Image sensor with selective light shielding for reference pixels

Abstract

An image sensor includes a photoelectric conversion layer including a plurality of first photoelectric conversion elements and a plurality of second photoelectric conversion elements adjacent to the first photoelectric conversion elements. A light-shielding layer shields the second photoelectric conversion elements and has respective openings therein providing light transmission to respective ones of the first photoelectric conversion elements. The image sensor further includes an array of microlenses on the photoelectric conversion layer, each microlens overlapping at least one of the first photoelectric conversion elements and at least one of the second photoelectric conversion elements.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2018-0086453, filed on July 25, 2018, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to image sensors, and more specifically, to photoelectric image sensors having reference pixels. Background Technology

[0004] Image sensors convert photonic images into electrical signals. Recent advancements in the computer and communications industries have led to a strong demand for high-performance image sensors in various consumer electronics devices, such as digital cameras, camcorders, PCS (personal communication systems), gaming devices, security cameras, and medical miniature cameras.

[0005] Image sensors can be categorized into various types, including charge-coupled device (CCD) and CMOS image sensors. CMOS image sensors typically have a relatively simple operating method and can be reduced in size because signal processing circuitry can be integrated into a single chip. CMOS image sensors generally have relatively low power consumption, which can be useful in battery-powered applications. Therefore, the use of CMOS image sensors has increased rapidly. Summary of the Invention

[0006] Some exemplary embodiments of the present invention provide image sensors with improved electrical characteristics. Embodiments of the present invention are not limited to those described herein.

[0007] According to some exemplary embodiments of the present invention, an image sensor includes a photoelectric conversion layer comprising a plurality of first photoelectric conversion elements and a plurality of second photoelectric conversion elements adjacent to the first photoelectric conversion elements. A light-shielding layer shields the second photoelectric conversion elements and has a corresponding opening therein for providing light transmission to a corresponding first photoelectric conversion element. The image sensor also includes an array of microlenses located on the photoelectric conversion layer, each microlens overlapping at least one of the first photoelectric conversion elements and at least one of the second photoelectric conversion elements.

[0008] In other exemplary embodiments of the invention, the image sensor includes a semiconductor substrate comprising a plurality of first photoelectric conversion elements and a plurality of second photoelectric conversion elements. The image sensor also includes a light-shielding layer on the semiconductor substrate having a corresponding opening among a plurality of openings for providing light to the first photoelectric conversion elements. The second photoelectric conversion elements are disposed between adjacent openings in the openings.

[0009] In further exemplary embodiments conceived according to the present invention, the image sensor includes a pixel array comprising a plurality of unit pixels arranged in rows and columns, each unit pixel including at least one light-receiving pixel and at least one reference pixel. The image sensor also includes a light-shielding layer that shields the reference pixels and has a corresponding opening therein for providing light to a respective light-receiving pixel among the light-receiving pixels. Attached Figure Description

[0010] Figure 1 This is a schematic block diagram illustrating some example embodiments of an image sensor according to a concept of the present invention.

[0011] Figure 2 This is a circuit diagram illustrating a pixel array of an image sensor according to some exemplary embodiments of the concept of the present invention.

[0012] Figure 3 This is a simplified plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0013] Figure 4 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0014] Figure 5A and Figure 5B This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 4 The cross-sectional view taken from line I-I'.

[0015] Figure 6 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0016] Figure 7 This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 6 The cross-sectional view taken from line II-II'.

[0017] Figures 8A to 8D This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0018] Figure 9 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0019] Figure 10 This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 9 The cross-sectional view taken from line III-III'.

[0020] Figure 11A and Figure 11BThis is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0021] Figure 12 This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 11A or Figure 11B A cross-sectional view taken from line IV-IV'.

[0022] Figure 13A and Figure 13B This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0023] Figure 14 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0024] Figure 15 This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 14 A cross-sectional view taken from line V-V'.

[0025] Figure 16 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0026] Figure 17 This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 16 The cross-sectional view taken from line VI-VI'.

[0027] Figure 18 This is a plan view illustrating an electronic device including an image sensor of some example embodiments according to a concept of the present invention.

[0028] Figure 19 This is a simplified schematic block diagram illustrating an electronic device that includes an image sensor according to some example embodiments of the concept of the present invention.

[0029] Figure 20 This is a cross-sectional view illustrating an electronic device including an image sensor of some example embodiments according to a concept of the present invention.

[0030] Figure 21 To show in more detail Figure 20 The cross-sectional view of the electronic device shown. Detailed Implementation

[0031] The following will describe in detail, with reference to the accompanying drawings, some exemplary embodiments of the image sensor according to the present invention.

[0032] Figure 1 This is a schematic block diagram illustrating some example embodiments of an image sensor according to a concept of the present invention.

[0033] Reference Figure 1 The image sensor may include an active pixel sensor array (APS) 1, a row decoder 2, a row driver 3, a column decoder 4, a timing generator 5, a correlated dual sampler (CDS) 6, an analog-to-digital converter (ADC) 7, and an input / output buffer 8.

[0034] The active pixel sensor array 1 may include multiple two-dimensionally arranged unit pixels, each configured to convert an optical signal into an electrical signal. The active pixel sensor array 1 may be driven by multiple drive signals from the row driver 3, such as pixel selection signals, reset signals, and charge transfer signals. The converted electrical signal can be provided to the associated dual sampler 6.

[0035] The row driver 3 can provide several driving signals to the active pixel sensor array 1 to drive several unit pixels based on the decoding results obtained from the row decoder 2. When the unit pixels are arranged in a matrix shape, driving signals can be provided for each row.

[0036] Timing generator 5 can provide timing and control signals for row decoder 2 and column decoder 4.

