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US 5,182,227 AGranted
Semiconductor device and method for manufacturing the same
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorTakayuki Matsukawa
Life of this patent
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Abstract
MOS transistors connected to each other are electrically isolated at both ends of a transfer gate by an LOCOS oxide film, and the bottom surface in a trenched capacitor portion and the side wall of a trench between adjacent capacitors are electrically isolated. A leakage current can be reduced, so that a semiconductor device comprising a capacitor having a reduced occupied area and large capacitance can be obtained.
Claims4
A method for manufacturing a semiconductor device, comprising:
- a first step for selectively forming an insulating film including a first silicon nitride film on a major surface of a semiconductor substrate,
- a second step for selectively etching said semiconductor substrate utilizing said insulating film as a mask and forming a trench having a wall of a given width and a bottom surface,
- a third step for forming a second silicon nitride film on the entire surface including the major surface of said semiconductor substrate, the wall, and the bottom surface of said trench,
- a fourth step for forming a resist film on the entire surface of said second silicon nitride film,
- a fifth step for leaving said resist on only a part of the wall of said trench of a width less than said given width and removing the remainder,
- a sixth step for selectively removing said second silicon nitride film utilizing said resist as a mask,
- a seventh step for removing said resist, and
- an eighth step for forming a local field isolation region by a selective oxidation process utilizing said first and second silicon nitride films as left.
5 more elements
Dependencies are inferred from the claim text.