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Pua Shen | 1 Nov 2007 04:44
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Problems with Cr isotropic etching with Cr 7s

Hi all,

I have some problems regarding about Cr isotropic etching. I'm currently deposit Cr with DC sputtering
system as a metal mask. The Cr layer thickness is around 400nm to 500nm on a 4" silica on silicon wafer. After
the PR patterned, i use Cr-7s etchant from rockwood to etch the Cr layer. From the information i found from
internet, the etch rate of Cr-7s is around 7mins/micron. But i'm using around 20 minutes to etch the 450nm
Cr layer completely, have anyone face the problem like this? When the etching goes on, the Cr layer will
change to dark color before it etch off, is this a normal phenomena? The etching is start from side to the
centre of the wafer, when the etching is end at the centre the pattern on the side will be over etched. Anyway
to prevent this or overcome this problem? Thanks
  for reading my mail, it will be great if anyone of you can answer my question. Thanks alot.

Best Regards,
Shen
Photonic Laboratory,
University of Malaya.

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Shay Kaplan | 1 Nov 2007 07:10

RE: TMAH Etching Silicon - loading effects

When you etch multiple wafers the local temperature is higher because the
process is exothermal.

Shay 

-----Original Message-----
From: mems-talk-bounces <at> memsnet.org [mailto:mems-talk-bounces <at> memsnet.org]
On Behalf Of Staller, Steven E
Sent: Wednesday, October 31, 2007 8:54 PM
To: mems-talk <at> memsnet.org
Subject: [mems-talk] TMAH Etching Silicon - loading effects

We believe we have observed a strong correlation of <100>:<1111> selectivity
to loading.

When we etch one wafer we get about &#189; the selectivity as we do when we
etch 25 or more.

Is this a known phenom? Should we expect the selectivity to be effected this
dramatically?

We are talking about selectivities of >65:1 vs ~30:1.

Steve
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Glenn Silveira | 1 Nov 2007 16:24
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RE: get a thin oxadation layer

X.Yan,
You can deposit low temp. PECVD TEOS or SiH4/N20

Best regards,
Glenn

-----Original Message-----
From: memser [mailto:memser <at> tom.com]
Sent: Tuesday, October 30, 2007 6:27 AM
To: mems-talk <at> memsnet.org
Subject: [mems-talk] get a thin oxadation layer

Hello all,
       I'd like to get  a thin oxadation layer (100-500A) on the surface of
my structure, but  thermal oxidation is forbidden for its high temperature
(lower than 300 &#161;&#227;C is OK).  Now, I want to dip the whole wafer
into hydrogen peroxide (H2O2)  or put it into oven (120 &#161;&#227;C) for a
while.   Are these method available?   If not, is there any other methods to
achieve such a thin oxadation layer (100-500A).  Does anyone has experience
to to this? 
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Nicolas Duarte | 1 Nov 2007 16:35
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Re: SiN/SiN bonding and substrate etch

Chemical etchants such as KOH or EDP can remove the Silicon with good  
selectivity.

Nicolas Duarte
Ph.D. Candidate at Penn State University

On Oct 30, 2007, at 12:12 AM, Nor Hafizah Ngajikin wrote:

> Hi,
>
> I have a question on how and what material can be used to bond SiN  
> (wafer 1) with SiN (wafer 2). Secondly, does anybody know what  
> process can be used to totally remove a part of back side Si Wafer  
> without affecting the SiN layer  at the front side.
>
> 

Nicolas Duarte
Ph.D. Candidate at Penn State University

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Nitin Shukla | 1 Nov 2007 17:13
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e-beaming high thermal conductivity non-metals!

Hi,
I want to deposit thin film of some nonmetal having high thermal conductivity (>10 W/m-K) on top of my
samples using e-beam PVD deposition. I tried Si (k~140 W/m-K) and Al2O3 (k~40 W/m-K) but it appears e-beam
produces amorphous form of these materials resulting in very low thermal conductivity of the deposited
film (~ 1-2 W/m-K).
I was wondering if anyone could suggest me some high thermal conductivity non-metal that would maintain
its high thermal conductivity in e-beam deposition.
Thanks,

  Nitin Shukla
  PhD Candidate
  Nanoscale Energy Transport Laboratory
  Department of Mechanical Engineering
  Virginia Tech
  Blacksburg, VA 24061
  Tel No: 540-231-5579
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Boris Kobrin | 1 Nov 2007 18:14
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RE: get a thin oxadation layer

You can deposit thin oxide layer using MVD vapor deposition method at low
temperatures.

