Geometry Optimization of Sub-100nm Node RF CMOS Utilizing Three Dimensional TCAD Simulation

For the purpose of 90nm technology node RF CMOS geometry optimization, the effect of geometrical variations on the high frequency characteristics are precisely analyzed utilizing a three dimensional TCAD device simulator. After showing the accuracy of small-signal 3D TCAD simulation, the dependence of MOSFET´s gate resistance on gate width is analyzed with the results showing that when gate width becomes shorter than 1mum gate resistance begins to increase dramatically. 3D TCAD is then applied to achieve a more practical CMOS design. The effects and trade-offs of geometrical factors, such as number, width and pitch size of gate fingers of comb-shaped transistors, are analyzed to attain an optimum combination