Jamie,

To answer the questions a bit backwards, SC1 (also known as RCA1 and APM) is
cleaning step 3 in the recipe you show, the step with ammonium hydroxide,
hydrogen peroxide, and DI (although typically, the proportions are 1 part NH4OH
: 1 part H2O2: 6 parts DI).

For the most part, the procedure you are using is okay, but from my experience,
you can leave out the Nitric Acid step.  The cleaning process you are using is
quite good at removing any residual organics and then activating your bond
surfaces by creating a layer of hydroxide groups.

If you are still concerned about danger, you may also be able to remove the
Piranha step, since the ammonium hydroxide step is also an organics clean. At
this point, you will be using a solution that is primarily diluted ammonium
hydroxide and hydrogen peroxide, which greatly reduces the danger.


Best Regards,
Chad Brubaker

EV Group       invent * innovate * implement
Technology - Tel: (602) 437-9492, Fax: (602)437-9435 e-mail:
[email protected], www.EVGroup.com

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 -----Original Message-----
From:   Zhimin J Yao [mailto:[email protected]]
Sent:   Wednesday, August 13, 2003 11:22 AM
To:     [email protected]; [email protected]
Subject:        Re: [mems-talk] Re: Glass-Glass thermal fusion bonding


Markus,

I need to achieve spontaneous bond between Si wafers with thermal oxide (1
um) on the surface.  The cleaning procedures I used (recommended by
someone) involves:
1. Piranha clean for 10 min.,
2. Nitric Acid (69%)  2.5 hours at 80C
3. 6:1:1  Ammonium Hydroxide (28-30%) : Hydrogen Peroxide (30%) : Water
             10 minutes at 65C
4.DI Rinse and spin dry.
It works, but it is very painful and dangerous, as you can imagine.

I was wondering if you could recommend a simpler recipe for doing it?  What
is SC1?  Comments from anybody would be appreciated.

Jamie Yao
Rockwell Scientific Company




                      "Markus GABRIEL" 
                      Sent by:                                          To:
                      mems-talk-bounces+zjyao=rsc.rockwell.com@         cc:
                      memsnet.org                                       Subject:
[mems-talk] Re: Glass-Glass thermal fusion bonding


                      08/13/2003 09:26 AM
                      Please respond to General MEMS discussion





Balaji,

in fact glass-glass bonding can be performed without intermediate layer.
Same requirements are valid as for Si-Si bonding regarding macroscopic and
microscopic roughness. Additional planarization step sometimes is necassary
before bonding to achieve the required values. Cleaning and hydrophilizing
can be done in HNO3 or SC1 in case of Quartz. Final rinsing in DI water +
Megasonic is recommended. Particle removal is a more severe problem for
quartz bonding than for Si bonding.
So prepared glass wafers should bond spontaneous at room temperature like
Si-Si. Annealing temp. can vary between 250 and 500 deg C (material
dependent). A problem might be void creation during the anneal process, but
can be prevented by additional steps.

Regards,




Markus Gabriel
Suss MicroTec Inc.
228 Suss Drive
Waterbury Center, VT 05677 USA
Tel.: +1 - 802 - 244 - 5181, ext. 380
Fax: + 1 - 802 - 244 - 7271
[email protected]
www.suss.com


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