Image sensing device

Abstract

Disclosed is an image sensing device including a pixel array including a plurality of unit pixels, the unit pixels in the pixel array may include a plurality of sub-pixels, a first isolation region may be disposed in an edge region of the sub-pixels, a second isolation region may extend from the first isolation region to a central portion of the sub-pixels, and a third isolation region may be disposed in an edge region of the sub-pixels. The second isolation region may include: a first inner isolation region protruding in a first direction from one region of the first isolation region to a central portion of the sub-pixel; and a second inner isolation region formed on the same straight line as the first inner isolation region and protruding in a second direction from another region of the first isolation region to a central portion of the sub-pixel, the first grid may be formed in an upper region located above a region between the first inner isolation region and the second inner isolation region, and the first grid may include an air layer.

Description

Technical Field

[0001] Various embodiments of the disclosed technology relate to an image sensing device, and more particularly, to an image sensing device capable of reducing optical loss. Background Art

[0002] Image sensing devices refer to semiconductor devices that capture optical images and convert them into electrical signals. With the development of the automotive, medical, computer and telecommunications industries, the demand for high-performance image sensing devices is increasing in various devices such as smartphones, digital cameras, gaming devices, IoT, robots, security cameras, medical micro cameras, etc.

[0003] The most common types of image sensing devices are charge coupled device (CCD) image sensing devices and complementary metal oxide semiconductor (CMOS) image sensing devices. Summary of the invention

[0004] The disclosed technology may be implemented in some embodiments to provide an image sensing device capable of reducing optical loss by forming an air grid without light absorbing material in an inner isolation region.

[0005] One embodiment is an image sensing device, comprising: a pixel array, comprising a plurality of unit pixels, the unit pixels in the pixel array may include a plurality of sub-pixels, a first isolation region may be disposed in an edge region of the sub-pixel, a second isolation region may extend from the first isolation region to a central portion of the sub-pixel, the second isolation region may include: a first inner isolation region, which protrudes in a first direction from one region of the first isolation region to a central portion of the sub-pixel; and a second inner isolation region, which is formed on the same straight line as the first inner isolation region and protrudes in a second direction from another region of the first isolation region to a central portion of the sub-pixel, a first grid may be formed in an upper region above a region between the first inner isolation region and the second inner isolation region, and the first grid may include an air layer.

[0006] The subpixel may include: a first inner isolation region; a second inner isolation region; a color filter formed over the first and second inner isolation regions; and a microlens formed over the color filter, and the first grid may be formed in a central region of the color filter.

[0007] A photodiode may be disposed below the first grid.

[0008] The second grid may be disposed over at least one region of the first isolation region.

[0009] The first grid may have an inclined portion disposed in an upper portion of the first grid, the inclined portion being closer to the microlens than a lower portion of the first grid.

[0010] The second inner isolation region may be formed at a position spaced apart from the first inner isolation region by a certain space.

[0011] The first grid may be disposed between one side of the second grid and another side of the second grid.

[0012] At least one region of the first grid may be disposed to overlap an upper region of the first inner isolation region and an upper region of the second inner isolation region.

[0013] The air layer may be a region without light absorbing material that absorbs visible light.

[0014] Another embodiment is an image sensing device, comprising: a pixel array, comprising a plurality of unit pixels, the unit pixels in the pixel array may include a plurality of sub-pixels, a first isolation region may be disposed in an edge region of the sub-pixel, a second isolation region may extend from the first isolation region to a central portion of the sub-pixel, the second isolation region may include: a first inner isolation region, which protrudes in a first direction from the first isolation region to the central portion of the sub-pixel; a second inner isolation region, which is formed on the same straight line as the first inner isolation region and protrudes in a second direction from the first isolation region to the central portion of the sub-pixel, the second inner isolation region being disposed facing the first inner isolation region; a third inner isolation region that protrudes along a third direction from the first isolation region to the central portion of the sub-pixel, the third direction being perpendicular to the first direction; and a fourth inner isolation region that is formed on the same straight line as the third inner isolation region and protrudes along a fourth direction from the first isolation region to the central portion of the sub-pixel, the fourth inner isolation region being arranged to face the third inner isolation region, the first grid may be formed in a first upper region above a region between the first inner isolation region and the second inner isolation region and in a second upper region above a region between the third inner isolation region and the fourth inner isolation region, and the first grid may include an air layer.

[0015] The sub-pixel may include: a first inner isolation region; a second inner isolation region; a third inner isolation region; a fourth inner isolation region; a color filter formed above the first inner isolation region, the second inner isolation region, the third inner isolation region, and the fourth inner isolation region; and a microlens formed above the color filter, and the first grid may be formed in a central portion of the color filter.

