Browse Prior Art Database

Contact Sites Self-aligned On Mos Gate Edges

IP.com Disclosure Number: IPCOM000060634D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Chin, D: AUTHOR [+2]

Abstract

Self-aligned contacts can be formed on MOS gate edges by localized doping of polysilicon and preferential etching. The us these self-aligned contacts prevents possible short circuits between the metal layer and polysilicon gates.

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Contact Sites Self-aligned On Mos Gate Edges

Self-aligned contacts can be formed on MOS gate edges by localized doping of polysilicon and preferential etching. The us these self-aligned contacts prevents possible short circuits between the metal layer and polysilicon gates.

In the Figure, a second layer of undoped polysilicon 1 is deposited over the previously deposited non-conducting layer of oxide or nitride 3 on polysilicon gate
2. Impurities in the boron silicate glass sidewall spacer, which remained after reactive-ion etching on the polygate sidewall, is then driven into this second layer of polysilicon. The polysilicon layer 1 is then preferentially etched such that the polysilicon 1 is left on the contact site and adjacent polygate sides but not on the other side of the gate edges by removing the BSG spacer before drive-in. The polysilicon layer is, consequently, self-aligned with the gate edges so that its total width is about 3 minimum feature sizes. This is sufficient to make a contact hole on the polysilicon layer whose etch rate is at least ten times slower than the insulating CVD oxide layer 4. The contact metal can be stacked on this second polysilicon layer to complete the contact site.

Disclosed anonymously.

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