WO2020186512A1 - Procédé de préparation de photodiode, photodiode et capteur d'image cmos - Google Patents

Procédé de préparation de photodiode, photodiode et capteur d'image cmos Download PDF

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Publication number
WO2020186512A1
WO2020186512A1 PCT/CN2019/079052 CN2019079052W WO2020186512A1 WO 2020186512 A1 WO2020186512 A1 WO 2020186512A1 CN 2019079052 W CN2019079052 W CN 2019079052W WO 2020186512 A1 WO2020186512 A1 WO 2020186512A1
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Prior art keywords
photoresist
shielding layer
thickness
predetermined position
layer
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Ceased
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PCT/CN2019/079052
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English (en)
Chinese (zh)
Inventor
姚国峰
沈健
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Shenzhen Goodix Technology Co Ltd
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Shenzhen Goodix Technology Co Ltd
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Priority to PCT/CN2019/079052 priority Critical patent/WO2020186512A1/fr
Priority to CN201980000504.4A priority patent/CN110088917B/zh
Publication of WO2020186512A1 publication Critical patent/WO2020186512A1/fr
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
    • H10F39/10—Integrated devices
    • H10F39/12—Image sensors
    • H10F39/18—Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
    • H10F30/20—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
    • H10F30/21—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
    • H10F39/80—Constructional details of image sensors
    • H10F39/803—Pixels having integrated switching, control, storage or amplification elements
    • H10F39/8033—Photosensitive area
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F71/00—Manufacture or treatment of devices covered by this subclass
    • H10F71/121—The active layers comprising only Group IV materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/10—Semiconductor bodies
    • H10F77/14—Shape of semiconductor bodies; Shapes, relative sizes or dispositions of semiconductor regions within semiconductor bodies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • This application relates to the technical field of image sensor manufacturing, and in particular to a method for manufacturing a photodiode, a photodiode, and a CMOS image sensor.
  • CMOS image Sensor is a sensor that can convert incident light signals into electrical signals, and is widely used in smart phones, digital cameras, driving recorders, and security monitoring equipment.
  • the CMOS image sensor is composed of multiple pixel units, that is, a pixel array, and each pixel unit corresponds to at least one photodiode.
  • the working principle of the CMOS image sensor is: when light is irradiated to the pixel unit of the image sensor, the photodiode corresponding to the pixel unit generates a corresponding amount of electric charge according to the incident light intensity. These electric charges are transferred to the pixel unit after analog-to-digital conversion and signal processing. The corresponding chromaticity is output at the corresponding position, and the images corresponding to all pixel units are added together to obtain the overall image.
  • the full well capacity refers to the maximum amount of charge that each pixel unit can store. Since the charge is mainly stored in the depletion area of the photodiode, an important factor in determining the full well capacity is the area of the photodiode.
  • the area of the photodiode corresponding to the pixel unit also decreases, resulting in a decrease in the full well capacity.
  • the low full well capacity will reduce the dynamic range of the detectable light of the pixel unit, which will seriously reduce the quality of the image.
  • the method of increasing the doping concentration of the photodiode is adopted to increase the full well capacity.
  • this method will make it difficult to deplete the carriers in the central area of the photodiode, so that there are carriers remaining, making it difficult for the pixel unit to transfer all the carriers when outputting an image, resulting in a decline in the quality of the output image, such as image smearing , Excessive dark current or white spots.
  • the present application provides a method for manufacturing a photodiode, a photodiode, and a CMOS image sensor, which increase the contact area between a substrate with a first doping type and a region with a second doping type, and improve the full well capacity of the photodiode .
  • the first aspect of the present application provides a method for manufacturing a photodiode, including:
  • a shielding layer is formed on a substrate, the substrate has a first doping type, a preset position is provided on the substrate, and the preset position is a position where the doping type is the second doping type.
  • the first doping type is different from the second doping type, the shielding layer is used to shield ions injected into the substrate, and the shielding strength of the shielding layer is related to the thickness of the shielding layer;
  • the method further includes:
  • the photoresist layer is processed, the thickness of the photoresist layer above the preset position is less than the thickness of the photoresist layer above the preset position, and the photoresist layer above the preset position
  • the surface is curved;
  • the processing the shielding layer includes:
  • the etching process is performed on the photoresist layer.
