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Eliminating Undercutting on Thick Metal Films and Manufacturing Thin Metal Masks

IP.com Disclosure Number: IPCOM000090481D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Landler, FJ: AUTHOR [+2]

Abstract

When coating, with photoresist 4, a metal film 2 of about 2 mu which is subsequently etched, heavy undercutting results. The etchant attacks film 2 under photoresist 4, reducing its cross-section, drawing A. The resultant undercutting is proportional to the layer thickness of film 2. In order to eliminate detrimental undercutting on conductors, for example, metal film 2', having a thickness of about 0.5 mu, is vapor-deposited on substrate 1, being subsequently lithographed by a photo-resist and etched, drawing B. As film 2' is only 0.5 mu thick, the resultant undercutting is negligible. The photoresist is removed and a further metal film 3 and 3' of up to five times the thickness of film 2' is vapor-deposited.

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Eliminating Undercutting on Thick Metal Films and Manufacturing Thin Metal Masks

When coating, with photoresist 4, a metal film 2 of about 2 mu which is subsequently etched, heavy undercutting results. The etchant attacks film 2 under photoresist 4, reducing its cross-section, drawing A. The resultant undercutting is proportional to the layer thickness of film 2. In order to eliminate detrimental undercutting on conductors, for example, metal film 2', having a thickness of about 0.5 mu, is vapor-deposited on substrate 1, being subsequently lithographed by a photo-resist and etched, drawing B. As film 2' is only 0.5 mu thick, the resultant undercutting is negligible. The photoresist is removed and a further metal film 3 and 3' of up to five times the thickness of film 2' is vapor- deposited. This film, in contrast to etched film 2', adheres only lightly to substrate 1 so that film 3' applied to substrate 1 can be readily removed from the latter. Film 3 adheres firmly to film 2'. The edges caused by stripping of film 3' are very sharp so that thin metal masks for the manufacture of semiconductors can be produced in this manner. The pattern can be used a random number of times. The method has the added advantage of permitting noble layers, gold, being applied to base carriers, copper, without the carriers being treated galvanically.

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