Wisconsin Alumni Research Foundation

Semiconductors & Integrated Circuits
Semiconductors Integrated Circuits
Method for Measuring Thin Film Stress from Substrate Displacement
WARF: P00370US

Inventors: Anton Jachim

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a novel method for calculating thin film stress.
The manufacture of semiconductor devices typically involves depositing or growing a thin film of a material, such as aluminum or silicon dioxide, on a semiconductor substrate. Thin films always exhibit some intrinsic stress, which if left uncontrolled can lead to device failure through film cracking and delamination.

To properly control film stress, it must first be accurately measured. One popular method is the so-called wafer curvature technique, a simple, inexpensive and non-destructive method that calculates stress from measurements of the substrate wafer’s shape. The main drawback to this technique is that current equations for calculating stress assume that stress is constant across the wafer, an assumption that in reality is rarely met.
The Invention
A UW-Madison resesarcher has developed a novel method for calculating thin film stress based on an inverse finite element analysis of the displaced substrate wafer. This technique produces accurate measurements regardless of whether stress is constant across a wafer, and can be employed with any system that measures substrate curvature.
  • Measuring thin film stress during manufacture of semicondutor devices
Key Benefits
  • Unlike current techniques, this method produces accurate film stress measurements regardless of whether stress is constant across the wafer substrate.
  • Measurement of film stress based on wafer shape is easy, quick and inexpensive to perform.
  • Potentially able to resolve thin film stress more accurately than techniques employed in current instruments
For current licensing status, please contact Emily Bauer at [javascript protected email address] or 608-960-9842