In the reversal mask process, the mask material film is deposited over the resist patterns. There is a problem in that the film step height at the surface of the mask material reduces the etch-back margin of the mask material. This is inevitable as long as the mask material film is deposited by spin-coating and no planarization process is used. In this article, the dependence of film step height on the half-pitches (periodic feature) or the widths (isolated feature) of the resist patterns is measured by means of both experiment and calculation. As a solution to avoid the effect of the film step height, a pattern transferring technique which makes use of a multiple exposure process and the reversal mask process is proposed and the fabrication of dense contact hole patterns was demonstrated. This technique is proven to be one of the practical applications of the reversal mask process and at the same time to be an effective method of fabricating the kind of patterns which a conventional single-exposure process is not able to fabricate due to insufficient lithography margin. (C) 2004 American Vacuum Society.