Browse Prior Art Database

Selective Sidewall Removal

IP.com Disclosure Number: IPCOM000051093D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Abbas, SA: AUTHOR [+2]

Abstract

This is a simplified SAM (self-aligned metal) stud etch process suitable for providing, for instance, sidewall poly resistor contacts. In a conventional SAM-type process the studs for interconnection and for poly-Si resistor contacts are broken before metallization. It requires a mask and a sequence of up to 4 RIE (reactive ion etch) steps to remove the sandwich layer of SiO(2)/Si/Si(3)N(4) and SiO(2). In addition, if poly-Si resistors are used, variations of the width (or length) are determined by corresponding mask variations, as indicated in Fig. 1.

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Selective Sidewall Removal

This is a simplified SAM (self-aligned metal) stud etch process suitable for providing, for instance, sidewall poly resistor contacts. In a conventional SAM- type process the studs for interconnection and for poly-Si resistor contacts are broken before metallization. It requires a mask and a sequence of up to 4 RIE (reactive ion etch) steps to remove the sandwich layer of SiO(2)/Si/Si(3)N(4) and SiO(2). In addition, if poly-Si resistors are used, variations of the width (or length) are determined by corresponding mask variations, as indicated in Fig. 1.

It is shown in the following that the sidewall (or stud) can be broken with one mask and one RIE step only without impacting the resistor tolerance process. After the poly-Si sidewall formation, a blockout mask is used and the poly-Si is RIE etched, resulting in the structure indicated in Fig. 2. After removal of the resist, the poly-Si sidewall Is reoxidized (everything else is covered by Si(3)N(4)). The thin (500 Angstrom) Si(3)N(4) in the contact area is RIE etched. This step also removes the Si(3)N(4) of the sidewall (non-directional RIE). Photoresist is applied to protect the Si(3)N(4) layer covering the poly-Si resistor area (and any spacers).

The Si(3)N(4) layer is removed over the other regions, followed by pyrocatechol etch of the poly-Si. Fig. 3 illustrates the structure at this stage of the process. The remaining SiO(2) layer is then etched, resulting in either the complete re...