question on Pyrex-silicon wafer bonding

Ben Jian opticalmachine at
Fri Sep 13 15:13:26 PDT 2002

Hi labmembers,

I need advice on wafer bonding. I have been trying to bond a silicon to 
Pyrex wafer using gold-silicon eutectic bonding without success (for some 
special reason, anodic bonding is not possible for me).

The process which I tried is the following: I first pattern a photoresist 
liftoff mask on the Corning Pyrex 7740 wafer surface, do a quick O2 RIE to 
clean the open surface, evaporate with TiPtAu (200A/700A/2500A), liftoff 
using ultrasonic bath of 1165 remover. The patterned metal surface is 
cleaned again in O2 RIE, then loaded into the EV bonder with a blank silicon 
wafer (which was dipped in diluted HF briefly beforehand). The wafer pair is 
heated to 400C, then high pressure is applied for 1 hour at 400C.

The bonding result: I can relatively easily separate the silicon wafer from 
the glass wafer. And the metal films are cleanly separated from the glass 
surface, and surprisingly, they adhere to the silicon wafer surface.

I need advice as to why this happened and how to solve this problem. Thanks 
in advance.


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