Image sensor and preparation method thereof

Abstract

The invention relates to an image sensor and a preparation method thereof. The image sensor comprises a substrate, photosensitive elements arranged in an array, a filter layer, a micro-lens layer and an anti-reflection layer, the photosensitive elements are located above the substrate, the filter layer is located above the photosensitive elements, the filter layer comprises a first filter unit and a second filter unit, the first filter unit is used for transmitting light in a first wave band range, and the second filter unit is used for transmitting light in a second wave band range. The first filtering unit is used for transmitting light in a first wave band range, the second filtering unit is used for transmitting light in a second wave band range, the micro lens layer is located above the filtering layer and comprises a first micro lens and a second micro lens, the first micro lens is located above the first filtering unit, the second micro lens is located above the second filtering unit, and the anti-reflection layer is located above the first micro lens. According to the invention, the anti-reflection layer can be prepared above one or a part of filtering units in the filtering layer in a targeted manner, and the optical efficiency of one or a part of filtering units is independently improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an image sensor and a preparation method thereof. Background Art

[0002] In the related art, image sensors, such as complementary metal oxide semiconductor image sensors (CMOS image sensors, CIS) and charge coupled device (CCD) image sensors, generally use a series of photodiodes formed in an array of pixel regions of a semiconductor substrate to sense when light impacts the photodiodes. Complementary metal oxide semiconductor image sensors can generally be formed in either a front side illumination group or a back side illumination group. In the front side illumination group, light is incident from the "front" side of the image sensor and is transmitted to the photodiode through the transfer transistor formed thereon. In the back side illumination group, the transfer transistor, metal layer and dielectric layer are formed on the back side of the substrate, the photodiode is formed on the front side, and the light is allowed to pass from the "back" side of the substrate to the photodiode so that the light hits the photodiode before it reaches the transfer transistor, dielectric layer, or metal layer. CIS may include color filters, microlenses, and anti-reflection coatings (ARCs) that allow light of different wavelengths and more light to reach the photodiode.

[0003] The conventional practice of adding an anti-reflective coating above the microlens is to deposit an anti-reflective film on the microlens through a chemical vapor deposition device. This film can slightly increase the transmittance of light in each pixel and reduce the reflection of light to improve the optical efficiency of the overall pixel.

[0004] However, in some application scenarios, for example, the optical quantum efficiency of the green filter film and the blue filter film in the color filter is higher, and the quantum efficiency of the red filter film is lower. Depositing an anti-reflection layer thin film on the microlens will cause image problems such as inaccurate image color, color imbalance, decreased red image signal-to-noise ratio, and imbalanced brightness and contrast. Summary of the invention

[0005] The purpose of the present application is to provide an image sensor and a preparation method thereof, which can specifically prepare an anti-reflection layer above a certain filter unit or a certain part of the filter layer, and can individually improve the optical efficiency of a certain filter unit or a certain part of the filter unit, thereby improving the color accuracy of the collected image, avoiding color imbalance, improving the signal-to-noise ratio of the image, and avoiding the problem of imbalance in brightness and contrast of the image.

[0006] According to a first aspect of an embodiment of the present application, there is provided an image sensor, including: substrate; Photosensitive elements arranged in an array are located above the substrate; A filter layer is located above the photosensitive element; the filter layer includes a first filter unit and a second filter unit, the first filter unit is used to transmit light within a first wavelength range, and the second filter unit is used to transmit light within a second wavelength range; a microlens layer, located above the filter layer; the microlens layer comprises a first microlens and a second microlens, the first microlens is located above the first filter unit, and the second microlens is located above the second filter unit; The anti-reflection layer is located above the first microlens and is used to reduce the reflectivity of the light within the first wavelength band.

[0007] In one embodiment, the first filter unit is adjacent to the second filter unit; and there is no overlapping interval between the first wavelength band range and the second wavelength band range.

[0008] In one embodiment, the image sensor further includes: an adhesion layer, the adhesion layer being located above the microlens layer; The adhesive layer includes a first adhesive film and a second adhesive film, the first adhesive film is located above the first microlens, the second adhesive film is located above the second microlens, and the anti-reflection layer is located above the first adhesive film.

[0009] In one embodiment, the material of the anti-reflection layer includes silicon dioxide.

[0010] In one embodiment, the first filter unit is a red filter unit for transmitting red light, and the second filter unit includes a green filter unit and a blue filter unit, the green filter unit is for transmitting green light, and the blue filter unit is for transmitting blue light; or The first filter unit is a green filter unit for transmitting green light, the second filter unit includes a red filter unit and a blue filter unit, the red filter unit is for transmitting red light, and the blue filter unit is for transmitting blue light; or The first filter unit is a blue filter unit for transmitting blue light. The second filter unit includes a red filter unit and a green filter unit. The red filter unit is for transmitting red light, and the green filter unit is for transmitting green light.

