A New Method for Creating Sloped Resist Profiles Using Mask Structures

A common photolithography requirement is to generate a slope in a developed resist pattern prior to etch. To generate the sloped profile the resist is either exposed out of focus, hard baked after develop to flow the resist, or eroded as part of the subsequent etch process. Each of these options requires control of multiple processes to generate a slope that is uniform across the wafer, between wafers and between lots. In this feasibility study, Skyworks evaluated one new approach that uses mask features below the resolution limit of the stepper to expose away part of the resist around the edges of designed features.