Browse Prior Art Database

BLANKET CVD W WITH REPEAT DEPOSITION ETCHBACK PROCESS

IP.com Disclosure Number: IPCOM000006882D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2002-Feb-08
Document File: 3 page(s) / 116K

Publishing Venue

Motorola

Related People

Li-Hsin Chang: AUTHOR [+2]

Abstract

A combination of CVD W plug technology with a low dielectric constant polyimide interlevel dielectric (ILD) material is very desirable for high density, high sped multilevel metal VLSI applications. However, poly- imide cracking has been a problem found on patterned wafers after blanket CVD W deposition and etchback process. Due to the highly tensile nature of the CVD W Elm and the low tensile strength of the polyimide (PI) fihn, cracks were sometimes developed at the comers of patterns with steep steps surrounded by large open field areas. High CVD W fihn stress may also induce W delamination or "blisters" from a BPSG ILD material.

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INC. Technical Developments Volume 19 June 1993

BLANKET CVD W WITH REPEAT DEPOSITION ETCHBACK PROCESS

by Li-Hsin Chang and Don Weston

  A combination of CVD W plug technology with a low dielectric constant polyimide interlevel dielectric (ILD) material is very desirable for high density, high sped multilevel metal VLSI applications. However, poly- imide cracking has been a problem found on patterned wafers after blanket CVD W deposition and etchback process. Due to the highly tensile nature of the CVD W Elm and the low tensile strength of the polyimide (PI) fihn, cracks were sometimes developed at the comers of patterns with steep steps surrounded by large open field areas. High CVD W fihn stress may also induce W delamination or "blisters" from a BPSG ILD material.

  For a normal blanket CVD W via plug process, the thickness of the tungsten deposition used is about 0.9 pm for lilling vias with similar depths. In the past, the PI cracking problem has been solved by techniques such as using PI with reduced thickness, or capping PI with a thick (e.g. 8 ti) compressive plasma nitride lihn to coun- ter the high tensile stress of the tungsten fti. For using reduced PI thickness, the PI thickness will be limited which will result in poor step coverage and increased

ILD capacitance. If a compressive nitride cap was used, PI "wrinklimg" has been observed.

  The CVD W fdm stress generally increases with increasing W tihn thickness in the range of the thicknesses of interest. The current art employs an alternating depo- sition and etchback technique using reduced W tihn thick- ness hence...