Pixels and image sensor including the same

Abstract

To provide pixels and an image sensor including the same.SOLUTION: An image sensor includes: a first epitaxial layer disposed on a first surface of a semiconductor substrate and having a first conductivity type formed by an epitaxial growth process; a photoelectric conversion element disposed on the first epitaxial layer and having a second conductivity type formed by the epitaxial growth process; and a second epitaxial layer disposed between the photoelectric conversion element and a second surface of the semiconductor substrate and having the second conductivity type formed by the epitaxial growth process.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an image sensor including a first epitaxial layer having a first conductivity type and a photoelectric conversion element having a second conductivity type formed by an epitaxial growth process. [Background technology]

[0002] An image sensor is a device that captures a two-dimensional or three-dimensional image of an object. Image sensors generate an image of an object by utilizing photoelectric conversion elements that react based on the intensity of light reflected from the object. In recent years, as the computer and communication industries have developed, there has been an increasing demand for image sensors with improved performance in various electronic devices such as digital cameras, camcorders, PCS (personal communication systems), game consoles, security cameras, medical micro cameras, and mobile phones.

[0003] The image sensor may include pixels, each of which may include a photoelectric conversion element that generates a photoelectric charge from light. When forming the photoelectric conversion element, impurities having a conductivity type different from that of the substrate may be implanted into the substrate by an ion implantation process. The implantation of the impurities creates lattice defects in the substrate, which may cause noise in the image data.

[0004] Therefore, techniques are needed to minimize noise in image data generated from an image sensor and improve image quality. Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a pixel and an image sensor including the pixel, in which a photoelectric conversion element of a second conductivity type is formed on a first epitaxial layer having a first conductivity type by an epitaxial growth process, thereby minimizing lattice defects and minimizing noise in image data. [Means for solving the problem]

[0006] As a technical means for achieving the above-mentioned technical problem, a first aspect of the present disclosure may provide an image sensor including a plurality of pixels, each of the plurality of pixels including: a first epitaxial layer disposed on a first surface of a semiconductor substrate and formed to have a first conductivity type by an epitaxial growth process; a photoelectric conversion element disposed on the first epitaxial layer and having a second conductivity type different from the first conductivity type; and a second epitaxial layer disposed between the photoelectric conversion element and a second surface of the semiconductor substrate and formed to have the second conductivity type by the epitaxial growth process, wherein the photoelectric conversion element is the epitaxial layer of the second conductivity type formed by the epitaxial growth process.

[0007] In addition, as a technical means for achieving the above-mentioned technical problem, a second aspect of the present disclosure may provide a pixel including a semiconductor substrate including a first surface and a second surface, a vertical transmission gate formed on the second surface of the semiconductor substrate, and a floating diffusion region configured to accumulate photocharges generated from the semiconductor substrate via the vertical transmission gate, wherein the semiconductor substrate includes: a first epitaxial layer disposed on the first surface of the semiconductor substrate and having a first conductivity type; a photoelectric conversion element in contact with the first epitaxial layer and formed by an epitaxial growth process in a direction from the first surface of the semiconductor substrate toward the second surface of the semiconductor substrate, the photoelectric conversion element having a second conductivity type different from the first conductivity type; and a second epitaxial layer in contact with the photoelectric conversion element in a direction from the first surface of the semiconductor substrate toward the second surface of the semiconductor substrate, the second epitaxial layer having the second conductivity type.

[0008] Furthermore, as a technical means for achieving the above-mentioned technical problem, a third aspect of the present disclosure may provide an image sensor including: a color filter arranged on a first surface of a semiconductor substrate in a second direction opposite to a first direction from the first surface of the semiconductor substrate toward a second surface of the semiconductor substrate; a lens layer arranged on the color filter in the second direction; a first epitaxial layer having a first conductivity type arranged between the first and second surfaces of the semiconductor substrate and arranged on the first surface of the semiconductor substrate in the first direction; a photoelectric conversion element that is an epitaxial layer having a second conductivity type arranged on the first epitaxial layer in the first direction; and a second epitaxial layer having a third conductivity type arranged between the first and second surfaces of the semiconductor substrate and arranged on the second surface of the semiconductor substrate in the second direction. Effect of the Invention

[0009] The pixel and image sensor according to the technical idea of ​​the present disclosure include a first epitaxial layer having a first conductivity type, a photoelectric conversion element having a second conductivity type, and a second epitaxial layer having a second conductivity type, and the photoelectric conversion element is formed by an epitaxial growth process, thereby minimizing lattice defects caused by ion implantation, thereby minimizing the generation of dark current due to free charge generation, minimizing noise contained in image data, and improving the image quality of the image sensor.

[0010] Effects that can be obtained from the exemplary embodiments of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly derived and understood by a person having ordinary skill in the art to which the exemplary embodiments of the present disclosure belong from the following description. That is, unintended effects by implementing the exemplary embodiments of the present disclosure will also be derived from the exemplary embodiments of the present disclosure by a person having ordinary skill in the art. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram illustrating an image sensor according to an exemplary embodiment of the present disclosure. [Diagram 2] FIG. 2 is a circuit diagram of a pixel included in an image sensor according to an exemplary embodiment of the present disclosure. [Diagram 3] FIG. 2 is a schematic cross-sectional view of a pixel according to an exemplary embodiment of the present disclosure. [Figure 4] 1 is a cross-sectional view illustrating a pixel of an image sensor according to an exemplary embodiment of the present disclosure. [Diagram 5] 1A to 1C are diagrams for explaining an isolation film according to an exemplary embodiment of the present disclosure. [Figure 6A] 1 is a cross-sectional view of a pixel for explaining a method of doping impurities into a photoelectric conversion element according to an exemplary embodiment of the present disclosure. [Figure 6B] 1 is a cross-sectional view of a pixel for explaining a method of doping impurities into a photoelectric conversion element according to an exemplary embodiment of the present disclosure. [Figure 7A] FIG. 2 is a cross-sectional view of a pixel for illustrating a photoelectric conversion element and a second epitaxial layer according to an exemplary embodiment of the present disclosure. [Figure 7B] FIG. 2 is a cross-sectional view of a pixel to illustrate the second epitaxial layer into which impurities are implanted, according to an exemplary embodiment of the present disclosure. [Figure 8] 2 is a cross-sectional view of a pixel showing a second epitaxial layer having a first conductivity type according to an exemplary embodiment of the present disclosure. [Figure 9] 4 is a flow chart illustrating a method for manufacturing an image sensor according to an exemplary embodiment of the present disclosure. [Figure 10A] 5A to 5C are cross-sectional views of a pixel for explaining a method of manufacturing an image sensor according to an exemplary embodiment of the present invention. [Figure 10B] 5A to 5C are cross-sectional views of a pixel for explaining a method of manufacturing an image sensor according to an exemplary embodiment of the present invention. [Figure 10C]5A to 5C are cross-sectional views of a pixel for explaining a method of manufacturing an image sensor according to an exemplary embodiment of the present invention. [Figure 10D] 5A to 5C are cross-sectional views of a pixel for explaining a method of manufacturing an image sensor according to an exemplary embodiment of the present invention. [Figure 10E] 5A to 5C are cross-sectional views of a pixel for explaining a method of manufacturing an image sensor according to an exemplary embodiment of the present invention. [Figure 10F] 5A to 5C are cross-sectional views of a pixel for explaining a method of manufacturing an image sensor according to an exemplary embodiment of the present invention. [Figure 11] 1A to 1C are cross-sectional views of a pixel for explaining a method for manufacturing an image sensor including an ion implantation process according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The same components in the drawings are designated by the same reference numerals, and duplicated explanations thereof will be omitted.

