Computer simulation method of impurity with pileup phenomenon

Abstract

A simulation method is provided, which makes it possible to simulate diffusion of doped impurity in Si and SiO.sub.2 in consideration of the pileup phenomenon of the doped impurity without using any intermediate layer. In the step (a), a mesh having mesh points is configured on a simulated zone including a SiO.sub.2 region and a Si region contracted therewith, thereby partitioning the simulated zone into domains. A first one of the mesh points is located in a SiO.sub.2 region. A second one of the mesh points is located in a Si region. A third one of the mesh points is located at an interface of the SiO.sub.2 and Si regions. The third one of the mesh points serves as a double mesh point having first and second impurity concentrations. The first impurity concentration represents a general impurity concentration of a first one of the domains located in the SiO.sub.2 region and adjacent to the interface of the SiO.sub.2 and Si regions. The second impurity concentration represents a general impurity concentration of a second one of the domains located in the Si region and adjacent to the interface of the SiO.sub.2 and Si regions. In the step (b), diffusion equations are provided at the respective mesh points in such a way that the doped impurity piles up in the first one of the domains located in the SiO.sub.2 region. In the step (c), the diffusion equations are solved.