# US 10,770,597 B2 · Logic circuit and semiconductor device

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- Number: US 10,770,597 B2
- Document ID: US10770597B2
- Status: Granted
- Kind: B2
- Application number: 16/787,562
- Filed: 2020-02-11
- Published: 2020-06-04
- Granted: 2020-09-08
- Earliest claimed: 2009-10-16
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Applicants: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Shunpei Yamazaki; Jun Koyama; Masashi Tsubuku; Kosei Noda
- Web page: https://patentgrep.com/patent/US10770597B2

## CPC

- H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate}
- H10D 30/6757: {characterised by the structure of the channel, e.g. transverse or longitudinal shape or doping profile (TFTs having channel structures for preventing kink or snapback effects H10D30/6708; TFTs having lightly-doped source or drain extensions H10D30/6715)}
- H10D 86/423: {comprising semiconductor materials not belonging to the Group IV, e.g. InGaZnO}
- H10D 86/60: wherein the TFTs are in active matrices
- H10D 89/10: Integrated device layouts
- H10P 74/277: {Circuits for electrically characterising or monitoring manufacturing processes, e.g. circuits in tested chips or circuits in testing wafers}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A logic circuit includes a thin film transistor having a channel formation region formed using an oxide semiconductor, and a capacitor having terminals one of which is brought into a floating state by turning off the thin film transistor. The oxide semiconductor has a hydrogen concentration of 5×1019 (atoms/cm3) or less and thus substantially serves as an insulator in a state where an electric field is not generated. Therefore, off-state current of a thin film transistor can be reduced, leadind to suppressing the leakage of electric charge stored in a capacitor, through the thin film transistor. Accordingly, a malfunction of the logic circuit can be prevented. Further, the excessive amount of current which flows in the logic circuit can be reduced through the reduction of off-state current of the thin film transistor, resulting in low power consumption of the logic circuit.

## Claims

### Claim 1

A display device comprising:
a driving transistor; and
a light-emitting element electrically connected to the driving transistor,
wherein a channel formation region of the driving transistor comprises an oxide semiconductor,
wherein an off-state current of the driving transistor in the channel length direction is smaller than or equal to (⅓)×10−12 A/μm at a measurement temperature of 120° C. and a drain voltage of 6 V, and
wherein the off-state current of the driving transistor in the channel length direction is smaller than or equal to (⅓)×10−12 A/μm at a measurement temperature of −30° C. and a drain voltage of 6 V.

### Claim 2 (depends on 1)

The display device according to claim 1, wherein the oxide semiconductor comprises In, Ga, and Zn.

### Claim 3 (depends on 1)

The display device according to claim 1, wherein a carrier density of the oxide semiconductor is smaller than or equal to 5×1014/cm3.

### Claim 4 (depends on 1)

The display device according to claim 1, wherein the oxide semiconductor includes a plurality of crystals.

### Claim 5 (depends on 1)

The display device according to claim 1, wherein a hydrogen concentration of the oxide semiconductor is smaller than or equal to 5×1019/cm3.

### Claim 6

A display device comprising:
a driving transistor;
a light-emitting element electrically connected to the driving transistor; and
a color filter layer,
wherein the color filter layer is located above the driving transistor and below the light-emitting element,
wherein a channel formation region of the driving transistor comprises an oxide semiconductor,
wherein an off-state current of the driving transistor in the channel length direction is smaller than or equal to (⅓)×10−12 A/μm at a measurement temperature of 120° C. and a drain voltage of 6 V, and
wherein the off-state current of the driving transistor in the channel length direction is smaller than or equal to (⅓)×10−12 A/μm at a measurement temperature of −30° C. and a drain voltage of 6 V.

### Claim 7 (depends on 6)

The display device according to claim 6, wherein the oxide semiconductor comprises In, Ga, and Zn.

### Claim 8 (depends on 6)

The display device according to claim 6, wherein a carrier density of the oxide semiconductor is smaller than or equal to 5×1014/cm3.

### Claim 9 (depends on 6)

The display device according to claim 6, wherein the oxide semiconductor includes a plurality of crystals.

### Claim 10 (depends on 6)

The display device according to claim 6, wherein a hydrogen concentration of the oxide semiconductor is smaller than or equal to 5×1019/cm3.

### Claim 11

A transistor comprising:
a channel formation region comprising an oxide semiconductor,
wherein an off-state current of the transistor is smaller than or equal to (⅓)×10−12 A/μm at a measurement temperature of 120° C. or −30° C. and a drain voltage of 6 V.

### Claim 12 (depends on 11)

The transistor according to claim 11, wherein the oxide semiconductor comprises In, Ga, and Zn.

### Claim 13 (depends on 11)

The transistor according to claim 11, wherein a carrier density of the oxide semiconductor is smaller than or equal to 5×1014/cm3.

### Claim 14 (depends on 11)

The transistor according to claim 11, wherein the oxide semiconductor includes a plurality of crystals.

### Claim 15 (depends on 11)

The transistor according to claim 11, wherein a hydrogen concentration of the oxide semiconductor is smaller than or equal to 5×1019/cm3.