Liquid crystal display device having a pixel TFT formed in a display region and a drive circuit formed in the periphery of the display region on the same substrate

• US 6,346,730 B1
• Filed: 04/03/2000
• Issued: 02/12/2002
• Est. Priority Date: 04/06/1999
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kasahara, Kenji, Kitakado, Hidehito, Kawasaki, Ritsuko
• Primary Examiner(s): Ngô , Ngân V.
• Application Number:
  US09/541,608
• Time in Patent Office: 680 Days
• Field of Search: 257/59, 257/72, 257/350, 257/344, 257/408, 257/296, 257/435
• US Class Current: 257/350
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• 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 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• 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 29/458 for thin film silicon, e.g. source or drain electrode
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/66765 Lateral single gate single channel transistors with inverted structure, i.e. the channel layer is formed after 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 29/78633 with a light shield

Abstract

The present invention provides a semiconductor device in which a bottom-gate TFT or an inverted stagger TFT arranged in each circuit is suitably constructed in conformity with the functionality of the respective circuits, thereby attaining an improvement in the operating efficiency and reliability of the semiconductor device. In the structure, LDD regions in a pixel TFT are arranged so as not to overlap with a channel protection insulating film and to overlap with a gate electrode by at least a portion thereof. LDD regions in an N-channel TFT of a drive circuit is arranged so as not to overlap with a channel protection insulating film and to overlap with a gate electrode by at least a portion thereof. LDD regions in a P-channel TFT of the drive circuit is arranged so as to overlap with a channel protection insulating film and to overlap with the gate electrode.

Claims

1. A semiconductor device comprising:

at least a pixel TFT being formed in a display region over a substrate; and

at least an n-channel TFT and at least a p-channel TFT in a drive circuit each being formed in a periphery of the display region over the substrate;

each of said pixel TFT, and said n-channel and p-channel TFTs in the drive circuit includes;

an active layer,

at least an LDD region being formed in the active layer,

a gate insulating film being provided between the active layer and the substrate, and

a gate electrode being provided between the gate insulating film and the substrate,

wherein at least a portion of the LDD region of the pixel TFT is formed so as to overlap with the gate electrode of the pixel TFT,

wherein at least a portion of the LDD region of the n-channel TFT in the drive circuit is formed so as to overlap with the gate electrode of the n-channel TFT in the drive circuit, and

wherein all of the LDD region of the p-channel TFT of the drive circuit is formed so as to overlap with a gate electrode in the p-channel TFT in the drive circuit.

3. A device according to claim 1,

wherein the p-channel TFT in the drive circuit includes:

a first impurity region including both a p-type impurity and an n-type impurity and,

a second impurity region including the p-type impurity, and

wherein the second impurity region is formed between the first impurity region and the LDD region of the p-channel TFT in the drive circuit.

4. A device according to claim 1, further comprising a storage capacitor being connected to the pixel TFT,

said storage capacitor including:

a capacitor wiring formed over the substrate;

an insulating film formed on the capacitor wiring; and

a semiconductor layer being formed on the insulating film.

5. A device according to claim 1, further comprising:

at least an organic resin film being formed over the pixel TFT,

a light shielding film being formed on the organic resin film;

a dielectric film being formed closely to the light shielding film; and

a pixel electrode connected to the pixel TFT, a portion of said pixel electrode being overlapped with the light shielding film

wherein a storage capacitor is formed with the light shielding film, the dielectric film and the portion of the pixel electrode.

6. A device according to claim 5,

wherein the light shielding film comprises at least a material selected from the group consisting of aluminum, tantalum and titanium, and

wherein the dielectric film comprises an oxide of the material.

7. A device according to claim 1,

wherein the semiconductor device is one selected from the group consisting of a cellular phone, a video camera, a mobile computer, a goggle-type display, a projector, a mobile book, a digital camera, a car navigation device, and a personal computer.

2. A semiconductor device comprising:

at least a pixel TFT being formed in a display region over a substrate;

at least an n-channel TFT and at least a p-channel TFT in a drive circuit each being formed in a periphery of the display region over the substrate,

each of said pixel TFT, and said n-channel and p-channel TFTs in drive circuit includes;

an active layer,

at least an LDD region being formed in the active layer,

a gate insulating film being provided between the active layer and the substrate, and

a gate electrode being provided between the gate insulating film and the substrate,

wherein the LDD region of the pixel TFT is formed so as not to overlap with a channel protection insulating film of the pixel TFT,

wherein a portion of the LDD region of the pixel TFT is formed so as to overlap with the gate electrode of the pixel TFT,

wherein the LDD region of the n-channel TFT in the drive circuit is formed so as not to overlap with a channel protection insulating film of the n-channel TFT in the drive circuit,

wherein a portion of the LDD region of the n-channel TFT in the drive circuit is formed so as to overlap with the gate electrode of the n-channel TFT in the drive circuit,

wherein the LDD region of the p-channel TFT in the drive circuit is formed so as to overlap with a channel protection insulating film of the p-channel TFT in the drive circuit, and

wherein all of the LDD region of the p-channel TFT in the drive circuit is formed so as to overlap with the gate electrode of the p-channel TFT in the drive circuit.

8. A device according to claim 2,

wherein the p-channel TFT in the drive circuit includes:

a first impurity region including both a p-type impurity and an n-type impurity and,

a second impurity region including the p-type impurity, and

wherein the second impurity region is formed between the first impurity region and the LDD region of the p-channel TFT in the drive circuit.

9. A device according to claim 2, further comprising a storage capacitor being connected to the pixel TFT,

said storage capacitor including:

a capacitor wiring formed over the substrate;

an insulating film formed on the capacitor wiring; and

a semiconductor layer being formed on the insulating film.

10. A device according to claim 2, further comprising:

at least an organic resin film being formed over the pixel TFT,

a light shielding film being formed on the organic resin film;

a dielectric film being formed closely to the light shielding film; and

a pixel electrode connected to the pixel TFT, a portion of said pixel electrode being overlapped with the light shielding film

wherein a storage capacitor is formed with the light shielding film, the dielectric film and the portion of the pixel electrode.

11. A device according to claim 10,

wherein the light shielding film comprises at least a material selected from the group consisting of aluminum, tantalum and titanium, and

wherein the dielectric film comprises an oxide of the material.

12. A device according to claim 2,

wherein the semiconductor device is one selected from the group consisting of a cellular phone, a video camera, a mobile computer, a goggle-type display, a projector, a mobile book, a digital camera, a car navigation device, and a personal computer.