Semiconductor Device and Fabrication Method Thereof

• US 20090014724A1
• Filed: 09/09/2008
• Published: 01/15/2009
• Est. Priority Date: 02/23/1999
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Murakami, Satoshi, Koyama, Jun, Kitakado, Hidehito, Tanaka, Yukio, Ohnumo, Hideto, Yamazaki, Shunpei
• Granted Patent: US 7,745,829 B2
• Time in Patent Office: Days
• US Class Current: 257/59
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2201/123 pixel
• CPC Class Codes: G02F 2202/104 poly-Si
• 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 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• 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 27/1248 with a particular composition or shape of the interlayer dielectric specially adapted to the circuit arrangement
• CPC Class Codes: H01L 27/1259 Multistep manufacturing methods
• CPC Class Codes: H01L 29/458 for thin film silicon, e.g. source or drain electrode
• 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 29/78675 with normal-type structure, e.g. with top gate
• CPC Class Codes: H10K 59/1201 Manufacture or treatment
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/124 : Insulating layers formed between TFT elements and OLED elements
• CPC Class Codes: H10K 59/126 : Shielding, e.g. light-blocking means over the TFTs
• CPC Class Codes: H10K 59/131 : Interconnections, e.g. wiring lines or terminals

Abstract

This invention provides a semiconductor device having high operation performance and high reliability. An LDD region 707 overlapping with a gate wiring is arranged in an n-channel TFT 802 forming a driving circuit, and a TFT structure highly resistant to hot carrier injection is achieved. LDD regions 717, 718, 719 and 720 not overlapping with a gate wiring are arranged in an n-channel TFT 804 forming a pixel unit. As a result, a TFT structure having a small OFF current value is achieved. In this instance, an element belonging to the Group 15 of the Periodic Table exists in a higher concentration in the LDD region 707 than in the LDD regions 717, 718, 719 and 720.

Claims

1. An EL display device comprising:

a plurality of pixels over a substrate, each of the plurality of pixels comprising;

a switching TFT comprising a first channel formation region, a first source region and a first drain region over the substrate, a gate insulating film over the first channel formation region, the first source region and the first drain region, and a first gate electrode over the gate insulating film;

a current controlling TFT comprising a second channel formation region, a second source region and a second drain region over the substrate, the gate insulating film over the second channel formation region, the second source region and the second drain region, and a second gate electrode over the gate insulating film;

a first insulating film over the switching TFT and the current controlling TFT;

a source wiring over the first insulating film and being connected to one of the first source region and the first drain region of the switching TFT;

a first drain wiring over the first insulating film and being connected to the other of the first source region and the first drain region of the switching TFT and the second gate electrode of the current controlling TFT;

a second drain wiring over the first insulating film and being connected to one of the second source region and the second drain region of the current controlling TFT;

a current supply line over the first insulating film and being connected to the other of the second source region and the second drain region of the current controlling TFT;

a second insulting film over the source wiring, the first drain wiring, the second drain wiring and the current supply line;

a first electrode over the second insulating film and being connected to the second drain wiring;

an EL layer over the first electrode;

a second electrode over the EL layer; and

a holding capacitance comprising a semiconductor layer, the gate insulating film and the second gate electrode of the current controlling TFT,

wherein the holding capacitance is overlapped with the current supply line.

5. The EL display device according to claim 1, wherein the first electrode is a pixel electrode comprising a transparent conductive film.

9. The EL display device according to claim 1, wherein the second electrode is a cathode comprising a shading conductive film.

13. The EL display device according to claim 1, wherein the second insulating film is a passivation film.

17. The EL display device according to claim 1, wherein the current controlling TFT is a p-channel TFT.

21. The EL display device according to claim 1, wherein the second source region and the second drain region of the current controlling TFT are apart from the semiconductor layer of the holding capacitance.

23. An electric appliance device having the EL display device according to claim 1, wherein the electric appliance device is one selected from the group consisting of a video camera, a digital camera, a projector, a projection TV, a goggle type display, a head-mount display, a navigation system, an audio reproduction apparatus, a notebook type personal computer, a game machine, a portable information terminal, and an image reproduction apparatus equipped with a recording medium.

2. An EL display device comprising:

a plurality of pixels over a substrate, each of the plurality of pixels comprising;

a switching TFT comprising a first semiconductor layer over the substrate, a gate insulating film over the first semiconductor layer, and a first gate electrode over the gate insulating film;

a current controlling TFT comprising a second semiconductor layer over the substrate, the gate insulating film over the second semiconductor layer, and a second gate electrode over the gate insulating film;

a first insulating film over the switching TFT and the current controlling TFT;

a source wiring over the first insulating film and being connected to the first semiconductor layer of the switching TFT;

a first drain wiring over the first insulating film and being connected to the first semiconductor layer of the switching TFT and the second gate electrode of the current controlling TFT;

a second drain wiring over the first insulating film and being connected to one of the second semiconductor layer of the current controlling TFT;

a current supply line over the first insulating film and being connected to the second semiconductor layer of the current controlling TFT;

a second insulating film over the source wiring, the first drain wiring, the second drain wiring and the current supply line;

a first electrode over the second insulating film and being connected to the second drain wiring;

an EL layer over the first electrode;

a second electrode over the EL layer; and

a holding capacitance provided between the second gate electrode of the current controlling TFT and the current supply line,

wherein the holding capacitance is overlapped with the current supply line.