[0037] The Correlated Double Sampler (CDS) 6 can receive the electrical signal generated in the active pixel sensor array 1, and hold and sample the received electrical signal. The Correlated Double Sampler 6 can perform a double sampling operation to sample a specific noise level and a signal level of the electrical signal, and then output the difference level corresponding to the difference between the noise level and the signal level.

[0038] The analog-to-digital converter (ADC) 7 can convert the analog signal corresponding to the difference level received from the correlated dual sampler 6 into a digital signal, and then output the converted digital signal.

[0039] The input / output buffer 8 can latch digital signals and then, in response to the decoding results obtained from the column decoder 4, sequentially output the latched digital signals to the image signal processing unit (not shown).

[0040] Figure 2 This is a circuit diagram illustrating a pixel array of an image sensor according to some exemplary embodiments of the concept of the present invention.

[0041] Reference Figure 2 The unit pixel P may include a transfer transistor TX and logic transistors RX, SX, and AX. The logic transistors RX, SX, and AX may include a reset transistor RX, a select transistor SX, and a source follower transistor AX or an amplifier transistor.

[0042] The transfer transistor TX may include a transfer gate electrode TG, a photoelectric conversion element PD, and a charge storage node FD (or a floating diffusion region).

[0043] A photoelectric conversion element (PD) can generate and accumulate photocharge in proportion to the amount of externally incident light. In some embodiments, the photoelectric conversion element (PD) can be one of a photodiode, a phototransistor, a photogate, a pinned photodiode (PPD), and any combination thereof.

[0044] The transfer transistor TX can transfer the charge accumulated in the photoelectric conversion element PD to the charge storage node FD. The transfer transistor TX can be controlled by a charge transfer signal provided through the transfer gate electrode TG.

[0045] The charge storage node FD can receive and accumulate the charge generated from the photoelectric conversion element PD, and the gate electrode of the source follower transistor AX can change its potential according to the amount of photocharge accumulated in the charge storage node FD.

[0046] The reset transistor RX can periodically reset the charge accumulated in the charge storage node FD. For example, the gate electrode of the reset transistor RX can be connected to the reset signal line RG, and a reset signal is provided to this reset signal line RG. The drain of the reset transistor RX can be connected to the charge storage node FD, and the source of the reset transistor RX can be connected to the power supply voltage V. DD When the reset transistor RX is turned on by the reset signal, the charge storage node FD can receive the power supply voltage V connected to the source of the reset transistor RX. DD Therefore, when the reset transistor RX is turned on, the photocharge accumulated in the charge storage node FD can be depleted, and then the charge storage node FD can be reset.

[0047] The source follower transistor AX can amplify the potential change of the charge storage node FD, and the amplified signal or pixel signal can be output to the output line V by selecting the transistor SX. OUT The source follower transistor AX can be a source follower buffer amplifier configured to generate a source-drain current proportional to the amount of photocharge applied to the gate electrode. The source follower transistor AX may include a gate electrode connected to the charge storage node FD and a connection to the supply voltage V. DD The drain of the transistor and the source connected to the drain of the select transistor SX.

[0048] The selector transistor SX can select a row of unit pixels to be read. The gate electrode of the selector transistor SX can be connected to the select line SG, through which a select signal is provided. When the selector transistor SX is turned on by the select signal, the output line V... OUT It can output pixel signals from the source of the source follower transistor AX.

[0049] Figure 2An example of a unit pixel P consisting of a four-transistor structure is shown, but the unit pixel P may include a three- or five-transistor structure, a five-transistor structure, or a photogate structure similar to a four-transistor structure.

[0050] Figure 3 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0051] Reference Figure 3 The image sensor may include a pixel array area R1, a control circuit area R2, and a pad area R3.

[0052] The pixel array region R1 may include multiple unit pixels P arranged in a two-dimensional pattern along rows and columns. The unit pixels P of the pixel array region R1 can output electrical signals converted from incident light.

[0053] In some embodiments, a unit pixel P may include a sensing pixel and a reference pixel. The sensing pixel can convert incident light into an electrical signal. The reference pixel can output an electrical signal generated from a unit pixel P where there is no light incident or very little light incident.

[0054] A control circuit region R2 may be disposed around the pixel array region R1 and may include control circuitry (not shown) to control the unit pixels P of the pixel array region R1. For example, the control circuit region R2 may include a reference... Figure 1 The control circuits discussed include the row decoder 2, row driver 3, column decoder 4, timing generator 5, correlated double sampler 6, analog-to-digital converter 7, and input / output buffer 8.

[0055] The pad area R3 may include multiple conductive pads CP for input and output control signals and photoelectric conversion signals. The pad area R3 may be located at the edge of the image sensor, thus facilitating easy electrical connection to external devices.

[0056] Figure 4 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention. Figure 5A and Figure 5B This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 4 The cross-sectional view taken from line I-I'.

[0057] Reference Figure 4 and Figure 5A Image sensors according to some exemplary embodiments of the present invention may include a photoelectric conversion layer 10, a readout circuit layer 20, a light-shielding layer 30, a color filter layer 40, and a microlens array 50.

[0058] When viewed in cross-section, the photoelectric conversion layer 10 can be disposed between the readout circuit layer 20 and the light-shielding layer 30. When viewed in cross-section, the light-shielding layer 30 can be disposed between the photoelectric conversion layer 10 and the microlens array 50. When viewed in cross-section, the color filter layer 40 can be disposed between the light-shielding layer 30 and the microlens array 50.

[0059] The photoelectric conversion layer 10 may include a semiconductor substrate 100 and photoelectric conversion regions 110a and 110b disposed in the semiconductor substrate 100. The semiconductor substrate 100 may have a first surface (or front surface) 100a and a second surface (or rear surface) 100b located on opposite sides of the substrate 100. The photoelectric conversion regions 110a and 110b may be impurity regions doped with impurities having a second conductivity type (e.g., n-type) opposite to the first conductivity type of the semiconductor substrate 100. The photoelectric conversion regions 110a and 110b can convert externally incident light into electrical signals.

