US-12627907-B2 - Image sensing device and imaging device including the same

US12627907B2US 12627907 B2US12627907 B2US 12627907B2US-12627907-B2

Abstract

An imaging device comprises a pixel including a photoelectric conversion device for generating pixel signals, a floating diffusion region, a first dual conversion gain (DCG) transistor for providing additional capacitance to the floating diffusion region, and a first DCG capacitor connected to the floating diffusion region through the first DCG transistor; and an analog-digital converter (ADC) for converting the pixel signals into image data, wherein the pixel includes a first metal layer including a first DCG gate electrode of the first DCG transistor and a first electrode of the first DCG capacitor, a second metal layer including a dual conversion line that supplies a first DCG gate signal to the first DCG gate electrode, and a second electrode overlapping the first electrode, a first insulating layer between the first DCG gate electrode and the dual conversion line, and a second insulating layer between the first electrode and the second electrode.

Inventors

Hyo Jun KWON

Assignees

SK Hynix Inc.

Dates

Publication Date: 20260512
Application Date: 20240910
Priority Date: 20240531

Claims (20)

1 . An imaging device comprising: a pixel region including a photoelectric conversion device configured to generate photocharges corresponding to an illuminance of an incident light at the photoelectric conversion device and produce a pixel signal representative of the generated photocharges, a floating diffusion region configured to receive and accumulate the generated photocharges from the photoelectric conversion device, a first dual conversion gain (DCG) transistor coupled to the floating diffusion region to provide an additional capacitance to the floating diffusion region, and a first DCG capacitor connected to the floating diffusion region through the first DCG transistor; and an analog-digital converter (ADC) coupled to configured to the pixel region to receive the pixel signal from the pixel region and convert the pixel signal into image data, wherein the pixel region includes: a first metal layer including a first DCG gate electrode of the first DCG transistor and a first electrode of the first DCG capacitor; a second metal layer including a dual conversion line that supplies a first DCG gate signal to the first DCG gate electrode on the first metal layer, and a second electrode overlapping the first electrode; a first insulating layer disposed between the first DCG gate electrode and the dual conversion line; and a second insulating layer disposed between the first electrode and the second electrode, wherein a permittivity of the second insulating layer is higher than a permittivity of the first insulating layer.
2 . The imaging device according to claim 1 , wherein the first DCG transistor has a source electrode connected to the first electrode, and a drain electrode connected to the floating diffusion region.
3 . The imaging device according to claim 1 , wherein the additional capacitance provided to the floating diffusion region corresponds to a sum of a parasitic capacitance of the first DCG transistor and the capacitance of the first DCG capacitor.
4 . The imaging device according to claim 3 , wherein the capacitance of the floating diffusion region in a state where the first DCG transistor is turned on is higher than the capacitance of the floating diffusion region in a state where the first DCG transistor is turned off.
5 . The imaging device according to claim 3 , further comprising an image signal processor for generating a high dynamic range (HDR) image based on the image data.
6 . The imaging device according to claim 5 , wherein the image signal processor is configured to determine gains to process image data generated in a low conversion gain (LCG) mode in which the additional capacitance is provided to the floating diffusion region, and image data generated in a high conversion gain (HCG) mode in which the additional capacitance is not provided to the floating diffusion region.
7 . The imaging device according to claim 6 , further comprising a second DCG transistor connected to the first DCG capacitor, and a second DCG capacitor connected to a source electrode of the second DCG transistor, and wherein the image signal processor is further configured to determine a gain to process image data generated in an MCG mode in which the additional capacitance is provided by the first DCG transistor and the first DCG capacitor.
8 . The imaging device according to claim 7 , wherein the first metal layer further includes a third electrode of the second DCG capacitor, the second metal layer further includes a fourth electrode of the second DCG capacitor, and the second insulating layer is further arranged between the third electrode and the fourth electrode.
9 . The imaging device according to claim 1 , wherein the first insulating layer includes SiCOH, and the second insulating layer includes at least one of HfO 2 , ZrO 2 , or Al 2 O 3 .
10 . The imaging device according to claim 1 , wherein the permittivity of the second insulating layer is 10 or higher.
11 . The imaging device according to claim 1 , further comprising a third insulating layer arranged between the second insulating layer and the first electrode or between the second insulating layer and the second electrode, wherein a permittivity of the third insulating layer is higher than the permittivity of the first insulating layer and lower than the permittivity of the second insulating layer.
12 . The imaging device according to claim 11 , wherein the third insulating layer includes SiO 2 .
13 . The imaging device according to claim 1 , wherein the pixel region further includes a reset transistor between a power supply voltage and the first DCG transistor, wherein the reset transistor is configured to reset a voltage of the floating diffusion region to the power supply voltage in response to a pixel reset signal.
14 . The imaging device according to claim 13 , wherein the pixel region further includes a driver transistor having a source electrode connected to the power supply voltage, and a gate electrode connected to the floating diffusion region, and a selection transistor disposed between the driver transistor and an output signal line, wherein the driver transistor is configured to amplify changes in an electrical potential of the floating diffusion region that receives the photocharges accumulated in the photoelectric conversion device and transmits the photocharges to the selection transistor, and the selection transistor is turned on by a row selection signal and outputs an electrical signal transferred from the driver transistor as the pixel signal through the output signal line.
15 . The imaging device according to claim 14 , further comprising a transfer transistor disposed between the photoelectric conversion device and the floating diffusion region, wherein the transfer transistor is configured to transfer the photocharges accumulated in the photoelectric conversion device to the floating diffusion region in response to a transfer signal.
16 . An imaging device comprising: a first metal layer including a floating diffusion electrode of a floating diffusion region that accumulates photocharges generated by a photoelectric conversion element configured to generate the photocharges in response to an incident light, a gate electrode of a dual conversion gain DCG transistor that provides an additional capacitance to the floating diffusion region, and a first electrode of a first DCG capacitor connected to a source electrode of the DCG transistor and surrounding the floating diffusion electrode; a second metal layer arranged on the first metal layer and including a dual conversion line for supplying a DCG gate signal, and a second electrode of the first DCG capacitor overlapping the first electrode; a first insulating layer disposed between a first DCG gate electrode and the dual conversion line; and a second insulating layer disposed between the first electrode and the second electrode, wherein the second insulating layer has a permittivity that is higher than a permittivity of the first insulating layer.
17 . The imaging device according to claim 16 , wherein the first electrode includes a first electrode region extended along a first direction, a second electrode region connected to the first electrode region and extended along a second direction intersecting the first direction, a third electrode region connected to the second electrode region and extended along the first direction, and a fourth electrode region connected to the third electrode region and extended along the second direction, wherein the second electrode overlaps the first electrode region and the third electrode region.
18 . The imaging device according to claim 17 , wherein the first electrode region and the fourth electrode region are spaced apart from each other.
19 . The imaging device according to claim 17 , wherein the second electrode overlaps the first electrode region to the fourth electrode region.
20 . The imaging device according to claim 19 , further comprising a third metal layer on the second metal layer, wherein the dual conversion line includes a first dual conversion line arranged on the second metal layer and extended along the first direction, and a second dual conversion line arranged on the third metal layer, electrically connected to the first dual conversion line, and extended along the second direction.

