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Browse Prior Art Database

Oxidizable P-Channel Gate Electrode

IP.com Disclosure Number: IPCOM000041903D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Nesbit, LA: AUTHOR [+2]

Abstract

This article describes a method for making dual work function gate structures to improve the characteristics of complementary devices. This is accomplished by providing a structure wherein an oxidizable P-channel silicide gate electrode is contacted by an N-channel polycide electrode without the polycide completely covering the P-channel gate electrode. The desire to have dual work function gates in CMOS products can be met by placing a work function adjust material, such as a silicide selected from a group consisting PtSi, MoSi2 or IrSi3, over the P-channel gate oxide. The work function adjust material can then be contacted by a doped polysilicon layer or by a polycide structure, which can also act as the gate electrode for the N-channel device.

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Oxidizable P-Channel Gate Electrode

This article describes a method for making dual work function gate structures to improve the characteristics of complementary devices. This is accomplished by providing a structure wherein an oxidizable P-channel silicide gate electrode is contacted by an N-channel polycide electrode without the polycide completely covering the P-channel gate electrode. The desire to have dual work function gates in CMOS products can be met by placing a work function adjust material, such as a silicide selected from a group consisting PtSi, MoSi2 or IrSi3, over the P-channel gate oxide. The work function adjust material can then be contacted by a doped polysilicon layer or by a polycide structure, which can also act as the gate electrode for the N-channel device. To limit the size of the structure, it is desired that this relatively thick polysilicon or polycide layer not be required to completely cover the P-channel silicide electrode. However, in order to oxidize the P-channel silicide, it is necessary to deposit a silicon capping layer on the P- channel in order to form an oxide layer on the silicide without consuming its silicon content. If the polysilicon or the polycide structure is deposited as a blanket layer and then etched so as to only partially cover the P-channel silicide, the silicon capping layer on the P-channel silicide will be etched off during the etching of the polysilicon or polycide structure. The method described in this article and illustrated in the drawings uses an etch stopping material, such as a layer of cobalt (Co), over the silicon capping layer to protect this silicon layer during the etching of the polysilicon or polycide layer for the f...