Semiconductor device and manufacturing method thereof

• US 7,335,911 B2
• Filed: 05/18/2004
• Issued: 02/26/2008
• Est. Priority Date: 07/22/1999
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Arai, Yasuyuki, Suzawa, Hideomi, Ono, Koji, Yamazaki, Shunpei
• Primary Examiner(s): LOUIE, WAI SING
• Application Number:
  US10/848,189
• Publication Number:
  US 20040192004A1
• Time in Patent Office: 1,379 Days
• Field of Search: 257/59, 257/72, 257/83, 257/290, 257/351, 349 42- 48
• US Class Current: 257/59
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• CPC Class Codes: H01L 2029/7863 with an LDD consisting of more than one lightly doped zone or having a non-homogeneous dopant distribution, e.g. graded LDD
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• CPC Class Codes: H01L 27/1237 with a different composition, shape, layout or thickness of the gate insulator in different devices
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 27/127 with a particular formation, treatment or patterning of the active layer specially adapted to the circuit arrangement
• CPC Class Codes: H01L 27/1277 using a crystallisation promoting species, e.g. local introduction of Ni catalyst
• CPC Class Codes: H01L 29/42384 for thin film field effect transistors, e.g. characterised by the thickness or the shape of the insulator or the dimensions, the shape or the lay-out of the conductor
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/66757 Lateral single gate single channel transistors with non-inverted structure, i.e. the channel layer is formed before the gate
• CPC Class Codes: H01L 29/78621 with LDD structure or an extension or an offset region or characterised by the doping profile
• CPC Class Codes: H01L 29/78627 with a significant overlap between the lightly doped drain and the gate electrode, e.g. GOLDD
• CPC Class Codes: H01L 29/78645 with multiple gate

Abstract

By providing appropriate TFT structures arranged in various circuits of the semiconductor device in response to the functions required by the circuits, it is made possible to improve the operating performances and the reliability of a semiconductor device, reduce power consumption as well as realizing reduced manufacturing cost and increase in yield by lessening the number of processing steps. An LDD region of a TFT is formed to have a concentration gradient of an impurity element for controlling conductivity which becomes higher as the distance from a drain region decreases. In order to form such an LDD region having a concentration gradient of an impurity element, the present invention uses a method in which a gate electrode having a taper portion is provided to thereby dope an ionized impurity element for controlling conductivity accelerated in the electric field so that it penetrates through the gate electrode and a gate insulating film into a semiconductor layer.

Claims

1. A display device comprising a pixel TFT disposed in a pixel section and a driver circuit comprising a p-channel TFT and an n-channel TFT disposed in a periphery of the pixel section, over a substrate, wherein:

the n-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a first impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode; and

a second impurity region which forms a source region or a drain region that is disposed on the outside of the first impurity region;

the p-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a third impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be entirely overlapped by the gate electrode; and

a fourth impurity region which forms a source region or a drain region which is disposed on the outside of the third impurity region;

the pixel TFT comprises a gate electrode which has a tapered portion;

a channel forming region;

a first impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode; and

a second impurity region which forms a source region or a drain region that is disposed on the outside of the first impurity region; and

a pixel electrode that is disposed in the pixel section and has a light reflective surface is formed over a second interlayer insulating film comprising an organic insulating material; and

is connected to the pixel TFT through an opening disposed at least in a first interlayer insulating film comprising an inorganic insulating material which is disposed over the gate electrode of the pixel TFT and in the second interlayer insulating film formed in close contact with the insulating film.

5. A display device according to claim 1 wherein the gate electrodes of the pixel TFT and the p-channel TFT and the n-channel TFT of the driver circuit comprise a heat resistant conductive material and a gate wiring that is connected to the gate electrode is extended from the driver circuit comprises a low resistivity conductive material.

9. A display device according to claim 5 wherein the heat resistant conductive material is selected from a group consisting of:

an element selected from tantalum (Ta), titanium (Ti) or tungsten (W);

a compound which comprises the element;

a compound which comprises a combination of the element;

a nitride which comprises the element; and

a silicide which comprises the element.

