| 摘要 |
PURPOSE: To prevent short circuit between wirings by making a groove of appropriate depth in the isolation region of a substrate, covering the groove with an insulation film to constitute an isolation region, and preventing the isolation region from being formed above the surface of substrate thereby eliminating the level difference. CONSTITUTION: For a normal trench type DRAM, isolation is effected not by means of LOCOS but by means of a shallow groove. A plate electrode 15 is formed in the isolation groove at a position lower than the substrate and the underside of a word line 13 is planarized perfectly. A plate electrode wiring is embedded in a trench 11 and the isolation groove. The plate electrode 15 is insulated from the substrate by means of a capacitor insulation film 21 in the trench 11 and by means of an insulation film 21 in the isolation groove. The plate electrode 15 is embedded in the isolation groove at a position lower than the surface of original substrate with the surface being protected by the insulation film. Surface of the substrate is planalized at the time of forming a gate insulation film 18. |
