Nonvolatile semiconductor memory device with alternately stacked isolation dielectric films and electrode films
In a nonvolatile semiconductor memory device, a stacked body is provided on a silicon substrate by alternately stacking pluralities of isolation dielectric films and electrode films, a through-hole is formed in the stacked body to extend in the stacking direction, a memory film is formed by stacking a block layer, a charge layer and a tunnel layer in this order at an inner face of the through-hole, and thereby a silicon pillar is buried in the through-hole. At this time, the electrode film is protruded further than the isolation dielectric film toward the silicon pillar at the inner face of the through-hole, and an end face of the isolation dielectric film has a curved shape displacing toward the silicon pillar side as the electrode film is approached.
1. A nonvolatile semiconductor memory device, comprising:
a substrate;
a stacked body provided on the substrate and including alternately stacked pluralities of isolation dielectric films and electrode films, a through-hole being formed in the stacked body to extend in the stacking direction;
a semiconductor pillar buried in the through-hole; and
a charge storage layer provided between the electrode films and the semiconductor pillar,
the isolation dielectric film including:
a first high density film;
a low density film provided on the first high density film, the low density film being less dense than the first high density film; and
a second high density film provided on the low density film, the second high density film being denser than the low density film, and
the electrode film protruding further than the isolation dielectric film toward the semiconductor pillar at an inner face of the through-hole, an end face of the isolation dielectric film having a curved shape displacing toward the semiconductor pillar side as the electrode film is approached.
2. The device according to claim 1 , wherein a jutting portion of the semiconductor pillar is enclosed by the isolation dielectric film, and the jutting portion juts further toward the outside of the semiconductor pillar than a portion enclosed by the electrode film.
3. The device according to claim 2 , wherein a corner of the jutting portion is rounded.
4. The device according to claim 1 , wherein the isolation dielectric film is made of silicon oxide and contains at least one of carbon and nitrogen as an unavoidable impurity.
5. The device according to claim 1 , wherein a corner of the electrode film at the inner face of the through-hole is rounded.
6. The device according to claim 5 , wherein the isolation dielectric film is made of silicon oxide and contains at least one of carbon and nitrogen as an unavoidable impurity.
7. A nonvolatile semiconductor memory device, comprising:
a substrate;
a stacked body provided on the substrate and including alternately stacked pluralities of isolation dielectric films and electrode films, a through-hole being formed in the stacked body to extend in the stacking direction;
a semiconductor pillar buried in the through-hole; and
a charge storage layer provided between the electrode films and the semiconductor pillar,
the isolation dielectric film including:
a first high density film;
a low density film provided on the first high density film, the low density film being less dense than the first high density film; and
a second high density film provided on the low density film, the second high density film being denser than the low density film, and
the electrode film protruding further than the isolation dielectric film toward the semiconductor pillar at an inner face of the through-hole, a corner of the electrode film being rounded.
8. The device according to claim 7 , wherein the isolation dielectric film is made of silicon oxide and contains at least one of carbon and nitrogen as an unavoidable impurity.