In search of high‐performance resists for 50 kV shaped‐beam exposure

A search was made to find a high‐performance resist to manifest the high‐resolution advantage of 50 kV electron‐beam exposure. Four resists were evaluated: Shipley SAL‐601, AT&T/OCG CAMP‐6, IBM KRS, and IBM TNS. All resists were found to have high contrast ≳3 and were capable of resolving <0.25 μm line/space pairs at 3000 A thickness. With the exception of TNS, the resists demonstrate a high bulk sensitivity of <15 μC/cm2 at 50 kV. The IBM KRS resist was found to have the highest figure of merit. It was capable of resolving less than 0.10 μm line/space at 4000 A thickness. Furthermore, at 8000–10 000 A, a resolution of ≤0.25 μm was obtained with a steep profile. The dry etch resistance of the resist relative to chrome was 2.4:1. This resist is not environmentally sensitive and needs no postexposure bake treatment. If KRS is made commercially available, it will be an outstanding resist for modern electron‐beam/x‐ray mask making and direct write for device fabrication.