Characterization in Silicon Processing

5

Tungsten-Based Conductors

ROC

BLUMENTHAL

and GREGORY C. SMITH

Contents

5.1 Applications for ULSI Processing

5.2 Deposition Principles

5.3 Blanket Tungsten Deposition

5.4 Selective Tungsten Deposition

5.1

Applications

for

ULSI Processing

Tungsten is used in integrated electronics as a high-conductivity interconnect met-

allization,

as a plug for vertical contacts and

vias

between metallization

layers,

or as

a

barrier between aluminum and silicon. Tungsten can be deposited by evaporation,

but sputtering and chemical vapor deposition (CVD) are the preferred techniques.

CVD films offer numerous advantages over sputtered films because of lower