METHOD FOR IMPURITY DIFFUSION

摘要

PURPOSE:To permit continuous diffusion at each temperature by inserting an ampoule in furnaces that the length of soaking at each temperature is at least about that of the ampoule. CONSTITUTION:Diffusion furnaces having temperature distribution including two kinds of the length of soaking are composed by furnaces 18 and quartz pipes 19 and the length of soaking at each temperature is equalized to that of an ampoule or longer. And the ampoule 20 enclosing a sample 21 and a diffusion impurity is inserted in a furnace. Firstly, diffusion is done at a low temperature section for a given period of time. Then, the ampoule 20 is moved to a high temperature section and the steam pressure of the impurity is increased by raising the temperature in the ampoule and the control of high density of the impurity on a principle surface and that of the thickness of a diffusion layer are simultaneously and easily performed by performing the diffusion in a short period. When zinc is diffused to GaAs-Ga1-xAlxAs having the different diffusion speed of the impurity by hetero junction crystal, the thickness of the diffusion layer is controlled with good reappearance by using this diffusion method.