[0016] A photodiode may be formed under the first grid.

[0017] The second grid may be disposed over at least one region of the first isolation region.

[0018] The second inner isolation region may be spaced apart from the first inner isolation region by a certain space.

[0019] The third inner isolation region may be spaced apart from the fourth inner isolation region by a certain space.

[0020] The second grid may be formed on both sides of the first grid.

[0021] The first grid may be formed in a cross shape by having four portions extending in four different directions.

[0022] At least one region of the first grid may be formed to overlap the first, second, third, and fourth inner isolation regions.

[0023] The air layer may be free of light absorbing materials that absorb visible light. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a block diagram of an image sensing device according to a first embodiment of the disclosed technology.

[0025] Figure 2 This is a diagram illustrating a pixel array according to the first embodiment of the disclosed technology.

[0026] Figure 3 FIG. 1 is a diagram illustrating sub-pixels of a pixel array according to the first embodiment of the disclosed technology.

[0027] Figure 4 is based on Figure 3 FIG. 1 is a cross-sectional view of the sub-pixel according to the first embodiment taken along line AA′.

[0028] Figure 5 is based on Figure 3 FIG. 1 is a cross-sectional view of the sub-pixel according to the first embodiment taken along line BB′.

[0029] Figure 6 FIG. 1 is a diagram illustrating the structure of a first grid according to an embodiment of the disclosed technology.

[0030] Figure 7 This is a diagram illustrating a pixel array according to a second embodiment of the disclosed technology.

[0031] Figure 8 FIG. 1 is a diagram illustrating sub-pixels of a pixel array according to a second embodiment of the disclosed technology.

[0032] Fig. 9 is based on Figure 8 FIG. 1 is a cross-sectional view of a sub-pixel according to the second embodiment taken along line CC′.

[0033] Fig.10 is based on Figure 8 FIG. 1 is a cross-sectional view of a sub-pixel according to the second embodiment taken along line DD′.

[0034] Fig.11 is based on Figure 8 FIG. 1 is a cross-sectional view of a sub-pixel according to a second embodiment taken along line EE′. DETAILED DESCRIPTION

[0035] Features and certain advantages associated with specific implementations of the disclosed technology disclosed in this patent document are described by way of example embodiments with reference to the accompanying drawings.

[0036] In image sensing devices with dual photodiodes (2PD) and quad photodiodes (4PD), light incident to a microlens is scattered by a deep trench isolation (DTI) region and enters each photodiode. In the case of small pixels, since the isolation region includes polysilicon (Poly Si), the incident light is scattered and absorbed simultaneously in the isolation region, which results in optical loss.

[0037] In some implementations, an air grid is formed above the inner isolation region of the sub-pixel. Due to the presence of the air grid, optical loss caused by incident light being scattered and absorbed in the inner isolation region can be prevented from occurring.

[0038] Figure 1 is a block diagram of an image sensing device according to an embodiment.

[0039] Reference Figure 1 , an image sensing device according to an embodiment may include a pixel array 1100, a row driver 1200, a correlated double sampler (CDS) 1300, an analog-to-digital converter (ADC) 1400, an output buffer 1500, a column driver 1600, a timing controller 1700, and a bias generator 1800. The components of the image sensing device shown are discussed only by way of example, and this patent document covers addition or omission of components as needed.

[0040] The pixel array 1100 may include a plurality of pixels arranged in a plurality of rows and columns. In one embodiment, the plurality of pixels may be arranged in a two-dimensional pixel array including rows and columns. In another example, a plurality of unit imaging pixels may be arranged in a three-dimensional pixel array. A plurality of pixels may convert an optical signal into an electrical signal on a unit pixel basis or on a pixel group basis, and the pixels in the pixel group share at least some internal circuits. The pixel array 1100 may receive a drive signal including a row selection signal, a pixel reset signal, and a transmission signal from a row driver 1200. When the drive signal is received, the corresponding pixel in the pixel array 1100 may be activated to perform operations corresponding to the row selection signal, the pixel reset signal, and the transmission signal.

