Silicon direct bonding (SDB)-a substrate material for electronic devices

Abstract

A silicon direct bonding process was developed using a special chamber for cleaning, contacting and prebonding wafers up to 100 mm. After prebonding the wafers at 200/spl deg/C, annealing was carried out at temperatures ranging from 600/spl deg/C to 1180/spl deg/C for times between 30 minutes and 20 hours. Bare silicon and oxidized wafers were bonded. The electrical specification was done by evaluating the I-V characteristics with respect to breakdown, reverse current, ideality factor and series and parallel resistance (R/sub s/, R/sub p/). A strong dependence of R/sub s/ and R/sub p/ on bonding temperature and time was observed. In order to prove the viability of the bonded substrate for power devices, the authors fabricated p-i-n diodes. The diodes exhibit breakdown voltages up to 1400 V and forward current densities of 2 A/mm/sup 2/. These p-i-n diodes were superior to diodes fabricated simultaneously on epitaxial material.<>