Image sensing device

Abstract

The invention relates to an image sensing device. The image sensing device includes: a semiconductor substrate; a unit pixel supported by the semiconductor substrate to detect light incident on the unit pixel and convert the detected light into a pixel signal; and an inter-pixel isolation structure disposed between adjacent unit pixels to physically isolate the adjacent unit pixels from each other. Each unit pixel includes: a photoelectric conversion element; an in-pixel isolation structure disposed between adjacent photoelectric conversion elements in the unit pixel; and at least one overflow path configured to interconnect the photoelectric conversion elements within the unit pixels, and wherein the shape of each unit pixel is a triangular shape when viewed in a plane.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent document claims priority to and the benefit of Korean Patent Application No. 10-2023-0113576, filed on August 29, 2023, which is incorporated herein by reference in its entirety as a part of the disclosure of this patent document. Technical Field

[0003] Techniques and embodiments disclosed in this patent document generally relate to image sensing devices having a triangular pixel structure. Background Art

[0004] Image sensors are used in electronic devices to convert optical images into electrical signals. In recent years, with the development of the automotive, medical, computer and communication industries, the demand for highly integrated, high-performance image sensors has increased rapidly in a variety of electronic devices such as digital cameras, camcorders, personal communication systems (PCS), video game consoles, surveillance cameras, medical micro cameras, robots, etc.

[0005] CCD image sensing devices can be driven more easily than CCD sensing devices. CMOS image sensing devices can integrate traditional circuits into a single chip, so that CMOS image sensing devices can be easily manufactured into small-sized products, and have higher integration and very low power consumption. In addition, CMOS image sensing devices are compatible with CMOS manufacturing technology, thereby reducing production costs. In recent years, CMOS image sensing devices have been intensively studied and rapidly widely used.

[0006] In addition, the image sensing device includes a phase difference detection auto focus (PDAF) function which automatically focuses by detecting a phase difference between adjacent pixels. Summary of the invention

[0007] Various embodiments of the disclosed technology are directed to an image sensing device capable of minimizing image distortion while improving phase difference detection characteristics.

[0008] According to an embodiment of the disclosed technology, an image sensing device may include: a semiconductor substrate; unit pixels supported by the semiconductor substrate to respectively detect light incident to the unit pixels and convert the detected light into pixel signals; and an inter-pixel isolation structure disposed between adjacent unit pixels to physically isolate adjacent unit pixels from each other. Each unit pixel may include: (1) a photoelectric conversion element that generates photocharges for generating a pixel signal of each unit pixel in response to incident light detected by the unit pixel; (2) an intra-pixel isolation structure disposed between adjacent photoelectric conversion elements within the unit pixel; and (3) at least one overflow path configured to interconnect the photoelectric conversion elements within the unit pixel, and wherein, when viewed in a plane, the shape of each unit pixel is a triangular shape.

[0009] According to another embodiment of the disclosed technology, an image sensing device may include: a plurality of unit pixels arranged continuously in a first direction and in a second direction intersecting the first direction, each unit pixel presenting a triangular shape when viewed in a plane, and configured to generate photocharges in response to incident light; and a first isolation structure disposed between adjacent unit pixels and configured to isolate adjacent unit pixels from each other. Each of the plurality of unit pixels may include: a first photoelectric conversion element that converts light into photocharges; a second photoelectric conversion element that converts light into photocharges and is disposed adjacent to the first photoelectric conversion element in a first diagonal direction; and a third photoelectric conversion element that converts light into photocharges and is disposed adjacent to the first photoelectric conversion element in a second diagonal direction intersecting the first diagonal direction, and disposed adjacent to the second photoelectric conversion element in a first direction intersecting the first diagonal direction and the second diagonal direction.

[0010] According to another embodiment of the disclosed technology, an image sensing device may include: a semiconductor substrate; an inter-pixel isolation structure, which is arranged between adjacent unit pixels within the semiconductor substrate; a plurality of photoelectric conversion elements, which are respectively arranged in unit pixels within the semiconductor substrate; an intra-pixel isolation structure, which is arranged between adjacent photoelectric conversion elements within the unit pixel; and at least one overflow path formed to interconnect the photoelectric conversion elements within the unit pixel, and wherein, when viewed in a plane, each unit pixel is formed into a triangular shape.

[0011] It is to be understood that both the foregoing general description and the following detailed description of the disclosed technology are illustrative and descriptive and are intended to provide further description of the disclosure as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other features and advantageous aspects of the disclosed technology will become readily apparent with reference to the following detailed description when considered in conjunction with the accompanying drawings.

[0013] Figure 1 is a block diagram illustrating an example of an image sensing device based on some embodiments of the disclosed technology.

