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

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°C, annealing was carried out at temperatures ranging from 600°C to 1180°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_s, R_p). A strong dependence of R_s and R_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/mm². These p-i-n diodes were superior to diodes fabricated simultaneously on epitaxial material