13. A display device according to claim 1 wherein an angle of the tapered portion of the gate electrode is between 5 and 45°

.

17. A display device according to claim 1 wherein the display device is one selected from a group consisting of:

a personal computer;

a video camera;

a portable information terminal;

a digital camera, a digital video disc player;

an electronic game machine; and

a projector.

41. A display device according to claim 1, wherein a concentration of an impurity element of one conductivity type in a region of the first impurity region that overlaps the gate electrode and a concentration of an impurity element of another conductivity type in the third impurity region are set to become higher as the distance from channel forming regions that are in contact increase.

2. A display device comprising a pixel TFT disposed in a pixel section and a driver circuit comprising a p-channel TFT and an n-channel TFT disposed in a periphery of the pixel section, over a substrate, wherein:

the n-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a first impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode; and

a second impurity region which forms a source region or a drain region that is disposed on the outside of the first impurity region;

the p-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a third impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be entirely overlapped by the gate electrode; and

a fourth impurity region which forms a source region or a drain region that is disposed on the outside of the third impurity region;

the pixel TFT comprises a gate electrode which has a tapered portion;

a channel forming region;

a first impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode; and

a second impurity region which forms a source region or a drain region that is disposed on the outside of the first impurity region; and

a pixel electrode that is disposed in the pixel section and has a light transmitting property is formed over a second interlayer insulating film comprising an organic insulating material; and

is connected to a conductive metal wiring which is connected to the pixel TFT, through an opening disposed at least in a first interlayer insulating film comprising an inorganic insulating material that is formed over the gate electrode of the pixel TFT and in the second interlayer insulating film formed in close contact with the insulating film.

6. A display device according to claim 2 wherein the gate electrodes of the pixel TFT and the p-channel TFT and the n-channel TFT of the driver circuit comprise a heat resistant conductive material and a gate wiring that is connected to the gate electrode is extended from the driver circuit comprises a low resistivity conductive material.

10. A display device according to claim 6 wherein the heat resistant conductive material is selected from a group consisting of:

an element selected from tantalum (Ta), titanium (Ti) or tungsten (W);

a compound which comprises the element;

a compound which comprises a combination of the element;

a nitride which comprises the element; and

a silicide which comprises the element.

14. A display device according to claim 2 wherein an angle of the tapered portion of the gate electrode is between 5 and 45°

.

18. A display device according to claim 2 wherein the display device is one selected from a group consisting of:

a personal computer;

a video camera;

a portable information terminal;

a digital camera, a digital video disc player;

an electronic game machine; and

a projector.

42. A display device according to claim 2, wherein a concentration of an impurity element of one conductivity type in a region of the first impurity region that overlaps the gate electrode and a concentration of an impurity element of another conductivity type in the third impurity region are set to become higher as the distance from channel forming regions that are in contact increase.

3. A display device which holds liquid crystal between a pair of substrates, wherein:

one substrate which comprises a pixel TFT disposed in a pixel section and a driver circuit comprising a p-channel TFT and an n-channel TFT in the periphery of the pixel section is characterized in that;

the n-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a first impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode; and

a second impurity region which forms a source region or a drain region that is disposed on the outside of the first impurity region;

the p-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a third impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be entirely overlapped by the gate electrode; and

a fourth impurity region which forms a source region or a drain region which is disposed on the outside of the third impurity region;

the pixel TFT comprises a gate electrode which has a tapered portion;

a channel forming region;

a first impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode; and

a second impurity region which forms a source region or a drain region that is disposed on the outside of the first impurity region;

a pixel electrode that is disposed in the pixel section and has a light reflective surface is formed over a second interlayer insulating film comprising an organic insulating material; and

is connected to the pixel TFT through an opening disposed at least in a first interlayer insulating film comprising an inorganic insulating material which is disposed over the gate electrode of the pixel TFT and in the second interlayer insulating film formed in close contact with the insulating film; and

it is stuck to the other '"'"'substrate which is formed with a transparent conductive film, through at least one columnar spacer formed above the opening formed in the second interlayer insulating film.