[0014] Figure 2 is a schematic diagram showing an example of a planar structure of a unit pixel based on some embodiments of the disclosed technology.

[0015] Figure 3 The following are some embodiments based on the disclosed technology. Figure 2 The diagram is a schematic diagram of an example of an arrangement shape in which unit pixels are arranged in an array shape.

[0016] Figure 4A The invention is a diagram showing an embodiment based on the disclosed technology. Figure 2 The cross-sectional view of the example of the pixel structure taken along the line XY-XY' is shown. Figure 4B The invention is a diagram showing an embodiment based on the disclosed technology. Figure 2 A cross-sectional view of an example of a pixel structure taken along line XX′ is shown.

[0017] Figure 5A Another embodiment of the disclosed technology is shown in FIG. Figure 2 The cross-sectional view of the example of the pixel structure taken along the line XY-XY' is shown. Figure 5B Another embodiment of the disclosed technology is shown in FIG. Figure 2 A cross-sectional view of an example of a pixel structure taken along line XX′ is shown.

[0018] Fig. 6A and Figure 6B is a schematic diagram showing an example of an intra-pixel isolation structure according to another embodiment of the disclosed technology.

[0019] Figure 7 The invention is a diagram showing an embodiment based on the disclosed technology. Fig. 6A and Figure 6B A cross-sectional view of an example of a pixel structure taken along line XX′ is shown.

[0020] Figure 8 Another embodiment of the disclosed technology is shown in FIG. Fig. 6A and Figure 6B A cross-sectional view of an example of a pixel structure taken along line XX′ is shown.

[0021] Fig. 9 is a schematic diagram showing an example of a planar structure of a unit pixel according to another embodiment of the disclosed technology.

[0022] Fig.10 is a schematic diagram showing an example of a planar structure of a unit pixel according to another embodiment of the disclosed technology. DETAILED DESCRIPTION

[0023] This patent document provides embodiments and examples of image sensing devices with triangular pixel structures, which can be used to substantially solve one or more technical or engineering problems and alleviate limitations or disadvantages encountered in some other image sensing devices. Some embodiments of the disclosed technology provide examples of image sensing devices that can minimize image distortion while improving phase difference detection characteristics. The disclosed technology provides multiple implementations of image sensing devices that can minimize image distortion while improving phase difference detection characteristics by improving pixel structures.

[0024] Reference will now be made in detail to certain embodiments of which examples are shown in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar components. In the following description, detailed descriptions of related known configurations or functions incorporated herein will be omitted to avoid confusing the subject matter.

[0025] In the following, various embodiments will be described with reference to the accompanying drawings. However, it should be understood that the disclosed technology is not limited to specific embodiments, but includes various modifications, equivalents and / or alternatives of the embodiments. The embodiments of the disclosed technology can provide various effects that can be directly or indirectly recognized by the disclosed technology.

[0026] Figure 1 is a block diagram illustrating an example of an image sensing device based on some embodiments of the disclosed technology.

[0027] refer to Figure 1 , the image sensing device may include a pixel array 100, a row driver 200, a correlated double sampler (CDS) 300, an analog-to-digital converter (ADC) 400, an output buffer 500, a column driver 600, and a timing controller 700. The present invention is discussed only by way of example. Figure 1 The components of the image sensing device shown in the patent document, and this patent document contains many other variations, substitutions, variations, changes and modifications. In this patent document, the word "pixel" may be used to indicate an image sensing pixel configured to detect incident light to generate an electrical signal carrying an image in the incident light, and a phase detection pixel configured to generate a second electrical signal for calculating a phase difference between images.

[0028] The pixel array 100 may include a plurality of unit pixels (PX) arranged in rows and columns. In one example, a plurality of unit pixels (PX) may be arranged into a two-dimensional (2D) pixel array including multiple rows and multiple columns. In another example, a plurality of unit pixels (PX) may be arranged into a three-dimensional (3D) pixel array. A plurality of unit pixels (PX) may convert an optical signal into an electrical signal based on a unit pixel or based on a pixel group, wherein the unit pixels in the pixel group share at least some internal circuits. The electrical signal generated from the unit pixel (PX) may be used as an image signal to generate an image corresponding to a target object to be captured, and may also be used as a phase difference detection signal for an autofocus operation. When viewed in a plane, each unit pixel (PX) may be formed into a triangular shape, and each unit pixel (PX) may include a plurality of photoelectric conversion elements. Each unit pixel (PX) may generate and output a plurality of electrical signals corresponding to the photocharge generated by each of the plurality of photoelectric conversion elements. A more detailed structure of each unit pixel (PX) will be described later.

