Forming a thin transistor with a redundant source of drain electrode
View Patent ↗An object is to obtain a semiconductor device with improved characteristics by reducing contact resistance of a semiconductor film with electrodes or wirings, and improving coverage of the semiconductor film and the electrodes or wirings. The present invention relates to a semiconductor device including a gate electrode over a substrate, a gate insulating film over the gate electrode, a first source or drain electrode over the gate insulating film, an island-shaped semiconductor film over the first source or drain electrode, and a second source or drain electrode over the island-shaped semiconductor film and the first source or drain electrode. Further, the second source or drain electrode is in contact with the first source or drain electrode, and the island-shaped semiconductor film is sandwiched between the first source or drain electrode and the second source or drain electrode. Moreover, the present invention relates to a manufacturing method of the semiconductor device.
1. A semiconductor device comprising:
a gate electrode over a substrate;
a gate insulating film over the gate electrode;
a first source or drain electrode over the gate insulating film;
an island-shaped semiconductor film including a channel forming region over the first source or drain electrode and the gate insulating film; and
a second source or drain electrode over the island-shaped semiconductor film and the first source or drain electrode,
wherein a part of the second source or drain electrode is formed over and directly in contact with the first source or drain electrode,
wherein the island-shaped semiconductor film is sandwiched between the first source or drain electrode and the second source or drain electrode, and
wherein edges of the island-shaped semiconductor film are tapered.
2. The semiconductor device according to claim 1 , wherein the first source or drain electrode is a titanium film.
3. The semiconductor device according to claim 1 , wherein the gate electrode and the first source or drain electrode are formed of a same material.
4. The semiconductor device according to claim 1 , wherein the gate electrode, the first source or drain electrode and the second source or drain electrode are formed of a same material.
5. A semiconductor device comprising:
a gate electrode over a substrate;
a gate insulating film over the gate electrode;
a first source or drain electrode over the gate insulating film;
an island-shaped semiconductor film including a channel forming region over the first source or drain electrode and the gate insulating film;
an island-shaped impurity semiconductor film added with an impurity imparting one conductivity type over the island-shaped semiconductor film; and
a second source or drain electrode over the island-shaped semiconductor film, the island-shaped impurity semiconductor film, and the first source or drain electrode,
wherein a part of the second source or drain electrode is formed over and directly in contact with the first source or drain electrode,
wherein the island-shaped semiconductor film and the island-shaped impurity semiconductor film are sandwiched between the first source or drain electrode and the second source or drain electrode, and
wherein edges of the island-shaped semiconductor film are tapered.
6. The semiconductor device according to claim 5 , wherein the impurity imparting the one conductivity type is phosphorus or arsenic.
7. The semiconductor device according to claim 5 , wherein the impurity imparting the one conductivity type is boron.
8. The semiconductor device according to claim 5 , wherein the first source or drain electrode is a titanium film.
9. The semiconductor device according to claim 5 , wherein the gate electrode and the first source or drain electrode are formed of a same material.
10. The semiconductor device according to claim 5 , wherein the gate electrode, the first source or drain electrode and the second source or drain electrode are formed of a same material.
11. A manufacturing method of a semiconductor device comprising the steps of:
forming a gate electrode over a substrate;
forming a gate insulating film over the gate electrode;
forming first source or drain electrode over the gale insulating film;
forming an island-shaped semiconductor film including a channel forming region over the first source or drain electrode and the gate insulating film; and
forming a second source or drain electrode over the first source or drain electrode and the island-shaped semiconductor film,
wherein a part of the second source or drain electrode is formed over and directly in contact with the first source or drain electrode,
wherein the island-shaped semiconductor film is sandwiched between the first source or drain electrode and the second source or drain electrode, and
wherein edges of the island-shaped semiconductor film are tapered.
12. The manufacturing method of a semiconductor device according to claim 11 , wherein at least one of the gate electrode, the gate insulating film, the first source or drain electrode, the island-shaped semiconductor film, and the second source or drain electrode is formed by an inkjet method.
13. The manufacturing method of a semiconductor device according to claim 11 , wherein the first source or drain electrode is a titanium film.
14. The manufacturing method of a semiconductor device according to claim 11 , wherein the gate electrode and the first source or drain electrode are formed of a same material.
15. The manufacturing method of a semiconductor device according to claim 11 , wherein the gate electrode, the first source or drain electrode and the second source or drain electrode are formed of a same material.
16. A manufacturing method of a semiconductor device comprising the steps of:
forming a first conductive film over a substrate;
forming a gate electrode using the first conductive film;
forming a gate insulating film over the gate electrode;
forming a second conductive film over the gate insulating film;
forming a first source or drain electrode using the second conductive film;
forming a semiconductor film over the first source or drain electrode;
forming an island-shaped semiconductor film including a channel forming region using the semiconductor film;
forming a third conductive film over the first source or drain electrode and the island-shaped semiconductor film; and
forming a second source or drain electrode using the third conductive film,
wherein a part of the second source or drain electrode is formed over and directly in contact with the first source or drain electrode,
wherein the island-shaped semiconductor film is sandwiched between the first source or drain electrode and the second source or drain electrode, and
wherein edges of the island-shaped semiconductor film are tapered.
17. The manufacturing method of a semiconductor device according to claim 16 , wherein the first source or drain electrode is a titanium film.
18. The manufacturing method of a semiconductor device according to claim 16 , wherein the gate electrode and the first source or drain electrode are formed of a same material.
19. The manufacturing method of a semiconductor device according to claim 16 , wherein the gate electrode, the first source or drain electrode and the second source or drain electrode are formed of a same material.
20. A manufacturing method of a semiconductor device comprising the steps of:
forming a gate electrode over a substrate;
forming a gate insulating film over the gate electrode;
forming a first source or drain electrode over the gate insulating film;
forming an island-shaped semiconductor film including a channel forming region over the first source or drain electrode and the gate insulating film;
forming an island-shaped impurity semiconductor film added with an impurity imparting one conductivity type over the island-shaped semiconductor film; and
forming a second source or drain electrode over the first source or drain electrode, the island-shaped semiconductor film, and the island-shaped impurity semiconductor film,
wherein a part of the second source or drain electrode is formed over and directly in contact with the first source or drain electrode,
wherein the island-shaped semiconductor film and the island-shaped impurity semiconductor film are sandwiched between the first source or drain electrode and the second source or drain electrode,
wherein edges of the island-shaped semiconductor film are tapered.
21. The manufacturing method of a semiconductor device according to claim 20 , wherein the impurity imparting the one conductivity type is phosphorus or arsenic.
22. The semiconductor device according to claim 20 , wherein the impurity imparting the one conductivity type is boron.
23. The manufacturing method of a semiconductor device according to claim 20 , wherein the first source or drain electrode is a titanium film.
24. The manufacturing method of a semiconductor device according to claim 20 , wherein the gate electrode and the first source or drain electrode are formed of a same material.
25. The manufacturing method of a semiconductor device according to claim 20 , wherein the gate electrode, the first source or drain electrode and the second source or drain electrode are formed of a same material.