Patent ID: 8652763

Claim:
A method for processing a substrate, said method comprising the steps of: providing a single layer of radiation sensitive material on at least a portion of said substrate, wherein said substrate comprises a layer stack having a first substrate layer, a first etch stop layer, a second substrate layer and a second etch stop layer, wherein said first substrate layer is positioned between said single layer of radiation sensitive material and said first etch stop layer, wherein said first etch stop layer is positioned between said first substrate layer and said second substrate layer and wherein said second substrate layer is positioned between said first etch stop layer and said second etch stop layer; exposing a first area of said single layer of radiation sensitive material to radiation having a first intensity, wherein said first intensity is a sub-threshold level of intensity; exposing a second area of said single layer of radiation sensitive material to radiation having a second intensity; wherein said second area at least partially overlaps said first area in an overlapping area and wherein said second intensity is a sub-threshold level of intensity; wherein said steps of exposing said first area and said second area of said single layer of radiation sensitive material are performed using maskless lithography; developing said single layer of radiation sensitive material by removing material from regions of said single layer of radiation sensitive material corresponding to the first and second areas, thereby generating a recessed feature having a first non-uniform depth profile in said single layer of radiation sensitive material; transferring at least a portion of said recessed feature having said first non-uniform depth profile in said single layer of radiation sensitive material into said first substrate layer, thereby opening up a first opened up region of said first etch stop layer; removing material from said first opened up region of said first etch stop layer, thereby opening up a second opened up region of said second substrate layer; transferring at least a portion of said recessed feature having said first non-uniform depth profile in said single layer of radiation sensitive material into said second substrate layer, thereby opening up a third opened up region of said second etch stop layer; and removing material from said third opened up region of said second etch stop layer; said transferring and removing steps generating a recessed feature having a second non-uniform depth profile in said substrate, thereby processing said substrate.