[0029] The pixel array 100 may receive a driving signal (eg, a row selection signal, a reset signal, a transmission (or transfer) signal, etc.) from the row driver 200. Upon receiving the driving signal, the unit pixel may be activated to perform operations corresponding to the row selection signal, the reset signal, and the transfer signal.

[0030] The row driver 200 may activate the pixel array 100 based on a control signal provided by a controller circuit such as a timing controller 700 to perform certain operations on the unit pixels in the corresponding row. In some embodiments, the row driver 200 may select one or more pixel groups arranged in one or more rows of the pixel array 100. The row driver 200 may generate a row selection signal for selecting one or more rows from a plurality of rows. The row driver 200 may sequentially enable a reset signal and a transfer signal for the unit pixels arranged in the selected row. The pixel signal generated by the unit pixels arranged in the selected row may be output to a correlated double sampler (CDS) 300.

[0031] The correlated double sampler (CDS) 300 can use correlated double sampling to remove the undesired offset value of the unit pixel. In one example, the correlated double sampler (CDS) 300 can remove the undesired offset value of the unit pixel by comparing the output voltage of the pixel signal (of the unit pixel) obtained before and after the photocharge generated by the incident light is accumulated in the sensing node (i.e., the floating diffusion (FD) node). As a result, the CDS 300 can obtain the pixel signal generated only by the incident light without causing noise. In some embodiments, when a clock signal is received from the timing controller 700, the CDS 300 can sequentially sample and maintain the voltage level of the reference signal and the pixel signal provided from the pixel array 100 to each of the plurality of column lines. That is, the CDS 300 can sample and maintain the voltage level of the reference signal and the pixel signal corresponding to each column of the pixel array 100. In some embodiments, the CDS 300 can transmit the reference signal and the pixel signal of each column as a correlated double sampling (CDS) signal to the ADC 400 based on the control signal from the timing controller 700.

[0032] The ADC 400 is used to convert the analog CDS signal received from the CDS 300 into a digital signal. In some embodiments, the ADC 400 may be implemented as a ramp comparison type ADC. The analog-to-digital converter (ADC) 400 may compare the ramp signal received from the timing controller 700 with the CDS signal received from the CDS 300, and thus may output a comparison signal indicating a comparison result between the ramp signal and the CDS signal. The analog-to-digital converter (ADC) 400 may count the level transition time of the comparison signal in response to the ramp signal received from the timing controller 700, and may output a count value indicating the counted level transition time to the output buffer 500.

[0033] The output buffer 500 may temporarily store the column-based image data provided from the ADC 400 based on the control signal of the timing controller 700. The image data received from the ADC 400 may be temporarily stored in the output buffer 500 based on the control signal of the timing controller 700. The output buffer 500 may provide an interface to compensate for a data rate difference or a transmission rate difference between the image sensing device and other devices.

[0034] The column driver 600 may select a column of the output buffer 500 upon receiving a control signal from the timing controller 700, and sequentially output the image data temporarily stored in the selected column of the output buffer 500. In some embodiments, when receiving an address signal from the timing controller 700, the column driver 600 may generate a column selection signal based on the address signal, may select a column of the output buffer 500 using the column selection signal, and may control the image data received from the selected column of the output buffer 500 to be output as an output signal.

[0035] The timing controller 700 may generate signals for controlling operations of the row driver 200, the ADC 400, the output buffer 500, and the column driver 600. The timing controller 700 may provide the row driver 200, the column driver 600, the ADC 400, and the output buffer 500 with clock signals required for operations of the respective components of the image sensing device, control signals for timing control, and address signals for selecting rows or columns.

[0036] Figure 2 is a schematic diagram showing an example of a planar structure of a unit pixel based on some embodiments of the disclosed technology. Figure 3 Some embodiments based on the disclosed technology are shown Figure 2 Schematic diagram of an example of arrangement of unit pixels shown.

[0037] Reference Figure 2 and Figure 3 , the pixel array 100 may include a plurality of unit pixels (PX) arranged continuously in a first direction (e.g., an X-axis direction) and a second direction (e.g., a Y-axis direction) perpendicular to the first direction. When viewed in a plane, each unit pixel (PX) may be formed into a triangle. Therefore, the plan view of each unit pixel (PX) has a triangular shape. In some embodiments, each unit pixel (PX) may be formed into an equilateral triangle having three sides of the same length.

[0038] In the pixel array 100, unit pixels positioned adjacent to each other in the first direction or the second direction may be symmetrical to each other about a reference line between the unit pixels. For example, in the pixel array 100, when a first unit pixel having three sides and a second unit pixel having three sides are arranged to be adjacent to each other in the first direction (e.g., X direction) or the second direction (e.g., Y direction), the first unit pixel and the second unit pixel share a common side, and the first unit pixel and the second unit pixel are symmetrically placed about the common side. In this case, one of the first unit pixel and the second unit pixel is arranged to have an inverted shape of the other of the first unit pixel and the second unit pixel.

