抄録
In the construction of diodes, n+ type surfaces of Si wafers are frequently brazed to metal contact discs (W or Mo) by using Al solder. After brazing, the diodes exhibit a large forward voltage drop (FVD). This is due to a p type regrowth layer formed on the n+ type Si from the melt. It is considered to be very important to reduce dissolution of the n+ type Si into the Al melt, since FVD in diodes is strongly affected by the regrowth layer and the n+ type surfce concentration. From this point of view, the effect of thickness of Al, the brazing temperature, use of Al solder containing Si, and the P concentration in the n+ type Si on FVD of diodes have been investigated. The following results have been obtained. (1) FVD in diodes is considerably increased with increasing brazing temperature. This tendency becomes more remarkable as the P concentration in the n+ type Si of diodes bceomes low. (2) FVD in diodes is also increased with increasing thickness of Al. (3) FVD in diodes is decreased by using Al-11.7%Si instead of Al because of the reduction of Si dissolved in liquid Al.
