| 摘要 |
PURPOSE:To increase the depletion layer capacitance of the junction and thus reduce the recombination by the surface level of the carrier generated by a short wavelength light by a method wherein the photo diode part is put in a three-layer structure sandwiched by a substrate and a semiconductor layer which form an original P-N junction, and the upper and down two semiconductor layers of high impurity concentration having the reverse conductivity type. CONSTITUTION:Preparing a wafer consisting of an N-substrate layer 9, a P<-> layer 4 of a buried layer is formed after forming a P-well layer 8. After the entire surface is covered with a nitride film, RIE of anisotropic etching is performed, thus forming a side wall 23 made of an oxide film on the side surface of a poly Si layer 7 covered with an element isolation insulation film 6 and an oxide film 22. Since the dimension d2 of the side wall 23 at the part covering the substrate is equal to the thickness of the first nitride film, it can be controlled by this thickness. Next, etching is performed by means of a photo resist pattern 24. After phosphorus treatment, an oxide film 25 is formed on the surfaces of the poly Si layer 7, N-layer 3 and drain N-layer 10. Finally, a side wall 26 is formed on the surface of the poly Si layer 7 covered with the side wall 23 and the oxide film 25 by RIE. |
