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Method for Checking Mask Errors

IP.com Disclosure Number: IPCOM000081182D
Original Publication Date: 1974-Apr-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Gurtler, WG: AUTHOR [+2]

Abstract

This method is used to make a rapid location of errors arising between a design layout for a semiconductor mask and the actual mask developed from the design by a processor.

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Method for Checking Mask Errors

This method is used to make a rapid location of errors arising between a design layout for a semiconductor mask and the actual mask developed from the design by a processor.

The two masks are compared by a photographic superposition process, where first one of the masks is used to partially expose a film. The exposure will normally be about 1/2 of the minimum exposure needed for full exposure of the film. The first mask is now replaced by the second mask and another exposure of the same strength is made on the film. The film is now removed and processed normally to bring the doubly (fully) exposed areas to a full development.

If there are any differences between the two masks as an omission of a connection 1 or an addition of a connection 2, as indicated on the product mask drawing above, then the composite print will have corresponding areas 3 which will have received only a partial exposure. These partially exposed areas will print out at only a fraction of the density of the fully exposed areas, and can be readily identified by inspection. The product mask can then be repaired as needed and used in regular production.

Either a positive or a negative composite print may be used, for with either type, the areas of error will be distinctly different from the other areas.

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