[0041] The row driver 1200 may activate the pixel array 1100 based on the command and control signal provided by the timing controller 1700 to perform certain operations on the pixels in the corresponding row. In one embodiment, the row driver 1200 may select at least one pixel arranged in at least one row of the pixel array 1100. The row driver 1200 may generate a row selection signal to select at least one row among a plurality of rows. The row driver 1200 may sequentially enable a pixel reset signal and a transmission signal for pixels corresponding to at least one selected row. Therefore, a reference signal and an image signal as an analog signal generated by each pixel of the selected row may be sequentially transmitted to the CDS 1300. At this time, the reference signal may be an electrical signal provided to the CDS 1300 when the sensing node (e.g., a floating diffusion node) of the pixel is reset, and the image signal may be an electrical signal provided to the CDS 1300 when the photocharge generated by the pixel is accumulated in the sensing node. The reference signal representing the reset noise inherent in the pixel and the image signal representing the intensity of the incident light may be collectively referred to as a pixel signal.

[0042] CMOS image sensors can use correlated double sampling (CDS) to remove undesired pixel offset values, known as fixed pattern noise, by sampling the pixel signal twice to remove the difference between the two samples. In some embodiments, correlated double sampling (CDS) can remove undesired pixel offset values ​​by comparing the pixel output voltage obtained before and after the photocharge generated by the pixel in response to the received incident light is accumulated in the sensing node, so that the pixel output voltage based only on the incident light can be measured. In one embodiment, CDS1300 can sequentially sample and hold reference signals and image signals provided from the pixel array 1100 to each of the plurality of column lines. Therefore, CDS1300 can sample and hold reference signals and image signals corresponding to each column of the pixel array 1100.

[0043] The CDS 1300 may transmit the reference signal and the image signal of each column as a correlated double sampling signal to the ADC 1400 based on a control signal from the timing controller 1700 .

[0044] ADC 1400 is used to convert the CDS signal into a digital signal for each column and output the digital signal. In one embodiment, ADC 1400 can be implemented as a ramp comparison ADC. The ramp comparison ADC may include: a comparator circuit for comparing an analog pixel signal with a ramp signal that ramps up or down over time; and a counter that counts until the ramp signal matches the analog pixel signal. In one embodiment, ADC 1400 may convert the correlated double sampling signal generated by CDS 1300 for each column into a digital signal and output the digital signal.

[0045] The ADC 1400 may include a plurality of column counters corresponding to each column of the pixel array 1100. Each column of the pixel array 1100 is connected to the column counter, and image data may be generated by converting a correlated double sampling signal corresponding to each column into a digital signal using the column counter. In another embodiment, the ADC 1400 may include a global counter to convert a correlated double sampling signal corresponding to each column into a digital signal using a global code provided from the global counter.

[0046] The output buffer 1500 may temporarily hold the column-based image data provided from the ADC 1400 to output the image data. The output buffer 1500 may temporarily store the image data output from the ADC 1400 based on a control signal of the timing controller 1700. The output buffer 1500 may serve as an interface to compensate for a data rate difference or a transmission (or processing) rate difference between the image sensing device and other devices.

[0047] The column driver 1600 may select a column of the output buffer 1500 based on a control signal from the timing controller 1700, and sequentially output image data temporarily stored in the selected column of the output buffer 1500. In one embodiment, upon receiving an address signal from the timing controller 1700, the column driver 1600 may generate a column selection signal based on the address signal and select a column of the output buffer 1500, and output image data from the selected column of the output buffer 1500 as an output signal.

[0048] The timing controller 1700 may control at least one of the row driver 1200 , the CDS 1300 , the ADC 1400 , the output buffer 1500 , the column driver 1600 , and the bias generator 1800 .

[0049] The timing controller 1700 may provide a clock signal required for the operation of the corresponding components of the image sensing device, a control signal for timing control, an address signal for selecting a row or column, a signal for controlling the level of a bias voltage applied to the pixel array 1100, etc. to at least one of the row driver 1200, the CDS 1300, the ADC 1400, the output buffer 1500, the column driver 1600, and the bias generator 1800. In an embodiment of the present disclosure, the timing controller 1700 may include a logic control circuit, a phase-locked loop (PLL) circuit, a timing control circuit, a communication interface circuit, and other circuits.

[0050] The bias generator 1800 may generate a bias voltage for suppressing a dark current generated in pixels of the pixel array 1100 , and provide the generated bias voltage to the pixel array 1100 .

[0051] The bias voltage may be determined during wafer probe testing of the image sensing device and stored in a one-time programmable (OTP) memory. For example, the bias voltage may be experimentally determined to be a value that maximizes the dark current suppression effect while minimizing unnecessary power consumption without impairing the performance of the image sensing device.

[0052] The bias generator 1800 may generate a voltage corresponding to a bias voltage stored in the OTP memory. According to an embodiment, the OTP memory may be included in the image sensing device, and in particular, may be included in the bias generator 1800.