[0013] FIG. 1 is a block diagram illustrating an image sensor according to an exemplary embodiment of the present disclosure.

[0014] The image sensor 1 may be mounted in an electronic device having an image sensing function or an optical sensing function. For example, the image sensor 1 may be mounted in electronic devices such as a camera, a smartphone, a wearable device, an Internet of Things (IoT) device, a home appliance, a tablet PC (personal computer), a PDA (personal digital assistant), a PMP (portable multimedia player), a navigation device, a drone, and an advanced driver-assistance system (ADAS). The image sensor 1 may also be mounted in electronic devices provided as components in vehicles, furniture, manufacturing equipment, doors, various measuring instruments, and the like.

[0015] Referring to FIG. 1, the image sensor 1 may include a pixel array 10, a row driver 20, a readout circuit 30, a ramp signal generator 40, a timing controller 50 and a signal processor 60, and the readout circuit 30 may include an analog-to-digital conversion circuit (hereinafter referred to as an “ADC circuit”) 31 and a data bus 32.

[0016] The pixel array 10 includes a plurality of row lines RL, a plurality of column lines CL, and a plurality of pixels PX connected to the plurality of row lines RL and the plurality of column lines CL and arranged in a matrix. In one embodiment, the plurality of pixels PX may be active pixel sensors (APS).

[0017] Each of the pixels PX may include at least one photoelectric conversion element, and the pixel PX may sense light using the photoelectric conversion element and output an image signal that is an electrical signal based on the sensed light. For example, the photoelectric conversion element may be a light sensing element made of an organic or inorganic material, such as an inorganic photodiode, an organic photodiode, a perovskite photodiode, a phototransistor, a photogate, or a pinned photodiode. In one embodiment, each of the pixels PX may include a plurality of photoelectric conversion elements.

[0018] In one embodiment, the photoelectric conversion element is epitaxially grown. The pixel PX may be an epitaxial layer formed by an epitaxial growth process. The pixel PX may include a first epitaxial layer, a photoelectric conversion element, and a second epitaxial layer. Each of the first epitaxial layer, the photoelectric conversion element, and the second epitaxial layer may be formed by an epitaxial growth method. The first epitaxial layer may be of a first conductive type, and the photoelectric conversion element may be of a second conductive type. Exemplarily, the pixel PX may include an N-type photoelectric conversion element formed on a P-type first epitaxial layer. The structure of the pixel PX will be described in detail later with reference to FIG. 3.

[0019] In one embodiment, the photoelectric conversion element having the second conductive type may further be implanted with impurities of the second conductive type through an ion implantation process. The photoelectric conversion element being an epitaxial layer having the second conductive type may further be implanted with impurities through an ion implantation process. For example, the photoelectric conversion element being an N-type epitaxial layer may be implanted with N-type impurities at a specific concentration.

[0020] Since the second conductive type impurity is further injected into the photoelectric conversion element, which is the epitaxial layer of the second conductive type, by the ion implantation process, the photoelectric conversion element can be formed even if the second conductive type impurity is injected into the photoelectric conversion element in an amount relatively smaller than the amount of the second conductive type impurity injected into the epitaxial layer having the first conductive type by the ion implantation process. Since the second conductive type impurity is further injected into the photoelectric conversion element, which is the epitaxial layer of the second conductive type, the photoelectric conversion element is generated with an appropriate second conductive type impurity concentration, and the photoelectric effect of the photoelectric conversion element can be improved. In addition, since a relatively small amount of the second conductive type impurity is injected by the ion implantation process, lattice defects can be minimized.

[0021] A microlens for collecting light may be disposed on each of the pixels PX or on each of the pixel groups formed by adjacent pixels PX. Each of the pixels PX may sense light in a specific spectral region from the light received through the microlens. For example, the pixel array 10 may include a red pixel for converting light in the red spectral region into an electrical signal, a green pixel for converting light in the green spectral region into an electrical signal, and a blue pixel for converting light in the blue spectral region into an electrical signal. A color filter for transmitting light in a specific spectral region may be disposed on each of the pixels PX. However, the present invention is not limited thereto, and the pixel array 10 may include pixels for converting light in other spectral regions into electrical signals in addition to red, green, and blue.

[0022] A color filter array for transmitting light in a specific spectral region is disposed on the upper portion of the pixels PX, and the color filter disposed on each of the pixels determines the hue that the pixel can sense. However, without being limited thereto, in one embodiment, in the case of a specific photoelectric conversion element, light in a specific wavelength band can be converted into an electrical signal depending on the level of an electrical signal applied to the photoelectric conversion element. According to one embodiment, the pixel PX may include two or more photoelectric conversion elements.

[0023] The row driver 20 drives the pixel array 10 on a row-by-row basis. The row driver 20 may decode a row control signal (e.g., an address signal) received from the timing controller 50, and select at least one of the row lines constituting the pixel array 10 in response to the decoded row control signal. For example, the row driver 20 may generate a selection signal for selecting one of a plurality of rows. Then, the pixel array 10 outputs a pixel signal PXS from a row selected by the selection signal provided from the row driver 20.

[0024] The row driver 20 transmits a control signal for outputting the pixel signal PXS to the pixel array 10, and the pixel PX can output the pixel signal PXS by operating in response to the control signal.

[0025] The ramp signal generator 40 can generate a ramp signal RAMP that increases or decreases with a predetermined slope, and provide the ramp signal RAMP to the ADC circuit 31 of the readout circuit 30.

