Electron beam lithography process

Claim 1

In a process of forming a patterned resist image on a substrate, the process including the steps of: forming a layer of resist material, which becomes more soluble in a developer when struck by electrons, on the substrate; exposing the layer to a scanning beam of electrons to form a pattern of exposed shapes, the beam having a fixed spot size which is moved step-wise on a two dimensional grid whose grid size is a fraction of the spot size; and developing a patterned resist image by removing the resist material in the exposed shapes with a developer; the improvement which comprises forming first exposed shapes in the layer with a series of a non-overlapping exposures each at a first exposure dosage and forming a second exposed shape in the layer with multiple overlapping exposures, with each overlapping exposure being at a dosage less than said first exposure dosage; and then developing the patterned resist layer with a developer to completely remove the resist in the first exposed shapes down to the substrate while at the same time removing only a portion of the resist in the second exposed shape down to the substrate.