Method for forming capacitor, semiconductor device, module, and electronic device
A miniaturized transistor is provided. A transistor with low parasitic capacitance is provided. A transistor having high frequency characteristics is provided. A transistor having a large amount of on-state current is provided. A semiconductor device including the transistor is provided. A semiconductor device with high integration is provided. A novel capacitor is provided. The capacitor includes a first conductor, a second conductor, and an insulator. The first conductor includes a region overlapping with the second conductor with the insulator provided therebetween. The first conductor includes tungsten and silicon. The insulator includes a silicon oxide film that is formed by oxidizing the first conductor.
1. A method for forming a transistor, comprising:
forming a second insulator over a first insulator;
forming a semiconductor over the second insulator;
forming a first conductor over the semiconductor;
etching a part of the first conductor by a first lithography method;
etching parts of the first conductor, the semiconductor, and the second insulator by a second lithography method, so that the first conductor is divided into a second conductor and a third conductor;
performing a plasma treatment containing oxygen on the second conductor and the third conductor, so that a silicon oxide film is formed on a side surface and a top surface of the second conductor, and a side surface and a top surface of the third conductor;
forming a third insulator to cover a top surface of the silicon oxide film, a top surface of the first insulator, a side surface of the second insulator, and a side surface of the semiconductor;
forming a fourth insulator over the third insulator;
forming a fourth conductor over the fourth insulator; and
etching a part of the fourth conductor by a third lithography method,
wherein the first conductor includes tungsten and silicon.
2. The method for forming the transistor according to claim 1 , wherein the plasma treatment includes high-density plasma treatment.
3. A method for manufacturing a semiconductor device, wherein the semiconductor device comprises the transistor formed by the method according to claim 1 .
4. A method for manufacturing a module,
wherein the module comprises:
the semiconductor device manufactured by the method according to claim 3 ; and
a printed circuit board.
5. A method for manufacturing an electronic device,
wherein the electronic device comprises:
the module manufactured by the method according to claim 4 ; and
at least one of a speaker and an operation key.
6. The method for forming the transistor according to claim 1 , wherein the silicon oxide film is formed by oxidizing the second conductor and the third conductor.
7. The method for forming the transistor according to claim 1 , wherein the fourth conductor is overlapped with a channel formation region in the semiconductor.
8. A semiconductor device comprising:
a second insulator over a first insulator;
a semiconductor over the second insulator;
a source electrode and a drain electrode over the semiconductor;
a first silicon oxide film on a side surface and a top surface of the source electrode;
a second silicon oxide film on a side surface and a top surface of the drain electrode;
a third insulator in contact with a top surface of the first silicon oxide film, a top surface of the second silicon oxide film, a top surface of the first insulator, a side surface of the second insulator, and a side surface of the semiconductor;
a fourth insulator over the third insulator; and
a gate electrode over the fourth insulator,
wherein each of the source electrode and the drain electrode includes tungsten and silicon.
9. A module comprising the semiconductor device according to claim 8 and a printed circuit board.
10. An electronic device comprising the module according to claim 9 and at least one of a speaker and an operation key.
11. The semiconductor device according to claim 8 , wherein the first silicon oxide film is formed by oxidizing the source electrode and the second silicon oxide film is formed by oxidizing the drain electrode.