Abstract
Alternate-type phase shifting masks (PSMs) have been investigated as a methods used to fabricate 0.18 micrometer and smaller rule devices. For practical use, an automatic shifter placement CAD, a DRC for the indicating errors in rules for alternate-type PSMs, and an optical proximity correction (OPC) tool are indispensable. We previously reported on the algorithm for the shifter placement and the DRC for alternate-type PSMs and the OPC tool. We now report that these tools enhance the practical CAD system, fully supporting the entire process from designing the physical layout to adjusting the mask patterns in order to prevent the optical proximity effects. First, the phase shifting patterns are generated automatically. Next, the DRC tool indicates rule errors for the design of alternate-type PSMs. The Designers must modify the indicated portions and replace the shifters or DRC until there are no errors. In order to be more general than our previous tools, it is important that the delivering data between the layout editor and the program be GDS formatted data. Following the designing of the PSMs, the OPC tool, which was developed on parallel processor units, adjusts the designed patterns. Our system was actually used to fabricate 0.18 micrometer rule full-chip devices, and thus we confirmed that the computing performance is satisfactorily practical and that the CAD system shows promises as a means of fabricating rule devices beyond current rules.
Published Version
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