7. A display device according to claim 3 wherein the gate electrodes of the pixel TFT and the p-channel TFT and the n-channel TFT of the driver circuit comprise a heat resistant conductive material and a gate wiring that is connected to the gate electrode is extended from the driver circuit comprises a low resistivity conductive material.

11. A display device according to claim 7 wherein the heatresistant conductive material is selected from a group consisting of:

an element selected from tantalum (Ta), titanium (Ti) or tungsten (W);

a compound which comprises the element;

a compound which comprises a combination of the element;

a nitride which comprises the element; and

a silicide which comprises the element.

15. A display device according to claim 3 wherein an angle of the tapered portion of the gate electrode is between 5 and 45°

.

19. A display device according to claim 3 wherein the display device is one selected from a group consisting of:

a personal computer;

a video camera;

a portable information terminal;

a digital camera, a digital video disc player;

an electronic game machine; and

a projector.

43. A display device according to claim 3, wherein a concentration of an impurity element of one conductivity type in a region of the first impurity region that overlaps the gate electrode and a concentration of an impurity element of another conductivity type in the third impurity region are set to become higher as the distance from channel forming regions that are in contact increase.

4. A display device which holds a liquid crystal between a pair of substrates, wherein:

one substrate which comprises a pixel TFT disposed in a pixel section and a driver circuit comprising a p-channel TFT and an n-channel TFT in the periphery of the pixel section is characterized in that;

the n-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a first impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode; and

a second impurity region which.forms a source region or a drain region that is disposed on the outside of the first impurity region;

the p-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a third impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be entirely overlapped by the gate electrode; and

a fourth impurity region which forms a source region or a drain region which is disposed on the outside of the third impurity region;

the pixel TFT comprises a gate electrode which has a tapered portion;

a channel forming region;

a first impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode; and

a second impurity region which forms a source region or a drain region that is disposed on the outside of the first impurity region;

a pixel electrode that is disposed in the pixel section and has a light transmitting property is formed over a second interlayer insulating film comprising an organic insulating material; and

is connected to a conductive metal wiring which is connected to the pixel TFT, through an opening disposed at least in a first interlayer insulating film comprising an inorganic insulating material that is formed over the gate electrode of the pixel TFT and in the second interlayer insulating film formed in close contact with the insulating film; and

it is stuck to the other substrate which is formed with a transparent conductive film, through at least one columnar spacer formed above the opening formed in the second interlayer insulating film.

8. A display device according to claim 4 wherein the gate electrodes of the pixel TFT and the p-channel TFT and the n-channel TFT of the driver circuit comprise a heat resistant conductive material and a gate wiring that is connected to the gate electrode is extended from the driver circuit comprises a low resistivity conductive material.

12. A display device according to claim 8 wherein the heat resistant conductive material is selected from a group consisting of:

an element selected from tantalum (Ta), titanium (Ti) or tungsten (W);

a compound which comprises the element;

a compound which comprises a combination of the element;

a nitride which comprises the element; and

a silicide which comprises the element.

16. A display device according to claim 4 wherein an angle of the tapered portion of the gate electrode is between 5 and 45°

.

20. A display device according to claim 4 wherein the display device is one selected from a group consisting of:

a personal computer;

a video camera;

a portable information terminal;

a digital camera, a digital video disc player;

an electronic game machine; and

a projector.

44. A display device according to claim 4, wherein a concentration of an impurity element of one conductivity type in a region of the first impurity region that overlaps the gate electrode and a concentration of an impurity element of another conductivity type in the third impurity region are set to become higher as the distance from channel forming regions that are in contact increase.

21. A display device comprising:

a pixel section comprising at least one pixel TFT over a substrate;

a driver circuit comprising at least one n-channel TFT and at least one p-channel TFT over the substrate;

a first interlayer insulating film comprising an inorganic insulating material over the pixel TFT;

a second interlayer insulating film comprising an organic insulating material over the first interlayer insulating film; and

at least one pixel electrode having a light reflective surface over the second interlayer insulating film, and connected to the pixel TFT through an opening disposed in the first interlayer insulating film and the second interlayer insulating film,

wherein each of the pixel TFT and the n-channel TFT comprises a gate electrode having a tapered portion, a channel forming region, a first impurity region forming an LDD region disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode, and a second impurity region forming a source region or a drain region disposed on the outside of the first impurity region, and

the p-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a third impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be entirely overlapped by the tapered portion; and

a fourth impurity region which forms a source region or a drain region which is disposed on the outside of the third impurity region.

