Semiconductor device and manufacturing method of the same

• US 20060267099A1
• Filed: 05/16/2006
• Published: 11/30/2006
• Est. Priority Date: 05/26/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Isobe, Atsuo, Takano, Tamae
• Granted Patent: US 7,829,394 B2
• Time in Patent Office: Days
• US Class Current: 257/350
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/1266 the substrate on which the devices are formed not being the final device substrate, e.g. using a temporary substrate
• CPC Class Codes: H01L 27/13 combined with thin-film or thick-film passive components
• CPC Class Codes: H01L 29/0603 characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions isolation regions between components H01L21/76; design considerations for integrated circuits H01L27/00; geometrical design considerations for devices H01L29/0657
• CPC Class Codes: H01L 29/78606 with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device H01L29/78642, H01L29/78645 take precedence
• CPC Class Codes: H01L 29/78609 for preventing leakage current H01L29/78618 takes precedence
• CPC Class Codes: H01L 29/78636 with supplementary region or layer for improving the flatness of the device

Abstract

The present invention provides a semiconductor device which suppresses a short circuit and a leakage current between a semiconductor film and a gate electrode generated by a break or thin thickness of a gate insulating film in an end portion of a channel region of the semiconductor film, and the manufacturing method of the semiconductor device. Plural thin film transistors which each have semiconductor film provided over a substrate continuously, conductive films provided over the semiconductor film through a gate insulating film, source and drain regions provided in the semiconductor film which are not overlapped with the conductive films, and channel regions provided in the semiconductor film existing under the conductive films and between the source and drain regions. And impurity regions provided in the semiconductor film which is not overlapped with the conductive film and provided adjacent to the source and drain regions. Further, the conductive films are provided over the channel regions and regions of the semiconductor film which are provided adjacent to the channel regions.

Claims

1. A semiconductor device comprising:

a first thin film transistor and a second thin film transistor over a substrate,

wherein the first thin film transistor comprises;

a first source region and a first drain region in a semiconductor film over a substrate;

a first channel region between the first source region and the first drain region in the semiconductor film;

an insulating film over the semiconductor film; and

a first conductive film over the first channel region with the insulating film interposed therebetween,

wherein the second thin film transistor comprises;

a second source region and a second drain region in the semiconductor film;

a second channel region between the second source region and the second drain region in the semiconductor film;

the insulating film over the semiconductor film; and

a second conductive film over the second channel region with the insulating film interposed therebetween, and

wherein the semiconductor film further comprises;

a first region which is formed under the first conductive film and adjacent to the first channel region;

a second region comprising a first impurity element which is not formed under the first conductive film and formed adjacent to the first source region and the first drain region;

a third region which is formed under the second conductive film and adjacent to the second channel region; and

a fourth region comprising a second impurity element which is not formed under the second conductive film and formed adjacent to the second source region and the second drain region.

3. The semiconductor device according to claim 1, wherein the first thin film transistor is an n-channel thin film transistor, and the second region and the fourth region have p-type conductivity.

5. The semiconductor device according to claim 1, wherein the second thin film transistor is a p-channel thin film transistor, and the second region and the fourth region have n-type conductivity.

16. The semiconductor device according to claim 1, wherein the first channel region of the first thin film transistor and the second channel region of the second thin film transistor are provided in the semiconductor film.

20. The semiconductor device according to claim 1, wherein the first impurity element is the same as the second impurity element.

2. A semiconductor device comprising:

a first thin film transistor and a second thin film transistor over a substrate,

wherein the first thin film transistor comprises;

a first source region and a first drain region in a semiconductor film over a substrate;

a first channel region between the first source region and the first drain region in the semiconductor film;

a first LDD region between the first channel region and the first source region;

a second LDD region between the first channel region and the first drain region;

a first insulating film over the semiconductor film;

a first conductive film over the first channel region with the first insulating film interposed therebetween;

a second insulating film on one side of the first conductive film; and

a third insulating film on another side of the first conductive film, wherein the second thin film transistor comprises;

