It really depends on the film.  For homogenous films, the stress is
independent of thickness.  However, if the stoichiometry of the film or
the crystal structure of the film changes as it grows, the stress will
vary.

Also, be sure you are measuring the stress of the film (the film
thickness should be part of the equation) and not the stress on the
substrate.  The stress on the substrate of course will grow as does the
thickness of the film.

Dan Ruiz

-----Original Message-----
From: mems-talk-bounces+dan.ruiz=honeywell.com@memsnet.org
[mailto:mems-talk-bounces+dan.ruiz=honeywell.com@memsnet.org] On Behalf
Of zhijian
Sent: Tuesday, June 14, 2011 8:44 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] residual stress vs. thin film thickness

Dear Everyone,

I am confused with this question for a long time. Does the residual
stress have a
relationship with the deposited film thickness?

I have heard that they are independent.

When I measured the residual stress of the low-stress LPCVD SiN, I found
that with the deposited SiN become thicker, the residual tensile stress
is also larger.

Has anybody had this experience?

Sincerely,
Zhijian ZHOU
Ph.D @ HKUST