[0039] The unit pixel (PX) may include a plurality of photoelectric conversion elements (PD1-PD3). In some embodiments, the three photoelectric conversion elements (PD1-PD3) may be located in corner regions corresponding to the three corners of each triangle. Each photoelectric conversion element (PD1-PD3) may include N-type impurities and may generate photocharges by photoelectric conversion of incident light.

[0040] The unit pixel (PX) can output three sub-pixel signals corresponding to the three photoelectric conversion elements (PD1 to PD3), respectively. For example, each unit pixel PX can output a first sub-pixel signal corresponding to the photocharge generated by the photoelectric conversion element PD1, a second sub-pixel signal corresponding to the photocharge generated by the photoelectric conversion element PD2, and a third sub-pixel signal corresponding to the photocharge generated by the photoelectric conversion element PD3.

[0041] The first to third sub-pixel signals may be used as image signals to generate an image corresponding to a target object to be captured. For example, for each unit pixel (PX), the first to third sub-pixel signals may be summed to create a pixel signal (i.e., image signal) of the corresponding unit pixel (PX). The unit pixel (PX) may include a red pixel, a green pixel, and a blue pixel, the red pixel being formed to generate an image signal corresponding to red light, the green pixel being formed to generate an image signal corresponding to green light, and the blue pixel being formed to generate an image signal corresponding to blue light. In some embodiments, the red pixel, the green pixel, and the blue pixel may be arranged in a Bayer pattern.

[0042] In some embodiments, the first to third sub-pixel signals may be used as phase detection signals for an autofocus operation. In a unit pixel (PX), sub-pixel signals of two adjacent photoelectric conversion elements (e.g., PD1 and PD2, PD1 and PD3, PD2 and PD3) may be compared with each other, so that a phase difference in adjacent directions of the two adjacent photoelectric conversion elements can be detected. For example, a first sub-pixel signal of the photoelectric conversion element PD1 and a second sub-pixel signal of the photoelectric conversion element PD2 may be compared with each other, so that a phase difference in a first diagonal direction (e.g., as Figure 3 The XY direction is shown in Since the first sub-pixel signal of the photoelectric conversion element PD1 and the third sub-pixel signal of the photoelectric conversion element PD3 are compared with each other, the second diagonal direction (for example, Figure 3 -XY direction shown In addition, since the second sub-pixel signal of the photoelectric conversion element PD2 and the third sub-pixel signal of the photoelectric conversion element PD3 are compared with each other, the horizontal direction (for example, Figure 3 The X direction direction) in the direction of the phase difference.

[0043] exist Figure 3 In the illustrated embodiment, all unit pixels (PX) can be used as pixels for phase difference detection. In some embodiments, only some unit pixels located at preset positions within the pixel array 100 can be used as pixels for phase difference detection. Figure 3 In some implementations of the present embodiment shown, all unit pixels in the pixel array 100 may be used as pixels for phase difference detection.

[0044] In each unit pixel (PX), adjacent photoelectric conversion elements (PD1-PD3) may be connected to each other through an overflow path (OFP). In some embodiments, since each unit pixel (PX) includes three photoelectric conversion elements (PD1-PD3), the size (capacity) of each photoelectric conversion element (PD1-PD3) is very small compared to a case where only one photoelectric conversion element is formed in the unit pixel (PX).

[0045] As described above, since the capacity of each photoelectric conversion element (PD1~PD3) is small, the possibility that the photoelectric charge generated by the photoelectric conversion element (PD1~PD3) overflows into other unit pixels is very high. In order to prevent or avoid overflow between pixels, an overflow path can be formed to interconnect adjacent photoelectric conversion elements (PD1~PD3) within each unit pixel (PX). As a result, when a photoelectric charge exceeding a certain level is generated in the photoelectric conversion element (PD1~PD3), such photoelectric charge generated exceeding the certain level can overflow into the adjacent photoelectric conversion element within the same unit pixel. Therefore, the photoelectric charge overflowing from any one of the photoelectric conversion elements (PD1~PD3) can move to other photoelectric conversion elements (PD1~PD3) within the same unit pixel (PX) without moving to other unit pixels (PX). The overflow path (OFP) may include impurities of the same type as the photoelectric conversion element (PD1~PD3) (e.g., N-type impurities).

[0046] The inter-pixel isolation structure (ISO1, ISO1') may be formed between adjacent unit pixels (PX) to physically isolate the unit pixels (PX) from each other. Each inter-pixel isolation structure (ISO1, ISO1') may include a trench isolation structure. For example, each inter-pixel isolation structure (ISO1, ISO1') may include a back deep trench isolation (BDTI) structure or a front deep trench isolation (FDTI) structure.

