A common method of determining film stress is to measure the induced
curvature in the substrate, then calculate the stress using Stoney's
equation.

Measuring the curvature of the substrate can be done using an optically
levered laser beam.  The setup can be as simple as a manual linear
translation stage to move the substrate, while monitoring the deflection
of a laser beam reflecting off it's surface onto a piece of graph paper
taped to a nearby wall.  There are several commercially available,
automated instruments based on this principle.

A somewhat simpler, but cumbersome method to determine substrate
curvature is to measure variation in depth of focus while translating
the substrate on the stage of a microscope.

A discussion of the first method by Sinha, Levenstein and Smith can be
found in the Journal of Applied Physics, Vol 49, No. 4, April 1978, p.
2423-2426

Roger Shile




Hi all,

       I am looking for a right tool to measure the stress in the
polymer
thin film(~50nm) at wafer level. The polymer is a fluorocarbon which is
like
Teflon. The film is deposited with the ICP. I had gone through long
range
surface profiler. But is there any other spectroscopic technique that
can be
used for wafer level stress measurement?

Thanks in advance,

Arun