[0053] Depending on the implementation, the bias voltage may include multiple values.

[0054] For example, the multiple values ​​may correspond to multiple operation modes of the image sensing device, respectively. The dark current generated under low light and the dark current generated under high light may be different from each other, and the bias voltage provided by the bias generator 1800 to effectively suppress the dark current in each environment may vary according to the mode.

[0055] In some implementations, the plurality of values ​​may respectively correspond to a plurality of regions of the pixel array 1100. The generated dark currents may be different from each other according to the positions of the pixels in the pixel array 1100, and the bias voltage provided by the bias generator 1800 to effectively suppress the dark current regardless of the position of the pixel may vary according to the region.

[0056] The bias voltage may be a negative voltage with a negative sign, but the present disclosure is not limited thereto.

[0057] Figure 2 is a diagram illustrating a pixel array according to the first embodiment, and Figure 3 is a diagram illustrating sub-pixels of a pixel array according to the first embodiment.

[0058] Reference Figure 2 , the image sensing device according to the embodiment may be a dual photodiode (2PD) type image sensing device.

[0059] In an embodiment, the pixel array 1100 may include a plurality of unit pixels, and each unit pixel may include four sub-pixels, the sub-pixels include the same type of color filters, and two photodiodes may be formed under each color filter. The sub-pixels generate sub-pixel signals associated with the pixel signals of the unit pixels in response to incident light. For example, the pixel signal generated by each unit pixel is the sum of the sub-pixel signals generated by the sub-pixels within the unit pixel.

[0060] Reference Figure 2 and Figure 3, the first isolation region 210 may be formed in an edge region of the sub-pixel 200 (a boundary region between the sub-pixels 200). In some implementations, in a plan view, the first isolation region 210 may be located on four sides of the sub-pixel 200. The first isolation region 210 may be formed in a shape extending vertically from the surface of the substrate to prevent crosstalk between adjacent sub-pixels 200, and may be formed, for example, by a deep trench isolation (DTI) process.

[0061] The first isolation region 210 may include at least one of a silicon oxynitride (SiON) layer, a silicon oxide (SiO) layer, a silicon nitride (SiN) layer, and / or a polysilicon (Poly Si) layer.

[0062] The second isolation region 220 may be formed on one side of the first isolation region 210 as the inner portion of the sub-pixel 200. The second isolation region 220 may extend in a direction from the first isolation region 210 to a central portion of the sub-pixel 200 in a plan view.

[0063] The second isolation region 220 may be formed in a shape vertically extending from the surface of the substrate to prevent crosstalk between adjacent photodiodes, and may be formed by a deep trench isolation (DTI) process.

[0064] The second isolation region 220 may include a silicon oxynitride (SiON) layer, a silicon oxide (SiO) layer, a silicon nitride (SiN) layer, and / or a polysilicon (Poly Si) layer.

[0065] In an implementation, the second isolation region 220 may include a first inner isolation region 221 and a second inner isolation region 222 .

[0066] The first inner isolation region 221 may protrude in a direction from one region of the first isolation region 210 to a central portion of the sub-pixel 200 .

[0067] The second inner isolation region 222 may be formed on the same straight line as the first inner isolation region 221 and may protrude in a direction from another region of the first isolation region 210 (a region opposite to the region where the first inner isolation region 221 is formed) to a central portion of the subpixel 200 .

[0068] The first grid 260 may be formed in an upper region above a region between the first inner isolation region 221 and the second inner isolation region 222. In an embodiment, the first grid 260 may be formed such that the first grid 260 has at least one region vertically overlapping the first inner isolation region 221 and / or the second inner isolation region 222. For example, a portion of the first grid 260 is disposed above the first inner isolation region 221, and / or another portion of the first grid 260 is disposed above the second inner isolation region 222.

[0069] In an embodiment, the first grid 260 may be configured as a section including a hollow area or an enclosure providing an air layer (air area) by not including a light absorbing material that absorbs visible light. Therefore, this hollow area providing the air layer of the first grid 260 does not have a light absorbing material. The refractive index of the first grid 260 may be 1.

[0070] Since the first grid 260 is formed in the upper region above the region between the first inner isolation region 221 and the second inner isolation region 222, it is possible to prevent optical loss from occurring due to incident light being scattered and absorbed simultaneously into the first inner isolation region 221 and the second inner isolation region 222. The first grid 260 allows incident light from the color filter 230 layer to enter each photodiode and prevents the incident light from reaching the first inner isolation region 221 and the second inner isolation region 222, thereby reducing optical loss caused by light absorption.