  • the processing the shielding layer includes:
  • the photoresist layer is processed.
  • processing the photoresist layer includes:
  • the photoresist in the photoresist layer is a positive photoresist
  • the light transmittance of the gray-scale mask above the predetermined position is greater than that of the gray mask above the predetermined position
  • the transmittance of the gray-scale mask, and the difference in the transmittance of the gray-scale mask above the predetermined position is negatively related to the thickness of the photoresist above the predetermined position; if said If the photoresist in the photoresist layer is a negative photoresist, the light transmittance of the gray-scale mask above the preset position is smaller than that of the gray-scale mask located above the non-predetermined position.
  • the light transmittance of the film plate, the light transmittance of the gray-scale mask above the predetermined position is proportional to the thickness of the photoresist above the predetermined position.
  • processing the photoresist layer includes:
  • the photoresist in the photoresist layer is a positive photoresist
  • direct-write photolithography is used to perform photolithography processing on the photoresist layer
  • the photolithography intensity above the preset position Is greater than the lithography intensity above the predetermined position, the difference in the lithography intensity above the predetermined position is negatively related to the thickness of the photoresist above the predetermined position; if the photoresist in the photoresist layer If the resist is a negative photoresist, the lithography intensity above the predetermined position is less than the lithography intensity above the predetermined position, and the lithography intensity above the predetermined position is the same as that above the predetermined position.
  • the thickness of the photoresist is positively correlated.
  • processing the photoresist layer includes:
  • the photoresist layer is imprinted by nanoimprinting, the imprinting depth above the preset position is greater than the imprinting depth above the preset position, and the imprinting depth above the preset position is greater than the imprinting depth above the preset position.
  • the thickness of the photoresist above the preset position is negatively correlated.
  • the processing the shielding layer includes:
  • the masking layer is imprinted by nanoimprinting, the imprinting depth above the preset position is greater than the imprinting depth above the preset position, and the imprinting depth above the preset position is greater than the imprinting depth above the preset position. It is assumed that the thickness of the photoresist above the position is negatively correlated.
  • the upper surface of the shielding layer is a spherical coronal curved surface or a comb-shaped curved surface.
  • the second aspect of the present application provides a photodiode, including:
  • a third aspect of the present application provides a CMOS image sensor, including: at least one photodiode as described in the second aspect.
  • the present application provides a method for manufacturing a photodiode, a photodiode, and a CMOS image sensor.
  • the method includes: forming a shielding layer on a substrate, the substrate has a first doping type, and a preset position is provided on the substrate.
  • the doping type is different from the second doping type; the shielding layer is processed, the thickness of the shielding layer above the preset position is smaller than the thickness of the shielding layer above the non-preset position, and the upper surface of the shielding layer above the preset position is curved Ion implantation to the substrate, so that the implanted ions form a region with a curved bottom surface and a second doping type to increase the contact area between the substrate and the region; remove the shielding layer to obtain a photodiode.
  • the application increases the contact area between the substrate with the first doping type and the region with the second doping type, and improves the full well capacity.
  • Fig. 1 is a schematic diagram 1 of a photodiode in the prior art
  • Figure 2 is a second schematic diagram of a photodiode in the prior art
  • Fig. 3 is a third schematic diagram of a photodiode in the prior art
  • FIG. 4 is a schematic diagram 1 of the process of manufacturing a photodiode provided by this application.
  • FIG. 5 is a schematic diagram 1 of the manufacturing process of the photodiode provided by this application.
  • Figure 6 is a schematic diagram of the imprint mold provided by this application.
  • FIG. 7 is a schematic diagram 2 of the process of manufacturing a photodiode provided by this application.
  • FIG. 8 is a second schematic diagram of the manufacturing process of the photodiode provided by this application.
  • FIG. 1 is a schematic diagram 1 of a photodiode in the prior art.
