Browse Prior Art Database

Deposition of Tungsten On Polysilicon

IP.com Disclosure Number: IPCOM000038315D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Chen, TC: AUTHOR [+2]

Abstract

Delamination and high contact resistance can be avoided by depositing a thin layer of tungsten on polysilicon via chemical vapor deposition and thereafter increasing the layer thickness with sputtered tungsten.

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Deposition of Tungsten On Polysilicon

Delamination and high contact resistance can be avoided by depositing a thin layer of tungsten on polysilicon via chemical vapor deposition and thereafter increasing the layer thickness with sputtered tungsten.

In the process, a thin layer of tungsten (30-50 nm) is deposited on polysilicon by substitution reaction using tungsten hexafluoride, which etches the native oxide on silicon and lowers the contact resistance. Oxygen in the film results in resistivity of 25-30 micro-ohm-cm above 800oC and supresses silicidation of the tungsten.

Thereafter, a second layer of tungsten having a low resistivity (10-12 micro- ohm-cm) and larger grain size is sputtered over the first. The composite structure can be annealed at high temperature and etched efficiently in dichlorodifluoromethane with oxygen for the sputtered tungsten and in carbon tetrafluoride and oxygen, for the first deposited tungsten and polysilicon.

Disclosed anonymously.

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