# MicroTec for Two-Dimensional Semiconductor Process and Device Simulation: Development Status Update

Capacitance calculated by the charge based method at various ramp speeds

MicroTec is very useful in practical optical sensor prototype development. It significantly out performs other available commercial tools by speed, robustness and is easy-to-use.

Siborg Systems Inc. from Waterloo, Ontario, has been working with Sensor Creations Inc. in Camarillo, California, for the past two years in developing a practical tool for simulating process flow and optical sensor performance.

Sensor Creations Inc. and Siborg Systems Inc. came together to develop both semiconductor device and process simulation for optical sensor structures. The optical sensors, due to their large sizes, require many steps during fabrication such as implantation, depositions, epitaxial growth, annealing and oxidation, etching, etc. When simulating these optical sensors, the size contributes to high CPU time when using conventional simulation tools. MicroTec, on the other hand, was able to run a typical process simulation on a regular PC within a few minutes.

MicroTec is useful for steady-state two-dimensional semiconductor device simulation but is insufficient for capacitance extraction. A new method to calculate capacitance of a semiconductor structure by solving equations for the total current conservation was created. This method is applicable for 1D, 2D and 3D structures, but is limited to low-leakage conditions and low frequencies. The most straightforward method for solving the equation of total current conservation, mutual capacitances may be calculated using the formula C=Idt/dV.

The formula can be improved by using a relation that involves both resistances and capacitances. In order to include both, one more data point is required. Including both resistances and capacitances may make the formula more accurate but it is still not equivalent to the actual compact model of the semiconductor structure because it is a set of interconnected transmission lines and therefore any simplification of the equivalent circuit results in less accuracy. The current method is inaccurate and requires simulation with a properly selected ramp speed. If the speed is too slow, the displacement current becomes too small and is swamped by the…