  • the photodiode forms an n-type doped region 101 on the p-type substrate 100
  • the depletion region of the photodiode is the contact area between the p-type substrate 100 and the n-type doped region 101, as shown in the figure.
  • the 103 is shown.
  • the area of the photodiode corresponding to the pixel unit also decreases.
  • the area of the depletion region in the photodiode is also reduced, resulting in a reduction in the full well capacity, thereby causing a problem of deterioration of image quality. It is worth noting that the schematic diagrams of the photodiodes shown in this application are all side views.
  • the method of increasing the doping concentration of the photodiode is used to increase the full well capacity.
  • this method may cause problems such as image smearing, excessive dark current, or white spots.
  • FIG. 2 is a second schematic diagram of a photodiode in the prior art.
  • the way to form a photodiode with multiple npn junctions is: inserting the p-type doped region 202 into the n-type doped region 101 to form a U-shaped structure, which can make the photodiode generate additional consumption. Exhaust areas 203a and 203b. Compared with FIG. 1, the area of the depletion region of the photodiode is increased, and the full well capacity of the photodiode is improved.
  • FIG. 3 is a third schematic diagram of a photodiode in the prior art. As shown in FIG. 3, by forming a deeper n-type doped region 302 under the n-type doped region 101, an additional depletion region 303 can be generated in the photodiode to increase the full well capacity.
  • the structure of the photodiode in FIGS. 2 and 3 formed by the above method does not affect the quality of the output image, the two methods require multiple ion implantation steps on the substrate, and the process is complicated.
  • the present application provides a method for manufacturing a photodiode. Not only can the area of the depletion region of the photodiode be increased, but also only one ion implantation is used, and the process is simple.
  • FIG. 4 is a schematic flow chart 1 of the method for manufacturing a photodiode provided by this application.
  • the execution subject of the method flow shown in FIG. 4 may be a photodiode manufacturing device.
  • the photodiode manufacturing method provided in this embodiment may include:
  • the shielding layer is used to shield the ions injected into the substrate, and the shielding strength of the shielding layer is related to the thickness of the shielding layer.
  • the photodiode preparation device in this embodiment can be a device that integrates coating, photolithography, etching, ion implantation and other functions into one, which can realize the formation of the shielding layer of the substrate and the coating of the photoresist layer. The process of cloth and so on. It can also be a device that integrates multiple modules that realize multiple functions such as coating, photolithography, etching, and ion implantation.
  • the photodiode in this embodiment may be a photodiode in a CMOS image sensor.
  • a substrate with the first doping type is provided.
  • the substrate may be a silicon wafer or epitaxial silicon grown on the silicon wafer.
  • the first doping type may be p-type doping or n-type doping.
  • a preset position is provided on the substrate, and the preset position is a position where the doping type is the second doping type, wherein ions with the second doping type are injected into the substrate at the preset position, and the substrate A region with the second doping type is formed in the bottom.
  • the first doping type is different from the second doping type, and the area where the area with the second doping type is in contact with the substrate is the depletion area.
  • the shielding layer is used to shield the ions injected into the substrate, and the shielding strength of the shielding layer is related to the thickness of the shielding layer. The greater the thickness of the shielding layer, the stronger the shielding strength for ions. Since a preset position is provided on the substrate, the preset position is a position where a region with the second doping type is formed after ion implantation; the non-preset position is a position where the first doping type of the substrate is maintained after ion implantation.
  • the shielding layer in this embodiment can be, but is not limited to, a photoresist layer formed of photoresist, a silicon dioxide layer formed of silicon dioxide, or PDMS formed of polydimethylsiloxane (PDMS). Floor.
  • FIG. 5 is a schematic diagram 1 of the manufacturing process of the photodiode provided by this application.
  • a shielding layer 501 is formed on the substrate 100, wherein the position between A and B of the substrate is a preset position of the substrate.
  • the shielding layer 501 has the same thickness for illustration. It is conceivable that the shielding layer 501 formed on the substrate 100 in this embodiment may have different thicknesses.
