# US 7,745,829 B2 · Semiconductor device and fabrication method thereof

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- Number: US 7,745,829 B2
- Document ID: US7745829B2
- Status: Granted
- Kind: B2
- Application number: 12/230,954
- Filed: 2008-09-09
- Published: 2009-01-15
- Granted: 2010-06-29
- Earliest claimed: 1999-02-23
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Shunpei Yamazaki; Satoshi Murakami; Jun Koyama; Yukio Tanaka; Hidehito Kitakado; Hideto Ohnuma
- Web page: https://patentgrep.com/patent/US7745829B2

## CPC

- G02F 1/1368: in which the switching element is a three-electrode device {(G02F1/136277 takes precedence)}
- G02F 1/133345: {Insulating layers (G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence)}
- G02F 1/13454: {Drivers integrated on the active matrix substrate (G02F1/136277 takes precedence)}
- G02F 1/136227: {Through-hole connection of the pixel electrode to the active element through an insulation layer}
- G02F 1/136286: {Wiring, e.g. gate line, drain line}
- H10D 30/6715: {characterised by the doping profiles, e.g. having lightly-doped source or drain extensions}
- H10D 30/6719: {having significant overlap between the lightly-doped drains and the gate electrodes, e.g. gate-overlapped LDD [GOLDD] TFTs}
- H10D 30/6731: {Top-gate only TFTs}
- H10D 30/6737: {characterised by the electrode materials}
- H10D 30/6743: {Silicon}
- H10D 30/6745: {Polycrystalline or microcrystalline silicon}
- H10D 86/00: Integrated devices formed in or on insulating or conducting substrates, e.g. formed in silicon-on-insulator [SOI] substrates or on stainless steel or glass substrates
- H10D 86/021: {of multiple TFTs}
- H10D 86/421: {having a particular composition, shape or crystalline structure of the active layer}
- H10D 86/441: {Interconnections, e.g. scanning lines}
- H10D 86/451: {characterised by the compositions or shapes of the interlayer dielectrics}
- H10D 86/60: wherein the TFTs are in active matrices
- H10K 59/1213: {the pixel elements being TFTs}
- H10K 59/123: Connection of the pixel electrodes to the thin film transistors [TFT]
- H10K 59/124: Insulating layers formed between TFT elements and OLED elements
- H10K 59/126: Shielding, e.g. light-blocking means over the TFTs
- H10K 59/131: Interconnections, e.g. wiring lines or terminals
- G02F 2201/123: pixel
- G02F 2202/104: poly-Si
- H10D 30/6721: {having lightly-doped extensions consisting of multiple lightly doped zones or having non-homogeneous dopant distributions, e.g. graded LDD}
- H10K 59/1201: {Manufacture or treatment}
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## 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

### Claim 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, an insulating layer over the first channel formation region, the first source region, and the first drain region, and a first gate electrode over the insulating layer;
a current controlling TFT comprising a second channel formation region, a second source region, and a second drain region over the substrate, the insulating layer over the second channel formation region, the second source region, and the second drain region, and a second gate electrode over the insulating layer;
a first insulating film over the switching TFT and the current controlling TFT;
a source wiring formed over the first insulating film and connected to one of the first source region and the first drain region of the switching TFT;
a first drain wiring formed over the first insulating film and connected to the other of the first source region and the first drain region of the switching TFT and to the second gate electrode of the current controlling TFT;
a second drain wiring formed over the first insulating film and connected to one of the second source region and the second drain region of the current controlling TFT;
a current supply line formed over the first insulating film and connected to the other of the second source region and the second drain region 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 formed over the second insulating film and 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, a portion of the insulating layer, and a first portion of the second gate electrode of the current controlling TFT extended from a second portion of the second gate electrode of the current controlling TFT overlapping with the second channel formation region,
wherein the current supply line overlaps with the holding capacitance.

### Claim 2 (depends on 1)

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

### Claim 3 (depends on 1)

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

### Claim 4 (depends on 1)

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

### Claim 5 (depends on 1)

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

### Claim 6 (depends on 1)

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.

### Claim 7 (depends on 1)

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.

