The dry etching resistance of 130 nm LS resist patterns was improved by irradiating the vacuum ultraviolet (VUV) light (wavelength of 172 nm) to ArF resist patterns in N2 atmosphere. The film thickness of resist decreased by about 30 under VUV irradiation and the density of C=O bonds of the resist was decreased. The line width also reduced. However, the surface roughness of resist after dry etching improved from 6.2 nm rms which value was obtained under no cure, to 1.9 nm rms which was obtained under VUV irradiation. The line width shrinkage by the electron beam irradiation of CD-SEM was greatly improved from 9 nm to 2 nm by using VUV Cure. Moreover, LER (Line Edge Roughness) of resist patterns was approximately 2 nm improved from 8.4 nm that is under no cure case, to 6.5 nm under VUV irradiation. Using VUV Cure, the dry etching pattern of a SiN film showed near the rectangle cross sectional view, and indicated almost the same LER value as the resist mask pattern. The VUV Cure technique is an attractive method of fine resist pattern fabrication by ArF lithography.
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