アルミニウムとn⁺型シリコンとの接着によって生成した再成長層の性質におよぼすりんの影響

抄録

When a n⁺-type surface of a diode is bonded to a tungsten or molybdenum electrode using aluminum solder, a thin p-type regrowth layer is formed on the n⁺-type silicon after bonding. This layer formation generates a considerable forward voltage drop (FVD) in the regrowth layer.
In order to clarify the role of phosphorous in brazing between n⁺-type silicon and aluminum, effects of P concentration on the thickness and the electrical property of regrowth layer have been investigated.
The P concentrations in n⁺-type silicon of diodes were 1×10²⁰ cm⁻³, 4×10²⁰ cm⁻³ and 2×10²¹ cm⁻³. Brazing atmospheres used were N₂, air and vacuum. In the case of brazing in N₂ atmosphere, the thickness of regrowth layer is increased with increasing P concentration in n⁺-type silicon. Difference in the thickness and the morphology of regrowth layer between n⁺-type silicon with high P concentration and that with low P concentration, becomes more remarkable by brazing in air. On the other hand, in the case of brazing in vacuum, the thickness of regrowth layer is nearly the same independent of P concentration. These results indicate that cleaning action in the interface between molten aluminum and n⁺-type silicon is greatly promoted by the presence of P. It is also found that in n⁺-type silicon with high P concentration, the junction formed between regrowth layer and n⁺-type silicon is more imperfect than that of n⁺-type silicon with low P concentration.