Field effect transistor
View Patent ↗It is an object to provide a low-cost oxide semiconductor material which is excellent in controllability of the carrier concentration and stability, and to provide a field effect transistor including the oxide semiconductor material. An oxide including indium, silicon, and zinc is used as the oxide semiconductor material. Here, the content of silicon in the oxide semiconductor film is greater than or equal to 4 mol % and less than or equal to 8 mol %. The field effect transistor including such an In—Si—Zn—O film can withstand heat treatment at a high temperature and is effective against −BT stress.
1. A field effect transistor comprising:
a substrate;
a gate electrode over the substrate;
a gate insulating film over the gate electrode;
an oxide semiconductor film over the gate insulating film; and
a source electrode and a drain electrode over the oxide semiconductor film,
wherein the oxide semiconductor film comprises indium and zinc,
wherein the oxide semiconductor film includes a taper shaped depression of a first taper angle between the source electrode and the drain electrode,
wherein each of the source electrode and the drain electrode includes a taper shaped edge of a second taper angle, and
wherein the first taper angle is different from the second taper angle.
2. The field effect transistor according to claim 1 , further comprising an insulating film between the substrate and the gate electrode.
3. The field effect transistor according to claim 1 , a concentration of hydrogen in the oxide semiconductor film is 5×10 19 atoms/cm 3 or lower.
4. The field effect transistor according to claim 1 , wherein the oxide semiconductor film comprises silicon.
5. The field effect transistor according to claim 4 , wherein a content of silicon in the oxide semiconductor film is greater than or equal to 4 mol% and less than or equal to 8 mol%.
6. A field effect transistor comprising:
a substrate;
a gate electrode over the substrate;
a gate insulating film over the gate electrode;
an oxide semiconductor film over the gate insulating film; and;
a source electrode and a drain electrode over the oxide semiconductor film,
wherein the oxide semiconductor film comprises indium and zinc,
wherein an electron carrier density of the oxide semiconductor film is 1×10 20 /cm 3 or lower,
wherein the oxide semiconductor film includes a taper shaped depression of a first taper angle between the source electrode and the drain electrode,
wherein each of the source electrode and the drain electrode includes a taper shaped edge of a second taper angle, and
wherein the first taper angle is different from the second taper angle.
7. The field effect transistor according to claim 6 , further comprising an insulating film between the substrate and the gate electrode.
8. The field effect transistor according to claim 6 , a concentration of hydrogen in the oxide semiconductor film is 5×10 19 atoms/cm 3 or lower.
9. The field effect transistor according to claim 6 , wherein the oxide semiconductor film comprises silicon.
10. A field effect transistor comprising:
a substrate;
a gate electrode over the substrate;
a gate insulating film over the gate electrode;
an oxide semiconductor film over the gate insulating film; and
a source electrode and a drain electrode over the oxide semiconductor film,
wherein the oxide semiconductor film comprises indium and zinc,
wherein Hall effect mobility of the oxide semiconductor film is 20 cm 2 /Vs or lower,
wherein the oxide semiconductor film includes a taper shaped depression of a first taper angle between the source electrode and the drain electrode,
wherein each of the source electrode and the drain electrode includes a taper shaped edge of a second taper angle, and
wherein the first taper angle is different from the second taper angle.
11. The field effect transistor according to claim 10 , further comprising an insulating film between the substrate and the gate electrode.
12. The field effect transistor according to claim 10 , a concentration of hydrogen in the oxide semiconductor film is 5×10 19 atoms/cm 3 or lower.
13. The field effect transistor according to claim 10 , wherein the oxide semiconductor film comprises silicon.