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pradeep # sharma | 1 Jun 2008 06:54
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Photoresist to withstand acidic anodization

Dear Friends,

We intend to do anodization of aluminum foil in sulphiric acid, oxalic acid and phosphoric acid.
Anodization voltage will be 25 V to 100 V and concentrations of acids will be about 4 percent by weight. 

We need to put a photoresist on Al surface and then open 2 micron diameter circles in photoresist by
photolithography. 

Please suggest some resist for our purpose. Make sure the resist can withstand the acids, and have adequate
breakdown voltage and offers resolution of about 0.5 to 1 micron.. 

Thanks to all. 

with love and best wishes,
Pradeep Sharma, 

Laboratory NB 02, 
IAMS, Academia Sinica, 
P.O. Box: 23-166,
Taipei-106, Taiwan, R.O.C.

Phone Number: 00886-2-2362-4901 (Laboratory)
              00886-910984500 (Mobile)  

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pradeep # sharma | 1 Jun 2008 06:57
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Database for photoresist

Dear Friends,

Please tell me some source for chemical/physical/electrical properties of photoresist like AZ, SP and SU-8.

I would like to know the electrical breakdown voltage of AZ, SP and SU-8 types of resist.  

You may forward a PDF or internet link. 

Thanks to all. 

with love and best wishes,
Pradeep Sharma, 

Laboratory NB 02, 
IAMS, Academia Sinica, 
P.O. Box: 23-166,
Taipei-106, Taiwan, R.O.C.

Phone Number: 00886-2-2362-4901 (Laboratory)
              00886-910984500 (Mobile)  

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Tolga YELBOGA | 1 Jun 2008 14:31
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Re: Damaging of boats during nickel evaporation

Hi;

As we know Al is very wettable material.Therefore evaporation of Alimunium
is very problematic. You can try to give current very slowly or use Alimuna
boat. But it's hard to use therefore breakable problem.

In addionally the the quality of boats of evaporation can be change
according to manufacturer. 

Tolga YELBOGA 
Project Engineer
Nanotechnology Researh Center 
Bilkent University 
Bilkent, Ankara 06800 TURKEY 
Voice: 90-312-290-1020 
http://www.nanointurkey.com
http://www.nanotam.bilkent.edu.tr

-----Original Message-----
From: X.P. Zhu [mailto:zhxp <at> yahoo.com] 
Sent: Friday, May 30, 2008 5:52 PM
To: General MEMS discussion
Subject: Re: [mems-talk] Damaging of boats during nickel evaporation

Hi,

   I met similar problem when I evaporated Al by
tungsten boat. When Al melted in tungsten boat, the
evaporation rate suddenly reduced and after a while
the boat was "ate" by the melted Al. So I can not
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刘畅 | 2 Jun 2008 11:03
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AFM scratch photoresist for nanograting

Dear All,

Recently, I use AFM to fabricate micro-nano structure, along with other
methods such as wet etching, sputter and photolithography.
The first step is to fabricate nano-grating by AFM. I have used many
photoresists such as SU-8 and AZ1800. I find that SU-8 is too
sticky to form a groove. AZ1800 is better than SU-8, however, depth-to-width
ratio is too small(1:10). The height of the groove is about
100nm, the groove bottom is about 300 nm, and the dap is nearly 750nm.

Tip Radius (max.) is 20nm. What is the main reason that the dap comes to
750nm?

I still can not find a suitable photoresist for AFM scratching.
If you have advice, please tell me in details.
Your help will be highly appreciated.

Thank you!

Liuchang
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Roger Shile | 2 Jun 2008 20:33
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Re: AFM scratch photoresist for nanograting

You might consider using Dip Pen Nanolithography (DPN) to deposit resist
or other material to form a grating pattern.  The material you deposit
could be the final grating structure or could be used as a resist to
transfer the grating pattern to the underlying material.

Roger Shile

-----Original Message-----

Dear All,

Recently, I use AFM to fabricate micro-nano structure, along with other
methods such as wet etching, sputter and photolithography.
The first step is to fabricate nano-grating by AFM. I have used many
photoresists such as SU-8 and AZ1800. I find that SU-8 is too sticky to
form a groove. AZ1800 is better than SU-8, however, depth-to-width ratio
is too small(1:10). The height of the groove is about 100nm, the groove
bottom is about 300 nm, and the dap is nearly 750nm.

Tip Radius (max.) is 20nm. What is the main reason that the dap comes to
750nm?

I still can not find a suitable photoresist for AFM scratching.
If you have advice, please tell me in details.
Your help will be highly appreciated.