[0060] A readout circuit layer 20 may be disposed on a first surface 100a of the semiconductor substrate 100. The readout circuit layer 20 may include readout circuitry (e.g., a MOS transistor) connected to the photoelectric conversion layer 10. The readout circuit layer 20 can process electrical signals generated by the photoelectric conversion layer 10. For example, a MOS transistor and a connection line 215 connected to the MOS transistor may be disposed on the first surface 100a of the semiconductor substrate 100. The connection line 215 may span the interlayer dielectric layers 210 stack, and contact plugs may connect the connection lines 215 disposed at different levels.

[0061] The light-shielding layer 30 can be configured to completely cover the second surface 100b of the semiconductor substrate 100. For example, the light-shielding layer 30 can have a plate shape extending in a first direction D1 and a second direction D2 that intersect each other. The light-shielding layer 30 can have openings OP that partially expose the photoelectric conversion regions 110a and 110b. The openings OP of the light-shielding layer 30 can be arranged spaced apart from each other along the first direction D1 and the second direction D2.

[0062] The color filter layer 40 may include a first color filter layer 321, a second color filter layer 323, and a third color filter layer 325 sequentially stacked on the light-shielding layer 30. The first color filter layer 321, the second color filter layer 323, and the third color filter layer 325 may have different colors from each other and may present black achieved by mixing the three colors.

[0063] The microlens array 50 may include multiple microlenses ML that focus externally incident light. The microlenses ML may be arranged in two dimensions along a first direction D1 and a second direction D2 that intersect each other.

[0064] For example, the semiconductor substrate 100 may be an epitaxial layer formed on a bulk silicon substrate (the bulk silicon substrate having the same first conductivity type as the epitaxial layer (e.g., p-type)), or a p-type epitaxial layer from which the bulk silicon substrate is removed during the fabrication of the image sensor. As another example, the semiconductor substrate 100 may be a bulk semiconductor substrate with a well having a first conductivity type.

[0065] The semiconductor substrate 100 may include a plurality of pixel regions Px1 and Px2 defined by the pixel isolation structure 103. The plurality of pixel regions Px1 and Px2 may be arranged in a matrix shape along a first direction D1 and a second direction D2 that intersect each other.

[0066] When viewed in a plane, the pixel isolation structure 103 may surround each of the pixel regions Px1 and Px2. For example, the pixel isolation structure 103 may include a plurality of first pixel isolation layers 103a extending parallel to a first direction D1, and a plurality of second pixel isolation layers 103b extending parallel to a second direction D2 and intersecting with the first pixel isolation layers 103a.

[0067] The first pixel isolation layers 103a may be spaced apart from each other along the second direction D2 by a first interval W1, and the second pixel isolation layers 103b may be spaced apart from each other along the first direction D1 by a first interval W1. In some embodiments, each of the pixel regions Px1 and Px2 may have a width W1 corresponding to the first interval W1 between adjacent first pixel isolation layers 103a or between adjacent second pixel isolation layers 103b.

[0068] The pixel isolation structure 103 may be formed of a dielectric material with a refractive index less than that of the semiconductor substrate 100 (e.g., silicon) and may include one or more dielectric layers. The pixel isolation structure 103 may include, for example, a silicon oxide layer, a silicon nitride layer, an undoped polysilicon layer, air, or a combination thereof. Forming the pixel isolation structure 103 may include forming a deep trench by patterning a first surface 100a and / or a second surface 100b of the semiconductor substrate 100, and then filling the deep trench with the dielectric material.

[0069] When viewed in cross-section, the pixel isolation structure 103 can extend vertically from the first surface 100a toward the second surface 100b of the semiconductor substrate 100, and can be spaced apart from the second surface 100b of the semiconductor substrate 100. For example, the pixel isolation structure 103 can have a vertical thickness less than the vertical thickness of the semiconductor substrate 100. As another example, the pixel isolation structure 103 can penetrate the semiconductor substrate 100. In this case, the pixel isolation structure 103 can have a vertical thickness substantially the same as the vertical thickness of the semiconductor substrate 100. As yet another example, the pixel isolation structure 103 can be an impurity region in the semiconductor substrate 100 doped with an impurity having a first conductivity type the same as the conductivity type of the semiconductor substrate 100.

[0070] In some embodiments, the pixel regions Px1 and Px2 defined by the pixel isolation structure 103 may include a plurality of first pixel regions Px1 and a plurality of second pixel regions Px2.

[0071] The first pixel region Px1 can be a sensing pixel whose output is an electrical signal proportional to the incident light. The electrical signal output from the first pixel region Px1 can include not only photoelectric conversion signals but also noise signals.

[0072] The second pixel region Px2 can be a reference pixel region whose output is an electrical signal (or reference signal) generated by thermally induced electrons under conditions where substantially no light is incident on the reference pixel region. The reference signal output from the second pixel region Px2 can be provided as a reference value for the electrical signal output from the first pixel region Px1. The reference signal generated from the second pixel region Px2 can be the average of the electrical signals output from each unit pixel of the second pixel region Px2, which can result in high accuracy of the reference signal. In some embodiments, the number of second pixel regions Px2 can be varied to improve the accuracy of the reference signal generated from the second pixel region Px2. For example, the number of second pixel regions Px2 can be greater than the number of first pixel regions Px1. One first pixel region Px1 and three second pixel regions Px2 can constitute a single pixel group, and multiple pixel groups can be arranged along a first direction D1 and a second direction D2.

[0073] Photoelectric conversion regions 110a and 110b can be disposed in corresponding pixel regions Px1 and Px2 of the semiconductor substrate 100. When viewed in a plan view, each of the photoelectric conversion regions 110a and 110b can be surrounded by the pixel isolation structure 103. In some embodiments, the photoelectric conversion regions 110a and 110b may include a first photoelectric conversion region 110a disposed on a first pixel region Px1 and a second photoelectric conversion region 110b disposed on a second pixel region Px2. The first photoelectric conversion region 110a and the second photoelectric conversion region 110b may have substantially the same structure and material.