[0026] The readout circuit 30 may read out a pixel signal PXS from a pixel PX in a row selected by the row driver 20 among the plurality of pixels PX. At this time, the pixel signal PXS may include a reset signal or an image signal (or a sensing signal). The readout circuit 30 may generate and output image data IDT by converting the reset signal and the image signal received from the pixel array 10 via the plurality of column lines CL into a digital signal based on the ramp signal RAMP from the ramp signal generator 40.

[0027] The ADC circuit 31 includes at least one analog-to-digital The ADC circuit 31 may include a ramp converter (RAMP). Exemplarily, the ADC circuit 31 may include a plurality of ADCs corresponding to the plurality of column lines CL, and each of the plurality of ADCs may compare a reset signal and an image signal received via a corresponding column line CL with a ramp signal RAMP, and generate a pixel value based on the comparison result. For example, the ADC may remove the reset signal from the image signal and generate a pixel value indicating the amount of light sensed at the pixel PX. The image data IDT may also include the pixel value.

[0028] The image data IDT generated by the ADC circuit 31 may be output via a data bus 32. For example, the image data IDT may be provided to a signal processor 60.

[0029] The data bus 32 may temporarily store and then output the image data IDT output from the ADC circuit 31. The data bus 32 may include a plurality of column memories and a column decoder. The image data IDT stored in the column memories may be output to the signal processor 60 under the control of the column decoder.

[0030] The ADC circuit 31 may include a plurality of CDS (correlated double sampling) circuits (not shown) and a plurality of counter circuits (not shown). The ADC circuit 31 can convert the pixel signal PXS input from the pixel array 10 into a pixel value, which is a digital signal. Each pixel signal PXS received via each of the plurality of column lines CL is converted into a pixel value, which is a digital signal, by the CDS circuit and the counter circuit.

[0031] The CDS circuit may compare the pixel signal PXS received through the column line CL with the ramp signal RAMP and output the comparison result. The CDS circuit may output a comparison signal that transitions from a first level (e.g., logic high) to a second level (e.g., logic low) when the level of the ramp signal RAMP is the same as the level of the pixel signal PXS. The time when the level of the comparison signal transitions may be determined by the level of the pixel signal PXS.

[0032] The CDS circuit samples and holds the pixel signal PXS provided from the pixel PX using a correlated double sampling (CDS) method, double samples the level of a specific noise (e.g., a reset signal) and the level due to the image signal, and can generate a comparison signal based on the level corresponding to the difference.

[0033] In some embodiments, the CDS circuitry may include one or more comparators, which may be embodied, for example, by an operational transconductance amplifier (OTA) (or differential amplifier).

[0034] The signal processor 60 may receive the image data IDT from the readout circuit 30. The signal processor 60 may perform image processing on the image data IDT. For example, the signal processor 60 may perform noise reduction processing, gain adjustment, waveform shaping processing, interpolation processing, white balance processing, gamma processing, edge enhancement processing, bad pixel correction (BPC) processing, and the like on pixel values ​​included in the image data IDT. 1 illustrates the signal processor 60 as being included in the image sensor 1, the present invention is not limited thereto, and according to an embodiment, the signal processor 60 may be provided outside the image sensor 1. For example, the signal processor 60 may be provided in an external processor of the image sensor 1.

[0035] 2 is a circuit diagram of a pixel included in an image sensor according to an exemplary embodiment of the present disclosure, the pixel PX in FIG. 2 is an example of one of the pixels PX included in the pixel array 10 in FIG.

[0036] Referring to FIG. 2, the pixel PX may include a photodiode PD and a transmission circuit TC. The photodiode PD may be replaced with another light sensing element. The photodiode PD may be referred to as a photoelectric conversion element. The transmission circuit TC may include a reset transistor RX, a transmission transistor TX, a driving transistor DX, and a selection transistor SX. However, the structure of the transmission circuit TC is not limited thereto, and the structure of the transmission circuit TC may be changed. The reset transistor RX may include a reset gate RG, the selection transistor SX may include a selection gate SG, and the transmission transistor TX may include a transmission gate TG.

[0037] The photodiode PD can generate a photocharge that varies depending on the intensity of incident light. The transmission circuit TC can generate an analog pixel signal PXS that corresponds to the photodiode PD or an internal reset noise.

[0038] The transmission circuit TC can operate based on the received control signal. The transmission transistor TX can transmit the photocharge from the photodiode PD to the floating diffusion region FD in response to the transmission control signal.

[0039] Due to the potential caused by the photocharges accumulated in the floating diffusion region FD, the driving transistor DX can amplify the photocharges and output them via the selection transistor SX. If the selection transistor SX is turned on in response to a selection control signal, a sensing signal corresponding to the voltage level of the floating diffusion region FD, i.e., a photo-sensing signal, can be output as, for example, a pixel signal PXS.

[0040] In addition, the reset transistor RX can reset the floating diffusion region FD based on the power supply voltage VDD by a reset control signal, and a reset signal corresponding to the voltage level of the floating diffusion region FD can be output as the pixel signal PXS.

[0041] The pixel signal PXS may be output via a column line CL to, for example, a readout circuit 30 (FIG. 1).

[0042] 3 is a schematic cross-sectional view of a pixel according to an exemplary embodiment of the present disclosure, for example, of the image sensor 1 (FIG. 1), illustrating the semiconductor substrate 100 of the pixel.

[0043] 3, the pixel PX may include a semiconductor substrate 100. The semiconductor substrate 100 may include a first surface suf1 and a second surface suf2 opposite to the first surface suf1. Here, for convenience, the surface included in the first epitaxial layer 110 is referred to as the first surface suf1, and the surface included in the second epitaxial layer 130 is referred to as the second surface suf2.

[0044] The semiconductor substrate 100 may include a first epitaxial layer 110, a photoelectric conversion element 120, and a second epitaxial layer 130. The first epitaxial layer 110 may be disposed on a first surface suf1 of the semiconductor substrate 100. The first epitaxial layer 110 may be disposed in a first direction (Z) on the first surface suf1.

[0045] The first epitaxial layer 110 may be a first conductive type epitaxial layer formed by an epitaxial growth process. Exemplarily, the first conductive type may be P type. The first epitaxial layer 110 may be a P type epitaxial layer. The P type first epitaxial layer 110 may be formed on a silicon bulk.

[0046] The photoelectric conversion element 120 may be located on the semiconductor substrate 100. The photoelectric conversion element 120 may be a photodiode region. The photoelectric conversion element 120 may generate photocharges based on light incident on the pixel PX. In response to the incident light, electron-hole pairs are generated, and the photoelectric conversion element 120 may collect such electrons or holes. The photoelectric conversion element 120 may be disposed on the first epitaxial layer 110. The photoelectric conversion element 120 may be disposed on the first epitaxial layer 110 in a first direction.

