Transparent oxide semiconductor thin film transistor
View Patent ↗This invention relates to novel, transparent oxide semiconductor thin film transistors (TFT's) and a process for making them.
1. A process comprising:
depositing an undoped transparent oxide semiconductor,
comprising at least one oxide selected from the group consisting of zinc oxide,
indium oxide, tin oxide, and cadmium oxide, in a field effect transistor, by a method selected from the group consisting of:
a) physical vapor deposition of an undoped transparent oxide semiconductor in a controlled partial pressure of oxygen of 0.1 P c to 10 P c , in an inert gas;
b) resistive evaporation of an undoped transparent oxide semiconductor in a controlled partial pressure of oxygen of 0.1P c to 10P c ;
c) laser evaporation of an undoped transparent oxide semiconductor in a controlled partial pressure of oxygen of 0.1 P c to 10 P c , in an inert gas;
d) electron beam evaporation of an undoped transparent oxide semiconductor in a controlled partial pressure of oxygen of 0.1 P c to 10 P c , in an inert gas; and
e) chemical vapor deposition of an undoped transparent oxide semiconductor in a controlled partial pressure of oxygen of 0.1 P c to 10 P c , in an inert gas, wherein P c is oxygen critical pressure.
2. The process of claim 1 wherein the physical vapor deposition is rf magnetron sputtering.
3. The process of claim 1 wherein the physical vapor deposition is dc magnetron sputtering.
4. The process of claim 1 wherein the physical vapor deposition is diode sputtering.
5. The process of claim 1 wherein the physical vapor deposition is triode sputtering.
6. The process of claim 1 wherein the physical vapor deposition is ion beam sputtering.
7. The process of any of claims 1 ( a ), 2 , 3 , 4 , 5 or 6 wherein deposition is by physical vapor deposition and wherein the inert gas is selected from the group consisting of helium, neon, argon, krypton, and xenon.
8. The process of claim 1 ( e ) wherein the chemical vapor deposition is low pressure chemical vapor deposition.
9. The process of claim 1 ( e ) wherein the chemical vapor deposition is plasma-enhanced chemical vapor deposition.
10. The process of claim 1 ( e ) wherein the chemical vapor deposition is laser-enhanced chemical vapor deposition.
11. The process of claim 1 ( e ) wherein the chemical vapor deposition is atomic layer chemical vapor deposition.
12. The process of claim 1 wherein the effective partial pressure of oxygen is between 0.5 and 2 times the critical pressure.