PREDICTION OF INPLANE DISTORTIONS DUE TO MASK FABRICATION PROCESSES

In the fabrication of a typical refractory X-ray lithography mask, the pattern transfer process subjects the membrane/pattern to the non-uni form deposition and removal of multiple stressed layers. This removal process can result in unacceptably large pattern distortions in the fi nal mask. This paper presents relationships obtained from finite eleme nt (FE) modeling, between pattern distortions and the following mask p arameters: membrane material, thickness, size and stress, and the remo ved film material, thickness and stress. In addition, the sensitivity of the distortions was investigated for stress gradients present in th e removed film. Finally, the capability of these models to predict pat tern specific distortions (PSD) is demonstrated.