We have developed a practical 3-D integrated process simulator (3-D MIPS) based on the orthogonal grid. 3-D MIPS has a 3-D topography simulator (3-D MULSS) and 3-D impurity simulator which simulates the processes of ion implantation, impurity diffusion and oxidation. In particular, its diffusion and segregation model is new and practical. It assumes the continuity of impurity concentration at the material boundary in order to coordinate with the topography simulator (3-D MULSS) with cells in which two or more kinds of materials exist. And then, we introduced a time-step control method using the Dufort-Frankel method of diffusion analysis for stable calculation, and a selective oxidation model to apply to more general structures than LOCOS structure. After that, the 3-D MIPS diffusion model is evaluated compared with experimental data. Finally, the 3-D MIPS is applied to 3-D simulations of the nMOS Tr. structure with LOCOS isolation, wiring interconnect and pn-junction capacitances, and DRAM storage node area.

A three-dimensional simulation program of oblique rotating ion implantation using the Monte Carlo method has been newly developed to simulate the N- and N+ drain formation of the gate/N- overlapped LDD MOSFET's. The binary scattering approximation is used for nuclear scattering, and the Lindhard-Scharff formula and the Bethe-Bloch formula are used for electronic scattering. The azimuth of the ion is initialized by a random number uniformly distributed between 0 and 2π to express the wafer rotation. The topography of the MOSFET's is approximately expressed in algebraic form to obtain effectively the touchdown points of ion particles on the target surface. The vectorized Monte Carlo method is used to reduce the CPU time. The simulation provides the two-dimensional distribution of the dopant and the Frenkel pairs (vacancy-interstitial), using the Kinchin-Pease equation. From the results of the calculation, it appears that the overlap length, which is defined as the distance between the polysilicon gate edge and the intersection of the 104/cm (equi-concentration/doseline) on the silicon surface, increases in accordance with the increase of the incidence angle of the ion beam, and it extends to 0.1 µm when 40-keV of phosphorus is implanted with an incidence angle of 60. It also appears that the concentration of the Frenkel pairs becomes lower in accordance with an increase in the incidence angle of the ion beam. The simulation also reveals that the effect of a shadowed drain region caused by the polysilicon gate is enlarged in accordance with the increase in the incidence angle, especially in the case of an incidence angle of 60, when the shadowed N+ drain region extends to the point 0.6 µm from the edge of the sidewall which is 0.35 µm in height.