This paper describes a new two-dimensional silicon oxidation model taking into consideration the deformation of silicon. In the model based on the steady-state oxidant diffusion and viscoelastic deformation of the oxide, it is assumed that the oxide is composed of two layers during the deformation of the oxide. Simulated results on a LOCOS structure were obtained using the boundary element method (BEM). It is proved that the present model can analyze oxidation-induced stress in the silicon substrate, which is not explained by previous models, as well as predict the oxide shape.

A new two-dimensional integrated process simulation system named SPIRIT-I (Simulation Processor for Integrated Representation of Impurity-profile and Topography-I) has been developed. This system includes elementary process simulators of deposition, lithography, etching, ion implantation, diffusion, and oxidation. SPIRIT features a closely coupled simulation between a topography simulator and impurity-profile simulators at each processing step. As an example of simulation, an LDD (Lightly-Doped Drain) MOSFET with tilted source and drain implantation has been derived. In addition, this process simulation system is closely connected with a 3D device simulator. Using this coupled simulation system, the critical effect of processing conditions on device characteristics is analyzed.

A two-dimensional etching simulator named ESPRIT (FOOTNOTE: ESPRIT--Etching Simulation PRogram with an Improved sTring model.) has been developed to simulate LSI patterning. The etching simulator includes isotropic and anisotropic components. Its calculation method is based on the string model. ESPRIT can simulate etched profiles for multilayers with different etching rates and calculate side etching using sloped incidental anisotropic components. In addition, location correction, loop elimination, point insertion, and point elimination are provided for stable and accurate calculations. Simulated profiles coincide well with those from experiments in terms of relationship between the groove width and etched depth. ESPRIT can support to design LSI patterning process.