A Three-Dimensional Process Simulator and its Application to Submicron VLSI's

A three-dimensional process simulator TRIP for submicron electron device fabrication was developed. TRIP includes, as the process models, the ion-implantation model, diffusion/oxidation model, and etching model. In the diffusion model, Fick's second equation is discretized by seven-point difference in the three-dimensional space. The oxidation-enhanced diffusion (OED) effect in the oxidizing atmosphere is taken into consideration is determining the diffusion coefficient. The OED effect at the mask corner in LOCOS is extended into three dimensions. The fabrication process of a junction is used to examine the accuracy of TRIP. It was seen as a result that the accuracy is practically satisfactory. Examining the problems in the process design for a submicron MOS device using TRIP, the impurity dilution effect and impurity crowding effect are found as problems peculiar to the three-dimensional process.