[0074] For example, the first photoelectric conversion region 110a and the second photoelectric conversion region 110b can be formed by implanting an impurity into the semiconductor substrate 100, the impurity having a second conductivity type opposite to the first conductivity type of the semiconductor substrate 100. A photodiode can be formed through a junction between the semiconductor substrate 100 having the first conductivity type and the first and second photoelectric conversion regions 110a and 110b having the second conductivity type.

[0075] In pixel regions Px1 and Px2, the transfer gate electrode TG can be disposed on the first surface 100a of the semiconductor substrate 100, and the readout circuit discussed with reference to FIG5 can also be disposed thereon.

[0076] When viewed in a planar view, the transfer gate electrode TG can be located at the center of each of the pixel regions Px1 and Px2. A portion of the transfer gate electrode TG can be disposed in the semiconductor substrate 100, and a gate dielectric layer can be inserted between the transfer gate electrode TG and the semiconductor substrate 100.

[0077] A floating diffusion region FD can be disposed in the semiconductor substrate 100 on one side of the transfer gate electrode TG. The floating diffusion region FD can be formed by implanting an impurity with a conductivity type opposite to that of the semiconductor substrate 100 into the semiconductor substrate 100. The floating diffusion region FD can be, for example, an n-type impurity region.

[0078] The interlayer dielectric layer 210 may be stacked on the first surface 100a of the semiconductor substrate 100 and may cover the transfer gate electrode TG and the MOS transistor constituting the readout circuit. The interlayer dielectric layer 210 may include, for example, silicon oxide, silicon nitride, or silicon oxynitride.

[0079] The connecting line 215 can be disposed on each interlayer dielectric layer 210 and can be electrically connected to the readout circuit via a contact plug.

[0080] A buffer dielectric layer 310 may be disposed on the second surface 100b of the semiconductor substrate 100. The buffer dielectric layer 310 can prevent the photoelectric conversion regions 110a and 110b from receiving charges (e.g., electrons or holes) due to defects on the second surface 100b of the semiconductor substrate 100. The buffer dielectric layer 310 may comprise a single layer or multiple layers. The buffer dielectric layer 310 may comprise a metal oxide, such as aluminum oxide or hafnium oxide.

[0081] A light-shielding layer 30 may be disposed on a buffer dielectric layer 310. The light-shielding layer 30 may have a plate shape extending along a first direction D1 and a second direction D2, and the opening OP of the light-shielding layer 30 may correspond to a first pixel region Px1 or a first photoelectric conversion region 110a. When viewed in a plan view, the opening OP of the light-shielding layer 30 may overlap with a corresponding portion of the first photoelectric conversion region 110a. In this case, each of the first photoelectric conversion regions 110a may receive incident light passing through the opening OP of the light-shielding layer 30.

[0082] The light-shielding layer 30 can extend continuously from the first photoelectric conversion region 110a to the second photoelectric conversion region 110b along the first direction D1 and the second direction D2. When viewed in a plan view, the light-shielding layer 30 can completely overlap with the second photoelectric conversion region 110b. Except for the opening OP of the light-shielding layer 30, the light-shielding layer 30 can reflect or block incident light traveling toward the second surface 100b of the semiconductor substrate 100. Therefore, the second photoelectric conversion region 110b may not receive incident light. The light-shielding layer 30 may include a metal, such as tungsten or aluminum. In some embodiments, the opening OP of the light-shielding layer 30 may have a rectangular or circular shape.

[0083] The openings OP of the light-shielding layer 30 can be spaced apart from each other along the first direction D1 and the second direction D2. Each opening OP can have a center aligned with the center of the first pixel region Px1 or the first photoelectric conversion region 110a.

[0084] In some embodiments, the width of the opening OP can be adjusted so that the first photoelectric conversion region 110a receives light with an incident angle not greater than a specific value, thus enabling the acquisition of an image of the material or nearby material. For example, each opening OP can have a width W2, which is smaller than the width W1 of each of the pixel regions Px1 and Px2 and also smaller than the spacing between adjacent openings OP. The width W2 of each opening OP can be optimized based on the vertical distance between the light-shielding layer 30 and the photoelectric conversion regions 110a and 110b, the vertical distance between the light-shielding layer 30 and the microlens ML, and the curvature of the microlens ML.

[0085] When viewed in a plan view, the openings OP of the light-shielding layer 30 can be arranged along the first direction D1 and the second direction D2, so as to be positioned between each second pixel region Px2. The openings OP of the light-shielding layer 30 can be spaced apart from each other at regular intervals along the first direction D1 and the second direction D2. When viewed in a plan view, the second pixel regions Px2 can be positioned around each first pixel region Px1.

[0086] A color filter layer 40 may be disposed on the light-shielding layer 30. Similar to the light-shielding layer 30, the color filter layer 40 may almost completely cover the second surface 100b of the semiconductor substrate 100 while exposing the opening OP of the light-shielding layer 30. As discussed above, the color filter layer 40 may include a first color filter layer 321, a second color filter layer 323, and a third color filter layer 325 stacked sequentially. The first color filter layer 321 may have a first aperture corresponding to the opening OP of the light-shielding layer 30. The first aperture of the first color filter layer 321 may have an inner wall perpendicularly aligned with the inner wall of the opening OP of the light-shielding layer 30. Each of the second color filter layer 323 and the third color filter layer 325 may have a second aperture corresponding to the opening OP of the light-shielding layer 30, and each second aperture may have a width greater than the width W2 of each opening OP.