Thank you!
_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
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Ken Healy | 2 Jun 2008 20:41
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Integrating a thick dielectric layer surrounding suspended silicon nitride membranes

Hello,

I'd like to ask for advice on how best to modify the standard procedure 
for fabricating suspended silicon nitride membranes to incorporate a 
thick dielectric layer (>=5um).

The aim is to reduce the capacitance from the top to the bottom of the 
chip supporting the membrane, as it will be used to separate two 
chambers of conductive fluid. The capacitance with standard membranes is 
very high since the thickest dielectric layer is the thin silicon 
nitride (50-100 nm in my case).

Reducing the fluid contact area will reduce the capacitance, but the 
microfluidics required to achieve an equivalent reduction in capacitance 
appears more complicated than adding a dielectric layer.

(The particular application I'm working on is nanopore-based DNA 
analysis, where the noise level scales with capacitance. For background 
info see http://eleceng.ucc.ie/nanopore/)

The best process I have come up with so far is as follows, but it's 
still significantly more complicated than the standard procedure for 
silicon nitride membrane fabrication. See the diagram below for reference.

membrane nitride
======================================================================
dielectric oxide               |        |
--------------------------------        ------------------------------
                               /          \
                              /            \
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Roger Shile | 2 Jun 2008 21:55
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Re: Integrating a thick dielectric layer surroundingsuspended silicon nitride membranes

Ken,

As I understand, the modification you're making is the addition of the
thick oxide under the nitride.  Growing such a thick oxide will take a
long time e.g. ~49 hours for a wet oxidation at 1100 degC.  An
alternative might be to use an oxide or other dielectric deposited by
CVD.

If you use SiO2 as a dielectric it might be better to wet etch with BOE,
since the CHF3/O2 RIE will probably etch the nitride faster than the
nitride.

Roger Shile

-----Original Message-----
From: mems-talk-bounces <at> memsnet.org
[mailto:mems-talk-bounces <at> memsnet.org] On Behalf Of Ken Healy
Sent: Monday, June 02, 2008 11:41 AM
To: mems-talk <at> memsnet.org
Subject: [mems-talk] Integrating a thick dielectric layer
surroundingsuspended silicon nitride membranes

Hello,

I'd like to ask for advice on how best to modify the standard procedure 
for fabricating suspended silicon nitride membranes to incorporate a 
thick dielectric layer (>=5um).

The aim is to reduce the capacitance from the top to the bottom of the 
chip supporting the membrane, as it will be used to separate two
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Paul Sunal | 2 Jun 2008 22:59

Re: Integrating a thick dielectric layer surrounding suspended silicon nitride membranes

Ken,

We can easily grow >10 um of thermal oxide, but the real trick is the 
final release of the nitride diaphragm.  If you have very large 
diaphragms, they may not survive once the anisotropic silicon etch is 
finished and it's free-standing.  The stress in this thick of an oxide 
may shatter if the diaphragm is large. 

You are correct by assuming a plasma etch will not work since the 
nitride does not serve as an etch stop and that you have such a thin 
layer.  This means you are limited to HF, either wet or vapor etching.  
Five microns of thermal oxide is not an easy thing to etch either.  This 
will take some time to do. 

In both cases you'll have undercutting of the membrane, which will make 
the diaphragm larger than you planned.  The curved oxide wall and larger 
diaphragm will affect your capacitance as well.

Best of luck,

Paul

> Hello,
>
> I'd like to ask for advice on how best to modify the standard 
> procedure for fabricating suspended silicon nitride membranes to 
> incorporate a thick dielectric layer (>=5um).
>
> The aim is to reduce the capacitance from the top to the bottom of the 
> chip supporting the membrane, as it will be used to separate two
(Continue reading)

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madhav rao | 3 Jun 2008 01:56
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Photolithography on Mica and Teflon sheets

Hi All,

      I wanted to do photolithography process to
pattern on teflon and mica sheets. Does any one has
any experience on this. I would like to use positive
resist, so can any one suggest me what resist and
developer I need to use. Does Shipley 1818 will work
for teflon and Mica ?
Let me know.

Thanks

Regards,
Madhav Rao
Graduate student ,
University of Alabama,
Tuscaloosa.

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Po-Jui Chen | 3 Jun 2008 03:47
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Machining fused quartz/silica?

Hi there,

Could anyone recommend a company/shop in the US (preferably in California) that does glass machining
especially fused quartz/silica? The pieces would be in circular shape around 5 mm diameter and with
couple <0.5 mm through-hole features. Please advise the places I can look for the service.

Thanks,
PJ

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Gmane