[0047] In one embodiment, the photoelectric conversion element 120 may be an epitaxial layer formed by an epitaxial growth process. The photoelectric conversion element 120 may be generated to have a second conductivity type by an epitaxial growth process. Exemplarily, the photoelectric conversion element 120 may be a depletion region. The second conductivity type may be different from the first conductivity type. For example, the first conductivity type may be a P type, and the second conductivity type may be an N type. In the epitaxial growth process, the impurities (dopants) and / or doping concentration may be adjusted to form a predetermined conductivity type and a predetermined doping concentration. The N-type photoelectric conversion element 120 may be formed on the first epitaxial layer 110 grown to be a P type by an epitaxial growth process.

[0048] A second epitaxial layer 130 may be located on the semiconductor substrate 100. The second epitaxial layer 130 may be disposed on the photoelectric conversion element 120. The second epitaxial layer 130 may be disposed on the photoelectric conversion element 120 in a first direction (+Z). The second epitaxial layer 130 may be disposed between the photoelectric conversion element 120 and the second surface suf2.

[0049] In one embodiment, the second epitaxial layer 130 may be an epitaxial layer formed by an epitaxial growth process. Exemplarily, the second epitaxial layer 130 may be generated to have the same conductivity type as the photoelectric conversion element 120 by an epitaxial growth process. The second epitaxial layer 130 may be formed to have the second conductivity type. For example, the second epitaxial layer 130 may be an N-type. However, it is not necessarily limited thereto, and the second epitaxial layer 130 may be generated to have the same conductivity type as the photoelectric conversion element 120.

[0050] The photoelectric conversion element 120 may be formed to have a first concentration of a second conductive type by an epitaxial growth process. The second epitaxial layer 130 may be formed to have a second concentration of a second conductive type by an epitaxial growth process. That is, the photoelectric conversion element 120 may be formed in an epitaxial layer of a first concentration, and the second epitaxial layer 130 may be formed in an epitaxial layer of a second concentration by an epitaxial growth process. In one embodiment, the first concentration and the second concentration may be different. Since the first concentration and the second concentration are different during the epitaxial growth process, the photoelectric conversion element 120 and the second epitaxial layer 130 may be distinguished. For example, the photoelectric conversion element 120 may be formed at a first concentration from the second portion p2 to the first portion p1 of the semiconductor substrate 100, and the second epitaxial layer 130 may be formed at a second concentration from the first portion p1 to the second surface suf2.

[0051] In one embodiment, the first concentration is higher than the second concentration. The second conductivity type impurity concentration of the photoelectric conversion element 120 is higher than the second conductivity type impurity concentration of the second epitaxial layer 130. Exemplarily, the photoelectric conversion element 120 may be formed to have a relatively high concentration of N-type impurities and the second epitaxial layer 130 may be formed to have a relatively low concentration of N-type impurities by the epitaxial growth process.

[0052] In the semiconductor substrate 100, the sizes of at least two of the first epitaxial layer 110, the photoelectric conversion element 120, and the second epitaxial layer 130 may be different. The size of the first epitaxial layer 110 may mean the length in the Z-axis direction of the region occupied by the first epitaxial layer 110 in the semiconductor substrate 100. The size of the photoelectric conversion element 120 may mean the length in the Z-axis direction of the region occupied by the photoelectric conversion element 120 in the semiconductor substrate 100. The size of the second epitaxial layer 130 may mean the length in the Z-axis direction of the region occupied by the second epitaxial layer 130 in the semiconductor substrate 100.

[0053] The size of the first epitaxial layer 110 and the size of the photoelectric conversion element 120 may be different. Exemplarily, the size of the first epitaxial layer 110 is smaller than the size of the photoelectric conversion element 120. For example, the size of the first epitaxial layer 110 may correspond to a first length w1, and the size of the photoelectric conversion element 120 may correspond to a second length w2. Since the first length w1 is shorter than the second length w2, the size of the first epitaxial layer 110 is smaller than the size of the photoelectric conversion element 120.

[0054] The size of the first epitaxial layer 110 and the size of the second epitaxial layer 130 may be different. For example, the size of the first epitaxial layer 110 may correspond to a first length w1, and the size of the second epitaxial layer 130 may correspond to a third length w3. Since the first length w1 is shorter than the third length w3, the size of the first epitaxial layer 110 is smaller than the size of the second epitaxial layer 130. Exemplarily, in the semiconductor substrate 100, the size occupied by the first epitaxial layer 110 may be 20%, and the size occupied by the photoelectric conversion element 120 and the second epitaxial layer 130 may be 80%. However, the above-mentioned numerical values ​​of the sizes are merely examples and are not necessarily limited thereto.

[0055] The pixel PX of the present invention includes a second conductive type photoelectric conversion element formed by an epitaxial growth process on a first conductive type first epitaxial layer, and therefore can minimize lattice defects in the semiconductor substrate 100. As a result, generation of dark current due to generation of free charges is minimized, noise included in image data is minimized, and image quality of the image sensor can be improved.

[0056] 4 is a cross-sectional view showing a pixel of an image sensor according to an exemplary embodiment of the present disclosure. FIG. 4 shows at least a portion of a pixel array 10, and shows a first pixel PX1 and a second pixel PX2 among the pixels included in the pixel array 10. The second pixel PX2 may be a pixel adjacent to the first pixel PX1. The pixel PX in FIG. 3 may be applied to the first pixel PX1 and the second pixel PX2 in FIG. 4. Content that overlaps with the above content will be omitted.

[0057] 4, the pixels PX1 and PX2 of the pixel array 10 may further include a lens layer 300 and color filters 201 and 202. The pixels PX1 and PX2 may also include, for example, pixel transistors (a reset transistor RX (FIG. 2), a transfer transistor TX (FIG. 2), a drive transistor DX (FIG. 2), and a select transistor SX (FIG. 2)) and a floating diffusion region FD.

[0058] The pixels PX1 and PX2 may include a semiconductor substrate 100. The semiconductor substrate 100 may include a first surface suf1. The first surface suf1 may be referred to as a back side of the semiconductor substrate 100. The semiconductor substrate 100 may include a second surface suf2 facing the first surface suf1. The second surface suf2 may be referred to as a front surface. A wiring layer may be disposed on the second surface suf2 of the semiconductor substrate 100, and a light transmitting layer may be disposed on the first surface suf1. The light transmitting layer may include, for example, color filters 201 and 202 and a lens layer 300.

