THIN FILM SEMICONDUCTOR DEVICE FOR DISPLAY AND METHOD OF PRODUCING SAME

• US 20010014493A1
• Filed: 11/03/1999
• Published: 08/16/2001
• Est. Priority Date: 11/05/1993
• Status: Active Grant

• Current Assignee: Hisao Hayashi, Yukio Kinoshita, Yuko Inoue
• Original Assignee: Hisao Hayashi, Yukio Kinoshita, Yuko Inoue
• Inventors: KINOSHITA, YUKIO, INOUE, YUKO, HAYASHI, HISAO
• Granted Patent: US 6,468,839 B2
• Time in Patent Office: Days
• 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 27/1214 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

Abstract

An LDD structure of a thin film transistor for pixel switching is realized on a large glass substrate by low-temperature processes. A thin film semiconductor device for display comprises a display part and a peripheral driving part formed on a glass substrate (0). Pixel electrodes (9) and NchLDD-TFTs are arranged in a matrix in the display part. Thin film transistor PchTFTs and NchTFTs which constitute circuit elements are formed in the peripheral driving part. Each thin film transistor consists of a gate electrode (1), an insulating film (2) formed on the gate electrode (1), a polycrystalline semiconductor layer (3) formed on the insulating layer (2), and a high concentration impurity layer constituting a source (4) and a drain (7) formed on the polycrystalline semiconductor layer (3). Further, an NchLDD-TFT thin film transistor for switching has an LDD structure in which a low concentration impurity layer (8) is interposed between the polycrystalline semiconductor layer (3) and the high concentration impurity layer (7).

Claims

1. A thin film semiconductor device comprising:

a glass substrate;

a display part formed on the glass substrate, a plurality of pixel electrodes and first thin film transistors for switching being formed in a matrix in the display part;

a peripheral drive circuit part formed on the glass substrate, second thin film transistors constituting circuit elements being formed in the peripheral drive circuit part,

each of the first and second thin film transistors comprising a gate electrode, a polycrystalline semiconductor layer formed on an insulating film on the gate electrode, and a high concentration impurity layer constituting source and drain regions formed on the polycrystalline semiconductor layer,

the first thin film transistors being of an LDD structure wherein a low concentration impurity layer is interposed between the polycrystalline semiconductor layer and the high concentration impurity layer.

2. A thi0n film semiconductor device according to

claim 1

, wherein the display part comprises an upper region containing the pixel electrodes, a lower region containing the first thin film transistors, and a planarization layer disposed between the upper and lower regions.

3. A thin film semiconductor device according to

claim 2

, further comprising a color filter layer and a black mask layer between the upper and lower regions.

4. A thin film semiconductor device according to

claim 3

, wherein the black mask layer contains a metal wiring pattern electrically connected to the high concentration impurity layer.

5. A thin film semiconductor device according to

claim 4

, wherein the pixel electrodes are electrically connected to the high concentration impurity layer by way of the metal wiring pattern.

6. A liquid crystal display device comprising:

a glass substrate;

a display part formed on the glass substrate, a plurality of pixel electrodes and first thin film transistors for switching being formed in a matrix in the display part;

a peripheral drive circuit part formed on the glass substrate, second thin film transistors constituting circuit elements being formed in the peripheral drive circuit part,

each of the first and second thin film transistors comprising a gate electrode, a polycrystalline semiconductor layer formed on an insulating film on the gate electrode, and a high concentration impurity layer constituting source and drain regions formed on the polycrystalline semiconductor layer,

the first thin film transistors being of an LDD structure wherein a low concentration impurity layer is interposed between the polycrystalline semiconductor layer and the high concentration impurity layer;

an opposed substrate disposed facing the glass substrate; and

a liquid crystal layer held between the glass substrate and the opposed substrate.

7. A liquid crystal display device according to

claim 6

, wherein the display part comprises an upper region containing the pixel electrodes, a lower region containing the first thin film transistors, and a planarization layer disposed between the upper and lower regions.

8. A thin film semiconductor device according to

claim 7

, further comprising a color filter layer and a black mask layer between the upper and lower regions.

9. A method for producing a thin film semiconductor device comprising a display part and a peripheral drive circuit part integrally formed on a glass substrate, comprising the steps of:

forming a gate electrode on a glass substrate;

forming a semiconductor thin film on an insulating film on the gate electrode;

performing laser annealing on the semiconductor thin film to transform the semiconductor thin film into a polycrystalline semiconductor layer;

selectively forming a low concentration impurity layer on the polycrystalline semiconductor layer in the display part; and

forming a high concentration impurity layer to constitute source and drain regions on the low concentration impurity layer, thereby forming a thin film transistor for switching having an LDD structure, and forming a high concentration impurity layer to constitute source and drain regions on the polycrystalline semiconductor layer in the peripheral drive circuit part, thereby forming a thin film transistor to constitute a circuit element.

10. A method for producing a thin film semiconductor device according to

claim 9

, further comprising a step of selectively performing additional laser annealing on the high concentration impurity layer in the peripheral drive circuit part to reduce the resistance of the polycrystalline semiconductor layer.

11. A stacked LDD structure bottom gate type thin film transistor comprising:

a glass substrate;

a gate electrode formed on the glass substrate;

a polycrystalline semiconductor layer formed on an insulating layer on the gate electrode;

a low concentration impurity layer formed on the polycrystalline semiconductor layer; and

a high concentration impurity layer constituting source and drain regions formed on the low concentration impurity layer.