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Improved Process for Clear Defect Mask Repair

IP.com Disclosure Number: IPCOM000039795D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kaplan, LH: AUTHOR

Abstract

This process covers pinhole defects in chrome masks used in semiconductor devices. Dye is mixed into photoresist which covers the defect so that it will have a high enough optical density (OD) so as to be as opaque as the chrome. It is possible to repair clear defects in optical masks in which a novolak/diazoquinone resist is patterned to cover the defects with resist film. The product of that step is then carbonized by a high temperature bake to form a permanent patch over the defects. Using that procedure, it is necessary to isolate the item being baked in an inert atmosphere and the elevated temperature required degrades the optical density of the unprotected Cr.

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Improved Process for Clear Defect Mask Repair

This process covers pinhole defects in chrome masks used in semiconductor devices. Dye is mixed into photoresist which covers the defect so that it will have a high enough optical density (OD) so as to be as opaque as the chrome. It is possible to repair clear defects in optical masks in which a novolak/diazoquinone resist is patterned to cover the defects with resist film. The product of that step is then carbonized by a high temperature bake to form a permanent patch over the defects. Using that procedure, it is necessary to isolate the item being baked in an inert atmosphere and the elevated temperature required degrades the optical density of the unprotected Cr. A more moderate temperature lessens the OD degradation, but the OD of the patch material baked at the lower temperature is low in certain regions of the optical spectrum. This process permits using lower baking temperatures and produces a film patch with an acceptable OD by the addition of a dye to the resist. Such a dye must be compatible with the resist system both as to its solubility in the liquid and its acceptance by the polymer matrix in the dried film. It must not seriously affect the exposability of the resist, and must be thermally stable so as to retain good OD up to acceptable temperatures. In this process, the plate is coated with a dye-containing resist, consisting of either a negative working resist or a positive working resist capable of re...