Try this
1 Put the wafer on a piece of paper
2 Scratch the edge where you want the break with a diamond scriber
3 Lift one end of the paper and the slight curvature will cause the crack
to propagate along a nearby plane.
Not the most accurate of ways, mainly because of hand-eye coordination but...
The advantage of this is that you don't have to align the blade with the plane.
As Michael says - it gets easier with practice. When I started working with
thin wafers, all I had to do was look at them and they would shatter ;-)
-----Original Message-----
From: Michael Barger [SMTP:mjbarger@safeplace.net]
Sent: Monday, April 21, 2003 11:17 AM
To: General MEMS discussion
Subject: RE: [mems-talk] cleaving of ultra-thin Si wafers
Dr. Broitman,
I don't know if you have been helped, yet, but I used a fairly crude
method
on thicker silicon wafers. I used an Exacto knife blade that had a
curved
tip. I placed the wafer on a very flat surface. I then placed the knife
blade next to the edge of the wafer, aligned with the (100) cleavage
plane.
I then rocked the blade onto the edge of the wafer. A crack would start
at
the edge and progress across the wafer, producing a very clean break.
This
process did not work every time, but seemed to improve with practice.
I did not have any success with scribing or dicing. Scribing generated a
multitude of defects that caused cracks to radiate in all directions.
Dicing
tore the wafer creating a lot of damage.
I hope this helps.
Regards,
Mike Barger
-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org]On Behalf Of Mario Robles
Sent: Thursday, April 17, 2003 3:51 PM
To: 'General MEMS discussion'
Subject: RE: [mems-talk] cleaving of ultra-thin Si wafers
Hello,
It sounds like you have tried a "scribe and break" process. This is when
you use a diamond tip to scribe the top surface of the silicon then
apply pressure on the backside to break the cleave mark. It could be
that the wafer is too stressed and not able to break properly.
How is the wafer thinned to the 30µm thickness? The thinning process is
critical to reduce the stress of the wafer. I would guess it was ground
then lapped or polished.
You can also use a dicing saw to cut he wafer to final substrate or die
size. This uses a diamond blade to cut through the wafer, which is
mounted on an adhesive tape or could be waxed onto another silicon wafer
for better support. You can choose the blades specification to achieve
the best cut quality.
If you like I can supply you with the names of companies that perform
dicing, grinding and scribing services. They could perform some test
cuts to show you the results. Or if you are looking to cut your wafers
in house I can also point you in the right direction. You can then
decide what your best option is.
Thank you,
Mario Robles
Tanaka Systems, Inc.
2577 Leghorn Street
Mountain View, CA 94043
650-966-8001 ofc
650-966-1881 fax
www.dicingblades.com
-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of Esteban Broitman
Sent: Tuesday, April 15, 2003 8:57 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] cleaving of ultra-thin Si wafers
Does anybody know how to "cleave" ultra thin Si wafers?
I need to cut, from ultra-thin (30 microns) Si wafers, substrates of ~
10 x 20 mm. I tried to use different kind of diamonds, but I always have
the same problem: the substrate is not more "flexible", if I try to bent
it, it cracks in many parts. I suspect that I am generating defects
during the cutting of the substrates that propagate during the bending.
Any suggestion?.
Thanks for the reply to my e-mail: broitman@andrew.cmu.edu
E. Broitman
----------------------------------
Dr. Esteban Broitman
Senior Research Associate
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
Phone: (412) 268-9537
FAX: (412) 268-7139
----------------------------------
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