[0047] In each unit pixel (PX), an intra-pixel isolation structure ISO2 may be formed between adjacent photoelectric conversion elements (PD1-PD3) and between the inter-pixel isolation structure ISO1 and the photoelectric conversion elements (PD1-PD3). The intra-pixel isolation structure may include a junction isolation structure doped with impurities (e.g., P-type impurities) of a type opposite to that of the photoelectric conversion elements (PD1-PD3) on the substrate.

[0048] Figure 4A The invention is a diagram showing an embodiment based on the disclosed technology. Figure 2 The cross-sectional view of the example of the pixel structure taken along the line XY-XY' is shown. Figure 4B The invention is a diagram showing an embodiment based on the disclosed technology. Figure 2 A cross-sectional view of an example of a pixel structure taken along line XX′ is shown. Figure 5A Another embodiment of the disclosed technology is shown in FIG. Figure 2 The cross-sectional view of the example of the pixel structure taken along the line XY-XY' is shown. Figure 5B Another embodiment of the disclosed technology is shown in FIG. Figure 2 A cross-sectional view of an example of a pixel structure taken along line XX′ is shown.

[0049] Reference Figure 4A , Figure 4B , Figure 5A and Figure 5B , the pixel array 100 may include a substrate layer 110 , a light receiving layer 120 , and an interconnection layer 130 .

[0050] The substrate layer 110 may include a substrate 112 , a pixel transistor 114 , a photoelectric conversion element ( PD1 ˜ PD3 ), an overflow path (OFP), an inter-pixel isolation structure ISO1 , and an intra-pixel isolation structure ISO2 .

[0051] The substrate 112 may include a semiconductor substrate containing a single crystal silicon material. The substrate 112 may include a P-type impurity. The substrate 112 may include a first surface and a second surface facing the first surface or opposite to the first surface. In this case, the first surface may be in contact with the light receiving layer 120 and may represent a surface onto which light is incident from the outside through the light receiving layer 120.

[0052] The pixel transistor 114 may be formed on the second surface of the substrate 112. The pixel transistor 114 may operate in response to a control signal from the row driver 200 and output a sub-pixel signal corresponding to the photocharge generated by the photoelectric conversion element (PD1-PD3). The pixel transistor 114 may include: a transfer transistor configured to transfer the photocharge generated by the photoelectric conversion element (PD1-PD3) to a floating diffusion node; a reset transistor configured to reset the floating diffusion node; a source follower transistor configured to generate and output a signal corresponding to the charge amount of the floating diffusion node; and a selection transistor configured to selectively transfer the output signal of the source follower transistor to an output buffer.

[0053] The photoelectric conversion elements (PD1-PD3) may generate photocharges by photoelectric conversion of incident light. The photoelectric conversion elements (PD1-PD3) may contain N-type impurities. Each of the photoelectric conversion elements (PD1-PD3) may be located at a corner region of a unit pixel (PX) formed in a triangular structure.

[0054] The overflow path (OFP) may interconnect adjacent photoelectric conversion elements (PD1-PD3) within each unit pixel (PX). The overflow path (OFP) may be a path that allows photocharges generated by the photoelectric conversion elements (PD1-PD3) to flow into adjacent photoelectric conversion elements (PD1-PD3). The overflow path (OFP) may include impurities of the same type as the photoelectric conversion elements (PD1-PD3). The overflow path (OFP) may be formed at a position higher than the bottom surface of the photoelectric conversion elements (PD1-PD3). For example, the bottom surface of the overflow path (OFP) may be located higher than the bottom surface of the photoelectric conversion elements (PD1-PD3).

[0055] Since the bottom surface of the overflow path (OFP) is located higher than the bottom surface of the photoelectric conversion element (PD1-PD3), there may be a time difference between the start time point of the integration time when the incident light is photoelectrically converted and integrated into the photoelectric conversion element and the overflow time point when the photocharge overflows. The image sensing device based on some embodiments of the disclosed technology can detect the phase difference by comparing the amount of charge (e.g., the size of the sub-pixel signal) generated by the photoelectric conversion element (PD1-PD3) during the time difference.

[0056] Reference Figure 4A , the top surface of the overflow path (OFP) may be located lower than the top surface of the photoelectric conversion element (PD1-PD3). However, other embodiments are also possible. In some other embodiments, the top surface of the overflow path (OFP) may be located at the same level as the top surface of the photoelectric conversion element (PD1-PD3).