[0059] Light can be incident on the photoelectric conversion element 120 through the light transmitting layer on the second surface suf2. In general, in an image sensor, a structure in which a wiring layer and a light transmitting layer are arranged on opposite surfaces of the semiconductor substrate 100, for example, a structure in which the wiring layer is arranged on the second surface suf2 of the semiconductor substrate 100 and the light transmitting layer is arranged on the first surface suf1, is called a BSI (back side illumination) structure. In contrast, a structure in which the wiring layer and the light transmitting layer are arranged on the same surface of the semiconductor substrate 100, for example, on the second surface suf2, is called an FSI (front side illumination) structure.

[0060] The semiconductor substrate 100 may include a first epitaxial layer 110, a photoelectric conversion element 120, and a second epitaxial layer 130. The first epitaxial layer 110 may be in contact with the photoelectric conversion element 120. The first epitaxial layer 110 may be in contact with the photoelectric conversion element 120 in a direction from the first surface suf1 to the second surface suf2. That is, the first epitaxial layer 110 may be in contact with the photoelectric conversion element 120 in a first direction (+Z). The photoelectric conversion element 120 may be formed on the first epitaxial layer 110 by an epitaxial growth process. The photoelectric conversion element 120 may be in contact with the second epitaxial layer 130. The photoelectric conversion element 120 may be in contact with the second epitaxial layer 130 in a first direction (+Z). The second epitaxial layer 130 can be disposed between the photoelectric conversion element 120 and the second surface suf2.

[0061] Color filters 201 and 202 may be disposed on the first surface suf1. The color filters 201 and 202 may be disposed on the first surface suf1 of the semiconductor substrate 100 in a second direction (-Z) opposite to the first direction (+Z). The color filters 201 and 202 may transmit light in a specific spectral region. For example, the color filters 201 and 202 may transmit light in the red, blue, and green regions.

[0062] The color filters 201, 202 disposed in the pixels PX1, PX2 may determine the hues that the pixels PX1, PX2 can sense. A first color filter 201 may be disposed on the first surface suf1 of the first pixel PX1. For example, the first color filter 201 may be a red color filter and may transmit light in the red region. The light in the red region transmitted through the first color filter 201 may be incident on the photoelectric conversion element 120, and the photoelectric conversion element 120 may generate photocharges from the light in the red region. If the first color filter 201 is a blue color filter, the light in the blue region transmitted through the first color filter 201 may be incident on the photoelectric conversion element 120, and the photoelectric conversion element 120 may generate photocharges from the light in the blue region. If the first color filter 201 is a green color filter, the light in the green region transmitted through the first color filter 201 may be incident on the photoelectric conversion element 120, and the photoelectric conversion element 120 may generate photocharges from the light in the green region. The photoelectric conversion element 120 can generate photocharges from light incident after passing through the color filters 201 and 202. For example, the photoelectric conversion element 120 can generate photocharges from light in the blue region, can generate photocharges from light in the red region, and can generate photocharges from light in the green region.

[0063] A second color filter 202 may be disposed on the first surface suf1 of the second pixel PX2. For example, the second color filter 202 may be a blue color filter and may transmit light in the blue region. However, the present invention is not necessarily limited thereto. The second pixel PX2 may be a pixel adjacent to the first pixel PX1 in the x-direction. Exemplarily, color filters 201 and 202 of different colors may be disposed in the adjacent pixels. The first color filter 201 and the second color filter 202 may be color filters of different colors. However, the present invention is not necessarily limited thereto. Even if the pixels are adjacent, color filters 201 and 202 of the same color may be disposed. For example, the first color filter 201 and the second color filter 202 may be color filters of the same color.

[0064] A lens layer 300 may be disposed on the color filters 201 and 202. A lens layer 300 may be disposed in a second direction (-Z) on the color filters 201 and 202. The lens layer 300 may collect light incident on the pixels PX1 and PX2. The lens layer 300 may be a microlens.

[0065] The pixels PX1 and PX2 may include a floating diffusion region FD and a pixel transistor. For example, the pixel transistor may include a transmission transistor TX, a reset transistor RX, a driving transistor DX, and a selection transistor SX as described in FIG. 2. Such pixel transistors may be formed on the second surface suf2 of the semiconductor substrate 100. For example, the pixel transistors may be connected to a wiring layer disposed on the second surface suf2 via a contact. In FIG. 4, for convenience, only the transmission gate TG of the transmission transistor TX is illustrated. According to an embodiment, the pixels PX1 and PX2 may share at least one of the transmission transistor TX, the reset transistor RX, the driving transistor DX, and the selection transistor SX with other pixels. For example, the first pixel PX1 and the second pixel PX2 may share the selection transistor SX.

[0066] The transmission gate TG may be formed on the second surface suf2. Exemplarily, the transmission gate TG may be a vertical transmission gate. In FIG. 4, the transmission gate TG is illustrated as being formed as a recessed gate type extending from the second surface suf2 into the semiconductor substrate 100, but this is merely an example, and the shape of the transmission gate TG is not limited thereto. Exemplarily, at least a portion of the transmission gate TG may be extended into the second epitaxial layer 130. The transmission gate TG may be disposed apart from the photoelectric conversion element 120, or may be disposed in contact with the photoelectric conversion element 120.

[0067] The floating diffusion region FD may accumulate photocharges generated in the photoelectric conversion element 120. The photocharges generated in the photoelectric conversion element 120 may be transferred to the floating diffusion region FD via the transmission gate TG. The floating diffusion region FD may be formed on the second surface suf2. At least a portion of the floating diffusion region FD may be formed in the second epitaxial layer 130. Exemplarily, the floating diffusion region FD may be formed inside the second epitaxial layer 130 on the second surface suf2. According to an embodiment, one pixel may share the floating diffusion region FD with another pixel. For example, the floating diffusion region FD may be shared between the first pixel PX1 and the second pixel PX2.

[0068] A wiring layer may be disposed on the second surface suf2 of the semiconductor substrate 100. The wiring layer may be electrically connected to the pixel transistors. According to an embodiment, the wiring layer may be formed in a multi-layer stacked structure.

[0069] 5 is a diagram for explaining an isolation film according to an exemplary embodiment of the present disclosure. Compared with FIG. 4, pixels PX1 and PX2 in FIG. 5 may further include an isolation film 400. Content that overlaps with the above content will be omitted.

[0070] Each of the pixels PX1 and PX2 may include an isolation layer 400. The isolation layer 400 may define at least a portion of a plurality of pixels included in the pixel array 10. The isolation layer 400 may be disposed on the semiconductor substrate 100 and define each of the plurality of pixels. The first pixel PX1 and the second pixel PX2 may be separated by the isolation layer 400.

