Elimination of Mask Substrate Defects
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Small voids in the chromium film of the incoming mask substrate result in mask defects and a high repair incidence. This procedure would repair those pinholes. 1. If the substrate is not already coated with positive photoresist, apply a positive photoresist. A very high quality resist film is not necessary. 2. Expose the photoresist film through the back of the substrate, thus exposing only the areas above the pinholes (blanket exposure of reverse side). 3. Develop the photoresist, and evaporate a chromium film onto the surface of the developed resist. Chromium will deposit on the substrate where the resist was exposed, covering the pinholes. 4. Dissolve the undeveloped photoresist with a suitable solvent, "lifting off" chrome which lies on resist surfaces.