Semiconductor device and method for manufacturing the same
View Patent ↗A semiconductor device includes a substrate and memory cell transistors having a gate electrode above the substrate, and an oxide film. The gate electrode includes a charge storage layer above the substrate, a first insulating film on the charge storage layer, and a control gate electrode on the first insulating film, the control gate electrode including a metal film. The oxide film is disposed on the metal film.
1. A semiconductor device comprising:
a semiconductor substrate; and
a plurality of memory cell transistors each having a gate electrode above the semiconductor substrate,
wherein each of the gate electrodes comprises:
a charge storage layer formed above the semiconductor substrate;
a first insulating film formed on the charge storage layer; and
a control gate electrode formed on the first insulating film, the control gate electrode including a metal film containing nitrogen, and an oxide film formed on a top surface of the metal film.
2. The device according to claim 1 , wherein
the oxide film contains nitrogen.
3. The device according to claim 1 , further comprising:
a second insulating film covering the memory cell transistors with air gaps between gates of the memory cell transistors.
4. The device according to claim 3 , wherein the air gaps extend above the top surface of the metal film.
5. The device according to claim 1 , wherein
nitrogen concentration in the top surface of the metal film is higher than nitrogen concentration in side surfaces thereof.
6. The semiconductor device according to claim 1 , wherein the metal film contains tungsten.
7. The device according to claim 1 , wherein the control gate electrodes are separated by an air gap.
8. A semiconductor device comprising:
a substrate;
a plurality of memory cell transistors connected in series along a first direction, each memory cell transistor having a gate electrode disposed above the substrate, wherein each of the gate electrodes comprises:
a charge storage layer above the substrate,
a first insulating film formed on the charge storage layer, and
a control gate electrode formed on the first insulating film; and
a metal layer disposed above the control gate electrodes, the metal layer having a width in the first direction that is substantially the same as a width of each of the control gate electrodes.
9. The semiconductor device according to claim 8 , wherein the metal layer includes tungsten.
10. The semiconductor device according to claim 9 , wherein the metal layer is nitrided.
11. The semiconductor device according to claim 8 , further comprising:
an oxide film disposed above the metal layer.
12. The semiconductor device according to claim 11 , wherein the oxide film has a width in the first direction that is substantially the same as a width of the control gate electrodes.
13. The semiconductor device according to claim 8 , further comprising:
a second insulating film covering the memory cell transistors with air gaps between gates of the memory cell transistors.
14. The semiconductor device according to claim 13 , wherein the air gaps extend above the top surface of the metal layer.
15. The semiconductor device according to claim 8 , wherein the control gate electrodes are separated by an air gap.
16. A method for manufacturing a semiconductor device, comprising:
forming a gate insulating film, a first film, a first insulating film, and a metal film above a semiconductor substrate;
forming an oxide film above the metal film;
forming a patterned mask layer above the oxide film;
patterning the oxide film, the metal film, the second conductive film, the first insulating film, and the first conductive film, using the patterned mask; and
nitridinq a surface region of the metal film, wherein the oxide film is formed on the surface region of the metal film, and a concentration of nitrogen in the surface region of the metal film is greater than a concentration of nitrogen in a region of the metal film that is below the surface region.
17. The method according to claim 16 , wherein the forming the oxide film comprises exposing the metal film to a silane gas (SiH 4 ) in a plasma CVD process.
18. The method according to claim 16 , further comprising:
forming a second insulating film to cover the patterned oxide film with air gaps between the patterned metal film.
19. The method according to claim 16 , further comprising forming an air gap on a side of the first film, the first insulating film, and the metal film.