[0011] According to a second aspect of an embodiment of the present application, a method for preparing an image sensor is provided, comprising: A semiconductor device is provided, the semiconductor device comprising a substrate, array-arranged photosensitive elements, a filter layer and a microlens layer, the photosensitive elements are located above the substrate, the filter layer is located above the photosensitive elements, the filter layer comprises a first filter unit and a second filter unit, the first filter unit is used to transmit light within a first wavelength range, and the second filter unit is used to transmit light within a second wavelength range; the microlens layer is located above the filter layer; the microlens layer comprises a first microlens and a second microlens, the first microlens is located above the first filter unit, and the second microlens is located above the second filter unit; forming a sacrificial material layer, wherein the sacrificial material layer is located above the microlens layer; forming a sacrificial layer opening on the sacrificial material layer to obtain a sacrificial layer; the sacrificial layer opening is used to expose the first microlens; forming an anti-reflection material layer, wherein the anti-reflection material layer comprises an anti-reflection layer and an anti-reflection film layer to be removed, wherein the anti-reflection film layer to be removed is located above the sacrificial layer, and the anti-reflection layer is located above the first microlens; The sacrificial layer and the anti-reflection film layer to be removed are peeled off to obtain the image sensor.

[0012] In one embodiment, before forming the sacrificial material layer, the method further comprises: forming an adhesive layer above the microlens layer; the adhesive layer comprises a first adhesive film, and the first adhesive film is located above the first microlens; The forming of the sacrificial material layer comprises: forming the sacrificial material layer above the adhesion layer; After forming a sacrificial layer opening on the sacrificial material layer, the sacrificial layer opening is used to expose the first adhesive film; After the anti-reflection material layer is formed, the anti-reflection layer is located above the first adhesive film, and the anti-reflection film layer to be removed is located above the sacrificial layer.

[0013] In one embodiment, the material of the sacrificial material layer includes photoresist; The step of forming a sacrificial layer opening on the sacrificial material layer to obtain a sacrificial layer comprises: A sacrificial layer opening is formed on the sacrificial material layer by adopting a photolithography process to obtain the sacrificial layer.

[0014] In one embodiment, the sacrificial material layer has a thickness of 4-8 microns.

[0015] In one embodiment, the step of stripping the sacrificial layer and the anti-reflection film layer to be removed to obtain the image sensor includes: The sacrificial layer and the anti-reflection film layer to be removed are peeled off by using a film stripping process to obtain the image sensor.

[0016] In one embodiment, the first filter unit is a red filter unit for transmitting red light, and the second filter unit includes a green filter unit and a blue filter unit, the green filter unit is for transmitting green light, and the blue filter unit is for transmitting blue light; or The first filter unit is a green filter unit for transmitting green light, the second filter unit includes a red filter unit and a blue filter unit, the red filter unit is for transmitting red light, and the blue filter unit is for transmitting blue light; or The first filter unit is a blue filter unit for transmitting blue light. The second filter unit includes a red filter unit and a green filter unit. The red filter unit is for transmitting red light, and the green filter unit is for transmitting green light.

[0017] Compared with the prior art, the beneficial effects of the present application are as follows: the image sensor comprises a substrate, array-arranged photosensitive elements, a filter layer, a microlens layer and an anti-reflection layer, the array-arranged photosensitive elements are located above the substrate, the filter layer is located above the array-arranged photosensitive elements, the filter layer comprises a first filter unit and a second filter unit, the first filter unit is used to transmit light in a first wavelength range, the second filter unit is used to transmit light in a second wavelength range, the microlens layer is located above the filter layer, the microlens layer comprises a first microlens and a second microlens, the first microlens is located above the first filter unit, the second microlens is located above the second filter unit, the anti-reflection layer is located above the first microlens, and is used to reduce the reflection of the light in the first wavelength range. The anti-reflection layer can reduce the reflectivity of the light in the first wavelength range and improve the transmittance of the light in the first wavelength range. Therefore, the optical efficiency of the first filter unit can be improved, and then the optical efficiency of the photosensitive element for sensing the light in the first wavelength range can be improved. That is, the anti-reflection layer can be prepared on one or part of the filter units in the filter layer in a targeted manner, and the optical efficiency of one or part of the filter units can be improved separately, so as to improve the color accuracy of the collected image, avoid color imbalance, improve the signal-to-noise ratio of the image, and avoid the problem of imbalance in brightness and contrast of the image.