[0057] The inter-pixel isolation structures (ISO1, ISO1') may be located within the substrate 112 between adjacent unit pixels (PX) to physically separate the unit pixels (PX) from each other. Each of the inter-pixel isolation structures (ISO1, ISO1') may include a trench isolation structure in which an insulating material is buried in a trench etched in the substrate 112. For example, Figure 4A As shown, the inter-pixel isolation structure ISO1 may include a back deep trench isolation (BDTI) structure formed to not penetrate the substrate 112 from the first surface of the substrate 112 to a predetermined depth. Figure 5A As shown, the inter-pixel isolation structure (ISO1 ′) may include a front deep trench isolation (FDTI) structure formed to penetrate the substrate 112 from the second surface of the substrate 112 .

[0058] The intra-pixel isolation structure (ISO2) may be located within each unit pixel (PX) and between the photoelectric conversion elements (PD1-PD3). The intra-pixel isolation structure ISO2 may include a junction isolation structure including impurities (e.g., P-type impurities) of a type opposite to that of the photoelectric conversion elements (PD1-PD3). In the region where the overflow path (OFP) is formed, the intra-pixel isolation structure (ISO2) may be formed above and below the overflow path (OFP). The intra-pixel isolation structure (ISO2) may also be formed between the photoelectric conversion elements (PD1-PD3) and the inter-pixel isolation structure (ISO1, ISO1').

[0059] The light receiving layer 120 may be formed over the first surface of the substrate 112. The light receiving layer 120 may include a color filter layer 122, a mesh structure 124, and a microlens 126.

[0060] The color filter layer 122 may include a color filter that filters visible light from incident light received through the microlens 126. For example, the color filter layer 122 may include a plurality of red color filters, a plurality of green color filters, and a plurality of blue color filters. Each red color filter may transmit red visible light. Each green color filter may transmit green visible light. Each blue color filter may transmit blue visible light. In each unit pixel (PX), color filters of the same color may be formed to be separated for each of the photoelectric conversion elements (PD1 to PD3).

[0061] The grid structure 124 may be disposed between color filters to prevent crosstalk between color filters. The grid structure 124 may be located not only between color filters of different colors in adjacent unit pixels (PX), but also between color filters of the same color in each unit pixel (PX). The grid structure 124 may include at least one of metal or air.

[0062] The microlens 126 can converge incident light and transmit the converged light to the corresponding photoelectric conversion element (PD1-PD3). For example, the microlens 126 can be arranged on the photoelectric conversion element (PD1-PD3) in a one-to-one correspondence with the photoelectric conversion element (PD1-PD3) and can converge the incident light onto the corresponding photoelectric conversion element (PD1-PD3).

[0063] The interconnection layer 130 may be disposed over the second surface of the substrate 112. The interconnection layer 130 may include an insulating layer 132 and a conductive line 134.

[0064] Insulating layer 132 may include insulating material between pixel transistor 114 , conductive line 134 , and contacts (not shown).

[0065] The conductive line 134 may be connected to the pixel transistor 114 , and thus may transmit a signal output from the pixel transistor 114 or a signal for controlling the operation of the pixel transistor 114 .

[0066] Fig. 6A and Figure 6B is a schematic diagram showing an example of an intra-pixel isolation structure according to another embodiment of the disclosed technology.

[0067] Reference Fig. 6A , the intra-pixel isolation structure may include a structure in which a trench isolation structure (ISO3, ISO3') is additionally formed in the junction isolation structure (ISO2). When viewed in a plane, each of the trench isolation structures (ISO3, ISO3') may be formed in a three-way cross shape extending from the center of the unit pixel (PX) in three directions (i.e., the direction toward the overflow path OFP). For example, each of the trench isolation structures (ISO3, ISO3') may be formed in a central area surrounded by the overflow path (OFP) in the junction isolation structure (ISO2) provided between the photoelectric conversion elements (PD1~PD3). Each of the trench isolation structures (ISO3, ISO3') may include a BDTI or FDTI structure.

[0068] Reference Figure 6B Except for the region where the overflow path OFP is formed, the trench isolation structure (ISO4, ISO4') may be entirely formed in the region disposed between the photoelectric conversion elements (PD1-PD3). The trench isolation structure (ISO4, ISO4') may also include a BDTI or FDTI structure.

[0069] Figure 7 The invention is a diagram showing an embodiment based on the disclosed technology. Fig. 6A and Figure 6B A cross-sectional view of an example of a pixel structure taken along line XX′ is shown. Figure 8Another embodiment of the disclosed technology is shown in FIG. Fig. 6A and Figure 6B A cross-sectional view of an example of a pixel structure taken along line XX′ is shown.

[0070] exist Figure 7 and Figure 8 In the embodiments of the present invention, the same reference numerals are given Figure 4A , Figure 4B , Figure 5A and Figure 5B , and therefore, redundant descriptions thereof will be omitted herein for brevity.

