Dear Cornel,

Thank you very much for your reply.

We have developed new techniques and procedures to measure the mechanical
properties of polysilicon films that are 3.5 micrometers thick. From the
previous 48 tests, we have found the following properties: Young's
modulus = 169 +/- 6.15 GPa, Poison's ratio = 0.22 +/- 0.011, and tensile
strength = 1.20 +/- 0.15 GPa. This work is included in the paper
"Measurement of Young's Modulus, Poisson's Ratio, and Tensile Strength of
Polysilicon", by W.N. Sharpe, Jr., Bin Yuan, R.L. Edwards, and R.
Vaidyanathan, poster at the Tenth IEEE International Workshop on
Microelectromechanical Systems, Magoya, Japan, January 26-30, 1997.

As it was reported that the mechanical properties of polysilicon changed
due to its exposure to HF, we would like to verify this report with our
techniques. From the first test on a two-hour HF soaked specimen, we have
not found any significant changes in its mechanical properties, though.
More tests will be conducted soon.

Sincerely,

Bin Yuan
Department of Mechanical Engineering
The Johns Hopkins University



On Sat, 18 Jan 1997, MARXER wrote:

> Hi!
>
> The etch rate of poly in HF depend on the HF concentration. We got for exemple
> in 7:1 BHF (thermal oxide etch rate 700 A/min) about 10 A/min poly etch rate.
> In more concentrated HF the etch rate is may be lower; above all the
> selectivity is much higher!
>
> Bye,
>
> Let me know about your interesting work on Mechanical properties of poly!
>
> yours
>
> Cornel Marxer
> res. assistent
> imt - Uni. Neuchatel
> Switzerland
>