[0071] The element isolation film 400 may prevent photocharges generated by light incident on the pixels PX1 and PX2 from flowing into the adjacent pixels PX1 and PX2. That is, the element isolation film 400 may prevent a crosstalk phenomenon between adjacent pixels. In one embodiment, the element isolation film 400 may penetrate the semiconductor substrate 100. The element isolation film 400 may extend from the second surface suf2 to the first surface suf1. In one embodiment, the element isolation film 400 may be disposed to penetrate the second epitaxial layer 130, the photoelectric conversion element 120, and the first epitaxial layer 110.

[0072] The element isolation film 400 may be formed by forming a deep trench in the semiconductor substrate 100 and filling the inside of the trench with an insulating material and a conductive material. The element isolation film 400 may be classified as a FDTI (front DTI) or a BDTI (back DTI) structure depending on whether the trench is formed on the front or back surface of the semiconductor substrate 100.

[0073] The device isolation layer 400 may have various shapes depending on the type of trench. In FIG. 4, the device isolation layer 400 is illustrated as having a rectangular shape, but is not necessarily limited thereto. The image sensor may reduce crosstalk between the pixels PX1 and PX2 and reduce noise. As a result, the image sensor of the present invention may obtain an image with improved image quality.

[0074] 6A is a cross-sectional view of a pixel for explaining a method of doping impurities into a photoelectric conversion element according to an exemplary embodiment of the present disclosure. In FIG. 6A, it is assumed that the photoelectric conversion element 120 and the second epitaxial layer 130 are formed by an epitaxial growth process with different concentrations.

[0075] The photoelectric conversion element 120 and the second epitaxial layer 130 may be epitaxial layers of a second conductivity type. In one embodiment, the concentrations of the photoelectric conversion element 120 and the second epitaxial layer 130 formed by the epitaxial growth process may be different from each other. Exemplarily, the photoelectric conversion element 120 of the second conductivity type may be formed with a first concentration, and the second epitaxial layer 130 of the second conductivity type may be formed with a second concentration by the epitaxial growth process.

[0076] The photoelectric conversion element 120 may be further doped with impurities of the same conductivity type as the conductivity type formed by the epitaxial growth process. The photoelectric conversion element 120 may be further doped with impurities of a second conductivity type by an ion implantation process. Exemplarily, N-type impurities may be further doped with the photoelectric conversion element 120, which is an N-type epitaxial layer, by an ion implantation process. By further doping the N-type impurities into the photoelectric conversion element 120, which is an N-type epitaxial layer, the impurity concentration of the photoelectric conversion element 120 may be more easily adjusted to a desired concentration. In addition, since the photoelectric conversion element 120 is formed by doping the N-type impurities into the P-type epitaxial layer by an ion implantation process, a small amount of N-type impurities is doped into the photoelectric conversion element 120, and the photoelectric effect may be improved while minimizing lattice defects.

[0077] 6B is a cross-sectional view of a pixel for explaining a method of doping impurities into a photoelectric conversion element according to an exemplary embodiment of the present disclosure. In FIG. 6B, it is assumed that the photoelectric conversion element 120 and the second epitaxial layer 130 are formed by an epitaxial growth process with the same concentration.

[0078] In one embodiment, the concentrations of the photoelectric conversion element 120 and the second epitaxial layer 130 formed by the epitaxial growth process may be the same as each other. Exemplarily, the photoelectric conversion element 120 and the second epitaxial layer 130 of the second conductivity type may be formed with a first concentration by the epitaxial growth process.

[0079] An ion implantation process may further implant impurities of a second conductivity type into the photoelectric conversion element 120. Since the impurities of the second conductivity type are further implanted into the photoelectric conversion element 120, the impurity concentration of the second conductivity type in the photoelectric conversion element 120 is higher than the impurity concentration of the second conductivity type in the second epitaxial layer 130. As a result, the photoelectric conversion element 120 may be doped with a high concentration of N-type impurities.

[0080] The ion implantation process may cause a difference in concentration of N-type impurities between the photoelectric conversion element 120 and the second epitaxial layer 130. The photoelectric conversion element 120 is doped with a high concentration of N-type impurities, and thus may perform the role of photoelectric conversion. By further injecting impurities of a second conductivity type into the photoelectric conversion element 120 through the ion implantation process, a difference in concentration of N-type impurities between the photoelectric conversion element 120 and the second epitaxial layer 130 may occur, and the second epitaxial layer 130 and the photoelectric conversion element 120 may be separated.

[0081] 7A is a cross-sectional view of a pixel for explaining a photoelectric conversion element and a second epitaxial layer according to an exemplary embodiment of the present disclosure. FIG. 7A assumes that the photoelectric conversion element 120 and the second epitaxial layer 130 are formed by an epitaxial growth process with the same concentration.

[0082] In one embodiment, the concentrations of the photoelectric conversion element 120 and the second epitaxial layer 130 formed by the epitaxial growth process may be the same. The photoelectric conversion element 120 and the second epitaxial layer 130 may be formed with a first concentration of a second conductivity type by an ion implantation process by the epitaxial growth process. If impurities are implanted into the second epitaxial layer 130, the photoelectric conversion element 120 and the second epitaxial layer 130 may be formed with the same concentration by the epitaxial growth process, but as a result, the concentrations may be different. Hereinafter, the second epitaxial layer 130 into which impurities are implanted will be described with reference to FIG. 7B.

[0083] FIG. 7B is a cross-sectional view of a pixel to illustrate the second epitaxial layer being implanted with impurities according to an exemplary embodiment of the present disclosure.

[0084] The second epitaxial layer 130 may be further doped with a first conductive type impurity by an ion implantation process. Impurities of a conductive type different from the conductive type formed by the epitaxial growth process may be implanted into the second epitaxial layer 130. Exemplarily, P-type impurities may be implanted into the N-type second epitaxial layer 130 by the ion implantation process. Since P-type impurities are further implanted into the second epitaxial layer 130, as a result, the N-type impurity concentration of the photoelectric conversion element 120 is higher than the N-type impurity concentration of the second epitaxial layer 130.

[0085] P-type impurities are implanted into the second epitaxial layer 130, and a difference in concentration of N-type impurities may occur between the photoelectric conversion element 120 and the second epitaxial layer 130. The N-type second epitaxial layer 130 may be doped with P-type impurities by an ion implantation process, and a barrier may be formed between the photoelectric conversion element 120 and the second epitaxial layer 130.

