p7 Thermo-Mechanical Stress Characterization of Tungsten-Fill Through-Silicon-Via

Abstract
Thermo-mechanical stress of tungsten-filled (W-fill) through-silicon-via (TSV) is strongly depending on via shape, size and inter-via spacing, which places constraints on TSV design, including 2-D integrated circuit layout and 3-D structure profile.

1. Introduction

2. TSV Test Structure Design

3. TSV Patterning

4. Tungsten Film Stress
(page 2)
WF6 precursor CVD is chosen for deposition
of W as it is known to provide good conformal film
and high throughput.

5. Flexus Wafer Bow Characterization
A typical interconnection via fill requires
0.6μm W film deposition.\

6. Wright-Etch Characterization
7. Mechanical Stress Simulation
Stress in the substrate can develop as a result
of thermal expansion mismatch between the different
materials composing the TSV and the substrate

Figure 4 shows the model structure of a
30μm long, isolated 3-D structure of the TSV used in
the simulations

Substrate stress is also affected by
interactions between adjacent TSV in an array.

8. Summary & Discussion
The Through Silicon Via (TSV) stress
depends strongly on TSV shape, size, spacing, and 3-
D profile, which would place constraints on TSV
design.