Semiconductor device and method of manufacturing the same
A semiconductor device includes a substrate; a stack structure including a plurality of insulating films and a plurality of metal films disposed alternately one above another. The stack structure is provided above the substrate and has a stairway portion including a plurality of terraces located at least at one end portion thereof. A liner film and a stopper film are disposed so as to cover an upper portion the stack structure in the stairway portion formed of the terraces. A plurality of holes are connected to each of the terraces. Each of the terraces is formed of a stack of the insulating films and the metal films. Each of the holes extends through the stopper film and the liner film and connect to the metal films of the terraces.
1. A method of manufacturing a semiconductor device comprising:
forming a stack structure above a substrate, the stack structure including a plurality of first insulating films and a plurality of second insulating films disposed alternately one above another;
forming a stairway portion at least at one end portion of the stack structure, the stair way portion including a plurality of terraces provided with a stack of the first insulating film and the second insulating film;
forming a third insulating film and a stopper film so as to cover an upper portion of the stack structure;
forming an interlayer insulating film above the stopper film;
forming a trench extending through the stack structure in portions of the stack structure where the stairway portion is not formed;
selectively etching away the first insulating film via the trench to define cavities;
filling the cavities with a metal film via the trench;
removing an excess portion of the metal film in the trench to divide the metal film formed in each of the cavities;
forming a fourth insulating film in the trench; and
forming a plurality of holes extending from upper surfaces of the terraces and through the interlayer insulating film so as to reach an upper surface of the metal film of the terraces by performing a first etch stopping on the stopper film and a second etch etching through the stopper film.
2. The method according to claim 1 , wherein the stopper film and the interlayer insulating film are made of different materials.
3. The method according to claim 1 , wherein the stopper film and the third insulating film are made of different materials.
4. The method according to claim 1 , wherein the stopper film comprises a silicon nitride film.
5. The method according to claim 1 , wherein the interlayer insulating film comprises a silicon oxide film.
6. The method according to claim 1 , wherein the first insulating film comprises a silicon oxide film.
7. The method according to claim 1 , wherein the second insulating film comprises a silicon nitride film.
8. The method according to claim 1 , wherein the third insulating film comprises a silicon oxide film.
9. The method according to claim 1 further comprising forming a pillar extending through the stack structure to reach the substrate between forming the third insulating film and the stopper film and forming the interlayer insulating film above the stopper film.
10. The method according to claim 9 , wherein the pillar comprises an insulating film.
11. The method according to claim 9 , wherein the pillar comprises a silicon oxide film.