[0071] Reference Figure 7 , each of the trench isolation structures (ISO3, ISO4) may include the same BDTI structure as the inter-pixel isolation structure (ISO1). The trench isolation structures (ISO3, ISO4) may be formed of the same material as the inter-pixel isolation structure (ISO1). However, each of the isolation structures (ISO3, ISO4) may be formed to have a shorter length (i.e., a smaller depth) than the inter-pixel isolation structure (ISO1).

[0072] Reference Figure 8 , each of the trench isolation structures (ISO3', ISO4') may include an FDTI structure in the same manner as the inter-pixel isolation structure (ISO1'). The trench isolation structures (ISO3', ISO4') may be formed of the same material as the inter-pixel isolation structure (ISO1'). The isolation structures (ISO3', ISO4') may be formed to penetrate the substrate 112 in the same manner as the inter-pixel isolation structure (ISO1').

[0073] Fig. 9 is a schematic diagram showing an example of a planar structure of a unit pixel according to another embodiment of the disclosed technology.

[0074] Reference Fig. 9 Each unit pixel (PX) may selectively include only one or two overflow paths (OFP). For example, the overflow path (OFP) may be in only one of the X direction, the XY direction, and the -XY direction (see Figure 3 ) may be connected to each other in one direction or the photoelectric conversion elements may be connected to each other in only two directions.

[0075] Fig.10 is a schematic diagram showing an example of a planar structure of a unit pixel according to another embodiment of the disclosed technology.

[0076] Reference Fig.10 , the unit pixel (PX) may include a plurality of photoelectric conversion elements (PD1'-PD3'). Figure 2Compared with the embodiment, Fig.10 Examples and Figure 2 The embodiment of the present invention is different in that the photoelectric conversion element is formed at a position in each unit pixel. Fig.10 It can be seen that the three photoelectric conversion elements (PD1'-PD3') can be respectively arranged in regions adjacent to the three sides of the triangle and corresponding to the three sides of the triangle. Figure 2 Each of the photoelectric conversion elements (PD1 to PD3) in FIG. 1 is arranged to have a region adjacent to a different side of the unit pixel, but the photoelectric conversion elements (PD1' to PD3') are adjacent to three sides of the unit pixel, respectively.

[0077] The photoelectric conversion elements (PD1' to PD3') may be connected to each other through an overflow path (OFP). Fig.10 Only three overflow paths (OFP) are shown in FIG. 1 , but the scope or spirit of the disclosed technology is not limited thereto, and it should be noted that Fig. 9 As shown, it is also possible to selectively form only one or two overflow paths (OFP).

[0078] although Fig.10 The in-pixel isolation structure provided between the photoelectric conversion elements (PD1' to PD3') shown is formed only by the junction isolation structure (ISO2), but Fig.10 An embodiment may include a junction isolation structure ISO2 and a Fig. 6A and Figure 6B The structure shown is a combination of trench isolation structures (ISO3, ISO3', ISO4, ISO4').

[0079] It is apparent from the above description that the image sensing device based on some embodiments of the disclosed technology can minimize image distortion while improving phase difference detection characteristics by improving the pixel structure.

[0080] Embodiments of the disclosed technology can provide various effects that can be directly or indirectly recognized through the above-mentioned patent documents.

[0081] Although a number of exemplary embodiments have been described, it should be appreciated that numerous modifications or enhancements of the disclosed embodiments and other embodiments may be devised based on what is described and / or illustrated in this patent document.

Claims

1. An image sensing device, comprising: Semiconductor substrate; unit pixels, which are supported by the semiconductor substrate to respectively detect light incident to the unit pixels and convert the detected light into pixel signals; and an inter-pixel isolation structure, which is disposed between adjacent unit pixels to physically isolate the adjacent unit pixels from each other, Each unit pixel is constructed to include: (1) a photoelectric conversion element that generates photocharges in response to incident light detected by each unit pixel, the photocharges being used to generate a pixel signal for the unit pixel; (2) an intra-pixel isolation structure disposed between adjacent photoelectric conversion elements within the unit pixel; and (3) at least one overflow path interconnecting the photoelectric conversion elements within the unit pixel, and When viewed in a plane, each unit pixel has a triangular shape.

2. The image sensing device according to claim 1, wherein: The photoelectric conversion elements in each unit pixel are respectively arranged in regions adjacent to corners of the triangle and corresponding to the corners of the triangle in a one-to-one manner.

3. The image sensing device according to claim 1, wherein: The photoelectric conversion elements in each unit pixel are respectively arranged in regions adjacent to the sides of the triangle and corresponding to the sides of the triangle in a one-to-one manner.

4. The image sensing device according to claim 1, wherein: The inter-pixel isolation structure includes a trench isolation structure.