[0018] Moreover, a sacrificial material layer is formed above the microlens layer, and a sacrificial layer opening is formed on the sacrificial material layer to obtain a sacrificial layer, wherein the sacrificial layer opening is used to expose the first microlens, and then an anti-reflection material layer is formed, wherein the anti-reflection material layer includes an anti-reflection layer and an anti-reflection film layer to be removed, the anti-reflection film layer to be removed is located above the sacrificial layer, and the anti-reflection layer is located above the first microlens, and finally, the anti-reflection film layer to be removed is peeled off together by peeling off the sacrificial layer, so that the anti-reflection layer is prepared only above the first filter unit, that is, the anti-reflection layer can be prepared specifically above one or part of the filter units in the filter layer, and the optical efficiency of one or part of the filter units can be improved separately, thereby improving the color accuracy of the collected image, avoiding color imbalance, improving the signal-to-noise ratio of the image, and avoiding the problem of brightness and contrast imbalance of the image. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The figure is a schematic diagram showing the structure of an image sensor according to an exemplary embodiment.

[0020] Figure 2 is a schematic structural diagram of an image sensor according to another exemplary embodiment.

[0021] Figure 3 is a schematic structural diagram of an image sensor according to another exemplary embodiment.

[0022] Figure 4 is a schematic structural diagram of an image sensor according to another exemplary embodiment.

[0023] Figure 5 is a schematic structural diagram of an image sensor according to another exemplary embodiment.

[0024] Figure 6 The figure is a flow chart of a method for manufacturing an image sensor according to an exemplary embodiment.

[0025] Figures 7 and 8 The figure is a schematic structural diagram of a semiconductor device according to an exemplary embodiment.

[0026] Fig. 9 The figure is a schematic diagram of the structure of an image sensor in the related art.

[0027] Figure 10-12 Schematic diagram of the intermediate structure produced during the preparation process of the image sensor. DETAILED DESCRIPTION

[0028] Unless otherwise defined, the technical terms or scientific terms used in this specification and claims shall have the usual meanings understood by persons with ordinary skills in the technical field to which the invention belongs. The specific embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be noted that in the specific description of these embodiments, in order to provide a concise description, it is impossible for this specification to provide a detailed description of all the features of the actual embodiments. Without departing from the spirit and scope of the present invention, those skilled in the art may modify and replace the embodiments of the present invention, and the resulting embodiments are also within the scope of protection of the present invention.

[0029] In the related technology, in a complementary metal oxide semiconductor image sensor, when the filter layer adopts the bayer pattern (Bayer array, a color filter matrix), the optical quantum efficiency of the green filter unit and the blue filter unit is higher, and the quantum efficiency of the red filter unit is lower, which will cause image problems such as inaccurate color, color imbalance, reduced signal-to-noise ratio of the red image, and imbalance in brightness and contrast of the image captured by the image sensor.

[0030] In order to solve the above technical problems, the present application proposes an image sensor and a preparation method thereof, which can specifically prepare an anti-reflection layer above one or a part of the filter units in the filter layer, and can individually improve the optical efficiency of one or a part of the filter units, thereby improving the color accuracy of the collected image, avoiding color imbalance, improving the signal-to-noise ratio of the image, and avoiding the problem of imbalance in brightness and contrast of the image.

[0031] It should be noted that the “pixel” referred to herein refers to a photosensitive element, such as a photodiode.

[0032] An embodiment of the present application provides an image sensor. The image sensor is used to collect images and can be applied to electronic devices with image collection functions, such as cameras, mobile phones, tablet computers, notebook computers, computers, and monitoring equipment.

[0033] like Figure 1 As shown, the image sensor includes a pixel area 100. The pixel area 100 may include array-arranged photosensitive elements (not shown) and related circuits (not shown). The array-arranged photosensitive elements may include a first photosensitive element and a second photosensitive element, and the first photosensitive element and the second photosensitive element may sense a visible light band.

[0034] In one embodiment, a red filter unit may be disposed above the first photosensitive element to allow only red light to pass through, and thus the first photosensitive element is used to sense red light and is a red light photosensitive element. The second photosensitive element may include a first sub-photosensitive element and a second sub-photosensitive element, and a green filter unit is disposed above the first sub-photosensitive element to allow only green light to pass through, and thus the first sub-photosensitive element is used to sense green light and is a green light photosensitive element. A blue filter unit is disposed above the second sub-photosensitive element to allow only blue light to pass through, and thus the second sub-photosensitive element is used to sense blue light and is a blue light photosensitive element.

