One-step lithography for fabrication of multifunction diffractive structures with grey-tone mask

A new method with coding grey-tone mask has been developed to fabricate multifunction diffractive structures. Instead of conducting two different lithography processes to produce multifunction diffractive structures on a substrate, the new method achieves such structures through one-step lithography using a grey-tone mask. Considering the nonlinear nature of aerial image formation and resist development, predistortion is introduced to encode the grey-tone mask. Based on the theory of partial coherent light and resist development model, the intensity distribution through the grey-tone mask and exposure of photoresist have been simulated. The simulated 3D photoresist profiles are in agreement with the intended multifunction diffractive structures.