One-level gray-tone design. Mask data preparation and pattern transfer
One-level gray-tone lithography, in spite of using a common mask technique and CMOS equipment, has quite different demands on data preparation and wafer processing. This paper reports on algorithms to transfer an initial height profile Hi(x,y) into a design representation shape nr(x,y) in the common data format GDSII, which could be used directly by a commercial mask shop. The great data amount of a reticle layout has been reduced significantly by a first order data compaction. The possibly nonlinear influences of the different process steps on the transfer function have been regarded. The specific parameters for the mask making and the resist process are determined. In the field of resist pattern transfer into a substrate material, a silicon etching process was evaluated.