Hello Ashwini,
I have not used an AML bonder but they all apply heat and force, some = just do
it better than others. 80% bonding on a quarter wafer is not = bad. Keep in
mind the damage to the edge of the wafer when you dice and = the roll off at the
edge of the wafer. I think you are in the ball park = with your recipe. Run a
full wafer and see what you get. There is a = good chance you are seeing the
limitations of the bonder. Try this:
1. Place two sheets of graphite foil 1mm thick (one under the sample = and one
on top of the sample)to improve the force uniformity.
2. Do a two step heating ramp. Heat to 320C and hold for 10 minutes = with low
force. This will allow the temperature become stable. Then = apply the bonding
force and heat to 400C or 420C and hold 15-20 minutes. = The hold time will be
different depending on your process so this can = be optimized.
3. Cool quickly with full force to 320C.
4. Remove force and cool to unload temp.
It works well to cool to just below the eutectic point with force but do = not
cool much lower or you will see cracking.=20
You didn't mention how much bond area you have. I'm guessing you are = doing
100% Au across the wafer for testing. Your force will change = depending on the
bond area.
Brad
Brad Johnson
Sales Application Engineer
DJK Global
US Distributor, Semiconductor Inspection Systems
2447 W. 12th St. - Suite 6, Tempe, AZ 85281
480-968-3343 Ext 112 office
602-501-4413 cell
[email protected]
http://www.djksemi.com
-----Original Message-----
From: ashwini jambhalikar [mailto:[email protected]]
Sent: Monday, December 17, 2007 4:12 AM
To: [email protected]
Subject: [mems-talk] eutectic bonding conditions
Dear Friends,
I am trying to get eutectic bonding between two Si wafers, with Au/Cr
as an intermediate layer.
I am using AML bonder.
For the ease of visual inspection I am using one glass wafer with Cr/
Au and other Si wafer.
I am giving 400 degree centigrade temperature(as I read one should
give more than eutectic temperature, 363 degree centigrade is eutectic
temp for Si-Au.)
I observed, on quarter wafer, when 1200 N platen force was given
reasonably good area(like almost 80 %) got bonded.
Can somebody mail me, exact what temperature and platen force I should
apply to get a good bond(99% to 100%)?
Thanks, AShwini
