Help!! Urgent.
normally the parasitic capacitance can be modeled by the parallel-plate capacitor model (also called area capacitance) and fringing capacitance,
the total capacitance is the sum of pp capacitor and fringing capacitance
for detail, you can study
Digital intergrated circuits:a design perspective a design perspective
Jan M.Rabaey
by the way, now the parastic RC can be extracted by many EDA tools, It is very hard for you to calculate them by yourself, if you tell the toos some parameters as listed in the links i given, for example
Poly over field oxide (area) 0.066 fF/um2
Poly over field oxide (perimeter) 0.046 fF/um
Metal-1 over field oxide (area) 0.030 fF/um2
Metal-1 over field oxide (perimeter) 0.044 fF/um
Metal-2 over field oxide (area) 0.016 fF/um2
Metal-2 over field oxide (perimeter) 0.042 fF/um
Metal-1 over poly (area) 0.053 fF/um2
Metal-1 over poly (perimeter) 0.051 fF/um
Metal-2 over poly (area) 0.021 fF/um2
Metal-2 over poly (perimeter) 0.045 fF/um
Metal-2 over metal-1 (area) 0.035 fF/um2
Metal-2 over metal-1 (perimeter) 0.051 fF/um
the tools can solve it,