| 摘要 |
PURPOSE:To inhibit the exudation of impurities to a semiconductor substrate from the direct contact sections of doped polysilicon and the substrate at the irreducible minimum of a demand by forming a first thin-film and depositing a second thin-film, the diffusion coefficient of an impurity in which is made sufficiently smaller than that in the first thin-film, with excellent parallelism before a diffusion by a diffusion method from the surface. CONSTITUTION:A silicon nitride film 7 is deposited from the oblique direction in structure in which the whole surface of a silicon substrate 1 is coated with non-doped polysilicon 6. The non-doped polysilicon film 6 on the outside of a channel and in the upper section of the side wall of the channel is coated with the silicon nitride film 7 by depositing the silicon nitride film 7 again from the reverse oblique direction. The incident direction 18 of the first sputtering silicon nitride and the second incident direction 19 are set previously at an advantageous value, thus bringing the quantity of diffusion into the silicon substrate 1 of phosphorus at the time when all heat treatment processes for shaping the channel capacitance are completed to a value at the irreducible minimum of a demand from the viewpoint of electrical coupling with a source region in an MOS transistor. |