[0035] like Figure 2 As shown, the image sensor may include a substrate 1021, a first photosensitive element 1022, a second photosensitive element 1023, a filter layer CF, a microlens layer ML, an adhesion layer 109, and an anti-reflection layer 108. The structure including the substrate 1021, the first photosensitive element 1022, and the second photosensitive element 1023 may be referred to as an image sensor 102 with a filter layer CF to be processed.

[0036] like Figure 2 As shown, the first photosensitive element 1022 and the second photosensitive element 1023 are located on the substrate 1021 .

[0037] In one embodiment, the first photosensitive element 1022 may be a red light photosensitive element R for sensing red light, and the second photosensitive element 1023 may include the green light photosensitive element and the blue light photosensitive element mentioned above.

[0038] like Figure 2 As shown, the filter layer CF is located above the first photosensitive element 1022 and the second photosensitive element 1023 , that is, located on a side of the first photosensitive element 1022 and the second photosensitive element 1023 away from the substrate 1021 .

[0039] In one embodiment, the filter layer CF may include a first filter unit and a second filter unit, the first filter unit is adjacent to the second filter unit, the first filter unit is used to transmit light in a first wavelength band range, and the second filter unit is used to transmit light in a second wavelength band range, and there is no overlapping interval between the first wavelength band range and the second wavelength band range.

[0040] In one embodiment, the first filter unit is a red filter unit for transmitting red light, and the second filter unit includes a green filter unit and a blue filter unit. The green filter unit is for transmitting green light, and the blue filter unit is for transmitting blue light.

[0041] like Figure 1As shown, in one embodiment, the filter layer CF may include a red filter unit 106, green filter units 104, 105, and a blue filter unit 103 arranged in an array. The red filter unit 106 is used to allow only red light within a specified wavelength range to pass through, the green filter units 104, 105 are used to allow only green light within a specified wavelength range to pass through, and the blue filter unit 103 is used to allow only blue light within a specified wavelength range to pass through. The red filter unit 106 is located above the red light sensing element R, the green filter units 104, 105 are located above the green light sensing element, and the blue filter unit 103 is located above the blue light sensing element.

[0042] Of course, in other embodiments, the filter layer CF may also include other filter units, such as a cyan filter unit, a yellow filter unit, a magenta filter unit, a near infrared filter unit, a white filter unit, and a transparent filter unit, etc. The cyan filter unit is used to transmit cyan light, the yellow filter unit is used to transmit yellow light, the magenta filter unit is used to transmit magenta light, the near infrared filter unit is used to transmit near infrared light, the white filter unit is used to reflect visible light, and the transparent filter unit is used to transmit visible light.

[0043] In one embodiment, Figure 1 As shown, the filter layer CF adopts a Bayer pattern 101. In one embodiment, as Figure 1 As shown, in the Bayer array 101, a BGGR arrangement is adopted, that is, the first row and the first column are blue filter units 103, the first row and the second column are first green filter units 104, the second row and the first column are second green filter units 105, and the second row and the second column are red filter units 106. The row direction is the X direction, the column direction is the Y direction, and the X direction is perpendicular to the Y direction. Accordingly, the green light sensing element may include a first green light sensing element and a second green light sensing element, the first green light filtering unit 104 is located above the first green light sensing element, and the second green light filtering unit 105 is located above the second green light sensing element. The blue light filtering unit 103 is located above the blue light sensing element, and the red light filtering unit 106 is located above the red light sensing element R.

[0044] In this document, the Bayer array 101 adopts the BGGR arrangement as an example for description. In other embodiments, the Bayer array 101 may also adopt other arrangements, such as the GRBG arrangement, the GBRG arrangement, or the RGGB arrangement. The GRBG arrangement is that the first row and the first column are the first green filter unit 104, the first row and the second column are the red filter unit 106, the second row and the first column are the blue filter unit 103, and the second row and the second column are the second green filter unit 105. The GBRG arrangement is that the first row and the first column are the first green filter unit 104, the first row and the second column are the blue filter unit 103, the second row and the first column are the red filter unit 106, and the second row and the second column are the second green filter unit 105. The RGGB arrangement is that the first row and the first column are the red filter unit 106, the first row and the second column are the first green filter unit 104, the second row and the first column are the second green filter unit 105, and the second row and the second column are the blue filter unit 103.

[0045] like Figure 2 As shown, the microlens layer ML is located above the filter layer CF. The microlens layer ML includes a microlens array formed by a plurality of microlenses 107. The microlenses 107 correspond to the photosensitive elements one by one. One microlens 107 is located above one photosensitive element. The microlens 107 is a convex lens used for focusing light to improve the light efficiency of the photosensitive element.