[0087] For example, the first color filter layer 321 can be a green color filter layer, the second color filter layer 323 can be a red color filter layer, and the third color filter layer 325 can be a blue color filter layer. As another example, the first color filter layer 321 can be a cyan color filter layer, the second color filter layer 323 can be a magenta color filter layer, and the third color filter layer 325 can be a yellow color filter layer. Yet another example, the color filter layer 40 may include the first color filter layer 321, but not the second color filter layer 323 or the third color filter layer 325.

[0088] like Figure 5B As shown, a color filter layer may not be provided on the light-shielding layer 30, and the planarization dielectric layer 330 may directly cover the light-shielding layer 30.

[0089] Return to reference Figure 5AThe planarization dielectric layer 330 can be disposed on the color filter layer 40 and can fill the opening OP of the light-shielding layer 30 and the pore sizes of the first color filter layer 321, the second color filter layer 323, and the third color filter layer 325. To increase photosensitivity, the planarization dielectric layer 330 can be formed of a material with a refractive index greater than that of silicon oxide. The planarization dielectric layer 330 can be formed of, for example, a material with a refractive index in the range of about 1.4 to about 4.0. For example, the planarization dielectric layer 330 may include Al2O3, CeF3, HfO2, ITO, MgO, Ta2O5, TiO2, ZrO2, Si, Ge, ZnSe, ZnS, or PbF2. For example, the planarization dielectric layer 330 can be formed of a high-refractive-index organic material, such as a siloxane resin, BCB (benzocyclobutene), polyimide, acrylic acid, polychloro-p-xylene, PMMA (polymethyl methacrylate), or PET (polyethylene terephthalate). Alternatively, the planarization dielectric layer 330 can be formed of strontium titanate (SrTiO3), polycarbonate, glass, bromine, sapphire, cubic zirconium oxide, potassium niobate (KNbO3), moissanite (SiC), gallium (III) phosphide (GaP), or gallium (III) arsenide (GaAs).

[0090] Microlenses ML can be arranged two-dimensionally along a first direction D1 and a second direction D2 on the planarized dielectric layer 330. Each microlens ML can be configured to correspond to the first photoelectric conversion region 110a. Each microlens ML can have a convex shape with a certain radius of curvature. The microlenses ML can alter the path of light incident on the image sensor and then focus the light into the opening OP of the light-shielding layer 30. The microlenses ML can be formed of a light-transmitting resin.

[0091] In some embodiments, microlenses ML can be configured to correspond to openings OP of the light-shielding layer 30. To focus incident light into the openings OP of the light-shielding layer 30, the centers of the microlenses ML can be aligned with the corresponding centers of the openings OP of the light-shielding layer 30. The diameter W3 of each microlens ML can be greater than the width W2 of each opening OP of the light-shielding layer 30. The diameter W3 of each microlens ML can be greater than the width W1 of each of pixel regions Px1 and Px2. For example, the diameter W3 of each microlens ML can be approximately twice the width W1 of each of pixel regions Px1 and Px2.

[0092] When viewed in a planar view, each microlens ML can completely overlap with its corresponding counterpart in the first photoelectric conversion region 110a and can partially overlap with the second photoelectric conversion region 110b. In this configuration, the boundary between the microlenses ML can be placed on the second photoelectric conversion region 110b.

[0093] In some embodiments, the curvature of the microlens ML can be optimized based on the width W2 of the opening OP of the light-shielding layer 30, the vertical distance between the light-shielding layer 30 and the photoelectric conversion regions 110a and 110b, and the vertical distance between the light-shielding layer 30 and the microlens ML.

[0094] The following will refer to Figures 6 to 17 An image sensor with some exemplary embodiments according to the concept of the present invention is described. For the sake of brevity, references are made to... Figure 4 , Figure 5A and Figure 5B The components discussed are those that are assigned the same reference numerals, and the same technical features will be omitted and the differences will be explained.

[0095] Figure 6 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention. Figure 7 This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 6 The cross-sectional view taken from line II-II'.

[0096] Reference Figure 6 and Figure 7 As discussed above, the second pixel region Px2 can be disposed around each of the first pixel regions Px1. When viewed in a planar view, the openings OP of the light-shielding layer 30 can be arranged in a zigzag pattern. For example, the openings OP in even-numbered columns can be staggered relative to the openings OP in odd-numbered columns. In this case, the spacing between adjacent openings OP in the first direction D1 can be different from the spacing between adjacent openings OP in the second direction D2. The microlenses ML corresponding to the openings OP of the light-shielding layer 30 can also be arranged in a zigzag pattern. Each microlens ML can completely overlap with a corresponding one in the first photoelectric conversion region 110a and can partially overlap with the second photoelectric conversion region 110b.

[0097] Figures 8A to 8D This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0098] Reference Figure 8A and Figure 8B The image sensor may include a pixel isolation structure 103 defining a plurality of first pixel regions Px1 and a plurality of second pixel regions Px2. An opening OP of a light-shielding layer 30 on the semiconductor substrate 100 may correspond to a first pixel region Px1. The number of first pixel regions Px1 may be the same as the number of second pixel regions Px2. As discussed above, a first pixel region Px1 may be a sensing pixel to which light is incident through the opening OP of the light-shielding layer 30, and a second pixel region Px2 may be a reference pixel to which light is blocked by the light-shielding layer 30.

[0099] Reference Figure 8A Two first pixel regions Px1 and two second pixel regions Px2 can constitute a single pixel group PG. The first pixel regions Px1 can be diagonally adjacent to each other, and the second pixel regions Px2 can also be diagonally adjacent to each other. Multiple pixel groups PG can be arranged along a first direction D1 and a second direction D2. Microlenses ML can be aligned with the corresponding centers of pixel groups PG. For example, each microlens ML can overlap with two openings OP.

