Active-matrix liquid crystal display and fabrication method thereof

• US 5,767,930 A
• Filed: 05/20/1997
• Issued: 06/16/1998
• Est. Priority Date: 05/20/1994
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Masutani, Yuichi, Kobayashi, Kazuhiro, Murai, Hiroyuki
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): TON, MINH TOAN T
• Application Number:
  US08/859,338
• Time in Patent Office: 392 Days
• Field of Search: 359/59, 257/59, 257/350, 257/66, 257/72, 257/351, 257/408, 349/42, 349/46
• US Class Current: 349/42
• 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 27/127 with a particular formation, treatment or patterning of the active layer specially adapted to the circuit arrangement
• 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

An active-matrix liquid crystal display integrally formed with a driver circuit including: a pair of substrates disposed in opposing relation to each other; and a liquid crystal material sandwiched between the pair of substrates, wherein the pair of substrates includes: a TFT substrate including at least an insulative substrate, source interconnection line and gate interconnection line which are formed in a matrix pattern on the insulative substrate, a thin film transistor provided to each pixel portion for use as a switching element for applying a voltage to a portion of the liquid crystal material which lies at a location where the source interconnection line and the gate interconnection line intersect each other, a pixel electrode connected to a drain electrode of the thin film transistor for supplying a voltage to the liquid crystal material, and a CMOS driver circuit having a CMOS which comprises thin film transistors for supplying an electric signal to the thin film transistor of the pixel portion through the source interconnection line and the gate interconnection line; and a counterpart substrate including an insulative substrate and a counter electrode formed thereon, the thin film transistor provided to the pixel portion being of a first conductivity type and of an offset or LDD structure, at least a first conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit being of an offset or LDD structure.

Claims

1. An active-matrix liquid crystal display integrally formed with a driver circuit comprising:

a pair of substrates disposed in opposing relation to each other; and

a liquid crystal material sandwiched between the pair of substrates;

wherein the pair of substrates comprises;

a TFT substrate including at least an insulative substrate, source interconnection lines and gate interconnection lines which are formed in a matrix pattern on the insulative substrate, a thin film transistors, provided to each pixel portion for use as a switching element for applying a voltage to a portion of the liquid crystal material, which lies at a location where the source interconnection line and the gate interconnection line intersect each other, a pixel electrode connected to a drain electrode of the thin film transistor for supplying a voltage to the liquid crystal material, and a CMOS driver circuit which comprises thin film transistors for supplying an electric signal to the thin film transistor of the pixel portion through the source interconnection lines and the gate interconnection lines; and

a counterpart substrate including an insulating substrate and a counter electrode formed thereon;

wherein the thin film transistor provided to the pixel portion is of a first conductivity type and has one of an offset structure and an LDD structure,

a first conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit being disposed adjacent to the thin film transistor provided to the pixel portion and having the same structure as the structure of the thin film transistor provided to the pixel portion, and

a second conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit having a planar structure.

2. The active-matrix liquid crystal display of claim 1, wherein said second conductivity type is opposite to said first conductivity type.

3. The active liquid crystal display of claim 2, wherein said first conductivity type is N-type and said second conductivity type is P-type.

4. The active liquid crystal display of claim 2, wherein said first conductivity type is P-type and said second conductivity type is N-type.

5. The active-matrix liquid display of claim 1, wherein the second conductivity type thin film transistor comprises a gate electrode which is subjected to ion implantation twice and the conductivity type of the gate electrode is an n-type.

6. The active-matrix liquid display of claim 1, wherein the second conductivity type thin film transistor comprises a gate electrode which is subjected to ion implantation twice.

7. The active-matrix liquid display of claim 1, wherein an offset length of the first conductivity type thin film transistor of the CMOS driver circuit is about 0.2 μ

m to about 2.0 μ

m.

8. An active-matrix liquid crystal display integrally formed with a driver circuit comprising:

a pair of substrates disposed in opposing relation to each other; and

a liquid crystal material sandwiched between the pair of substrates;

wherein the pair of substrates comprises;

a TFT substrate including at least an insulative substrate, source interconnection lines and gate interconnection lines which are formed in a matrix pattern on the insulative substrate, a thin film transistor, provided to each pixel portion for use as a switching element for applying a voltage to a portion of the liquid crystal material, which lies at a location where the source interconnection line and the gate interconnection line intersect each other, a pixel electrode connected to a drain electrode of the thin film transistor for supplying a voltage to the liquid crystal material, and a CMOS driver circuit which comprises thin film transistors for supplying an electric signal to the thin film transistor of the pixel portion through the source interconnection lines and the gate interconnection lines; and

a counterpart substrate including an insulating substrate and a counter electrode formed thereon;

wherein the thin film transistor provided to the pixel portion is of a first conductivity type and has an LDD structure,

a first conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit, disposed adjacent to the thin film transistor provided to the pixel portion, having the same structure as the structure of the thin film transistor provided to the pixel portion,

a second conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit having a conventional planar structure, that is non-LDD and non-offset structure,

wherein a distance L₁ between one end face of a gate electrode of the first conductivity type thin film transistor and an end face of a first LDD region is substantially identical with a distance L₂ between another end face of the gate electrode and an end face of a second LDD region, and

wherein a length L₇ of the first LDD region is identical to a length L₈ of the second LDD region.

9. The active-matrix liquid display of claim 8, wherein the second conductivity type thin film transistor comprises a gate electrode which is subjected to ion implantation twice and the conductivity type of the gate electrode is an n-type.

10. The active-matrix liquid display of claim 8, where the second conductivity type thin film transistor comprises a gate electrode which is subjected to ion implantation twice.

