In the former device, there were no problem until i changed the sputtering
target.

At least ,we cann't see any grass on the Al layer at all by microscope.

But  now, no matter which target i used, the grass can be found and cause
short circuit.

if the problem is about stress, the phenomena should be minimized after
annealing.
but After i anneal Al layer at 400 degreeC for 1 hour, remove the grass,
then do the anodic bonding.
it still grows Al grass.

what if the stress is from  7740 glass?

Thank you :)


On Tue, Mar 6, 2012 at 2:45 AM, shay kaplan  wrote:

> This phenomena is known in the semiconductor (hillocks) - caused by
> aluminum
> stressing and relieving stress. Slightly better with 1% Si inside but
> almost
> impossible to get rid of it. Replace the aluminum with another metal.
>
> Shay
>
>
> -----Original Message-----
> From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
> On Behalf Of Xin Yan
> Sent: Monday, March 05, 2012 4:02 PM
> To: General MEMS discussion
> Subject: [mems-talk] Al grass on the 7740 glass
>
> Hi everyone,
>
> the process flow as follows,
> 1 etch cavity on the 7740 glass
> 2 deposit  200nm Al layer  on the cavity of  7740 glass,
> 3 anodic bonding process with silicon,  400 degreeC, 800V
>
> the problem:
>  we always find the  Al grass on the al layer after the anodic bonding,
>  the
> Al grass dimension: about 2~3um long, and with a diameter of 200nm
>
> the quantity of grass is  not too much , but it cause the device short
> circuit.
>
> have somebody met this problem before?  what's the source of this
> phenomenon?
>
> Any suggestions would be appreciated!
>
>
>
>
> --
> Yan Xin
> _______________________________________________
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--
Yan Xin
_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
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