Influence of Phosphorus on the Solid State Reaction between Copper and Silicon or Germanium

摘要

The influence of a trace of a third element on the reaction in a binary system, i.e., the solid state reaction between copper and silicon in diffusion couples, was studied. If a trace of phosphorus is present in copper, the incubation time disappears and the grain boundary diffusion mechanism is operative until 530C. This incubation time is due to an oxide layer on the silicon, which is removed by segregation of phosphorus to the reaction interface. In the absence and in the presence of phosphorus the only reaction product is Cu3Si, although the phase diagram also predicts the formation of Cu15Si4 and Cu5Si. The reaction between copper and germanium is not influenced by the presence of phosphorus, or by the applied compressive stress. The reaction is diffusion limited, no incubation times are found. Copper diffuses with a bulk diffusion mechanism between 400 and 570C. Germanium oxide does not hinder the reaction with copper, while silicon oxide is an effective diffusion barrier for copper.