a second source region and a second drain region in the semiconductor film;

a second channel region between the second source region and the second drain region in the semiconductor film;

the first insulating film over the semiconductor film;

a second conductive film over the second channel region with the first insulating film interposed therebetween;

a fourth insulating film on one side of the second conductive film; and

a fifth insulating film on another side of the second conductive film, and

wherein the semiconductor film further comprises;

a first region which is formed under the first conductive film and adjacent to the first channel region;

a second region comprising a first impurity element which is not formed under the first conductive film and formed adjacent to the first source region and the first drain region;

a third region which is formed under the second conductive film and adjacent to the second channel region; and

a fourth region comprising a second impurity element which is not formed under the second conductive film and formed adjacent to the second source region and the second drain region.

4. The semiconductor device according to claim 2, wherein the first thin film transistor is an n-channel thin film transistor, and the second region and the fourth region have p-type conductivity.

6. The semiconductor device according to claim 2, wherein the second thin film transistor is a p-channel thin film transistor, and the second region and the fourth region have n-type conductivity.

17. The semiconductor device according to claim 2, wherein the first channel region of the first thin film transistor and the second channel region of the second thin film transistor are provided in the semiconductor film.

21. The semiconductor device according to claim 2, wherein the first impurity element is the same as the second impurity element.

7. A semiconductor device comprising:

a first thin film transistor and a second thin film transistor over a substrate,

wherein the first thin film transistor comprises;

a first source region and a first drain region in a semiconductor film over a substrate;

a first channel region between the first source region and the first drain region in the semiconductor film;

an insulating film over the semiconductor film; and

a first conductive film over the first channel region with the insulating film interposed therebetween,

wherein the second thin film transistor comprises;

a second source region and a second drain region in the semiconductor film;

a second channel region between the second source region and the second drain region in the semiconductor film;

the insulating film over the semiconductor film; and

a second conductive film over the second channel region with the insulating film interposed therebetween, and

wherein the semiconductor film further comprises;

a first region which is formed under the first conductive film and adjacent to the first channel region;

a second region comprising a first impurity element which is not formed under the first conductive film and formed adjacent to the first source region and the first drain region;

a third region which is formed under the second conductive film and adjacent to the second channel region;

a fourth region comprising a second impurity element which is not formed under the second conductive film and formed adjacent to the second source region and the second drain region;

a fifth region surrounding the first region and the second region; and

a sixth region surrounding the third region and the fourth region.

10. The semiconductor device according to claim 7, wherein the concentration of the first impurity element added in the second region and the second impurity element in the fourth region is lower than a concentration of a fifth impurity element added in the fifth region or the sixth region.

12. The semiconductor device according to claim 7, wherein the first thin film transistor is an n-channel thin film transistor, and the second region and the fourth region has n-type conductivity and the fifth impurity region has p-type conductivity.

14. The semiconductor device according to claim 7, wherein the second thin film transistor is a p-channel thin film transistor, and the second region and the fourth region have n-type conductivity and the sixth region has n-type conductivity.

18. The semiconductor device according to claim 7, wherein the first channel region of the first thin film transistor and the second channel region of the second thin film transistor are provided in the semiconductor film.

22. The semiconductor device according to claim 7, wherein the first impurity element is the same as the second impurity element.

8. A semiconductor device comprising:

a first thin film transistor and a second thin film transistor over a substrate,

wherein the first thin film transistor comprises;

a first source region and a first drain region in a semiconductor film over a substrate;

a first channel region between the first source region and the first drain region in the semiconductor film;

a first LDD region between the first channel region and the first source region;

a second LDD region between the first channel region and the first drain region;

a first insulating film over the semiconductor film;

a first conductive film over the first channel region with the first insulating film interposed therebetween;

a second insulating film on one side of the first conductive film; and

a third insulating film on another side of the first conductive film, wherein the second thin film transistor comprises;

a second source region and a second drain region in the semiconductor film;

a second channel region between the second source region and the second drain region in the semiconductor film;

the first insulating film over the semiconductor film;

