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Improved E Beam Registration Mark Process

IP.com Disclosure Number: IPCOM000088431D
Original Publication Date: 1977-Jun-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Lane, JG: AUTHOR [+2]

Abstract

An improved electron(E)-beam lithographic registration mark technique consists of utilizing a set of registration marks with proper sidewall profile throughout semiconductor chip construction.

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Improved E Beam Registration Mark Process

An improved electron(E)-beam lithographic registration mark technique consists of utilizing a set of registration marks with proper sidewall profile throughout semiconductor chip construction.

A set of registration marks is etched in the silicon substrate prior to standard chip processing. All subsequent lithography levels are registered to these marks. The marks should have steep sidewalls such that they are highly visible to the E- beam registration diodes and detection circuitry, and also are not significantly degraded by normal semiconductor processing. Such marks can be formed by using thermal SiO(2) as a mask and reactive ion etching (RIE) of the marks in silicon. RIE can be done in a diode system using the proper mixture of reactant gases.

Reactive ion etching the marks will result in steep sidewalls, as shown in the figure, unlike the more shallow sidewalls produced by wet chemical etching. This allows reduction in alignment tolerance by using a single mark alignment approach, reduction in alignment tolerance due to less processing degradation of the mark, and reduction in silicon area required for registration marks by using only one set of marks.

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