11. The active-matrix liquid display of claim 8, wherein an LDD length of the first conductivity type thin film transistor of the CMOS driver circuit is about 0.2 μ

m to about 2.0 μ

m.

12. The active-matrix liquid display of claim 9, wherein the second conductivity type thin film transistor of the CMOS driver circuit comprises a source/drain region having two conductivity types of impurities such that in a channel lengthwise direction, a center of a first region implanted with B ions is located inside a center of a second region implanted with P ions.

13. An active-matrix liquid crystal display integrally formed with a driver circuit comprising:

a pair of substrates disposed in opposing relation to each other; and

a liquid crystal material sandwiched between the pair of substrates;

wherein the pair of substrates comprises;

a TFT substrate including at least an insulative substrate, source interconnection lines and gate interconnection lines which are formed in a matrix pattern on the insulative substrate, a thin film transistor, provided to each pixel portion for use as a switching element for applying a voltage to a portion of the liquid crystal material, which lies at a location where the source interconnection line and the gate interconnection line intersect each other, a pixel electrode connected to a drain electrode of the thin film transistor for supplying a voltage to the liquid crystal material, and a CMOS driver circuit which comprises thin film transistors for supplying an electric signal to the thin film transistor of the pixel portion through the source interconnection lines and the gate interconnection lines; and

a counterpart substrate including an insulating substrate and a counter electrode formed thereon;

wherein the thin film transistor provided to the pixel portion is of a first conductivity type and has an offset structure,

a first conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit, being disposed adjacent to the thin film transistor provided to the pixel portion, having the same structure as the structure of the thin film transistor provided to the pixel portion,

a second conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit having a conventional planar structure, that is a non-offset structure and a non-LDD structure, and

wherein a gate electrode of the second conductivity type thin film transistor of the CMOS driver circuit is subjected to ion implantation twice and the conductivity type of the gate electrode is an n-type, and

a length L₅ of a first LDD region is identical to a length L₆ of a second LDD region.

14. The active-matrix liquid display of claim 13, wherein the second conductivity type thin film transistor of the CMOS driver circuit comprises a source/drain region having two conductivity types of impurities such that in a channel lengthwise direction, a center of a first region implanted with B ions is located inside a center of a second region implanted with P ions.

15. The active-matrix liquid display of claim 14, wherein a geometrical center line in the channel lengthwise direction of the second conductivity type thin film transistor is located outside a center line of the source/drain region.

16. The active-matrix liquid display of claim 13, wherein the second conductivity type thin film transistor comprises a gate electrode which is subjected to ion implantation twice and the conductivity type of the gate electrode is an n-type.

17. The active-matrix liquid display of claim 13, wherein an offset length of the first conductivity type thin film transistor of the CMOS driver circuit is about 0.2 μ

m to about 2.0 μ

m.

18. An active-matrix liquid crystal display integrally formed with a driver circuit comprising:

a pair of substrates disposed in opposing relation to each other; and

a liquid crystal material sandwiched between the pair of substrates;

wherein the pair of substrates comprises;

a TFT substrate including at least an insulative substrate, source interconnection lines and gate interconnection lines which are formed in a matrix pattern on the insulative substrate, a thin film transistor, provided to each pixel portion for use as a switching element for applying a voltage to a portion of the liquid crystal material, which lies at a location where the source interconnection line and the gate interconnection line intersect each other, a pixel electrode connected to a drain electrode of the thin film transistor for supplying a voltage to the liquid crystal material, and a CMOS driver circuit which comprises thin film transistors for supplying an electric signal to the thin film transistor of the pixel portion through the source interconnection lines and the gate interconnection lines; and

a counterpart substrate including an insulating substrate and a counter electrode formed thereon;

wherein the thin film transistor provided to the pixel portion is of a first conductivity type and has an offset structure,

a first conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit, disposed adjacent to the thin film transistor provided to the pixel portion, having the same structure as the structure of the thin film transistor provided to the pixel portion,

a second conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit having a conventional planar structure, that is a non-offset and a non-LDD structure, and

wherein a gate electrode of the second conductivity type thin film transistor of the CMOS driver circuit is subjected to ion implantation twice, and wherein a length L₇ of LDD region located on a source side in the channel lengthwise direction is substantially identical with a length L₈ of LDD region located on a drain side in the channel lengthwise direction.

19. An active-matrix liquid crystal display integrally formed with a driver circuit comprising:

a pair of substrates disposed in opposing relation to each other; and

a liquid crystal material sandwiched between the pair of substrates;

wherein the pair of substrates comprises;

a TFT substrate including at least an insulative substrate, source interconnection lines and gate interconnection lines which are formed in a matrix pattern on the insulative substrate, a thin film transistor, provided to each pixel portion for use as a switching element for applying a voltage to a portion of the liquid crystal material, which lies at a location where the source interconnection line and the gate interconnection line intersect each other, a pixel electrode connected to a drain electrode of the thin film transistor for supplying a voltage to the liquid crystal material, and a CMOS driver circuit which comprises thin film transistors for supplying an electric signal to the thin film transistor of the pixel portion through the source interconnection lines and the gate interconnection lines; and

a counterpart substrate including an insulating substrate and a counter electrode formed thereon;

wherein the thin film transistor provided to the pixel portion is of a first conductivity type and has an LDD structure,

a first conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit, disposed adjacent to the thin film transistor provided to the pixel portion, having the same structure as the structure of the thin film transistor provided to the pixel portion,

a second conductivity type thin film transistor of the thin film transistors of the CMOS driver circuit having a conventional planar structure, that is a non-offset and a non-LDD structure,

wherein a length L₇ of a LDD region located on a source side in the channel lengthwise direction is substantially identical with a length L₈ of the LDD region located on a drain side in the channel lengthwise direction.