| 摘要 |
PURPOSE:To form a thick interlayer insulating film, and to enhance the voltage withstanding property of a semiconductor memory device by a method wherein when a polycrystalline silicon layer is to be etched, a silicon oxide film is made as to protect a groundwork silicon nitride film. CONSTITUTION:After the silicon oxide film 12, the silicon nitride film 13 and a silicon oxide film 14 are formed in order on the suface of a P type silicon substrate 10 having insulatingly isolating oxide films 11, the part other than the prescribed region of the silicon oxide film 14 is removed. Then, after the polycrystalline silicon layer is formed on the silicon nitride film 13 and the silicon oxide film 14, the polycrystalline silicon layer of the part other than the circumference of the silicon oxide film 14 and the silicon nitride film 13 is removed, and a capacitor electrode 15 for storage of informations is formed. Then, the silicon oxide film 14 excluding the part covered with the electrode 15 is removed, and the electrode 15 is oxidized to form the interlayer insulating film 17. Then, the silicon nitride film 13 and the silicon oxide film 12 are removed, and a gate oxide film 18 is formed at the region theeof. After a polycrystalline silicon film is formed on the gate oxide film 18 and the interlayer insulating film 17 in succession, a gate electrode 19 is formed. Accordingly, the thick interlayer insulating film 17 can be formed regardless of formation of the gate oxide film 18. |