[0071] In an embodiment, the second grid 270 may be formed over the first isolation region 210. In an embodiment, the second grid 270 may be formed over at least one region of the first isolation region 210. In an embodiment, the second grid 270 may include an air layer (air region) without a light absorbing material that absorbs visible light. In an embodiment, the refractive index of the second grid 270 may be 1.

[0072] Since the second grid 270 is formed over the first isolation region 210, incident light is prevented from reaching the first isolation region 210, thereby reducing optical loss caused by light absorption.

[0073] In an implementation, the second inner isolation region 222 may be formed at a position spaced apart by a certain space from the first inner isolation region 221. The certain space may have various values ​​depending on the configuration.

[0074] Figure 4 is based on Figure 3 FIG. 1 is a cross-sectional view of the sub-pixel according to the first embodiment taken along line AA′. Figure 5 is based on Figure 3 FIG. 1 is a cross-sectional view of the sub-pixel according to the first embodiment taken along line BB′.

[0075] Reference Figure 4 and Figure 5 The sub-pixel 200 may include a first isolation region 210 , a first inner isolation region 221 , a second inner isolation region 222 , a color filter 230 , a microlens 240 , a photodiode 250 , a first grid 260 , a second grid 270 , and a substrate 280 .

[0076] The first isolation region 210 may be formed between adjacent sub-pixels 200 .

[0077] The first and second inner isolation regions 221 and 222 may be formed under the color filter 230 .

[0078] The color filter 230 may be formed over the substrate 280 and may filter and transmit certain visible light from incident light entering the microlens 240. In some implementations, the color filter 230 may include one of a blue filter that transmits only blue light from visible light, a green filter that transmits only green light from visible light, and a red filter that transmits only red light from visible light.

[0079] The microlens 240 may be formed above the color filter 230 and may serve to collect incident light entering from the outside.

[0080] The photodiode 250 may be formed in an inner region of the substrate 280 and may be formed below the first grid 260, and the n-type impurity region and the p-type impurity region may be vertically stacked in the photodiode 250. The n-type impurity region and the p-type impurity region may be formed by an ion implantation process. The photodiode 250 is described as an example of a photoelectric conversion element configured to convert incident light into electric charge. In some implementations, the photoelectric conversion element may be a phototransistor, a photogate, or a combination thereof, etc.

[0081] The first grid 260 may be formed in a central region of the color filter 230. The first grid 260 may include an air layer (air region) therein. In an embodiment, a refractive index of the first grid 260 may be less than a refractive index of the color filter 230.

[0082] The first grid 260 may allow incident light from the color filter 230 to enter each photodiode 250 and prevent the incident light from reaching the first and second inner isolation regions 221 and 222 , thereby reducing optical loss due to light absorption.

[0083] The first grid 260 may be formed between one side of the second grid 270 and the other side of the second grid 270. The second grid 270 may be formed on both sides of the first grid 260.

[0084] The second grid 270 may be formed over the first isolation region 210 .

[0085] In an implementation, the second grid 270 may include a metal layer or an air layer.

[0086] In an embodiment, the second grid 270 may include a metal layer including a first metal layer (not shown) and a second metal layer (not shown) formed over the first metal layer (not shown). In an embodiment, the first metal layer (not shown) may include a titanium nitride layer (TiN). In an embodiment, the second metal layer (not shown) may include tungsten (W).

[0087] In an example, the second grid 270 may be constructed as a section including a hollow area that provides an air layer including an air region without a light absorbing material that absorbs visible light. Thus, this hollow area providing the air layer of the second grid 270 is free of light absorbing material.

[0088] The substrate 280 may include a silicon (Si) material in a single crystal state.

[0089] Figure 6 is a diagram illustrating a structure of a first grid according to an embodiment.

[0090] Reference Figure 6 In an embodiment, the first grid 260 may have an inclined portion. The inclined portion is arranged to be closer to the microlens 240 than the rest of the first grid. The first grid 260 may be arranged between a first surface and a second surface of the color filter 230, the second surface being opposite to the first surface. When the microlens 240 is arranged on the first surface of the color filter 230, the inclined portion of the first grid 260 is closer to the first surface of the color filter 230 than the second surface of the color filter 230. In an embodiment, the first grid 260 may have a shape that narrows upward (e.g., in the direction toward the microlens 240). The first grid 260 may be used to isolate incident light from a dual photodiode (2PD) or a quad photodiode (4PD). The first grid 260 may allow incident light to enter each photodiode from the dual photodiode (2PD) or the quad photodiode (4PD).

