Electrooptical device and a method of manufacturing the same

• US 7,575,961 B2
• Filed: 09/29/2006
• Issued: 08/18/2009
• Est. Priority Date: 04/07/1999
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ikeda, Takayuki, Yamazaki, Shunpei
• Primary Examiner(s): LEE, HSIEN MING
• Application Number:
  US11/529,334
• Publication Number:
  US 20070026583A1
• Time in Patent Office: 1,054 Days
• Field of Search: 438/149, 438151-154, 438/157, 438/283, 257/59, 257/72, 257/351
• US Class Current: 438/149
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• 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 29/78621 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

Abstract

To provide a semiconductor device of high reliability by arranging TFTs that have appropriate structures in accordance with circuit functions. In a semiconductor device having a driver circuit portion and a pixel portion on the same insulator, gate insulating films of a driver TFT are designed to be thinner than a gate insulating film of a pixel TFT. In the pixel TFT, channel forming regions are formed under a gate electrode, and a separation region is formed between the channel forming regions. At this point, LDD regions have a region that overlaps with the gate electrode and a region that does not.

Claims

1. A method of manufacturing a semiconductor device, comprising the steps of:

forming a semiconductor layer on an insulator;

doping a part of said semiconductor layer with an element that belongs to group XV in the periodic table to form a low concentration impurity region;

doping at least two parts of said semiconductor layer with the element that belongs to group XV in the periodic table at a concentration higher than said low concentration impurity region to form a first high concentration impurity region and a second high concentration impurity region;

forming an insulating film on said semiconductor layer; and

forming a gate wiring and a capacitor electrode on said insulating film, wherein said gate wiring overlaps with said first high concentration impurity region and said second high concentration impurity region is formed below said capacitor electrode.

2. The method according to claim 1, wherein said low concentration impurity region is doped with the element that belongs to group XV in the periodic table in a concentration of 2×

10¹⁶ to 5 ×

10¹⁹ atoms/cm³, and said first and second high concentration impurity regions are doped with the element in a concentration of 5×

10¹⁹ to 3×

10²¹ atoms/cm³.

3. The method according to claim 1, further comprising the steps of:

forming an insulating film over the gate wiring; and

forming a wiring over the insulating film, wherein said wiring extends in a direction different from a direction in which the gate wiring extends,

wherein a first portion of said wiring overlapped with said gate wiring has smaller line width than a second portion of said wiring not overlapped with said gate wiring.

4. The method according to claim 3, further comprising the step of:

forming a pixel electrode, wherein a portion of said second portion of said wiring overlaps with said pixel electrode.

5. The method according to claim 1, wherein said semiconductor device is an electronic equipment selected from the group consisting of a video camera, a digital camera, a projector, a projection TV, a goggle type display, a navigation system, a sound reproduction device, a notebook type personal computer, a game machine, a portable information terminal, a mobile computer, a portable telephone, a portable game machine, an electronic book, and an image reproduction device having a recording medium.

6. A method of manufacturing a semiconductor device having a pixel portion comprising a plurality of pixels each having a pixel TFT and a storage capacitor, said method comprising the steps of:

forming a semiconductor layer on an insulator;

doping a part of said semiconductor layer with an element that belongs to group XV in the periodic table to form a low concentration impurity region;

doping a part of said semiconductor layer with the element that belongs to group XV in the periodic table at a concentration higher than said low concentration impurity region to form a first high concentration impurity region and a second high concentration impurity region;

forming an insulating film over said semiconductor layer, wherein said insulating film has a first region having a first thickness and a second region having a second thickness thinner than the first thickness; and

forming a gate wiring on the first region of said insulating film, and forming at the same time a capacitor electrode on the second region of said insulating film,

wherein said first high concentration impurity region is formed below said gate wiring and said second high concentration impurity region is formed below said capacitor electrode.

7. The method according to claim 6, wherein said low concentration impurity region is doped with the element that belongs to group XV in the periodic table in a concentration of 2×

10¹⁶ to 5×

10¹⁹ atoms/cm³, and said first and second high concentration impurity regions are doped with the element in a concentration of 5×

10¹⁹ to 3×

10²¹ atoms/cm³.

8. The method according to claim 6, further comprising the steps of:

forming an insulating film over the gate wiring; and

forming a wiring over the insulating film, wherein said wiring extends in a direction different from a direction in which the gate wiring extends,

wherein a first portion of said wiring overlapped with said gate wiring has smaller line width than a second portion of said wiring not overlapped with said gate wiring.

