Impurity diffusion method

摘要

An impurity diffusion method which can control a surface atomic concentration from a low to a high surface atomic concentration with a good uniformity is provided. Natural oxide is removed from the surface of a semiconductor substrate with a deoxidizing atmosphere gas as a diffusion atmosphere gas in advance, and then an impurity gas is passed thereto, while passing the deoxidizing atmosphere gas thereto, thereby conducting the diffusion. Flow rate or concentration of impurity of the impurity gas is so set that the impurity atomic concentration of the diffusion layer can be controlled by the flow rate or the concentration of impurity of the impurity gas. The impurity atomic concentration of the diffusion layer can be controlled by adjusting the flow rate or concentration of impurity of the impurity gas, and a diffusion layer having a low impurity atomic concentration can be formed. A shallow junction having a depth of not more than 50 nm can be formed.