[0091] Figure 7 is a diagram illustrating a pixel array according to the second embodiment. Figure 8 is a diagram for describing sub-pixels of a pixel array according to the second embodiment.

[0092] Reference Figure 7 , the image sensing device according to the embodiment may be a quad photodiode (4PD) type image sensing device.

[0093] In an implementation, the pixel array 1100 may include a plurality of unit pixels, and each unit pixel may include four sub-pixels including the same type of color filters, and four photodiodes may be formed under each color filter.

[0094] Reference Figure 7 and Figure 8 , the first isolation region 710 may be formed in an edge region of the sub-pixel 700 (a boundary region between the sub-pixels 700). In some implementations, in a plan view, the first isolation region 710 may be located on four sides of the sub-pixel 700. The first isolation region 710 may be formed in a shape extending vertically from the surface of the substrate to prevent crosstalk between adjacent sub-pixels 700, and may be formed, for example, by a deep trench isolation (DTI) process.

[0095] The first isolation region 710 may include at least one of a silicon oxynitride (SiON) layer, a silicon oxide (SiO) layer, a silicon nitride (SiN) layer, and / or a polysilicon (Poly Si) layer.

[0096] The second isolation region 720 may be formed on one side of the first isolation region 710 as the inner portion of the sub-pixel. The second isolation region 720 may extend in a direction from the first isolation region 710 to a central portion of the sub-pixel 700 in a plan view.

[0097] The second isolation region 720 may be formed in a shape vertically extending from the surface of the substrate to prevent crosstalk between adjacent photodiodes and may be formed by a deep trench isolation (DTI) process.

[0098] The second isolation region 720 may include a silicon oxynitride (SiON) layer, a silicon oxide (SiO) layer, a silicon nitride (SiN) layer, and / or a polysilicon (Poly Si) layer.

[0099] In an implementation, the second isolation region 720 may include a first inner isolation region 721 , a second inner isolation region 722 , a third inner isolation region 723 , and a fourth inner isolation region 724 .

[0100] The first inner isolation region 721 may protrude in a first direction from one region of the first isolation region 710 to a central portion of the sub-pixel 700 .

[0101] The second inner isolation region 722 may be formed on the same straight line as the first inner isolation region 721, and may protrude in a second direction from another region of the first isolation region 710 (a region opposite to the region where the first inner isolation region 721 is disposed) to the central portion of the sub-pixel 700. The second direction is a direction opposite to the first direction.

[0102] The third inner isolation region 723 may protrude in a third direction from the first isolation region 710 to a central portion of the sub-pixel 700 , the third direction being perpendicular to the first direction in which the first isolation region 710 protrudes.

[0103] The fourth inner isolation region 724 may be formed on the same straight line as the third inner isolation region 723 and protrude in a fourth direction from the first isolation region 710 to the central portion of the sub-pixel 700. The fourth direction is the opposite direction of the third direction. The fourth inner isolation region 724 is disposed to face the third inner isolation region 723.

[0104] The first grid 760 may be formed in an upper region above a region between the first inner isolation region 721 and the second inner isolation region 722 and in an upper region above a region between the third inner isolation region 723 and the fourth inner isolation region 724. In an embodiment, the first grid 760 may be formed in such a manner that at least one region of the first grid 760 overlaps the first inner isolation region 721, the second inner isolation region 722, the third inner isolation region 723, and / or the fourth inner isolation region 724. For example, a first portion of the first grid 760 is disposed above the first inner isolation region 721, a second portion of the first grid 760 is disposed above the second inner isolation region 722, a third portion of the first grid 760 is disposed above the third inner isolation region 723, and / or a fourth portion of the first grid 760 is disposed above the fourth inner isolation region 724.

[0105] In an embodiment, the first grid 760 may be configured to include a section of a hollow region that provides an air layer without a light absorbing material that absorbs visible light. Thus, this hollow region that provides the air layer of the first grid 760 is free of light absorbing material.

[0106] Since the first grid 760 is formed in the upper region above the region between the first inner isolation region 721 and the second inner isolation region 722 and in the upper region above the region between the third inner isolation region 723 and the fourth inner isolation region 724, it is possible to prevent optical loss that occurs due to incident light being scattered and absorbed simultaneously into the first inner isolation region 721, the second inner isolation region 722, the third inner isolation region 723, and the fourth inner isolation region 724. The first grid 760 allows incident light from the color filter 730 layer to enter the respective photodiodes and prevents the incident light from reaching the first inner isolation region 221, the second inner isolation region 222, the third inner isolation region 723, and the fourth inner isolation region 724, thereby reducing optical loss caused by light absorption.

