lambda/2 at a position x having the values of the equation, T=exp(-x/2//w/2/), and that no periodicities in the pattern appear on a scale larger than lambda.

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