25. A display device according to claim 21 wherein the gate electrodes of the pixel TFT and the p-channel TFT and the n-channel TFT of the driver circuit comprise a heat resistant conductive material and a gate wiring that is connected to the gate electrode is extended from the driver circuit comprises a low resistivity conductive material.

29. A display device according to claim 25 wherein the heat resistant conductive material is selected from a group consisting of:

an element selected from tantalum (Ta), titanium (Ti) or tungsten (W);

a compound which comprises the element;

a compound which comprises a combination of the element;

a nitride which comprises the element; and

a silicide which comprises the element.

33. A display device according to claim 21 wherein an angle of the tapered portion of the gate electrode is between 5 and 45°

.

37. A display device according to claim 21 wherein the display device is one selected from a group consisting of:

a personal computer;

a video camera;

a portable information terminal;

a digital camera, a digital video disc player;

an electronic game machine; and

a projector.

45. A display device according to claim 21, wherein a concentration of an impurity element of one conductivity type in a region of the first impurity region that overlaps the gate electrode is set to become higher as the distance from channel forming regions that are in contact increase.

22. A display device comprising:

a pixel section comprising at least one pixel TFT over a substrate;

a driver circuit comprising at least one n-channel TFT and at least one p-channel TFT over the substrate;

a first interlayer insulating film comprising an inorganic insulating material over the pixel TFT;

a second interlayer insulating film comprising an organic insulating material over the first interlayer insulating film; and

at least one pixel electrode having a light transmitting property over the second interlayer insulating film, and connected to a conductive metal wiring connected to the pixel TFT through an opening disposed in the first interlayer insulating film and the second interlayer insulating film,

wherein each of the pixel TFT and the n-channel TFT comprises a gate electrode having a tapered portion, a channel forming region, a first impurity region forming an LDD region disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode, and a second impurity region forming a source region or a drain region disposed on the outside of the first impurity region, and

the p-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a third impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be entirely overlapped by the tapered portion; and

a fourth impurity region which forms a source region or a drain region which is disposed on the outside of the third impurity region.

26. A display device according to claim 22 wherein the gate electrodes of the pixel TFT and the p-channel TFT and the n-channel TFT of the driver circuit comprise a heat resistant conductive material and a gate wiring that is connected to the gate electrode is extended from the driver circuit comprises a low resistivity conductive material.

30. A display device according to claim 26 wherein the heat resistant conductive material is selected from a group consisting of:

an element selected from tantalum (Ta), titanium (Ti) or tungsten (W);

a compound which comprises the element;

a compound which comprises a combination of the element;

a nitride which comprises the element; and

a silicide which comprises the element.

34. A display device according to claim 22 wherein an angle of the tapered portion of the gate electrode is between 5 and 45°

.

38. A display device according to claim 22 wherein the display device is one selected from a group consisting of:

a personal computer;

a video camera;

a portable information terminal;

a digital camera, a digital video disc player;

an electronic game machine; and

a projector.

46. A display device according to claim 22, wherein a concentration of an impurity element of one conductivity type in a region of the first impurity region that overlaps the gate electrode is set to become higher as the distance from channel forming regions that are in contact increase.

23. A display device holding a liquid crystal between a first substrate and a second substrate comprising:

a pixel section comprising at least one pixel TFT over the first substrate;

a driver circuit comprising at least one n-channel TFT and at least one p-channel TFT over the first substrate;

a first interlayer insulating film comprising an inorganic insulating material over the pixel TFT;

a second interlayer insulating film comprising an organic insulating material over the first interlayer insulating film; and

at least one pixel electrode having a light reflective surface over the second interlayer insulating film, and connected to the pixel TFT through an opening disposed in the first interlayer insulating film and the second interlayer insulating film,

wherein each of the pixel TFT and the n-channel TFT comprises a gate electrode having a tapered portion, a channel forming region, a first impurity region forming an LDD region disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode, and a second impurity region forming a source region or a drain region disposed on the outside of the first impurity region,

the p-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a third impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be entirely overlapped by the tapered portion; and

a fourth impurity region which forms a source region or a drain region which is disposed on the outside of the third impurity region, and

wherein the first substrate is stuck to the second substrate formed on a transparent conductive film, through at least one columnar spacer formed above the opening.