6. The EL display device according to claim 2, wherein the first electrode is a pixel electrode comprising a transparent conductive film.

10. The EL display device according to claim 2, wherein the second electrode is a cathode comprising a shading conductive film.

14. The EL display device according to claim 2, wherein the second insulating film is a passivation film.

18. The EL display device according to claim 2, wherein the current controlling TFT is a p-channel TFT.

24. An electric appliance device having the EL display device according to claim 2, wherein the electric appliance device is one selected from the group consisting of a video camera, a digital camera, a projector, a projection TV, a goggle type display, a head-mount display, a navigation system, an audio reproduction apparatus, a notebook type personal computer, a game machine, a portable information terminal, and an image reproduction apparatus equipped with a recording medium.

3. An EL display device comprising:

a plurality of pixels over a substrate, each of the plurality of pixels comprising;

a switching TFT comprising first, second and third channel formation regions, a first source region and a first drain region over the substrate, a gate insulating film over the first, second and third channel formation regions, the first source region and the first drain region, and a first gate electrode over the gate insulating film;

a current controlling TFT comprising fourth, fifth and sixth channel formation regions, a second source region and a second drain region over the substrate, the gate insulating film over the fourth, fifth and sixth channel formation regions, the second source region and the second drain region, and a second gate electrode over the gate insulating film;

a first insulating film over the switching TFT and the current controlling TFT;

a source wiring over the first insulating film and being connected to the one of the first source region and the first drain region of the switching TFT;

a first drain wiring over the first insulating film and being connected to the other of the first source region and the first drain region of the switching TFT and the second gate electrode of the current controlling TFT;

a second drain wiring over the first insulating film and being connected to one of the second source region and the second drain region of the current controlling TFT;

a current supply line over the first insulating film and being connected to the other of the second source region and the second drain region of the current controlling TFT;

a second insulting film over the source wiring, the first drain wiring, the second drain wiring and the current supply line;

a first electrode over the second insulating film and being connected to the second drain wiring;

an EL layer over the first electrode;

a second electrode over the EL layer; and

a holding capacitance comprising a semiconductor layer, the gate insulating film and the second gate electrode of the current controlling TFT,

wherein the holding capacitance is overlapped with the current supply line.

7. The EL display device according to claim 3, wherein the first electrode is a pixel electrode comprising a transparent conductive film.

11. The EL display device according to claim 3, wherein the second electrode is a cathode comprising a shading conductive film.

15. The EL display device according to claim 3, wherein the second insulating film is a passivation film.

19. The EL display device according to claim 3, wherein the current controlling TFT is a p-channel TFT.

22. The EL display device according to claim 3, wherein the second source region and the second drain region of the current controlling TFT are apart from the semiconductor layer of the holding capacitance.

25. An electric appliance device having the EL display device according to claim 3, wherein the electric appliance device is one selected from the group consisting of a video camera, a digital camera, a projector, a projection TV, a goggle type display, a head-mount display, a navigation system, an audio reproduction apparatus, a notebook type personal computer, a game machine, a portable information terminal, and an image reproduction apparatus equipped with a recording medium.

4. An EL display device comprising:

a plurality of pixels over a substrate, each of the plurality of pixels comprising;

a switching TFT comprising a first semiconductor layer over the substrate, a gate insulating film over the first semiconductor layer, and a first gate electrode having a triple-gate structure over the gate insulating film;

a current controlling TFT comprising a second semiconductor layer over the substrate, the gate insulating film over the second semiconductor layer, and a second gate electrode having a triple-gate structure over the gate insulating film;

a first insulating film over the switching TFT and the current controlling TFT;

a source wiring over the first insulating film and being connected to the first semiconductor layer of the switching TFT;

a first drain wiring over the first insulating film and being connected to the first semiconductor layer of the switching TFT and the second gate electrode of the current controlling TFT;

a second drain wiring over the first insulating film and being connected to one of the second semiconductor layer of current controlling TFT;

a current supply line over the first insulating film and being connected to the second semiconductor layer of the current controlling TFT;

a second insulting film over the source wiring, the first drain wiring, the second drain wiring and the current supply line;

a first electrode over the second insulating film and being connected to the second drain wiring;

an EL layer over the first electrode;

a second electrode over the EL layer; and

a holding capacitance provided between the second gate electrode of the current controlling TFT and the current supply line,

wherein the holding capacitance is overlapped with the current supply line.

8. The EL display device according to claim 4, wherein the first electrode is a pixel electrode comprising a transparent conductive film.

12. The EL display device according to claim 4, wherein the second electrode is a cathode comprising a shading conductive film.

16. The EL display device according to claim 4, wherein the second insulating film is a passivation film.

20. The EL display device according to claim 4, wherein the current controlling TFT is a p-channel TFT.

26. An electric appliance device having the EL display device according to claim 4, wherein the electric appliance device is one selected from the group consisting of a video camera, a digital camera, a projector, a projection TV, a goggle type display, a head-mount display, a navigation system, an audio reproduction apparatus, a notebook type personal computer, a game machine, a portable information terminal, and an image reproduction apparatus equipped with a recording medium.