SEMICONDUCTOR DEVICE

• US 20110108836A1
• Filed: 11/03/2010
• Published: 05/12/2011
• Est. Priority Date: 11/06/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: YAMAZAKI, Shunpei, KOYAMA, Jun
• Granted Patent: US 8,378,391 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: H01L 27/1203 the substrate comprising an insulating body on a semiconductor body, e.g. SOI three-dimensional layout H01L27/0688
• 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 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/14612 involving a transistor
• CPC Class Codes: H01L 27/14616 characterised by the channel of the transistor, e.g. channel having a doping gradient
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14632 Wafer-level processed structures
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous
• CPC Class Codes: H01L 31/095 comprising amorphous semiconductors
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
• CPC Class Codes: H04N 25/778 comprising amplifiers shared between a plurality of pixels, i.e. at least one part of the amplifier must be on the sensor array itself
• CPC Class Codes: H10B 10/18 Peripheral circuit regions

Abstract

A solid-state image sensor which holds a potential for a long time and includes a thin film transistor with stable electrical characteristics is provided. When the off-state current of a thin film transistor including an oxide semiconductor layer is set to 1×10⁻¹³ A or less and the thin film transistor is used as a reset transistor and a transfer transistor of the solid-state image sensor, the potential of the signal charge storage portion is kept constant, so that a dynamic range can be improved. When a silicon semiconductor which can be used for a complementary metal oxide semiconductor is used for a peripheral circuit, a high-speed semiconductor device with low power consumption can be manufactured.

Claims

1. A semiconductor device comprising:

a pixel portion over a substrate comprising a silicon semiconductor, the pixel portion comprising;

a photoelectric conversion element portion buried in the substrate;

a transfer transistor electrically connected to the photoelectric conversion element portion;

a signal charge storage portion electrically connected to the transfer transistor;

a reset transistor electrically connected to the signal charge storage portion;

an amplifier transistor electrically connected to the signal charge storage portion; and

wherein a channel formation region of the transfer transistor and a channel formation region of the reset transistor comprise an oxide semiconductor and a channel formation region of the amplifier transistor comprises the silicon semiconductor.

2. The semiconductor device according to claim 1, wherein the transfer transistor or the reset transistor is formed over the amplifier transistor.

3. The semiconductor device according to claim 1, wherein off-state current of each of the transfer transistor and the reset transistor is 1×

10<sup>−

13</sup> A or less.

4. The semiconductor device according to claim 1, wherein a carrier concentration in the oxide semiconductor is lower than 1×

10¹⁴/cm³.

5. The semiconductor device according to claim 1, wherein the pixel portion is electrically connected to a peripheral circuit portion including a complementary transistor having a silicon semiconductor in a channel formation region.

6. The semiconductor device according to claim 1, wherein the signal charge storage portion includes an insulating layer as a dielectric.

7. An electronic device comprising the semiconductor device according to claim 1.