Semiconductor device and manufacturing method thereof
View Patent ↗A first oxide insulating film is formed over a substrate. After a first oxide semiconductor film is formed over the first oxide insulating film, heat treatment is performed, so that hydrogen contained in the first oxide semiconductor film is released and part of oxygen contained in the first oxide insulating film is diffused into the first oxide semiconductor film. Thus, a second oxide semiconductor film with reduced hydrogen concentration and reduced oxygen defect is formed. Then, the second oxide semiconductor film is selectively etched to form a third oxide semiconductor film, and a second oxide insulating film is formed. The second oxide insulating film is selectively etched and a protective film covering an end portion of the third oxide semiconductor film is formed. Then, a pair of electrodes, a gate insulating film, and a gate electrode are formed over the third oxide semiconductor film and the protective film.
1. A method for manufacturing a semiconductor device, comprising steps of:
forming a first oxide insulating film over a substrate;
forming an oxide semiconductor film over the first oxide insulating film;
performing heat treatment to the oxide semiconductor film;
selectively etching the oxide semiconductor film to have an end portion of the oxide semiconductor film, wherein the end portion of the oxide semiconductor film comprises a side surface and a top surface of the oxide semiconductor film;
forming a second oxide insulating film over the oxide semiconductor film;
selectively etching the second oxide insulating film, thereby forming a protective film covering the end portion of the oxide semiconductor film;
forming a pair of wirings in direct contact with the protective film and the oxide semiconductor film;
forming a gate insulating film in direct contact with the top surface of the oxide semiconductor film after forming the protective film; and
forming a gate electrode overlapping with the oxide semiconductor film over the gate insulating film.
2. The method for manufacturing a semiconductor device according to claim 1 , further comprising a step of:
adding a dopant to the oxide semiconductor film after forming the gate electrode, so that a first oxide semiconductor region overlapping with the gate electrode, a pair of second oxide semiconductor regions between which the first oxide semiconductor region is sandwiched, and a pair of third oxide semiconductor regions which overlaps with the pair of wirings and between which the pair of second oxide semiconductor regions is sandwiched are formed.
3. The method for manufacturing a semiconductor device according to claim 2 ,
wherein the pair of second oxide semiconductor regions is regions containing the dopant, and
wherein the dopant is at least one of nitrogen, phosphorus, arsenic, hydrogen, helium, neon, argon, krypton, and xenon.
4. The method for manufacturing a semiconductor device according to claim 1 , wherein an oxide insulating film from which part of oxygen is released by heat treatment is formed as the first oxide insulating film and the second oxide insulating film.
5. The method for manufacturing a semiconductor device according to claim 1 , wherein an oxide insulating film containing oxygen at a proportion exceeding a stoichiometric proportion is formed as the first oxide insulating film and the second oxide insulating film.
6. The method for manufacturing a semiconductor device according to claim 1 , wherein the heat treatment is performed at a temperature higher than or equal to 150° C. and lower than a strain point of the substrate.
7. The method for manufacturing a semiconductor device according to claim 1 , wherein the oxide semiconductor film includes at least one element selected from In, Ga, Sn, and Zn.
8. The method for manufacturing a semiconductor device according to claim 1 , wherein the heat treatment is performed at a temperature at which hydrogen is released from the oxide semiconductor film and oxygen contained in the first oxide insulating film is diffused into the oxide semiconductor film.
9. The method for manufacturing a semiconductor device according to claim 1 , wherein the heat treatment is performed at a temperature at which hydrogen is released from the oxide semiconductor film and oxygen contained in the first oxide insulating film and the second oxide insulating film is diffused into the oxide semiconductor film.
10. The method for manufacturing a semiconductor device according to claim 1 , wherein the gate insulating film is formed to be in direct contact with top surfaces of the pair of wirings.
11. A method for manufacturing a semiconductor device, comprising steps of:
forming a first oxide insulating film over a substrate;
forming an oxide semiconductor film over the first oxide insulating film;
performing heat treatment to the oxide semiconductor film;
selectively etching the oxide semiconductor film to have an end portion of the oxide semiconductor film;
forming a second oxide insulating film over the oxide semiconductor film;
selectively etching the second oxide insulating film, thereby forming a protective film covering the end portion of the oxide semiconductor film, wherein the end portion of the oxide semiconductor film comprises a side surface and a top surface of the oxide semiconductor film;
forming a pair of wirings in direct contact with the protective film and the oxide semiconductor film;
forming a gate insulating film in direct contact with the top surface of the oxide semiconductor film after forming the protective film; and
forming a gate electrode overlapping with the oxide semiconductor film over the gate insulating film,
wherein the step of selectively etching the oxide semiconductor film is performed after the step of performing heat treatment.
12. The method for manufacturing a semiconductor device according to claim 11 , further comprising a step of:
adding a dopant to the oxide semiconductor film after forming the gate electrode, so that a first oxide semiconductor region overlapping with the gate electrode, a pair of second oxide semiconductor regions between which the first oxide semiconductor region is sandwiched, and a pair of third oxide semiconductor regions which overlaps with the pair of wirings and between which the pair of second oxide semiconductor regions is sandwiched are formed.