Description

CROSS REFERENCE TO RELATED APPLICATION This patent document claims priority to Korean Patent Application No. 10-2024-0071449, filed May 31, 2024, the entire contents of which is incorporated herein for all purposes by this reference. TECHNICAL FIELD The disclosed technology relates to an image sensing device and an imaging device including the same. BACKGROUND With the advancement in the information and communication industry and digitalization of electronic devices, image sensors with improved performance are used in various fields such as digital cameras, camcorders, cellular phones, personal communication systems (PCSs), gaming devices, security cameras, medical micro cameras, and the like. Generally, an image sensor has a pixel area including a photodiode and a peripheral circuit region. A unit pixel includes a photodiode and a transfer transistor. The transfer transistor is arranged between the photodiode and the floating diffusion region and transfers charges generated by the photodiode to the floating diffusion region. SUMMARY Some implementations of the disclosed technology provide an imaging device that can supply additional capacitance to a floating diffusion region. Some implementations of the disclosed technology provide an imaging device that can increase capacitance of a Dual Conversion Gain (DCG) capacitor. Some implementations of the disclosed technology provide an imaging device that may increase the conversion ratio of Conversion Gain (CG) by increasing capacitance of a DCG capacitor. Some implementations of the disclosed technology provide an imaging device that can increase capacitance of a Dual Conversion Gain (DCG) capacitor in a shared structure of a floating diffusion region. In one aspect of the present disclosure, there is provided an imaging device comprising: a pixel including a photoelectric conversion device for generating pixel signals each having a size corresponding to illuminance and generating photo charges corresponding to the illuminance, a floating diffusion region for accumulating the generated photo charges, a first dual conversion gain (DCG) transistor for providing additional capacitance to the floating diffusion region, and a first DCG capacitor connected to the floating diffusion region through the first DCG transistor; and an analog-digital converter (ADC) for converting the pixel signals into image data, wherein the pixel includes a first metal layer including a first DCG gate electrode of the first DCG transistor and a first electrode of the first DCG capacitor, a second metal layer including a dual conversion line that supplies a first DCG gate signal to the first DCG gate electrode on the first metal layer, and a second electrode overlapping the first electrode, a first insulating layer between the first DCG gate electrode and the dual conversion line, and a second insulating layer between the first electrode and the second electrode, wherein a permittivity of the second insulating layer is higher than a permittivity of the first insulating layer. According to another aspect of the present disclosure, there is provided an imaging device comprising: a first metal layer including a floating diffusion electrode of a floating diffusion region that accumulates photo charges generated by a photoelectric conversion device, a gate electrode of a DCG transistor that provides additional capacitance to the floating diffusion region, and a first electrode of a first DCG capacitor connected to the source electrode of the DCG transistor and surrounding the floating diffusion electrode; a second metal layer arranged on the first metal layer and including a dual conversion line for supplying a DCG gate signal, and a second electrode of the first DCG capacitor overlapping the first electrode; a first insulating layer between the first DCG gate electrode and the dual conversion line; and a second insulating layer between the first electrode and the second electrode, wherein permittivity of the second insulating layer is higher than the permittivity of the first insulating layer. Details of other embodiments are included in the detailed description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an imaging system according to an embodiment of the disclosed technology. FIG. 2 is a block diagram showing the image sensing device shown in FIG. 1 in more detail. FIG. 3 is a schematic plan view showing the pixel array according to FIG. 2. FIG. 4 is an equivalent circuit diagram showing a sub-pixel included in the pixel array of FIG. 3. FIG. 5 is a timing diagram for explaining the operation of the pixel shown in FIG. 4. FIG. 6 is a graph for explaining an HCG mode and an LCG mode. FIG. 7 is a graph showing signal strength according to time (or light amount) in the HCG mode. FIG. 8 is a graph showing signal strength according to time (or light amount) in the LCG mode. FIG. 9 is a detailed plan view showing a pixel array according to an embodiment. FIG