Patent ID: 8236484
Filing Date: 2012-08-07
Classification: G03F,G11B

Abstract:
1. A liftoff method for photolithography, comprising: depositing a single layer of photoresist on a substrate; exposing and developing said photoresist layer thereby forming a photoresist pattern having sidewalls and an upper surface; irradiating said upper surface with an ion beam having a direction parallel to said sidewalls, said ion beam comprising ions whose energy is too low to sputter said layer of photoresist; maintaining said ion beam irradiation for a time period whereby a hardened layer is formed that extends a distance downwards from said upper surface, all remaining photoresist being unhardened; then exposing said photoresist pattern to ozone whereby said sidewalls are eroded and said hardened layer is unchanged so that the hardened layer overhangs the unhardened layer; depositing a layer of a material onto all horizontal surfaces to a thickness that is less than that of said unhardened photoresist layer; and selectively removing said unhardened photoresist layer whereby all of said material that is deposited onto said hardened photoresist layer is lifted off.