  • S402 Process the shielding layer so that the thickness of the shielding layer above the preset position is smaller than the thickness of the shielding layer above the non-preset position, and the upper surface of the shielding layer above the preset position is a curved surface.
  • the preset position is a position where a region with the second doping type is formed after ion implantation
  • the non-preset position is a position where the first doping type of the substrate is maintained after ion implantation, under the premise of the same ion implantation energy .
  • the thickness of the shielding layer above the preset position needs to be smaller than the thickness of the shielding layer above the non-preset position. Only in this way, the shielding layer above the non-preset position can effectively shield the ion implantation into the substrate.
  • the upper surface of the shielding layer above the preset position is a curved surface.
  • the curved surface is not limited to a spherical crown curved surface or a comb-like curved surface; the spherical crown curved surface may be a spherical crown convex surface or a spherical crown concave surface.
  • the processing method for the shielding layer in this embodiment can be different according to the shielding layer.
  • the thickness of the shielding layer above the preset position can be obtained by nanoimprinting less than the shielding layer above the non-preset position.
  • the thickness of the layer, and the upper surface of the shielding layer above the preset position is a curved photoresist layer. In order to make the thickness of the photoresist layer above the non-predetermined position greater than the thickness of the photoresist layer above the preset position, and the upper surface of the photoresist layer above the preset position is curved.
  • the negative correlation between the embossing depth at the preset position and the thickness of the photoresist above the preset position means that the greater the thickness of the photoresist above the preset position, the smaller the embossing depth.
  • Fig. 6 is a schematic diagram of the imprinting mold provided by this application. As shown in FIG. 6, the positions on both sides of the imprinting mold correspond to non-preset positions on the substrate, and the position in the middle of the imprinting mold corresponds to the preset position on the substrate. It can be seen that the imprint depth on both sides of the imprint mold is smaller than the imprint depth in the middle of the imprint mold, and the imprint depth in the middle of the imprint mold is set according to the shape of the finally formed curved surface.
  • Fig. 6 exemplarily shows that the pattern on the imprint mold corresponding to the preset position on the substrate is comb-shaped. It is conceivable that the embossing depth at the position of the protruding teeth in the comb tooth shape is smaller than the embossing depth at the position of the recessed teeth on the imprinting mold.
  • the pattern on the imprinting mold can be transferred to the photoresist layer by means of nanoimprinting, and the shielding layer can be obtained.
  • the thickness of the photoresist layer 5011b above the non-preset position is greater than the thickness of the photoresist layer 5011a above the preset position, and the thickness of the photoresist layer 5011a above the preset position
  • the upper surface is a curved photoresist layer.
  • the thickness of the masking layer above the preset position can be directly obtained by the method of nanoimprinting, which is less than the thickness of the masking layer above the non-predetermined position, and above the preset position
  • the upper surface of the shielding layer is a curved shielding layer.
  • the shielding layer can be obtained by etching, photolithography, etc. in the prior art, which will not be repeated here.
  • ion implantation is performed on the substrate through the shielding layer.
  • the implanted ions have the second doping type.
  • the shielding layer above the non-predetermined area can completely shield the implanted ions, so that the ions implanted at the non-predetermined position do not enter the substrate. Since the thickness of the shielding layer above the preset area is less than the thickness of the shielding layer, the injected ions can penetrate the shielding layer and enter the substrate, starting from the inner surface above the substrate, extending downward to form a second doping type area.
  • the shielding strength for the implanted ions is different.
  • the shielding strength of the shielding layer is related to the thickness of the shielding layer, the lower surface of the region with the second doping type is also a curved surface, and the curved surface has the same shape as the curved surface of the upper surface of the shielding layer above the preset position.
  • the lower surface of the region with the second doping type formed in this embodiment is a curved surface, and has a larger contact area with the substrate, and therefore has a larger area of depletion region than in the prior art.
  • the lower surface of the region with the second doping type as shown in FIG. 1 is a plane parallel to the horizontal plane, and its depletion region is shown by the depletion region in the dashed frame.
  • the region 502 with the second doping type formed in the substrate in this embodiment is shown in c in FIG. 5, and the lower surface of the region is comb-shaped, compared to the lower surface of the region in FIG. 1, It has a larger contact area with the substrate.
