Browse Prior Art Database

Mask On Mask for Reduced Pinholes

IP.com Disclosure Number: IPCOM000084644D
Original Publication Date: 1975-Dec-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Via, GG: AUTHOR

Abstract

A positive chromium mask and its mirror image are combined as a single mask to (1) reduce pinhole defects, (2) eliminate dust contamination, (3) increase pattern resolution, and (4) extend mask lifetime.

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Mask On Mask for Reduced Pinholes

A positive chromium mask and its mirror image are combined as a single mask to (1) reduce pinhole defects, (2) eliminate dust contamination, (3) increase pattern resolution, and (4) extend mask lifetime.

Fig. 1 shows a first chromium mask 10 comprising a glass substrate 12 coated with a chromium layer 14 including patterns defining the numerals 1...4, as shown in Fig. 2. A second chromium mask 19 comprises a glass substrate 18 and a chromium layer 20 that includes a mirror image, as shown in Fig. 3, of the patterns in the mask 10.

Prior to placing the masks 10 and 19 in face-to-face relation, the patterns are inspected for black defects and removed by a laser tool under a microscope. The masks are bonded together by a suitable sealant 22. Pinhole defects in the combined masks are reduced based upon the statistical improbability of coincident imperfections in the overlying masks.

In addition to reducing the pinhole defects in the masks, the dual-metal thickness increases the contrast ratio which is particularly important for projection printing systems. Sealing of the chromium surfaces 14 and 20 within the masks reduces scratching and extends mask lifetime. Also mask contamination from dust is reduced by the sealed pattern structure.

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