Technology CAD (TCAD) has grown in both sophistication and maturity and is now an essential engineering tool for new technology development in industrial environments. The use of TCAD for reduced development cost and cycle-time, for design model generation, for an improved physical understanding of device operation and for process boundary and sensitivity analysis was discussed, with reference to industrial processes at 0.5 ~tm and 0.35 txm.
Process and device simulation tools enable process development times to be reduced. This was illustrated by reference to well architecture definition for 0.35 Ixm CMOS, where a retrograde well approach, utilising high energy implantation, was predicted to meet required electrical performance, whilst offering process simplification.
TCAD has an important role to play in reducing the time to market for new products, by providing early prediction of ECAD design models. The accuracy of such models depends critically on the predictability of underlying physical models. Improved accuracy can be achieved by "local" calibration during the process development phase. Here, TCAD supplements available electrical data, to generate the most accurate circuit simulation model at any particular stage in the development process. For example, TCAD can be used to predict performance at process boundaries, before these have been explored experimentally.
An additional area in which TCAD can support design activities is in an assessment of metallisation parasitics. Data was reported for a 0.5 Ixm, oxide IMD, TLM CMOS process, showing excellent agreement between measured and simulated capacitances, for a wide range of conductor structures. This enables TCAD to be used predictively by the design community to better analyse, for example, coupling capacitance, which may become a serious performance limitation for deep sub micron technologies.
Examples were reported illustrating the growing use of TCAD to assess manufacturability. These included a comparison of alternative LOCOS based isolation schemes (LOCOS, PBL, high temperature and high pressure oxidation) and the use of TCAD to improve CD control. In the latter case, the lithography simulator SOLID was utilised to optimise LOCOS stack layer thicknesses