  • the area in the dashed frame in c in FIG. 5 is the depletion area.
  • the shielding layer can be removed by an etching method to obtain a photodiode with a larger depletion region.
  • the present application removes the photoresist layer to obtain a substrate 100 having the first doping type, and forming a comb-shaped lower surface with a second doping type Of the photodiode in the area 502.
  • the photoresist above the preset position area can be further etched so that the thickness of the photoresist 5011a above the preset position area is lithographically 0, such as As shown in e in Figure 5.
  • the manufacturing method of the photodiode provided in this embodiment includes: forming a shielding layer on a substrate, the substrate has a first doping type, a preset position is provided on the substrate, the first doping type and the second doping type Different; the shielding layer is processed so that the thickness of the shielding layer above the preset position is smaller than the thickness of the shielding layer above the non-preset position, and the upper surface of the shielding layer above the preset position is curved; ion implantation is performed on the substrate, The implanted ions form a region with a curved bottom surface and the second doping type to increase the contact area between the substrate and the region, remove the shielding layer, and obtain a photodiode.
  • the contact area between the substrate with the first doping type and the region with the second doping type is increased, that is, it increases.
  • the area of the depletion region increases the full well capacity.
  • the processing method for the shielding layer in this application is different.
  • the processing method of the shielding layer will be described in accordance with the characteristics of the shielding layer. Specifically, the method of processing the shielding layer will be explained mainly based on the hardness characteristics of the shielding layer.
  • the photodiode manufacturing device in this embodiment stores a preset hardness, and the hardness of the shielding layer can be input to the photodiode manufacturing device before the photodiode is manufactured, so that the photodiode manufacturing device can obtain the hardness of the shielding layer.
  • the material of the shielding layer is a material with a hardness less than or equal to the preset hardness.
  • the material of the shielding layer can be, but is not limited to, photoresist or polydimethylsiloxane. Since the hardness of the masking layer is relatively small, the masking layer can be imprinted by nano-imprinting. The embossing depth above the preset position is greater than the embossing depth above the non-preset position, and the embossing depth above the preset position is negatively related to the thickness of the photoresist above the preset position.
  • the thickness of the imprint mold above the preset position is greater than the thickness of the imprint mold above the non-preset position, and the thickness of the imprint mold above the preset position is negatively related to the thickness of the photoresist above the preset position. Exemplarily, it may be as shown in FIG. 6.
  • processing the shielding layer is processing the photoresist layer.
  • the photoresist layer is processed, in addition to the nanoimprinting method described above, the photoresist layer may also be processed by variable dose photolithography.
  • a gray-scale mask is placed on the photoresist layer, and the photoresist layer is exposed.
  • the transmittance of the gray-scale mask above the preset position is greater than the transmittance of the gray-scale mask located above the non-preset position, and the transmittance of the gray-scale mask above the preset position is higher than that of the preset position. It is assumed that the thickness of the photoresist above the position is negatively correlated. For example, the greater the light transmittance of the gray mask above the preset position, the smaller the thickness of the photoresist above the preset position, and vice versa, the greater the thickness of the photoresist above the preset position.
  • the transmittance of gray-scale masks can be between 0% and 100% Arbitrary setting, that is, when the photoresist is exposed, the exposure dose is adjustable, and the size of the exposure dose determines the thickness of the photoresist after development.
  • the photoresist can be divided into positive photoresist and negative photoresist according to the development characteristics of the photoresist.
  • the photoresist in the photoresist layer is a positive photoresist
  • the light transmittance of the gray mask above the preset position is greater than that of the gray mask located above the non-preset position
  • the exposure dose of the photoresist above the preset position is greater than the exposure dose of the photoresist above the non-preset position, that is, the thickness of the photoresist above the preset position can be made smaller than the photoresist above the non-preset position The thickness of the glue.
  • the transmittance of the gray-scale mask above the preset position is negatively related to the thickness of the photoresist above the preset position, that is, the exposure dose of the photoresist above the preset position and the photoresist above the preset position
  • the thickness is negatively related, that is, the larger the exposure dose, the smaller the thickness of the photoresist above the preset position, so that the upper surface of the photoresist above the preset position is curved.