[0100] Reference Figure 8B Two first pixel regions Px1 and two second pixel regions Px2 can constitute a single pixel group PG. Two first pixel regions Px1 can be located between adjacent second pixel regions Px2 along the first direction D1, and a first pixel region Px1 can be located between adjacent second pixel regions Px2 along the second direction D2.

[0101] Reference Figure 8C and Figure 8D Three first pixel regions Px1 and one second pixel region Px2 can constitute a single pixel group PG, and multiple pixel groups PG can be arranged along a first direction D1 and a second direction D2. The number of first pixel regions Px1 can be greater than the number of second pixel regions Px2. The microlens ML can be set to correspond to the pixel group PG.

[0102] Reference Figure 8C The number of first pixel regions Px1 in odd-numbered columns can be different from the number of second pixel regions Px2 in even-numbered columns. First pixel regions Px1 can be positioned around each second pixel region Px2. Each microlens ML can overlap with three openings OP.

[0103] Reference Figure 8D Two second pixel regions Px2 can be set between first pixel regions Px1 that are adjacent to each other along the first direction D1 or along the second direction D2.

[0104] Figure 9 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention. Figure 10 This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 9 The cross-sectional view taken from line III-III'.

[0105] Reference Figure 9 and Figure 10The image sensor may include a pixel isolation structure 103 defining a plurality of first pixel regions Px1 and a plurality of second pixel regions Px2, and the first pixel regions Px1 and the second pixel regions Px2 may be arranged alternately along a first direction D1 and along a second direction D2.

[0106] The opening OP of the light-shielding layer 30 can be set to correspond to the first pixel region Px1. Each second photoelectric conversion region 110b can be disposed between openings OP that are adjacent to each other along the first direction D1 and the second direction D2.

[0107] Microlenses ML can have a center aligned with the center of the opening OP. When viewed in a planar view, each microlens ML can completely overlap with the first photoelectric conversion region 110a on the first pixel region Px1. The diameter of each microlens ML can be smaller than the width of each of pixel regions Px1 and Px2 (see [reference]). Figure 4 Twice that of W1.

[0108] Figure 11A and Figure 11B This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention. Figure 12 This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 11A or Figure 11B A cross-sectional view taken from line IV-IV'.

[0109] Reference Figure 11A , Figure 11B and Figure 12 The microlens ML can be configured to correspond to pixel region Px1 and pixel region Px2. For example, each microlens ML can have a width corresponding to each of pixel region Px1 and pixel region Px2 (see [link to documentation]). Figure 4 The diameter of the microlens ML is basically the same as or smaller than that of the opening OP. The center of the microlens ML can be aligned with the center of the opening OP. Each second photoelectric conversion region 110b can be disposed between openings OP that are adjacent to each other along the first direction D1 and the second direction D2.

[0110] Reference Figure 11A The first pixel region Px1 and the second pixel region Px2 can be arranged alternately along the first direction D1 and along the second direction D2. (Refer to...) Figure 11B The first pixel region Px1 can be set around each second pixel region Px2.

[0111] Figure 13A and Figure 13B This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention.

[0112] Reference Figure 13A and Figure 13B Four first pixel regions Px1 can constitute a first pixel group PG1, and four second pixel regions Px2 can constitute a second pixel group PG2. Microlenses ML can be configured to correspond to each of the first pixel group PG1 and the second pixel group PG2. For example, each microlens ML can have a width corresponding to each of the pixel regions Px1 and Px2 (see...). Figure 4 The diameter is basically the same as or smaller than that of W1.

[0113] Reference Figure 13A Multiple first pixel groups PG1 can be arranged around a second pixel group PG2. For example, when viewed in a planar view, multiple first pixel groups PG1 can surround a second pixel group PG2.

[0114] Reference Figure 13B The first pixel group PG1 and the second pixel group PG2 can be arranged alternately along the first direction D1 and along the second direction D2.

[0115] Figure 14 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention. Figure 15 This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 14 A cross-sectional view taken from line V-V'.

[0116] according to Figure 14 and Figure 15 The image sensor of the example embodiment shown can be configured such that the number of second pixel regions Px2 is greater than the number of first pixel regions Px1. For example, refer to Figure 14 and Figure 15 Pixel regions Px1 and Px2 arranged in a 3×3 configuration can constitute a single pixel group PG, and multiple pixel groups PG can be arranged along a first direction D1 and a second direction D2. A single pixel group PG may include a first pixel region Px1, and the opening OP of the light-shielding layer 30 may correspond to the first pixel region Px1. For example, two second photoelectric conversion regions 110b may be disposed between openings OP that are adjacent to each other along the first direction D1 or along the second direction D2.

[0117] Microlenses ML can be configured to correspond to pixel group PG, and their centers can be aligned with the center of opening OP. The diameter of each microlens ML can be greater than the width of each of pixel regions Px1 and Px2 (see [reference]). Figure 4 It is about twice that of W1.

[0118] Figure 16 This is a plan view illustrating some example embodiments of an image sensor according to a concept conceived in this invention. Figure 17This illustrates some example embodiments of an image sensor according to the concept of the present invention. Figure 16 The cross-sectional view taken from line VI-VI'.

[0119] Reference Figure 16 and Figure 17 Pixel regions Px1 and Px2 arranged in a 3×3 configuration can constitute a single pixel group PG, and multiple pixel groups PG can be arranged along a first direction D1 and a second direction D2. A single pixel group PG may include four first pixel regions Px1, and each microlens ML may be configured to overlap with the four first pixel regions Px1.

[0120] Figure 18 This is a plan view illustrating an electronic device including an image sensor of some example embodiments according to a concept of the present invention.

[0121] Reference Figure 18 The electronic device 1000 may include a panel 1100 and an image sensor beneath a partial region PA of the panel 1100. The electronic device 1000 may be a portable electronic device or personal portable terminal, such as a smartphone, tablet, or computer. The image sensor may be one of the image sensors discussed above in some exemplary embodiments of the present invention, and may sense a user's fingerprint and perform authentication operations based on the sensed fingerprint. The image sensor may be a fingerprint detection sensor or a fingerprint recognition sensor that provides user authentication functionality.

