| 摘要 |
PURPOSE:To obtain a fine element isolation film by executing double layer masks consisting of SiO2 and Si3N4 to a P<-> type Si substrate, forming a groove with an inclined plane, covering the inclined plane with three-layer masks composed of poly Si, Si3N4 and CVD SiO2, boring Si3N4 on the bottom of the groove and burying the groove through thermal oxidation. CONSTITUTION:SiO2 12, and Si3N4 13 are superposed on a (100) face in a P<-> type Si substrate, a resist mask 14 is executed and a groove with an inclined plane is formed through RIE, and B ions are implanted. The resist 14 is removed, poly Si 16, Si3N4 17 and CVD SiO2 18 are laminated, and a mask 18' is formed on the inclined plane of the groove through RIE. Si3N4 17 on the bottom of the groove and in an element region is removed through etching while using a mask 18'' as a mask, and the mask 18'' is removed through etching. The whole is thermally oxidized while employing Si3N4 17 as a mask, a field oxide film 19 is formed while a B ion implanted layer is activated to shape a P type inversion preventive layer 20, and exposed poly Si 16 is also changed into SiO2 21. Si3N4 13, 17 are removed through etching after SiO2 21. According to the method, the reduction of a film consisting of Si3N4 13 on the element region is prevented, flaws are not generated in Si3N4 17, the difference of the change of patterns is minimized, and an insulating isolation film can be fined. |
