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Dimensionally Stable Metal Mask Fabrication Process

IP.com Disclosure Number: IPCOM000085131D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Crimi, JS: AUTHOR [+3]

Abstract

A method has been devised for fabricating an electroform mask which avoids gross changes in the overall dimension of such mask.

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Dimensionally Stable Metal Mask Fabrication Process

A method has been devised for fabricating an electroform mask which avoids gross changes in the overall dimension of such mask.

The mask is made e by plating both sides (see Fig. 1) of a copper foil 2 with nickel films 4 and 6. Positive resist films 8 and 10, as seen in Fig. 2, are placed on respective nickel films 4 and 6.

By conventional exposure through masks and development of the photoresist layers after exposure, openings 12 are obtained in the photoresist films 8 and 10. An etching fluid enters these openings to etch away the opposing films of nickel 4 and 6, as seen in Fig. 3.

The copper 2 is then etched away, as seen in Fig. 4, followed by removal of the photoresist 8 and 10 to attain the mask of Fig. 5.

The method described above is a subtractive method, that is, all the needed films are put on first and then etched away, rather than being put on additively after processing the photoresist.

An electroform mask fabricated by the subtractive method avoids the problems inherent in making the mask by an additive process. In the latter process, maximum dimensional changes occur during the nickel plating of the foil after image formation, because the amount and distribution of plated nickel 4 and 6 is different on either side of the foil 2. Such changes are unpredictable and cannot be compensated for.

In the subtractive process both sides of the copper foil 2 for uniformly nickel plated simultaneously, so th...