[0122] Panel 1100 can interact with a user. For example, panel 1100 can provide the user with various visual information output from electronic device 1000. As another example, the user can use panel 1100 to input various types of information into electronic device 1000. For this purpose, panel 1100 may include a touch panel for sensing the user's touch or a display panel for visually expressing information to the user.

[0123] Electronic device 1000 can perform fingerprint detection to provide services to authenticated users. Electronic device 1000 can collect and store information associated with a user's fingerprint. Electronic device 1000 can provide services only to users authenticated based on stored fingerprint information. Electronic device 1000 can use an image sensor located below panel 1100 to detect the user's fingerprint.

[0124] A user of electronic device 1000 can use an object to contact electronic device 1000. For example, the object can be the user's finger. Electronic device 1000 can identify the object in response to contact or proximity of the object on or to the panel 1100.

[0125] When a user's finger touches or approaches a local area PA of panel 1100, the image sensor can acquire an image associated with the fingerprint of the finger touching or approaching the local area PA. Based on the acquired image, the electronic device 1000 can determine whether the fingerprint of the finger touching or approaching the local area PA is the fingerprint of an authenticated user.

[0126] Figure 19 This is a simplified schematic block diagram illustrating an electronic device that includes an image sensor according to some example embodiments of the concept of the present invention.

[0127] Reference Figure 19 The electronic device 1000 may include a touch sensor panel 1110, a touch processor 1112, a display panel 1120, a display driver 1122, a main processor 1130, a memory 1140, and an image sensor 100C.

[0128] Touch sensor panel 1110 can sense the touch or proximity of an object (e.g., a user's finger). For example, touch sensor panel 1110 can generate a sensing signal in response to the touch or proximity of an object. In some embodiments, touch sensor panel 1110 may include a plurality of sensing capacitors formed in rows and columns.

[0129] The touch processor 1112 can process operations associated with contact or proximity to an object based on sensing signals output from the touch sensor panel 1110. For example, when the sensing signals are associated with the execution or operation of a specific application, the touch processor 1112 can provide the main processor 1130 with a command to execute or operate that specific application.

[0130] Display panel 1120 may include a plurality of pixels arranged along rows and columns, thus enabling the display of images. Each pixel of display panel 1120 may be configured to emit light having a specific color that forms an image. As light is emitted together from the plurality of pixels, display panel 1120 can display the desired image. Touch sensor panel 1110 and display panel 1120 may be implemented separately from each other, or may be configured as a single panel.

[0131] Display driver 1122 can drive display panel 1120. In response to commands from main processor 1130, display driver 1122 can drive each pixel of display panel 1120 to display the desired image.

[0132] The main processor 1130 can perform / process various arithmetic / logic operations to provide the functionality of the electronic device 1000. The main processor 1130 may include a microprocessor or a central processing unit (CPU). The main processor 1130 can communicate with the touch processor 1112, the display driver 1122, the memory 1140, and the image sensor 100C via the address bus, control bus, and data bus.

[0133] The memory 1140 can store data required for the operation of the electronic device 1000. For example, the memory 1140 may include dynamic random access memory (DRAM), mobile DRAM, static random access memory (SRAM), or flash memory.

[0134] Based on the light emitted from the display panel 1120, the image sensor 100C can generate and output an image that is associated with a portion of the display panel 1120 (e.g., ...). Figure 18 Image signals associated with objects in a local region (PA) (e.g., signals used to form an image associated with a fingerprint).

[0135] Figure 20 This is a cross-sectional view illustrating an electronic device including an image sensor of some example embodiments according to a concept of the present invention. Figure 21 To show in more detail Figure 20 The cross-sectional view of the electronic device shown.

[0136] Reference Figure 20 and Figure 21 The electronic device 1000 may include a display panel 1120, an image sensor package 100P, and a board 1000S.

[0137] Display panel 1120 may be an organic light-emitting diode (OLED) display panel, which includes OLEDs that display images by emitting light having one or more colors. However, the inventive concept is not limited thereto, and therefore various types of display panels, such as LCD display panels, may be used as display panel 1120.

[0138] The image sensor package 100P may include a package substrate 100S and an image sensor 100C mounted on the package substrate 100S. An adhesive 150 may be provided to hold the image sensor package 100P in a position below the display panel 1120.

[0139] The packaging substrate 100S can be a printed circuit board (PCB), and multiple solder balls SB can be attached to the bottom surface of the packaging substrate 100S. The packaging substrate 100S may have connection pads electrically connected to the solder balls SB on its top surface. The connection pads of the packaging substrate 100S can be electrically connected to the readout circuit layer 20 of the image sensor 100C via vias. In this configuration, electrical signals output from the image sensor 100C, to which light is incident, can be transmitted to other external devices (e.g., a main processor) via the solder balls SB.

[0140] As discussed above, the image sensor 100C may include a plurality of sensing pixels P1 and a plurality of reference pixels P2. The microlens array 50 may receive light reflected from the fingerprint FP, and the light may then be incident on the sensing pixels P1 after passing through the aperture of the light-shielding layer 30.

[0141] Sensing pixel P1 can sense light reflected from different areas of the fingerprint FP and output an electrical signal corresponding to the sensed light. Sensing pixel P1 can generate an electrical signal corresponding to light reflected from ridges or valleys between ridges of the fingerprint FP. The amount of light sensed by the photoelectric conversion element can vary based on the shape of the fingerprint FP reflecting the light, and the electrical signal can be generated with different levels depending on the amount of light sensed. For example, the electrical signal output from sensing pixel P1 may include brightness information (or image information), and based on the electrical signals output from sensing pixel P1 and reference pixel P2, signal processing can be performed to determine whether the location corresponding to sensing pixel P1 is a ridge or a valley. The result is that the entire fingerprint image can be obtained by combining the determined information.