  • the photoresist in the photoresist layer is a negative photoresist
  • the light transmittance of the gray-scale mask above the preset position is smaller than that of the gray-scale mask located above the non-preset position.
  • the light rate is such that the exposure dose of the photoresist above the preset position is less than the exposure dose of the photoresist above the non-predetermined position, that is, the thickness of the photoresist above the preset position can be made smaller than the light The thickness of the resist.
  • the light transmittance of the gray mask above the preset position is positively related to the thickness of the photoresist above the preset position, that is, the exposure dose of the photoresist above the preset position and the photoresist above the preset position
  • the thickness is positively correlated, that is, the greater the exposure dose, the greater the thickness of the photoresist above the preset position, so that the upper surface of the photoresist above the preset position is a curved surface.
  • the photoresist can be divided into positive photoresist and negative photoresist according to the development characteristics of the photoresist.
  • direct writing lithography can be used to perform photolithography processing on the photoresist layer.
  • the photolithography intensity above the preset position is greater than the photolithography intensity above the non-predetermined position, and the photolithography intensity above the preset position is equal to the preset
  • the thickness of the photoresist above the position is negatively correlated, that is, the greater the photolithography intensity, the smaller the thickness of the photoresist above the preset position.
  • Direct-write lithography can directly change the intensity or energy of the laser or electron beam in the micro area, thereby changing the exposure dose, and then achieving the same effect as the gray-scale mask mentioned above, that is, obtaining the thickness of the photoresist above the preset position It is less than the thickness of the photoresist above the non-predetermined position, and the upper surface of the photoresist above the preset position is curved.
  • the photoresist in the photoresist layer is negative photoresist
  • the photolithography intensity above the preset position is less than the photolithography intensity above the non-predetermined position
  • the photolithography intensity above the preset position is compared with the It is assumed that the thickness of the photoresist above the position is positively correlated.
  • the material of the shielding layer is a material with a hardness greater than the preset hardness
  • the material of the shielding layer may be but not limited to silicon dioxide. Due to the high hardness of silica, it cannot be directly processed by nanoimprinting.
  • FIG. 7 is a description of the method for manufacturing the photodiode provided by the application Flow chart two, as shown in FIG. 7, the manufacturing method of the photodiode provided in this embodiment may include:
  • the hardness of the shielding layer is greater than the preset hardness, a photoresist layer needs to be formed on the shielding layer.
  • the method of forming the photoresist layer may be to coat photoresist on the shielding layer to obtain the photoresist layer. .
  • S703 Process the photoresist layer so that the thickness of the photoresist layer above the preset position is smaller than the thickness of the photoresist layer above the non-preset position, and the upper surface of the photoresist layer above the preset position is curved .
  • variable-dose lithography can be used, such as setting a gray-scale mask or using direct-write lithography to process the photoresist layer to obtain that the thickness of the photoresist layer above the preset position is less than the non-preset
  • the thickness of the photoresist layer above the position, and the upper surface of the photoresist layer above the preset position is a curved photoresist layer.
  • nanoimprinting can also be used to imprint the photoresist layer to obtain that the thickness of the photoresist layer above the preset position is less than the thickness of the photoresist layer above the non-preset position
  • the thickness of the adhesive layer, the upper surface of the photoresist layer above the preset position is a curved photoresist layer.
  • FIG. 8 is a second schematic diagram of the manufacturing process of the photodiode provided by this application.
  • a silicon dioxide layer 5012 is formed on the substrate 100, and a photoresist layer 5011 is formed on the silicon dioxide layer 5012.
  • the photoresist layer 5011 is processed.
  • the thickness of the photoresist layer 5011a above the preset position is smaller than the thickness of the photoresist layer 5011b above the non-predetermined position, and the upper surface of the photoresist layer 5011a above the preset position is spherical.
  • the shape of the photoresist layer can be transferred to the shielding layer by etching the photoresist layer.
