In order to produce future generations of integrated circuits (ICs), it is advantageous to have tighter coupling between process technology development and IC layout design. The first part of this paper describes a framework being developed in the technology computer aided design (TCAD) area that facilitates such coupling. The second part of the paper provides examples of coupling of product design with one of the areas within TCAD, lithography simulation. The success of optical proximity correction (OPC), for example, depends on accurate models that represent the lithography process, including photoresist performance. Some of the challenges in developing accurate resist models are addressed. In addition to OPC and the short-range effects it addresses, the impact of long-range effects is also described. Two such effects are lens aberrations and flare, with the latter being particularly dependent on the total layout.