[0107] In an embodiment, the second grid 770 may be formed above the first isolation region 710. In an embodiment, the second grid 770 may be formed above at least one region of the first isolation region 710. In an embodiment, the second grid 770 may include an air layer (air region) without a light absorbing material. Therefore, the air layer has no light absorbing material.

[0108] Since the second grid 770 is formed over the first isolation region 710, incident light is prevented from reaching the first isolation region 710, thereby reducing optical loss caused by light absorption.

[0109] In an embodiment, the second inner isolation region 722 may be formed at a position spaced apart from the first inner isolation region 721, and the fourth inner isolation region 724 may be formed at a position spaced apart from the third inner isolation region 723. The space may have various values ​​depending on the setting.

[0110] Fig. 9 is based on Figure 8 FIG. 1 is a cross-sectional view of a sub-pixel according to the second embodiment taken along line CC′. Fig.10 is based on Figure 8 FIG. 1 is a cross-sectional view of a sub-pixel according to the second embodiment taken along line DD′. Fig.11 is based on Figure 8 FIG. 1 is a cross-sectional view of a sub-pixel according to a second embodiment taken along line EE′.

[0111] Reference Figures 9 to 11 , the sub-pixel 700 may include a first isolation region 710, a first inner isolation region 721, a second inner isolation region 722, a third inner isolation region 723, a fourth inner isolation region 724, a color filter 730, a microlens 740, a photodiode 750, a first grid 760, a second grid 770 and a substrate 780.

[0112] The first isolation region 710 may be formed between adjacent sub-pixels 700 .

[0113] A first inner isolation region 721 , a second inner isolation region 722 , a third inner isolation region 723 , and a fourth inner isolation region 724 may be formed under the color filter 730 .

[0114] The color filter 730 may be formed over the substrate 780 and may filter and transmit some visible light from incident light entering the microlens 740. The color filter 730 may include one of a blue filter that transmits only blue light from visible light, a green filter that transmits only green light from visible light, and a red filter that transmits only red light from visible light.

[0115] The microlens 740 may be formed over the color filter 730 and may serve to collect incident light entering from the outside.

[0116] The photodiode 750 may be formed in an inner region of the substrate 780 and may be formed below the first grid 760, and the n-type impurity region and the p-type impurity region may be vertically stacked in the photodiode 750. The n-type impurity region and the p-type impurity region may be formed by an ion implantation process. The photodiode 750 is described as an example of a photoelectric conversion element configured to convert incident light into electric charge. In some implementations, the photoelectric conversion element may be a phototransistor, a photogate, or a combination thereof, etc.

[0117] The first grid 760 may be formed in a central region of the color filter 730. The first grid 760 may include air therein. In an implementation, a refractive index of the first grid 760 may be less than a refractive index of the color filter 730.

[0118] The first grid 760 may allow incident light from the color filter 730 to enter each photodiode 750 and prevent the incident light from reaching the first, second, third, and fourth inner isolation regions 721, 722, 723, and 724, thereby reducing optical loss due to light absorption.

[0119] The first grid 760 may be formed between one side of the second grid 270 and the other side of the second grid 770. The second grid 770 may be formed on both sides of the first grid 760.

[0120] The first grid 760 may be formed in a cross shape. The first grid 760 may have four portions extending from the center of the substrate in four different directions.

[0121] The second grid 770 may be formed over the first isolation region 710 .

[0122] In an implementation, the second grid 770 may include a metal layer or an air layer.

[0123] In an embodiment, the second grid 770 may include a metal layer including a first metal layer (not shown) and a second metal layer (not shown) formed over the first metal layer (not shown). In an embodiment, the first metal layer (not shown) may include a titanium nitride layer (TiN). In an embodiment, the second metal layer (not shown) may include tungsten (W).

[0124] In an embodiment, the second grid 770 may be configured as a section including a hollow area that provides an air layer including an air region without a light absorbing material that absorbs visible light. Thus, this hollow area providing the air layer of the second grid 270 is free of light absorbing material.

[0125] The substrate 780 may include a silicon (Si) material in a single crystal state.

[0126] Although various implementations have been described above, variations and improvements to the disclosed implementations, as well as other implementations, may be made based on what is described or illustrated in this document.

[0127] Priority claims and cross-references to related applications

[0128] This patent document claims priority to and the benefit of Korean Patent Application No. 10-2023-0142091, filed on October 23, 2023, the entire contents of which are incorporated by reference as a part of the disclosure of this patent document.