27. A display device according to claim 23 wherein the gate electrodes of the pixel TFT and the p-channel TFT and the n-channel TFT of the driver circuit comprise a heat resistant conductive material and a gate wiring that is connected to the gate electrode is extended from the driver circuit comprises a low resistivity conductive material.

31. A display device according to claim 27 wherein the heat resistant conductive material is selected from a group consisting of:

an element selected from tantalum (Ta), titanium (Ti) or tungsten (W);

a compound which comprises the element;

a compound which comprises a combination of the element a nitride which comprises the element; and

a silicide which comprises the element.

35. A display device according to claim 23 wherein an angle of the tapered portion of the gate electrode is between 5 and 45°

.

39. A display device according to claim 23 wherein the display device is one selected from a group consisting of:

a personal computer;

a video camera;

a portable information terminal;

a digital camera, a digital video disc player;

an electronic game machine; and

a projector.

47. A display device according to claim 23, wherein a concentration of an impurity element of one conductivity type in a region of the first impurity region that overlaps the gate electrode is set to become higher as the distance from channel forming regions that are in contact increase.

24. A display device holding a liquid crystal between a first substrate and a second substrate comprising:

a pixel section comprising at least one pixel TFT, over the first substrate;

a driver circuit comprising at least one n-channel TFT and at least one p-channel TFT over the first substrate;

a first interlayer insulating film comprising an inorganic insulating material over the pixel TFT;

a second interlayer insulating film comprising an organic insulating material over the first interlayer insulating film; and

at least one pixel electrode having a light transmitting property over the second interlayer insulating film, and connected to a conductive metal wiring connected to the pixel TFT through an opening disposed in the first interlayer insulating film and the second interlayer insulating film,

wherein each of the pixel TFT and the n-channel TFT comprises a gate electrode having a tapered portion, a channel forming region, a first impurity region forming an LDD region disposed in contact with the channel forming region and so as to be partly overlapped by the gate electrode, and a second impurity region forming a source region or a drain region disposed on the outside of the first impurity region,

the p-channel TFT of the driver circuit comprises;

a gate electrode which has a tapered portion;

a channel forming region;

a third impurity region which forms an LDD region that is disposed in contact with the channel forming region and so as to be entirely overlapped by the tapered portion; and

a fourth impurity region which forms a source region or a drain region which is disposed on the outside of the third impurity region, and

wherein the first substrate is stuck to the second substrate formed on a transparent conductive film, through at least one columnar spacer formed above the opening.

28. A display device according to claim 24 wherein the gate electrodes of the pixel TFT and the p-channel TFT and the n-channel TFT of the driver circuit comprise a heat resistant conductive material and a gate wiring that is connected to the gate electrode is extended from the driver circuit comprises a low resistivity conductive material.

32. A display device according to claim 28 wherein the heat resistant conductive material is selected from a group consisting of:

an element selected from tantalum (Ta), titanium (Ti) or tungsten (W);

a compound which comprises the element;

a compound which comprises a combination of the element;

a nitride which comprises the element; and

a silicide which comprises the element.

36. A display device according to claim 24 wherein an angle of the tapered portion of the gate electrode is between 5 and 45°

.

40. A display device according to claim 24 wherein the display device is one selected from a group consisting of:

a personal computer;

a video camera;

a portable information terminal;

a digital camera, a digital video disc player;

an electronic game machine; and

a projector.

48. A display device according to claim 24, wherein a concentration of an impurity element of one conductivity type in a region of the first impurity region that overlaps the gate electrode is set to become higher as the distance from channel forming regions that are in contact increase.