Browse Prior Art Database

Evaporation Mask for Mask Changing and Registration Under Vacuum

IP.com Disclosure Number: IPCOM000075176D
Original Publication Date: 1971-Aug-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Krongelb, S: AUTHOR

Abstract

The fabrication of certain devices is more easily done by a series of evaporations through suitable masks than by a deposition and subtractive etch approach. For evaporation through masks, each mask has had to be registered in the vacuum system with the pattern on the wafer. This registration has been a problem because (1) the masks are translated over relatively large distances to position them under the substrate and (2) the heated substrate causes thermal expansion and consequent dimensional changes in each mask as it is brought into the vicinity of the substrate.

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Evaporation Mask for Mask Changing and Registration Under Vacuum

The fabrication of certain devices is more easily done by a series of evaporations through suitable masks than by a deposition and subtractive etch approach. For evaporation through masks, each mask has had to be registered in the vacuum system with the pattern on the wafer. This registration has been a problem because (1) the masks are translated over relatively large distances to position them under the substrate and (2) the heated substrate causes thermal expansion and consequent dimensional changes in each mask as it is brought into the vicinity of the substrate.

A masking method is described which overcomes the above-noted problems. For a circumstance where it is desired to fabricate an array of devices using a series of four evaporations through mask patterns A, B, C, D, respectively, these patterns are fabricated in a group on a single mask plate, as shown in the figure and the group is repeated for each device in the array. The number of patterns in a group may be more or less than the four shown in this example; and spacing between devices need only be large enough to accommodate a single group of masks. The substrate, not shown, is located above the mask plate and evaporation takes place through the pattern which lies over the opening in the aperture plate. Mask changing is accomplished by translating the mask plate in the x and y directions to bring the desired pattern over the aperture....