Claims

1. An image sensing device, comprising: A pixel array, the pixel array comprising a plurality of unit pixels, Wherein, a unit pixel in the pixel array includes a plurality of sub-pixels. The first isolation region is arranged in the edge region of the sub-pixel. wherein the second isolation region extends from the first isolation region to the central portion of the sub-pixel, Wherein, the second isolation area includes: a first inner isolation region protruding in a first direction from a region of the first isolation region to the central portion of the sub-pixel; and a second inner isolation region, the second inner isolation region being formed on the same straight line as the first inner isolation region and protruding in a second direction from another region of the first isolation region to the central portion of the sub-pixel, wherein a first grid is formed in an upper region above a region between the first inner isolation region and the second inner isolation region, and Wherein, the first grid includes an air layer.

2. The image sensing device according to claim 1, in, The sub-pixel comprises: the first inner isolation area; the second inner isolation area; a color filter formed over the first inner isolation region and the second inner isolation region; and a microlens formed above the color filter, and Wherein, the first grid is formed in a central area of ​​the color filter.

3. The image sensing device according to claim 2, in, A photodiode is disposed below the first grid.

4. The image sensing device according to claim 2, in, A second grid is disposed over at least one region of the first isolation region.

5. The image sensing device according to claim 2, in, The first grid has an inclined portion provided in an upper portion of the first grid, the inclined portion being closer to the microlens than a lower portion of the first grid.

6. The image sensing device according to claim 1, in, The second inner isolation region is formed at a position spaced apart from the first inner isolation region by a certain space.

7. The image sensing device according to claim 2, in, The first grid is disposed between one side of the second grid and another side of the second grid.

8. The image sensing device according to claim 2, in, At least one region of the first grid is disposed to overlap with an upper region of the first inner isolation region and an upper region of the second inner isolation region.

9. The image sensing device according to claim 1, wherein: The air layer is a region without light-absorbing material that absorbs visible light.

10. An image sensing device, comprising: A pixel array, the pixel array comprising a plurality of unit pixels, Wherein, a unit pixel in the pixel array includes a plurality of sub-pixels. The first isolation region is arranged in the edge region of the sub-pixel. wherein the second isolation region extends from the first isolation region to the central portion of the sub-pixel, Wherein, the second isolation area includes: a first inner isolation region protruding in a first direction from the first isolation region to the central portion of the sub-pixel; a second inner isolation region, the second inner isolation region being formed on the same straight line as the first inner isolation region and protruding in a second direction from the first isolation region to the central portion of the sub-pixel, the second inner isolation region being arranged to face the first inner isolation region; a third inner isolation region protruding in a third direction from the first isolation region to the central portion of the sub-pixel, the third direction being perpendicular to the first direction; and a fourth inner isolation region, the fourth inner isolation region being formed on the same straight line as the third inner isolation region and protruding in a fourth direction from the first isolation region to the central portion of the sub-pixel, the fourth inner isolation region being arranged to face the third inner isolation region, wherein a first grid is formed in a first upper region above a region between the first inner isolation region and the second inner isolation region and in a second upper region above a region between the third inner isolation region and the fourth inner isolation region, and Wherein, the first grid includes an air layer.

11. The image sensing device according to claim 10, in, The sub-pixel comprises: the first inner isolation area; the second inner isolation area; the third inner isolation area; the fourth inner isolation area; a color filter formed over the first inner isolation region, the second inner isolation region, the third inner isolation region, and the fourth inner isolation region; and a microlens formed above the color filter, and Wherein, the first grid is formed in a central portion of the color filter.

12. The image sensing device according to claim 11, in, A photodiode is formed under the first grid.

13. The image sensing device according to claim 11, further comprising: A second grid is disposed over at least one region of the first isolation region.

14. The image sensing device according to claim 10, in, The second inner isolation region is spaced apart from the first inner isolation region by a certain space.

15. The image sensing device according to claim 10, in, The third inner isolation region is spaced apart from the fourth inner isolation region by a certain space.

16. The image sensing device according to claim 11, further comprising: A second grid is formed on both sides of the first grid.

17. The image sensing device according to claim 16, in, The first grid is formed in a cross shape by having four portions extending in four different directions.

18. The image sensing device according to claim 11, in, At least one region of the first grid is formed to overlap the first inner isolation region, the second inner isolation region, the third inner isolation region, and the fourth inner isolation region.

19. The image sensing device according to claim 11, wherein: The air layer has no light absorbing material that absorbs visible light.

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