| Abstract |
A Silicon Direct Bonding (SDB) process using a special chamber for cleaning, contacting and prebonding wafers was developed. Yields above 80% on each wafer were achieved. The silicon wafers were contacted immediately after cleaning under cleanroom conditions. Then the contacted wafers were prebonded at 200°C using a bonding pressure up to 0.1 N/cm2. Annealing was carried out for times ranging from 30 minutes to 10 hours at temperatures of 1050°C and 1180°C. In order to characterize the bonded interface, scanning electron microscopy (SEM), infrared analysis and current voltage (I-V) measurements were conducted. The electrical specification was done by evaluating the I-V characteristics of the p-n junction with respect to the ideality factor (n), series and parallel resistance (Rs, Rp), and reverse current (Is). Strong dependence of Rs and non bonding temperature and time was observed. At 1180 °C, a series resistance of 3,16 Ohm and a n-factor of 1.07 was achieved. In order to proof the viability of the bonded substrates to the application for power devices, p-i-n diodes were fabricated exhibiting breakdown voltages up to 1400 V and forward current densities of 2.5 A/mm² (total area 13,5 mm²). These diodes proved to be superior to comparable epitaxial diodes. |
