Browse Prior Art Database

E-Beam Multi-Layer Metal Wafer Registration Without Blockouts

IP.com Disclosure Number: IPCOM000035704D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Viccica, T: AUTHOR [+2]

Abstract

It is proposed to minimize large blocked out areas written on E-beam lithography tools used for semiconductor processing. The proposal suggests writing new wafer alignment registration marks (WARMs) on previously used sites and registering over scan marks from prior levels of exposure.

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E-Beam Multi-Layer Metal Wafer Registration Without Blockouts

It is proposed to minimize large blocked out areas written on E-beam lithography tools used for semiconductor processing. The proposal suggests writing new wafer alignment registration marks (WARMs) on previously used sites and registering over scan marks from prior levels of exposure.

Previous methods for wafer registration for multi-layer metal (MLM) product for E-beam lithography tools utilized three chip sites for exposure of, and, subsequent, blockout of WARMs. New WARMs are exposed at the S1 (contact stud), K (1st metal) and M (2nd metal) levels. These are 100% exposed, or blocked out, at L1 (1st stud via) level and V1 (2nd stud via) level to replicate the WARM for future use. Quartz is removed from the WARMs by their being also blocked out at S3 (blockout), L3 and V3 (quartz deposition and etchback) levels. The L1, V1 and V2 (2nd shallow nitride via) blockouts also covers can marks which would appear as a result of registration. No WARM is reused for wafer registration without a blockout nor is a new WARM ever exposed at a previously used site.

When single wafer reactive ion etch (RIE) tools are used for lift- off, the 100% blockouts at L1 and V1 cause problems since the etch rate is strongly dependent on the pattern factor, or area exposed. The L1 and V1 product has a pattern factor of 1% with the substantial difference between the product and blockouts leading to either under- or over-etching of the product or blockout. Th...