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Process to Define E-Beam Registration Marks

IP.com Disclosure Number: IPCOM000045204D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Frederick, R: AUTHOR [+3]

Abstract

Semiconductor wafers being prepared for electron beam-exposed photolithographic process steps require registration marks. The marks must be etched into the semiconductor surface so that all subsequent masking steps can be aligned to the marks. It is advantageous that the registration marks be included in the first mask used in the actual wafer processing.

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Process to Define E-Beam Registration Marks

Semiconductor wafers being prepared for electron beam-exposed photolithographic process steps require registration marks. The marks must be etched into the semiconductor surface so that all subsequent masking steps can be aligned to the marks. It is advantageous that the registration marks be included in the first mask used in the actual wafer processing.

Conventionally, the first masking step in bipolar transistor fabrication determines the locations of the subcollectors. The registration marks as well as the subcollector areas are included in this first mask so that the marks are self- aligned with the areas and so that both may be made into apertures in the same oxide masking layer at the same time.

Blanket photoresist is applied, and a block-out mask is used to expose only the portion of the apertured oxide layer bearing the registration marks. The resist is developed, and the registration marks are etched into the wafer. Then, the resist is removed, and the subcollector areas (and, unavoidably, also the registration mark areas) are diffused. The diffusion of the registration areas is unnecessary but inconsequential.

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