Enlarge the process window of patterns in 22nm node by using mask topography aware OPC and SMO

The mask three dimensional (M3D) effect of thin Opaque MoSi on Glass (OMOG) mask is analyzed by investigating the difference of diffraction orders between rigorous electro-magnetic field (EMF) simulation and thin mask approximation. Then the potential of extending the process window of AttPSM and OMOG masks with 22nm node SRAM cell patterns by using Optical Proximity Correction (OPC) and Source Mask Optimization (SMO) is compared. Both the OMOG and AttPSM masks are simulated and discussed. For this case, the results show that the overlapped process window (PW) greatly reduces without considering the M3D effects in OPC. In addition, M3D aware SMO improves the total process window one step further.