Semiconductor device
A semiconductor device includes a semiconductor device may include, but is not limited to, a semiconductor substrate, an isolation electrode, a gate electrode, a gate insulating film, and a first insulating film. The semiconductor substrate has a first groove and a second groove. An isolation electrode is positioned in the first groove. The gate electrode is positioned in the second groove. The gate insulating film is adjacent to the gate electrode. The first insulating film is adjacent to the isolation electrode. The isolation electrode is greater in threshold voltage than the gate electrode.
1. A semiconductor device comprising:
a semiconductor substrate having first and second grooves;
a isolation electrode in the first groove;
a gate electrode in the second groove;
a gate insulating film between the semiconductor substrate and the gate electrode; and
a first insulating film extending at least beneath the isolation electrode, the first insulating film beneath the isolation electrode being thicker than the gate insulating film beneath the gate electrode, wherein
at least one of the isolation electrode and the gate electrode includes an upper electrode and a lower electrode.
2. The semiconductor device according to claim 1 , wherein
the upper electrode includes N + polysilicon, aluminum, or conductive carbon, and
the lower electrode includes N + polysilicon or a lamination of titanium nitride and tungsten.
3. The semiconductor device according to claim 1 , wherein the upper electrode and the lower electrode of at least one of the isolation electrode and the gate electrode have different work functions.
4. The semiconductor device according to claim 3 , wherein the upper electrode includes a material having a work function lower than that of a material included in the lower electrode.
5. The semiconductor device according to claim 1 , wherein a bottom of the isolation electrode is substantially the same in level as a bottom of the gate electrode.
6. The semiconductor device according to claim 1 , wherein the semiconductor substrate includes a first portion underneath the first groove and a second portion underneath the second groove, the first portion is higher in impurity concentration than the second portion.
7. The semiconductor device according to claim 1 , further comprising a first diffusion region underneath the first groove, the first diffusion region having the same conductivity type as the semiconductor substrate, the first diffusion region being greater in impurity concentration than a different portion of the semiconductor substrate.
8. The semiconductor device according to claim 1 , further comprising a second diffusion region underneath the second groove, the second diffusion region having the same conductivity type as the semiconductor substrate, the second diffusion region being lower in impurity concentration than a different portion of the semiconductor substrate.
9. The semiconductor device according to claim 1 , wherein a bottom portion of the first insulating film is lower in level than a bottom portion of the gate insulating film.
10. The semiconductor device according to claim 1 , wherein
the first insulating film includes a bottom portion and side portions,
the bottom portion of the first insulating film is positioned underneath a bottom of the isolation electrode,
the side portions are positioned adjacent to side surfaces of the isolation electrode, and
the bottom portion of the first insulating film is thicker than the side portions of the first insulating film.
11. The semiconductor device according to claim 10 , wherein the bottom portion of the first insulating layer has a multi-layered structure.
12. A semiconductor device comprising:
a semiconductor substrate having first and second grooves, the semiconductor substrate comprising a first portion underneath the first groove and a second portion underneath the second groove, the first portion being higher in impurity concentration than the second portion;
an isolation electrode in the first groove;
a gate electrode in the second groove;
a gate insulating film adjacent to the gate electrode; and
a first insulating film adjacent to the isolation electrode, wherein
at least one of the isolation electrode and the gate electrode includes an upper electrode and a lower electrode.
13. The semiconductor device according to claim 12 , wherein the gate insulating film and the first insulating films are substantially the same in thickness as each other.