  • the thickness of the silicon dioxide layer 5012a above the preset position is smaller than the thickness of the silicon dioxide layer 5012b above the non-preset position, and
  • the upper surface of the silicon dioxide layer 5012a above the preset position is a spherical crown.
  • the thickness of the photoresist layer 5011b above the non-predetermined position is large, after the photoresist layer is etched, a part of the photoresist layer 5011b may remain.
  • S705 Perform ion implantation on the substrate through the shielding layer, so that the implanted ions form a region with a curved lower surface and a second doping type.
  • the lining can be A region 802 with the second doping type whose lower surface is curved is obtained from the bottom. Since the lower surface is a curved surface, under the same other conditions, compared to the area with the second doping type in FIG. 1, the contact surface of the substrate and the area 802 increases, and the depletion area of the photodiode increases. This increases the full well capacity of the photodiode.
  • the dashed frame in d in Figure 8 is the depletion zone.
  • the shielding layer is removed. If there is an unetched photoresist layer, it can also be removed together to obtain the photoelectricity of the second doping type region 802 with a curved bottom surface. diode.
  • a photoresist layer can be formed on the shielding layer, and a variable dose photolithography or nanoimprint method is used to obtain a curved surface above the preset position.
  • the photoresist layer is then etched to obtain a curved shielding layer above the preset position, and then ion implantation is used to form a second doping type region with a curved bottom surface in the substrate, which increases the photodiode’s
  • the depletion region increases, thereby increasing the full well capacity of the photodiode.
  • This application also provides a photodiode, as shown in d in FIG. 5 or e in FIG. 8, the photodiode includes:
  • the photodiode in this embodiment is prepared by the above-mentioned photodiode manufacturing method. Since the lower surface of the region with the second doping type in the substrate in the photodiode is curved, the depletion region in the photodiode is increased The area improves the full well capacity of the photodiode.
  • the application also provides a CMOS image sensor.
  • the CMOS image sensor includes at least one photodiode manufactured by the photodiode manufacturing method in the foregoing embodiment.
  • CMOS image sensor provided by the present application has the same technical effects as the manufacturing method of the photodiode in the foregoing embodiment, and will not be repeated here.
  • a person of ordinary skill in the art can understand that all or part of the steps in the foregoing method embodiments can be implemented by a program instructing relevant hardware.
  • the aforementioned program can be stored in a computer readable storage medium.
  • the steps including the foregoing method embodiments are executed; and the foregoing storage medium includes: ROM, RAM, magnetic disk, or optical disk and other media that can store program codes.

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  • Solid State Image Pick-Up Elements (AREA)

Abstract

La présente invention concerne un procédé de préparation de photodiode, une photodiode et un capteur d'image à semi-conducteur métal-oxyde complémentaire (CMOS), ledit procédé consistant à : former une couche de masquage sur un substrat, le substrat ayant un premier type de dopant, le substrat étant pourvu d'une position prédéfinie, le premier type de dopant et le second type de dopant étant différents ; traiter une couche de masquage, de telle sorte que l'épaisseur de la couche de masquage au-dessus de la position prédéfinie est inférieure à l'épaisseur de la couche de masquage au-dessus de la position non prédéfinie ; réaliser une implantation ionique sur le substrat de telle sorte que les ions implantés forment une région ayant une surface inférieure incurvée et un second type de dopant de façon à augmenter la zone de contact entre le substrat et la région ; retirer la couche de masquage pour obtenir une photodiode. La présente invention augmente les zones de contact entre le substrat et le premier type de dopant et entre la région et le second type de dopant, améliorant la capacité de puits complet.
PCT/CN2019/079052 2019-03-21 2019-03-21 Procédé de préparation de photodiode, photodiode et capteur d'image cmos Ceased WO2020186512A1 (fr)

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CN201980000504.4A CN110088917B (zh) 2019-03-21 2019-03-21 光电二极管的制备方法、光电二极管和cmos图像传感器

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CN121463734B (zh) * 2026-01-08 2026-04-10 上海邦芯半导体科技有限公司 一种半导体结构及其制作方法

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