Daniel, Wow, you asked a big question. I'll start off with one assumption, and that is you are looking to directly bond two silicon wafers, with no intermediate materials. This will narrow things down from a nearly infinite discussion to something a bit more manageable. For direct bonding, under standard circumstances, the substrate requirements are: <2nm surface roughness, <5A roughness for hermetic seal reasonable TTV (<5µm, typically) Minimal bow/warp Now, in terms of a bonding process: Under standard conditions - wet chemical clean performed is a reversed RCA clean, with no HF dif Reversed RCA: RCA 2 - HCl:H2O2:H20 1:1:6, 60 C, ~15 - 20 minutes RCA 1 - NH4OH:H2O2:H2O 1:1:5, 60C, ~15 minutes After the chemical activation, you would want to contact these wafers under very controlled circumstances. Vacuum is not necessary for blank substrates, but is absolutely required for patterned wafers. I've achieved excellent results by placing the pair into an EVG520 bonder. The tooling will hold the substrates in separation until a moderate vacuum (10E-2 mbar) is achieved (if vacuum is necessary). Then, a probe will push the wafers together at the center to initiate the bond front, after which the separators are removed. This step is absolutely critical. By initiating contact at one point, it ensures that only a single bond front will form, allowing bonding to the edge of the substrate. If the front begins at more than one point, the competing fronts will meet at a "tented" edge. Once the wafers are fully in contact, the bond exists, but is still weak (and can be separated by prying the wafers apart with a small amount of force). To strengthen and complete the bond, an anneal step must take place, typically for a few hours a temperatures >1000C. EVG also offers our Low Tem Dry Activation Plasma Bonding system, which utilizes a plasma rather than the wet chemical method to activate the surfaces. The primary benefit from this is that full bonding strength can be achieved at temperatures <300C. Best Regards, Chad Brubaker EV Group invent * innovate * implement Technology - Tel: 480.727.9635, Fax: 480.727.9700 e-mail: c.brubaker@EVGroup.com, www.EVGroup.com This message and any attachments contain confidential or privileged information, which is intended for the named addressee(s) only. If you have received it in error, please notify the sender immediately and then delete this e-mail. Please note that unauthorized review, copying, disclosing, distributing or otherwise making use of the information is strictly prohibited. -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of Danielq k Sent: Wednesday, October 27, 2004 12:27 PM To: mems-talk@memsnet.org Subject: [mems-talk] wafer bonding Hi all Any one know how to bond two si wafers? what requirement in term of heat, vacuum, chemical clean.. Thanks Daniel _______________________________________________ MEMS-talk@memsnet.org mailing list: to unsubscribe or change your list options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk Hosted by the MEMS Exchange, providers of MEMS processing services. Visit us at http://www.memsnet.org/