| 摘要 |
PURPOSE:To maintain the sharpness of the switching of the composition by a method wherein a wall of a reaction tube is composed of double-wall and a large number of fine holes are drilled in an inner wall and a gas is spouted out of a space between the inner and outer walls toward the center of the reaction tube so that the material gas is prevented from flowing toward the wall of the reaction tube. CONSTITUTION:A substrate holder 3 on which a semiconductor substrate 4 is placed is contained in a reaction tube. The 2nd tube wall 2' in which a large number of fine piercing holes are drilled is provided to the inside of the 1st tube wall 2 of the reaction tube. One end of the 2nd tube wall 2' is joined with the 1st tube wall 2 and another end is kept open. H2, N2 or an inert gas is introduced into the space between the tube walls 2 and 2' to produce a protecting gas layer on the inner surface of the tube wall 2'. Under this condition, reactive gas is introduced through a reaction tube inlet 1 and forwarded toward the substrate 4 while being surroundedby the protecting gas layer. With this constitution, a sharp composition profile at a boundary of the substrate 4 and a growth layer can be obtained. |
