We develop a new method based on the high-frequency electromagnetic (EM)-semiconductor coupled simulation to analyze the impact of multi-type process variations happen around semiconductor-metal structure. It is competent to simultaneously handle geometrical variations like surface roughness and material variations like semi-conductor doping profile, which are difficult for traditional "stand alone" simulation methods. A sparse grid based stochastic spectral collocation method (SSCM) combined with principle factor analysis (PFA) is implemented to accelerate the stochastic simulation. Numerical results confirm the validity and significance of our variational coupled simulation framework.