[0086] FIG. 8 is a cross-sectional view of a pixel showing a second epitaxial layer having a first conductivity type according to an exemplary embodiment of the present disclosure.

[0087] In one embodiment, the second epitaxial layer 130 may be generated to have a different conductivity type from the photoelectric conversion element 120. The second epitaxial layer 130 may be formed in a first conductivity type epitaxial layer by an epitaxial growth process. Exemplarily, the first epitaxial layer 110 may be a P-type epitaxial layer, the photoelectric conversion element 120 may be an N-type epitaxial layer, and the second epitaxial layer 130 may be a P-type epitaxial layer. The P-type second epitaxial layer 130 may be formed on the photoelectric conversion element 120.

[0088] 9 is a flow chart illustrating a method for manufacturing an image sensor according to an exemplary embodiment of the present disclosure. FIGs. 10A to 10F are cross-sectional views of a pixel for illustrating a method for manufacturing an image sensor according to an exemplary embodiment of the present disclosure. Content that overlaps with the above content will be omitted.

[0089] 9 and 10A, for example, a method for manufacturing the image sensor 1 (FIG. 1) may include forming a first conductive type epitaxial layer 110a on a silicon bulk by an epitaxial growth process (S910). Exemplarily, a P-type epitaxial layer 110a may be formed on the silicon bulk by the epitaxial growth process. The epitaxial layer 110a may be epitaxially grown in a first direction (+Z) on the silicon bulk.

[0090] 9 and 10B, the method for manufacturing an image sensor may include forming a second conductive type photoelectric conversion element 120 (S920). The photoelectric conversion element 120 may be formed on the first conductive type epitaxial layer 110a by an epitaxial growth process.

[0091] The epitaxial layer 110a may include a surface a opposite to the surface in contact with the silicon bulk. A second conductive type epitaxial layer may be grown on the first conductive type epitaxial layer 110a to form the photoelectric conversion element 120. The photoelectric conversion element 120 may be formed in a first direction (+Z) from the surface a. The photoelectric conversion element 120 may be formed to have a first concentration of the second conductive type by an epitaxial growth process. Exemplarily, the photoelectric conversion element 120 may be an N-type epitaxial layer.

[0092] 9 and 10C, the method for manufacturing an image sensor may include forming a second epitaxial layer 130 (S930). The second epitaxial layer 130 may be formed on the photoelectric conversion element 120 by an epitaxial growth process.

[0093] The photoelectric conversion element 120 may include a surface b opposite to the surface a. A second epitaxial layer 130 may be formed on the second conductive type photoelectric conversion element 120 by an epitaxial growth process. The second epitaxial layer 130 may be formed in a first direction (+Z) from the surface b. Exemplarily, the second epitaxial layer 130 may be an N-type epitaxial layer.

[0094] The second epitaxial layer 130 may be formed to have a second concentration by an epitaxial growth process. Exemplarily, the N-type impurity concentration of the photoelectric conversion element 120 formed by the epitaxial growth process may be different from the N-type impurity concentration of the second epitaxial layer 130 formed by the epitaxial growth process. That is, the first concentration and the second concentration may be different from each other. For example, the first concentration is higher than the second concentration.

[0095] 9 and 10D, the method for manufacturing an image sensor may include a step of forming a circuit region 140 (S940). The circuit region 140 may be formed on a semiconductor substrate. The semiconductor substrate may include at least a portion of the epitaxial layer 110a, a photoelectric conversion element 120, and a second epitaxial layer 130. The circuit region 140 may include, for example, pixel transistors (e.g., a transfer transistor TX (FIG. 2), a reset transistor RX (FIG. 2), a driving transistor DX (FIG. 2), and a selection transistor SX (FIG. 2)), a floating diffusion region, etc. A transfer gate and a floating diffusion region may be formed on a second surface suf2 of the semiconductor substrate. Exemplarily, at least a portion of the transfer gate and at least a portion of the floating diffusion region may be formed in the second epitaxial layer 130.

[0096] 9 and 10E, the method for manufacturing an image sensor may include forming an isolation layer 400 (S950). The semiconductor substrate may be selectively etched to form the isolation layer 400. The isolation layer 400 may be formed in a second direction (-Z) on a second surface suf2 of the semiconductor substrate. Exemplarily, the isolation layer 400 may be formed by a photolithography process.

[0097] The element isolation films 400 may be formed to be spaced apart from each other in the X direction. The element isolation films 400 may be formed to be spaced apart from each other at a specific interval. The element isolation films 400 may be formed to penetrate at least a portion of the semiconductor substrate. The element isolation films 400 may be etched from the second surface suf2 into the semiconductor substrate. In one embodiment, the element isolation films 400 may be formed to penetrate at least a portion of the epitaxial layer 110a, the second epitaxial layer 130, and the photoelectric conversion element 120.

[0098] 9 and 10F, the method for manufacturing an image sensor may include etching at least a portion 110b of the first conductive type epitaxial layer 110a (S960). After the device isolation layer 400 is formed, at least a portion 110b of the epitaxial layer 110a may be etched as necessary.

[0099] For example, at least a partial region 110b of the epitaxial layer 110a may be etched to form a first epitaxial layer 110. The first epitaxial layer 110 may be an epitaxial layer of a first conductivity type (e.g., P type). The first epitaxial layer 110, the photoelectric conversion element 120, and the second epitaxial layer 130 may form a semiconductor substrate 100. The semiconductor substrate 100 may include a second surface suf2 and a first surface suf1 facing the second surface.

[0100] FIG. 11 is a cross-sectional view of a pixel for explaining a method for manufacturing an image sensor including an ion implantation process according to an exemplary embodiment of the present disclosure.

[0101] In an embodiment, the method for manufacturing an image sensor may further include a step of injecting impurities into the photoelectric conversion element 120 by an ion implantation process. Exemplarily, after the step S930 of FIG. 9 is performed, a step of injecting impurities into the photoelectric conversion element 120 of FIG. 11 by an ion implantation process may be performed. The first conductive type epitaxial layer 110a, the second conductive type photoelectric conversion element 120, and the second conductive type second epitaxial layer 130 may be formed on a silicon bulk, and the impurities may be injected into the photoelectric conversion element 120. However, in the method for manufacturing an image sensor, the order of the step of further injecting impurities into the photoelectric conversion element 120 by an ion implantation process is not necessarily limited thereto.