### Claim 8

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, an insulating layer over the first semiconductor layer, and a first gate electrode over the insulating layer;
a current controlling TFT comprising a second semiconductor layer over the substrate, the insulating layer over the second semiconductor layer, and a second gate electrode over the insulating layer;
a first insulating film over the switching TFT and the current controlling TFT;
a source wiring formed over the first insulating film and connected to the first semiconductor layer of the switching TFT;
a first drain wiring formed over the first insulating film and connected to the first semiconductor layer of the switching TFT and to the second gate electrode of the current controlling TFT;
a second drain wiring formed over the first insulating film and connected to the second semiconductor layer of the current controlling TFT;
a current supply line formed over the first insulating film and 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 formed over the second insulating film and 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 portion of the second gate electrode of the current controlling TFT and a portion of the current supply line,
wherein the current supply line overlaps with the holding capacitance.

### Claim 9 (depends on 8)

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

### Claim 10 (depends on 8)

The EL display device according to claim 8, wherein the second electrode is a cathode comprising a shading conductive film.

### Claim 11 (depends on 8)

The EL display device according to claim 8, wherein the second insulating film is a passivation film.

### Claim 12 (depends on 8)

The EL display device according to claim 8, wherein the current controlling TFT is a p-channel TFT.

### Claim 13 (depends on 8)

An electric appliance device having the EL display device according to claim 8, 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.

### Claim 14

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, an insulating layer 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 insulating layer;
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 insulating layer 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 insulating layer;
a first insulating film over the switching TFT and the current controlling TFT;
a source wiring formed over the first insulating film and connected to one of the first source region and the first drain region of the switching TFT;
a first drain wiring formed over the first insulating film and connected to the other of the first source region and the first drain region of the switching TFT and to the second gate electrode of the current controlling TFT;
a second drain wiring formed over the first insulating film and connected to one of the second source region and the second drain region of the current controlling TFT;
a current supply line formed over the first insulating film and connected to the other of the second source region and the second drain region 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 formed over the second insulating film and 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, a portion of the insulating layer, and a first portion of the second gate electrode of the current controlling TFT extended from a second portion of the second gate electrode of the current controlling TFT overlapping with the second channel formation region,
wherein the current supply line overlaps with the holding capacitance.

### Claim 15 (depends on 14)

The EL display device according to claim 14, wherein the first electrode is a pixel electrode comprising a transparent conductive film.

### Claim 16 (depends on 14)

The EL display device according to claim 14, wherein the second electrode is a cathode comprising a shading conductive film.

### Claim 17 (depends on 14)

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

### Claim 18 (depends on 14)

The EL display device according to claim 14, wherein the current controlling TFT is a p-channel TFT.

### Claim 19 (depends on 14)

The EL display device according to claim 14, 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.

### Claim 20 (depends on 14)

An electric appliance device having the EL display device according to claim 14, 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.

### Claim 21

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, an insulating layer over the first semiconductor layer, and a first gate electrode having a triple-gate structure over the insulating layer;
a current controlling TFT comprising a second semiconductor layer over the substrate, the insulating layer over the second semiconductor layer, and a second gate electrode having a triple-gate structure over the insulating layer;
a first insulating film over the switching TFT and the current controlling TFT;
a source wiring formed over the first insulating film and connected to the first semiconductor layer of the switching TFT;
a first drain wiring formed over the first insulating film and connected to the first semiconductor layer of the switching TFT and to the second gate electrode of the current controlling TFT;
a second drain wiring formed over the first insulating film and connected to one of the second semiconductor layer of the current controlling TFT;
a current supply line formed over the first insulating film and 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 formed over the second insulating film and 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 portion of the second gate electrode of the current controlling TFT and a portion of the current supply line,
wherein the current supply line overlaps with the holding capacitance.

### Claim 22 (depends on 21)

The EL display device according to claim 21, wherein the first electrode is a pixel electrode comprising a transparent conductive film.

### Claim 23 (depends on 21)

The EL display device according to claim 21, wherein the second electrode is a cathode comprising a shading conductive film.

### Claim 24 (depends on 21)

The EL display device according to claim 21, wherein the second insulating film is a passivation film.

### Claim 25 (depends on 21)

The EL display device according to claim 21, wherein the current controlling TFT is a p-channel TFT.

### Claim 26 (depends on 21)

An electric appliance device having the EL display device according to claim 21, 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.