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Portable Conformable Mask Patterning for Contact Hole Etching and Lift-Off of Contact Hole Stud

IP.com Disclosure Number: IPCOM000039338D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 80K

Publishing Venue

IBM

Related People

Fineman, JP: AUTHOR [+3]

Abstract

This article relates to a method of protecting exposed silicon at the bottom of a contact hole from reactive ion etch (RIE) metal level patterning with a metal contact stud. To effectively utilize the RIE technology to pattern metal films, exposed silicon at the bottom of a contact hole must be adequately protected. One technique used is to form a stud of material in a contact hole which is sufficiently thick to protect the silicon below from a RIE over-etch. A multilevel resist scheme combined with a metal lift-off process is used to form a metal stud in a contact hole. This approach is compatible with current tooling and does not require new metallurgical materials. At contact level photoresist, spin on two levels of photoresist, as shown in Fig. 1, instead of the usual one level.

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Portable Conformable Mask Patterning for Contact Hole Etching and Lift- Off of Contact Hole Stud

This article relates to a method of protecting exposed silicon at the bottom of a contact hole from reactive ion etch (RIE) metal level patterning with a metal contact stud. To effectively utilize the RIE technology to pattern metal films, exposed silicon at the bottom of a contact hole must be adequately protected. One technique used is to form a stud of material in a contact hole which is sufficiently thick to protect the silicon below from a RIE over-etch. A multilevel resist scheme combined with a metal lift-off process is used to form a metal stud in a contact hole. This approach is compatible with current tooling and does not require new metallurgical materials. At contact level photoresist, spin on two levels of photoresist, as shown in Fig. 1, instead of the usual one level. Over boron phosphorus silicon glass (BPSG) a thin film of polymethylglutarimid (PMGI) is applied, followed by a novalac resin photoresist (NRP), standard in the industry. Photopattern the NRP and develop in the usual manner. The PMGI underlayer is blanket exposed with deep ultraviolet (DUV) light and developed so that a significant undercut is obtained, as shown in Fig. 2. The NRP photoresist is opaque to DUV and can be used as a mask for the PMGI photoresist underlayer. An alternative PMGI development method is to extend the development time of the NRP resist. A short blanket exposure of...