13. The method for manufacturing a semiconductor device according to claim 12 ,
wherein the pair of second oxide semiconductor regions is regions containing the dopant, and
wherein the dopant is at least one of nitrogen, phosphorus, arsenic, hydrogen, helium, neon, argon, krypton, and xenon.
14. The method for manufacturing a semiconductor device according to claim 11 , wherein an oxide insulating film from which part of oxygen is released by heat treatment is formed as the first oxide insulating film and the second oxide insulating film.
15. The method for manufacturing a semiconductor device according to claim 11 , wherein an oxide insulating film containing oxygen at a proportion exceeding a stoichiometric proportion is formed as the first oxide insulating film and the second oxide insulating film.
16. The method for manufacturing a semiconductor device according to claim 11 , wherein the heat treatment is performed at a temperature higher than or equal to 150° C. and lower than a strain point of the substrate.
17. The method for manufacturing a semiconductor device according to claim 11 , wherein the oxide semiconductor film includes at least one element selected from In, Ga, Sn, and Zn.
18. The method for manufacturing a semiconductor device according to claim 11 , wherein the heat treatment is performed at a temperature at which hydrogen is released from the oxide semiconductor film and oxygen contained in the first oxide insulating film is diffused into the oxide semiconductor film.
19. The method for manufacturing a semiconductor device, according to claim 11 , further comprising a step of:
selectively etching the second oxide insulating film, thereby forming a third oxide insulating film having a pair of openings, before forming the protective film,
wherein the pair of wirings is formed in direct contact with the third oxide insulating film having the pair of openings and the oxide semiconductor film.
20. The method for manufacturing a semiconductor device according to claim 11 , wherein the gate insulating film is formed to be in direct contact with top surfaces of the pair of wirings.
21. A method for manufacturing a semiconductor device, comprising steps of:
forming a first oxide insulating film over a substrate;
forming an oxide semiconductor film over the first oxide insulating film;
performing heat treatment to the oxide semiconductor film;
selectively etching the oxide semiconductor film to have an end portion of the oxide semiconductor film;
forming a second oxide insulating film over the oxide semiconductor film;
selectively etching the second oxide insulating film, thereby forming a protective film covering the end portion of the oxide semiconductor film, wherein the end portion of the oxide semiconductor film comprises a side surface and a top surface of the oxide semiconductor film;
forming a pair of wirings in direct contact with the protective film and the oxide semiconductor film;
forming a gate insulating film in direct contact with the top surface of the oxide semiconductor film after forming the protective film; and
forming a gate electrode overlapping with the oxide semiconductor film over the gate insulating film,
wherein the step of performing heat treatment is performed after the step of selectively etching the oxide semiconductor film.
22. The method for manufacturing a semiconductor device according to claim 21 , further comprising a step of:
adding a dopant to the oxide semiconductor film after forming the gate electrode, so that a first oxide semiconductor region overlapping with the gate electrode, a pair of second oxide semiconductor regions between which the first oxide semiconductor region is sandwiched, and a pair of third oxide semiconductor regions which overlaps with the pair of wirings and between which the pair of second oxide semiconductor regions is sandwiched are formed.
23. The method for manufacturing a semiconductor device according to claim 22 ,
wherein the pair of second oxide semiconductor regions is regions containing the dopant, and
wherein the dopant is at least one of nitrogen, phosphorus, arsenic, hydrogen, helium, neon, argon, krypton, and xenon.
24. The method for manufacturing a semiconductor device according to claim 21 , wherein an oxide insulating film from which part of oxygen is released by heat treatment is formed as the first oxide insulating film and the second oxide insulating film.
25. The method for manufacturing a semiconductor device according to claim 21 , wherein an oxide insulating film containing oxygen at a proportion exceeding a stoichiometric proportion is formed as the first oxide insulating film and the second oxide insulating film.
26. The method for manufacturing a semiconductor device according to claim 21 , wherein the heat treatment is performed at a temperature higher than or equal to 150° C. and lower than a strain point of the substrate.
27. The method for manufacturing a semiconductor device according to claim 21 , wherein the oxide semiconductor film includes at least one element selected from In, Ga, Sn, and Zn.
28. The method for manufacturing a semiconductor device according to claim 21 , wherein the heat treatment is performed at a temperature at which hydrogen is released from the oxide semiconductor film and oxygen contained in the first oxide insulating film and the second oxide insulating film is diffused into the oxide semiconductor film.
29. The method for manufacturing a semiconductor device, according to claim 21 , further comprising a step of:
selectively etching the second oxide insulating film, thereby forming a third oxide insulating film having a pair of openings, before forming the protective film,
wherein the pair of wirings is formed in direct contact with the third oxide insulating film having the pair of openings and the oxide semiconductor film.
30. The method for manufacturing a semiconductor device according to claim 21 , wherein the gate insulating film is formed to be in direct contact with top surfaces of the pair of wirings.