X-RAY MASK PROCESS-INDUCED DISTORTION STUDY

X-ray masks for fabrication of 0.25-mu-m 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.