[0142] Board 1000S can correspond to a motherboard such as a printed circuit board (PCB) for smartphones, and image sensor package 100P can be mounted on board 1000S to form an on-board chip package.

[0143] Image data can be provided to board 1000S via connection terminals formed on one surface of image sensor package 100P. For example, image data can be provided to board 1000S via solder balls SB attached to the bottom surface of package substrate 100S.

[0144] According to some exemplary embodiments of the present invention, because the number of reference pixels generating the reference signal is increased, a more accurate reference signal can be provided when processing the electrical signal output from the sensing pixel that is proportional to the incident light. Furthermore, because the reference pixels and sensing pixels are arranged together on the pixel array region, the size of the image sensor can be reduced.

[0145] Furthermore, image sensors can be integrated into electronic devices to perform fingerprint detection functions, providing services to authenticated users. The compactness of image sensors reduces the area they occupy within electronic devices.

[0146] Although the invention has been described with reference to some exemplary embodiments of the inventive concept shown in the accompanying drawings, those skilled in the art will understand that various changes and modifications can be made without departing from the technical spirit and essential characteristics of the inventive concept. It will be apparent to those skilled in the art that various substitutions, modifications, and alterations can be made without departing from the scope and spirit of the inventive concept.

Claims

1. An image sensor, comprising: A substrate having a first surface and a second surface opposite to the first surface; The first photoelectric conversion region and the second photoelectric conversion region are located in the substrate; The third photoelectric conversion region is located between the first photoelectric conversion region and the second photoelectric conversion region in the first direction; The first layer includes a first opening and a second opening, and the first layer is configured to cover the second surface; The second layer includes a third opening and a fourth opening, and the second layer is disposed on the first layer; A planarization layer is applied to the second layer; as well as A first lens corresponding to the first photoelectric conversion region and a second lens corresponding to the second photoelectric conversion region. Wherein, the first opening is perpendicularly aligned with the third opening, and the second opening is perpendicularly aligned with the fourth opening. The first opening is perpendicularly aligned with the center portion of the first photoelectric conversion region. Wherein, the third opening is at least as wide as the first opening in the first direction, and The third photoelectric conversion region is completely covered by the first layer.

2. The image sensor according to claim 1, wherein, The first opening and the second opening are arranged along the first direction, and the third opening and the fourth opening are arranged along the first direction. Wherein, the width of the third opening in the first direction is greater than the width of the first opening in the first direction.

3. The image sensor according to claim 2, wherein, The first opening has a first height in a second direction perpendicular to the first direction, and the third opening has a second height in the second direction. The second height is greater than the first height.

4. The image sensor according to claim 1, wherein, The first opening and the second opening are arranged along the first direction, and the third opening and the fourth opening are arranged along the first direction.

5. The image sensor according to claim 1, wherein, The first layer has a first thickness, and the second layer has a second thickness greater than the first thickness.

6. An image sensor, comprising: A substrate having a first surface and a second surface opposite to the first surface; The first photoelectric conversion region and the second photoelectric conversion region are located in the substrate; The third photoelectric conversion region is located between the first photoelectric conversion region and the second photoelectric conversion region in the first direction; The first layer includes a first opening and a second opening, and the first layer is configured to cover the second surface; The second layer is disposed on the first layer and includes a third opening and a fourth opening; The third layer is disposed on the second layer and includes a fifth opening and a sixth opening; A planarization layer is disposed on the third layer; as well as A first lens corresponding to the first photoelectric conversion region and a second lens corresponding to the second photoelectric conversion region. The first opening is perpendicularly aligned with the center portion of the first photoelectric conversion region, and the second opening is perpendicularly aligned with the center portion of the second photoelectric conversion region. Wherein, the distance between the first photoelectric conversion region and the second photoelectric conversion region in the first direction is greater than the width of the first opening in the first direction. The first opening is perpendicularly aligned with the third and fifth openings. The second opening is perpendicularly aligned with the fourth and sixth openings. The third photoelectric conversion region is completely covered by the first layer.

7. The image sensor according to claim 6, wherein, The first opening has a circular shape.

8. The image sensor according to claim 7, wherein, The first layer has a first thickness in a second direction perpendicular to the first direction, and the second layer has a second thickness in the second direction. The second thickness is greater than the first thickness.

9. The image sensor according to claim 8, wherein, The third layer has a third thickness in the second direction, and the second thickness is greater than the third thickness.

10. The image sensor according to claim 9, further comprising: The fourth layer is located between the second layer and the third layer.

11. The image sensor according to claim 9, wherein, The width of the fifth opening in the first direction is greater than the width of the first opening in the first direction.

12. An image sensor, comprising: A substrate having a first surface and a second surface opposite to the first surface; The first photoelectric conversion region and the second photoelectric conversion region are located in the substrate; The third photoelectric conversion region is located between the first photoelectric conversion region and the second photoelectric conversion region in the first direction; The first layer includes a first opening and a second opening, and the first layer is configured to cover the second surface; The second layer is set on top of the first layer; The third layer is set on top of the second layer; A planarization layer is disposed on the third layer; as well as A first lens corresponding to the first photoelectric conversion region and a second lens corresponding to the second photoelectric conversion region. The first opening is perpendicularly aligned with the center portion of the first photoelectric conversion region, and the second opening is perpendicularly aligned with the center portion of the second photoelectric conversion region. Wherein, the distance between the first photoelectric conversion region and the second photoelectric conversion region in the first direction is greater than the width of the first opening in the first direction. The first layer has a first thickness in a second direction perpendicular to the first direction, and the second layer has a second thickness in the second direction. Wherein, the second thickness is greater than the first thickness, and The third photoelectric conversion region is completely covered by the first layer.

Images