a second conductive film over the second channel region with the first insulating film interposed therebetween;

a fourth insulating film on one side of the second conductive film; and

a fifth insulating film on another side of the second conductive film, and

wherein the semiconductor film further comprises;

a first region which is formed under the first conductive film and adjacent to the first channel region;

a second region comprising a first impurity element which is not formed under the first conductive film and formed adjacent to the first source region and the first drain region;

a third region which is formed under the second conductive film and adjacent to the second channel region;

a fourth region comprising a second impurity element which is not formed under the second conductive film and formed adjacent to the second source region and the second drain region;

a fifth region comprising a third impurity surrounding the first region and the second region; and

a sixth region comprising a fourth impurity surrounding the third region and the fourth region.

9. The semiconductor device according to claim 8, wherein a concentration of the first impurity element added in the second region and the second impurity element added in the fourth region is equal to a concentration of a fifth impurity element added in the first LDD region and the second LDD region of the first thin film transistor.

11. The semiconductor device according to claim 8, wherein the concentration of the first impurity element added in the second region and the second impurity element in the fourth region is lower than a concentration of a fifth impurity element added in the fifth region or the sixth region.

13. The semiconductor device according to claim 8, wherein the first thin film transistor is an n-channel thin film transistor, and the second region and the fourth region has n-type conductivity and the fifth impurity region has p-type conductivity.

15. The semiconductor device according to claim 8, wherein the second thin film transistor is a p-channel thin film transistor, and the second region and the fourth region have n-type conductivity and the sixth region has n-type conductivity.

19. The semiconductor device according to claim 8, wherein the first channel region of the first thin film transistor and the second channel region of the second thin film transistor are provided in the semiconductor film.

23. The semiconductor device according to claim 8, wherein the first impurity element is the same as the second impurity element.

24. A semiconductor device comprising:

a thin film transistor over a substrate,

wherein the thin film transistor comprises;

a source region and a drain region in a semiconductor film over a substrate;

a channel region between the source region and the drain region in the semiconductor film;

an insulating film over the semiconductor film; and

a conductive film over the channel region with the insulating film interposed therebetween,

wherein the semiconductor film further comprises;

a first region which is formed under the conductive film and adjacent to the channel region; and

a second region comprising a first impurity element which is not formed under the conductive film and formed adjacent to the source region and the drain region.

25. The semiconductor device according to claim 24, wherein the semiconductor film further comprises:

a first LDD region between the channel region and the source region; and

a second LDD region between the channel region and the drain region.

26. The semiconductor device according to claim 24, wherein the semiconductor film further comprises a third region comprising a second impurity element surrounding the first region and the second region.

27. A manufacturing method of a semiconductor device comprising:

forming a semiconductor film over a substrate;

forming a gate insulating film over the semiconductor film;

forming a gate electrode selectively over the semiconductor film with the gate insulating film interposed therebetween;

forming selectively a first resist to cover a portion of the gate electrode and a portion of the semiconductor film, and then forming a first impurity region selectively in the semiconductor film by adding a first impurity element selectively to the semiconductor film using the first resist as a first mask;

removing the first mask;

forming a second impurity region selectively in the semiconductor film by adding a second impurity element selectively to the semiconductor film using the gate electrode as a second mask;

forming side walls adjacent to sides of the gate electrode;

forming a second resist to cover a portion of the gate electrode and a portion of the semiconductor film, and

forming a third impurity region selectively by adding a third impurity element selectively to the semiconductor film using the second resist as a third mask;

forming an insulating film over the gate electrode and the gate insulating film; and

forming a conductive film over the insulating film,

wherein the conductive film is electrically connected with the semiconductor film.

28. The manufacturing method of a semiconductor device according to claim 27, wherein an impurity element of p-type conductivity is used as the first impurity element, and an impurity element of n-type conductivity is used as the second impurity element and the third impurity element.

29. The manufacturing method of a semiconductor device according to claim 27, wherein a concentration of the second impurity element is lower than a concentration of the third impurity element.