5. The image sensing device according to claim 1, wherein: The intra-pixel isolation structure comprises: A junction isolation structure includes doping impurities whose doping type is different from that of the doping impurities included in the photoelectric conversion element.

6. The image sensing device according to claim 5, wherein: The intra-pixel isolation structure further includes: A trench isolation structure is disposed in a central region of each unit pixel and is located within the junction isolation structure.

7. The image sensing device according to claim 6, wherein: The trench isolation structure includes a portion having a length shorter than a length of the inter-pixel isolation structure in a vertical direction.

8. The image sensing device according to claim 6, wherein: The trench isolation structure includes a three-way cross structure extending in three directions from a central portion of each unit pixel.

9. The image sensing device according to claim 1, wherein: The photoelectric conversion element in each unit pixel includes: a first photoelectric conversion element; a second photoelectric conversion element disposed adjacent to the first photoelectric conversion element in a first diagonal direction; and A third photoelectric conversion element is disposed adjacent to the first photoelectric conversion element in a second diagonal direction intersecting the first diagonal direction, and is disposed adjacent to the second photoelectric conversion element in a first direction intersecting the first diagonal direction and the second diagonal direction.

10. The image sensing device according to claim 9, wherein: The at least one overflow path comprises: a first overflow path configured to interconnect the first photoelectric conversion element and the second photoelectric conversion element; a second overflow path configured to interconnect the first photoelectric conversion element and the third photoelectric conversion element; and A third overflow path is configured to interconnect the second photoelectric conversion element and the third photoelectric conversion element.

11. The image sensing device according to claim 10, wherein: The intra-pixel isolation structure comprises: a junction isolation structure including a doping impurity whose doping type is different from that of the doping impurity included in the photoelectric conversion element, and The doping impurities included in the junction isolation structure are located in a region other than a region where the first overflow path to the third overflow path are formed.

12. The image sensing device according to claim 11, wherein: The intra-pixel isolation structure further includes: A trench isolation structure is provided in a region surrounded by the first to third overflow paths and is located within the junction isolation structure.

13. The image sensing device according to claim 1, wherein: The at least one overflow path is located above a bottom surface of the photoelectric conversion element.

14. An image sensing device, comprising: a plurality of unit pixels which are arranged continuously in a first direction and in a second direction intersecting the first direction, each unit pixel presenting a triangular shape when viewed in a plane and generating photocharges in response to incident light; as well as A first isolation structure is provided between adjacent unit pixels to isolate the adjacent unit pixels from each other. Wherein, each unit pixel of the plurality of unit pixels comprises: a first photoelectric conversion element that converts light into photocharges; a second photoelectric conversion element that converts light into photocharges and is disposed adjacent to the first photoelectric conversion element in a first diagonal direction; and A third photoelectric conversion element converts light into photocharges and is disposed adjacent to the first photoelectric conversion element in a second diagonal direction intersecting the first diagonal direction, and adjacent to the second photoelectric conversion element in a first direction intersecting the first diagonal direction and the second diagonal direction.

15. The image sensing device according to claim 14, further comprising: At least one overflow path interconnects at least two of the first to third photoelectric conversion elements in at least one of the first diagonal direction, the second diagonal direction, and the first direction.

16. The image sensing device according to claim 15, wherein: The at least one overflow path comprises: a first overflow path interconnecting the first photoelectric conversion element and the second photoelectric conversion element; a second overflow path interconnecting the first photoelectric conversion element and the third photoelectric conversion element; and A third overflow path interconnects the second photoelectric conversion element and the third photoelectric conversion element.

17. The image sensing device according to claim 14, wherein: The first to third photoelectric conversion elements are respectively disposed in regions adjacent to three corners of the triangular shape and corresponding to the three corners of the triangular shape in a one-to-one manner.

18. The image sensing device according to claim 14, wherein: The first to third photoelectric conversion elements are respectively disposed in regions adjacent to three sides of the triangular shape and corresponding to the three sides of the triangular shape in a one-to-one manner.

19. The image sensing device according to claim 14, further comprising: The second isolation structure is disposed between the first photoelectric conversion element to the third photoelectric conversion element in each unit pixel.

20. An image sensing device, comprising: Semiconductor substrate; An inter-pixel isolation structure, which is arranged between adjacent unit pixels in the semiconductor substrate; A plurality of photoelectric conversion elements are respectively arranged in the unit pixels in the semiconductor substrate; An intra-pixel isolation structure, which is arranged between adjacent photoelectric conversion elements in the unit pixel; as well as At least one overflow path interconnects the photoelectric conversion elements within the unit pixels, wherein each of the unit pixels is formed in a triangular shape when viewed in a plane.

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