 Solution

The deposited energy is a blurred, nonlocal version of the commanded write pattern. Forward scattering spreads energy within the resist; backscattered electrons from the substrate contribute a wider background; secondary electrons and the finite incident probe add further spreading. Development then removes regions whose accumulated dose exceeds the effective clearing requirement.

Line ends and isolated short rectangles receive less supporting exposure from neighboring written regions. Their ends can recede and round, and isolated features may shrink to narrow openings. Dense features receive more overlapping scattered dose. Thus one global dose cannot generally reproduce both isolated and dense shapes faithfully.

Use electron beam proximity correction: calibrate a scattering point-spread model for the actual resist, thickness, substrate and beam energy, then adjust local dwell time or beam electric current. Increase or reshape the write dose at underexposed isolated features and line ends, while compensating for the excess background in dense regions. Geometric prebias, such as modest line-end extension, can complement dose correction. A thinner resist and an appropriate higher beam energy may reduce forward-scattering blur, but the backscatter distribution must still be included. Correction must be based on the developed result, rather than assuming the incident beam diameter is the only resolution limit.