The purpose of this paper is to investigate experimentally the important concepts affecting resist focus latitude. Exposure margin (EM), contrast, inhibition, and the newly introduced parameter (RD/EM) were investigated for a variety of resist systems. The quantity (RD), is the removal dose for some fractional film thickness near mask edge. The resist examples employed in this study included positive and negative, chemically amplified resists and novolac/DNQ systems. It is concluded in this work that the focus tolerance of the resist is influenced largely by (EM) in one direction and by resist inhibition and contrast in the other.
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