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Self Registered Masks for E Beam Pattern Generation

IP.com Disclosure Number: IPCOM000087684D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Underhill, JA: AUTHOR

Abstract

This articles describes a technique which eliminates error in the registration mark position, from layer to layer, by using the same mask substrate for all layers upon which a registration mark has been initially applied by a suitable lithographic process, so that iterative use of one mask substrate with permanent electron-beam (E-beam) registration marks, for all mask levels in integrated circuit manufacture, can be realized. Thus, this technique eliminates a major source of overlay error for E-beam generated mask patterns.

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Self Registered Masks for E Beam Pattern Generation

This articles describes a technique which eliminates error in the registration mark position, from layer to layer, by using the same mask substrate for all layers upon which a registration mark has been initially applied by a suitable lithographic process, so that iterative use of one mask substrate with permanent electron-beam (E-beam) registration marks, for all mask levels in integrated circuit manufacture, can be realized. Thus, this technique eliminates a major source of overlay error for E-beam generated mask patterns.

It is known that one technique for making high resolution masks is via E- beam lithography. For this approach registration marks are needed that are precisely located with respect to each other from layer to layer. Current methods for reproducing these marks result in overlay errors that are too large to take maximum advantage of E-beam pattern generation.

The problems encountered in the past can be avoided by providing a registration mark on a mask substrate by any suitable lithographic process. The mark comprises a metal that will produce strong signals in subsequent detection with an electron beam. Once the registration marks are produced on the substrate, the pattern for the first layer is then generated with reference to these marks using a material appropriate to the lithographic process, for example, chromium. It is also necessary that the material used for the pattern be sufficiently different from that used for the marks to assure that the etchants used to effect the pattern material will not affect the material used for the...