X-ray mask process-induced distortion study

X‐ray masks for fabrication of 0.25 μm ultralarge‐scale‐integration devices have to meet very tight pattern placement requirements. Because of the nature of x‐ray mask substrates, control of the distortion caused by the processing of the mask after e‐beam lithography is important. The pattern placement distortions that occur during the processing of an x‐ray mask are examined, and the effect of gold absorber electroplating, e‐beam‐resist strip, and plating‐base strip processes are studied. It has been found that x‐ray mask process‐induced distortion is very sensitive to the amount of gold coverage and the connectivity of the gold pattern.