Boris 
boris_kobrin <at> appliedmst.com 

-----Original Message-----
From: memser [mailto:memser <at> tom.com]
Sent: Tuesday, October 30, 2007 6:27 AM
To: mems-talk <at> memsnet.org
Subject: 

Hello all,
       I'd like to get  a thin oxadation layer (100-500A) on the surface of
my structure, but  thermal oxidation is forbidden for its high temperature
(lower than 300 &#161;&#227;C is OK).  Now, I want to dip the whole wafer
into hydrogen peroxide (H2O2)  or put it into oven (120 &#161;&#227;C) for a
while.   Are these method available?   If not, is there any other methods to
achieve such a thin oxadation layer (100-500A).  Does anyone has experience
to to this? 
_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
Visit us at http://www.mems-exchange.org

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Gary Hillman | 2 Nov 2007 15:47

RE: e-beaming high thermal conductivity non-metals!

Nitin, maybe reactive sputtering of Al with Argon and nitrogen to form ALN
would work. Maybe worth a try. Gary

Gary Hillman
Service Support Specialties, Inc.
PO Box 365
9 Mars Court
Montville, NJ 07045
Telephone 973-263-0640 extension 35
Fax 973-263-8888

-----Original Message-----
From: mems-talk-bounces <at> memsnet.org
[mailto:mems-talk-bounces <at> memsnet.org]On Behalf Of Nitin Shukla
Sent: Thursday, November 01, 2007 12:14 PM
To: mems-talk <at> memsnet.org
Subject: [mems-talk] e-beaming high thermal conductivity non-metals!

Hi,
I want to deposit thin film of some nonmetal having high thermal
conductivity (>10 W/m-K) on top of my samples using e-beam PVD deposition. I
tried Si (k~140 W/m-K) and Al2O3 (k~40 W/m-K) but it appears e-beam produces
amorphous form of these materials resulting in very low thermal conductivity
of the deposited film (~ 1-2 W/m-K).
I was wondering if anyone could suggest me some high thermal conductivity
non-metal that would maintain its high thermal conductivity in e-beam
deposition.
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provider of MEMS and Nanotechnology design and fabrication services.
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Mikael Evander | 2 Nov 2007 15:58
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proper glass-glass bonding

Hello.

I'm familiar with the "standard" glass-glass thermal fusion bonding method where you wash your glass
wafers, preferable surface activate them with O2-plasma or such-like and thermo-cycle them in an oven a
bit over Tg with some pressure on the wafers. As far as I know most people using this get a pretty low bonding
efficiency, some voids and usually not the nice "mirror-finish" on the glass that you usually see before
you bond.

I'm also aware that the companies doing glass-structuring and bonding commercially must have, and have,
much better bonding efficiencies and incredably good looking bonding. 

I find it kind of surprising that whatever tips and tricks are being used in getting at least a slightly
better bond hasn't seeped out from the industry. As far as I know at least ...

Does anyone have any nice tips and tricks to share that would help me, and hopefully lot of other people, to
get more efficient bonding?

Kind regards
Mikael 

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fyzhang | 2 Nov 2007 19:55
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etchant for stainless steel

Hello all,

We are looking for etchants for stainless steel. The price information is desirable. Any recommendation
or reference will also be greatly appreciated. Thanks!

Have a nice weekend,

Fengyuan
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Bob Henderson | 2 Nov 2007 20:57

Re: proper glass-glass bonding

Mikael:

Maybe groups that provide the superior bonding like to be paid for their IP
investment. I alway maintain that deluxe cost 5 cents extra. Bob Henderson
----- Original Message ----- 
From: "Mikael Evander" <Mikael.Evander <at> elmat.lth.se>
To: <mems-talk <at> memsnet.org>
Sent: Friday, November 02, 2007 7:58 AM
Subject: [mems-talk] proper glass-glass bonding

> Hello.
>
> I'm familiar with the "standard" glass-glass thermal fusion bonding method
where you wash your glass wafers, preferable surface activate them with
O2-plasma or such-like and thermo-cycle them in an oven a bit over Tg with
some pressure on the wafers. As far as I know most people using this get a
pretty low bonding efficiency, some voids and usually not the nice
"mirror-finish" on the glass that you usually see before you bond.
>
> I'm also aware that the companies doing glass-structuring and bonding
commercially must have, and have, much better bonding efficiencies and
incredably good looking bonding.
>
> I find it kind of surprising that whatever tips and tricks are being used
in getting at least a slightly better bond hasn't seeped out from the
industry. As far as I know at least ...
>
> Does anyone have any nice tips and tricks to share that would help me, and
hopefully lot of other people, to get more efficient bonding?
_______________________________________________
(Continue reading)

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Gmane