Thanks for your comments.

Dear Jie

Hi. I think that my explanation regarding the distortion after DRIE was not
enough, so the confusing was caused to you. The device layer was not peeled
off the BOX, it is still well-attached on BOX. I fully agree with you that
the peeling-off the device layer on BOX is impossible. And I also agree that
temperature issue may not be a candidate for distortion.
What is the meaning of microloading? I don't know the meaning, but our beams
are located in less crowd region, so your comments can be one answer for
that phenomena. Thanks.

Dear Jordi
Hi. Unfortunately no images were taken. Did you mean the footing? The
overetching can be one of reason. We will consider that issue more deeply in
next process. Your comment is so helpful. Thanks.


Jungwook Choi

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
On Behalf Of Jordi Teva
Sent: Saturday, January 17, 2009 10:49 PM
To: General MEMS discussion
Subject: Re: [mems-talk] Distortion of silicon beam after DRIE process

have you consider the notching as the root cause of that "distorsion",
could you send a picture?

Hope this helps,

jordi


On Sat, Jan 17, 2009 at 4:08 AM, Jie Zou  wrote:
> Hi, so the stress was so strong that it overcome the adhesion force between
> the BOX and the Device layer? It sounds very strange to me. You mean it
> peeled off the BOX or it slided on the BOX? Both look impossible. And the
> DRIE usually comes with a cryogenic back cooling, thus I don't think it
> brings too much heating issues.
> how wide is your beams? I have some 2~3 um legs (after 1um undercutting from
> one side) and device layer 5um thick, but never saw the distortion
> happened.
>
> Just one thought. Did you mean the beams were not straight? Microloading
> would cause faster etching rate in the region with larger intervals between
> objects than the crowd region. So the beam could look like distorted to the
> less crowd region.
>
> Jie