9. The method according to claim 8, further comprising the step of:

forming a pixel electrode, wherein a portion of said second portion of said wiring overlaps with said pixel electrode.

10. The method according to claim 6, wherein said semiconductor device is an electronic equipment selected from the group consisting of a video camera, a digital camera, a projector, a projection TV, a goggle type display, a navigation system, a sound reproduction device, a notebook type personal computer, a game machine, a portable information terminal, a mobile computer, a portable telephone, a portable game machine, an electronic book, and an image reproduction device having a recording medium.

11. A method of manufacturing semiconductor device, comprising the steps of:

forming a semiconductor layer on an insulator;

forming a first low concentration impurity region, a second low concentration impurity region, and a third low concentration impurity region in the semiconductor layer by doping the semiconductor layer with an element that belongs to group XV in the periodic table;

doping a part of said second low concentration impurity region with the element that belongs to group XV in the periodic table at a concentration higher than said first to third low concentration impurity regions to form a high concentration impurity region, wherein said high concentration impurity region separates the second low concentration impurity region into two low concentration impurity regions;

forming an insulating film over said semiconductor layer; and

forming a gate wiring over said insulating film in order to overlap the second low concentration impurity region and the high concentration impurity region.

12. The method according to claim 11, wherein said first, second and third low concentration impurity regions are doped with the element that belongs to group XV in the periodic table in a concentration of 2×

10¹⁶ to 5×

10¹⁹ atoms/cm³, and said high concentration impurity region is doped with the element in a concentration of 5×

10¹⁹ to 3×

10²¹ atoms/cm³.

13. The method according to claim 11, further comprising the steps of:

forming an insulating film over the gate wiring; and

forming a wiring over the insulating film, wherein said wiring extends in a direction different from a direction in which the gate wiring extends,

wherein a first portion of said wiring overlapped with said gate wiring has smaller line width than a second portion of said wiring not overlapped with said gate wiring.

14. The method according to claim 13, further comprising the step of:

forming a pixel electrode, wherein a portion of said second portion of said wiring overlaps with said pixel electrode.

15. The method according to claim 11, wherein said semiconductor device is an electronic equipment selected from the group consisting of a video camera, a digital camera, a projector, a projection TV, a goggle type display, a navigation system, a sound reproduction device, a notebook type personal computer, a game machine, a portable information terminal, a mobile computer, a portable telephone, a portable game machine, an electronic book, and an image reproduction device having a recording medium.

16. A method of manufacturing semiconductor device, comprising the steps of:

forming a semiconductor layer on an insulator;

forming a first low concentration impurity region, a second low concentration impurity region, and a third low concentration impurity region in the semiconductor layer by doping the semiconductor layer with an element that belongs to group XV in the periodic table;

doping a part of said second low concentration impurity region and a part of the semiconductor layer with the element that belongs to group XV in the periodic table at a concentration higher than said first to third low concentration impurity regions to form a first high concentration impurity region and a second high concentration impurity region, wherein said first high concentration impurity region separates the second low concentration impurity region into two low concentration impurity regions;

forming an insulating film over said semiconductor layer; and

forming a gate wiring and a capacitor electrode over said insulating film, wherein said gate wiring overlaps the second low concentration impurity region and the first high concentration impurity region, and said capacitor electrode overlaps the second high concentration impurity region.

17. The method according to claim 16, wherein said first, second and third low concentration impurity regions are doped with the element that belongs to group XV in the periodic table in a concentration of 2×

10¹⁶ to 5×

10¹⁹ atoms/cm³, and said first and second high concentration impurity regions are doped with the element in a concentration of 5×

10¹⁹ to 3×

10²¹ atoms/cm³.

18. The method according to claim 16, further comprising the steps of:

forming an insulating film over the gate wiring; and

forming a wiring over the insulating film, wherein said wiring extends in a direction different from a direction in which the gate wiring extends,

wherein a first portion of said wiring overlapped with said gate wiring has smaller line width than a second portion of said wiring not overlapped with said gate wiring.

19. The method according to claim 18, further comprising the step of:

forming a pixel electrode, wherein a portion of said second portion of said wiring overlaps with said pixel electrode.

20. The method according to claim 16, wherein said semiconductor device is an electronic equipment selected from the group consisting of a video camera, a digital camera, a projector, a projection TV, a goggle type display, a navigation system, a sound reproduction device, a notebook type personal computer, a game machine, a portable information terminal, a mobile computer, a portable telephone, a portable game machine, an electronic book, and an image reproduction device having a recording medium.