You can perform this sort of measurement very inexpensively using a home-made
levered laser setup.  This is accomplished by reflecting a laser beam off the
sample as it is moved on a linear trasnlation stage.   The radius of curvature
of the sample can be calculated as a function of the displacement of the laser
spot on a screen (which may consist of a sheet of graph paper), verses  the
translation distance of the sample.

The technique is discussed by Sinha, Levinstein, and Smith:  Thermal stresses
and cracking resistance of dielectric films (SiN, Si3N4, and SiO2) on Si
Substrates
J. Appl. Phys, Vol 49, No 4, April 1978.

Roger Shile


l>>> [email protected] 04/08/02 03:41PM >>>
Hi David,

I don't know if there is a non-contact equipment around Boston you can use.
I'm guessing you don't have a Flexus. The dimensions you mentioned can be
measured comfortably in a Flexus system. If the deflection is large enough,
you might be able to get away with anchoring one end of your sample and
measure the deflection on the other end using a microscope. That will at
least give you a stress delta. Good luck!

Henry

"David Tang" @memsnet.org on 04/04/2002 05:33:00 PM

Please respond to [email protected]

Sent by:    [email protected]


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Subject:    [mems-talk] radius of curvature measurement



Hello,

I am trying to characterize thin film material properties by measuring the
radius of curvature of specimens that are ~1cmx10cm long.  Does anyone know
of vendors/labs/universities around Boston that have non-contact equipment
to measure radius of curvature?  Thanks.

David Tang
MEMSIC Inc.
100 Burtt Road
Andover, MA 01810
Phone:  978-623-8188 x 237
www.memsic.com
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