Angular-resolved optical scatterometry is a new promising technology for metrology in lithography for the construction of VLSI chips such as DRAMs and CPUs. In order to measure the geometry dimensions and material properties of markers and interconnect lines, one needs to solve Maxwell's equations for an electromagnetic scattering problem. The well known RCWA discretization method is too slow for 3D applications whence one takes resort to either a finite element discretization method or a volume integral method (VIM). VIM systems of equations can be solved faster than FEM systems of...