[0102] Impurities of the same conductivity type as the conductivity type of the photoelectric conversion element 120 formed by the epitaxial growth process may be further injected into the photoelectric conversion element 120. Impurities of a second conductivity type may be further injected into the photoelectric conversion element 120 by an ion implantation process. Exemplarily, N-type impurities may be further injected into the photoelectric conversion element 120, which is an N-type epitaxial layer, by the ion implantation process. By further injecting N-type impurities into the photoelectric conversion element 120, which is an N-type epitaxial layer, the impurity concentration of the photoelectric conversion element 120 may be more easily adjusted to a desired concentration.

[0103] As described above, the exemplary embodiment has been disclosed by the drawings and the specification. In this specification, specific terms are used to describe the present embodiment, but they are used only for the purpose of describing the technical idea of ​​the present disclosure, and are not used to limit the meaning or the scope of the present disclosure described in the claims. Therefore, a person having ordinary skill in the art will understand that various modifications and other equivalent embodiments are possible. Therefore, the true technical scope of protection of the present disclosure is defined by the technical idea of ​​the claims. [Explanation of symbols]

[0104] 1 Image sensor 10 Pixel Array 20 Row Driver 30 Readout circuit 31 Analog-to-digital conversion circuit 32 Data Bus 40 Ramp Signal Generator 50 Timing Controller 60 Signal Processing Section 100 Semiconductor substrate 110 First epitaxial layer 120 Photoelectric conversion element 130 Second epitaxial layer 201 1st color filter 202 2nd color filter 300 Lens Layers PX Pixels

Claims

1. 1. An image sensor including a plurality of pixels, Each of the plurality of pixels comprises: a first epitaxial layer disposed on a first surface of a semiconductor substrate and formed to have a first conductivity type by an epitaxial growth process; a photoelectric conversion element disposed on the first epitaxial layer and having a second conductivity type different from the first conductivity type; a second epitaxial layer disposed between the photoelectric conversion element and a second surface of the semiconductor substrate, the second epitaxial layer being formed to have the second conductivity type by the epitaxial growth process; the photoelectric conversion element is an epitaxial layer of the second conductivity type formed by the epitaxial growth process.

2. the photoelectric conversion element is an epitaxial layer having a first concentration of the second conductivity type, the second epitaxial layer is an epitaxial layer having a second concentration of the second conductivity type; The image sensor of claim 1 , wherein the first concentration is different from the second concentration.

3. The image sensor of claim 2 , wherein the first concentration is greater than the second concentration.

4. 2. The image sensor according to claim 1, wherein the photoelectric conversion element is formed by further implanting impurities of the second conductivity type by an ion implantation process.

5. 2. The image sensor of claim 1, wherein the second epitaxial layer is formed by further implanting impurities of the first conductivity type by an ion implantation process.

6. 6. The image sensor according to claim 5, wherein the second epitaxial layer is formed by the epitaxial growth step so as to have the same concentration of the second conductivity type as that of the photoelectric conversion element.

7. The image sensor of claim 1 , wherein the first conductivity type is P-type and the second conductivity type is N-type.

8. the first epitaxial layer is in contact with the photoelectric conversion element in a direction from the first surface of the semiconductor substrate toward the second surface of the semiconductor substrate; The image sensor of claim 1 , wherein the photoelectric conversion element contacts the second epitaxial layer in a direction from the first surface of the semiconductor substrate toward the second surface of the semiconductor substrate.

9. The image sensor according to claim 1 , further comprising an isolation film in the semiconductor substrate that separates at least a portion of the plurality of pixels.

10. The image sensor according to claim 9 , wherein the element isolation film penetrates the second epitaxial layer, the photoelectric conversion element, and the first epitaxial layer.

11. The image sensor according to claim 1 , wherein a size of the first epitaxial layer is smaller than a size of the photoelectric conversion element.

12. A pixel, a semiconductor substrate including a first side and a second side; a vertical transmission gate formed on the second surface of the semiconductor substrate; a floating diffusion region configured to accumulate photocharges generated from the semiconductor substrate through the vertical transmission gate; The semiconductor substrate is a first epitaxial layer disposed on the first surface of the semiconductor substrate and having a first conductivity type; a photoelectric conversion element in contact with the first epitaxial layer and formed by an epitaxial growth process in a direction from the first surface of the semiconductor substrate toward the second surface of the semiconductor substrate, the photoelectric conversion element having a second conductivity type different from the first conductivity type; a second epitaxial layer in contact with the photoelectric conversion element in a direction from the first surface of the semiconductor substrate toward the second surface of the semiconductor substrate, the second epitaxial layer having the second conductivity type.

13. The pixel according to claim 12 , wherein the photoelectric conversion element is formed by further implanting impurities of the second conductivity type by an ion implantation process after the epitaxial layer of the second conductivity type is formed by the epitaxial growth process.

14. The pixel of claim 12 , wherein a concentration of the second conductivity type of the photoelectric conversion element based on the epitaxial growth process is higher than a concentration of the second conductivity type of the second epitaxial layer based on the epitaxial growth process.

15. a concentration of the second conductivity type of the photoelectric conversion element based on the epitaxial growth process is equal to a concentration of the second conductivity type of the second epitaxial layer based on the epitaxial growth process; The pixel of claim 12 , wherein the second epitaxial layer is formed by further implanting impurities of the first conductivity type by an ion implantation process.

16. The semiconductor device further includes an isolation layer disposed on one side of the semiconductor substrate, The pixel of claim 12 , wherein the device isolation film extends from the second surface of the semiconductor substrate to the first surface of the semiconductor substrate and penetrates the second epitaxial layer, the photoelectric conversion element, and the first epitaxial layer.

17. 13. The pixel of claim 12, wherein at least a portion of the vertical transmission gate and at least a portion of the floating diffusion region are formed in the second epitaxial layer.

18. 1. An image sensor comprising: a color filter disposed on the first surface of the semiconductor substrate in a second direction opposite to a first direction from the first surface of the semiconductor substrate toward the second surface of the semiconductor substrate; a lens layer disposed on the color filter in the second direction; a first epitaxial layer disposed between the first surface and the second surface of the semiconductor substrate and disposed on the first surface of the semiconductor substrate in the first direction, the first epitaxial layer having a first conductivity type; a photoelectric conversion element disposed on the first epitaxial layer in the first direction, the photoelectric conversion element including an epitaxial layer having a second conductivity type; a second epitaxial layer disposed between the first surface and the second surface of the semiconductor substrate and disposed on the second surface of the semiconductor substrate in the second direction, the second epitaxial layer having a third conductivity type.

19. the first conductivity type is different from the second conductivity type; 20. The image sensor of claim 18, wherein the second conductivity type is the same as the third conductivity type.

20. the first conductivity type is different from the second conductivity type; 20. The image sensor of claim 18, wherein the third conductivity type is the same as the first conductivity type.

Images