[0046] like Figure 2 As shown, the microlens layer ML includes a first microlens ML1 and a second microlens ML2, wherein the first microlens ML1 is located above the first filter unit, and the second microlens ML2 is located above the second filter unit. For example, the first microlens ML1 is located above the red filter unit 106, and the second microlens ML2 is located above the second green filter unit 105.

[0047] like Figure 2 As shown, the adhesion layer 109 is located above the microlens layer ML. The adhesion layer 109 is used to increase adhesion, and the adhesion layer 109 includes a resin material that cannot be photolithographic. The thickness of the adhesion layer 109 is less than or equal to 10 nanometers, for example, the thickness of the adhesion layer 109 is 6 nanometers, 8 nanometers, or 10 nanometers.

[0048] like Figure 2 As shown, the adhesive layer 109 may include a first adhesive film 1091 and a second adhesive film 1092 . The first adhesive film 1091 is located above the first microlens ML1 , and the second adhesive film 1092 is located above the second microlens ML2 .

[0049] like Figure 2As shown, the anti-reflection layer 108 is located above the adhesive layer 109, and the adhesive layer 109 is used to adhere the anti-reflection layer 108. For example, the anti-reflection layer 108 is located above the first adhesive film 1091 to reduce the reflectivity of red light.

[0050] The anti-reflection layer 108 is located above the red filter unit 106 . Since the anti-reflection layer 108 can improve light transmittance, the optical efficiency of the red filter unit 106 can be improved.

[0051] In one embodiment, the material of the anti-reflection layer 108 includes silicon dioxide.

[0052] In one embodiment, when the first photosensitive element 1022 is a red light photosensitive element R, the refractive index of the anti-reflection layer 108 for red light with a wavelength of 540 nm is 1.47, and the extinction coefficient is 0.

[0053] In the embodiment of the present application, there is an anti-reflection layer above the first filter unit, and there is no anti-reflection layer above the second filter unit. Since the anti-reflection layer can reduce the reflectivity of light in the first wavelength range, the optical efficiency of the first filter unit can be improved, and then the optical efficiency of the photosensitive element used to sense the light in the first wavelength range can be improved. That is, the anti-reflection layer can be prepared in a targeted manner above one or a part of the filter units in the filter layer, and the optical efficiency of one or a part of the filter units can be improved separately, thereby improving the color accuracy of the captured image, avoiding color imbalance, improving the signal-to-noise ratio of the image, and avoiding the problem of imbalance in brightness and contrast of the image.

[0054] Another embodiment of the present application also provides an image sensor. Figure 3 , the first photosensitive element 1022 is a blue light photosensitive element B, and the second photosensitive element 1023 includes a red light photosensitive element R and a green light photosensitive element.

[0055] In this embodiment, the first filter unit is a blue filter unit for transmitting blue light, and the second filter unit includes a red filter unit and a green filter unit. The red filter unit is for transmitting red light, and the green filter unit is for transmitting green light.

[0056] In this embodiment, the blue light filter unit 103 is located above the blue light sensing element B, and the anti-reflection layer 108 is located above the blue light filter unit 103 .

[0057] In this embodiment, the optical efficiency of the blue filter unit 103 can be improved, and the anti-reflection layer 108 can be specifically prepared above one or a part of the blue filter unit 103 in the filter layer CF, so that the optical efficiency of the blue filter unit 103 can be improved separately, thereby improving the color accuracy of the collected image, avoiding color imbalance, improving the signal-to-noise ratio of the image, and avoiding the problem of imbalance in brightness and contrast of the image.

[0058] Another embodiment of the present application also provides an image sensor. Figure 4 The first photosensitive element 1022 is a first green light photosensitive element G1, and the second photosensitive element 1023 includes a red light photosensitive element R, a second green light photosensitive element and a blue light photosensitive element.

[0059] In this embodiment, the first filter unit is a first green filter unit 104 for transmitting green light, and the second filter unit includes a second green filter unit 105, a red filter unit and a blue filter unit. The red filter unit is used to transmit red light, the blue filter unit is used to transmit blue light, and the second green filter unit 105 is used to transmit green light.

[0060] In this embodiment, the first green filter unit 104 is located above the first green light sensing element G1 , and the anti-reflection layer 108 is located above the first green filter unit 104 .

[0061] In this embodiment, the optical efficiency of the first green filter unit 104 can be improved, and the anti-reflection layer 108 can be specifically prepared above one or a part of the first green filter unit 104 in the filter layer of the image sensor, so that the optical efficiency of the first green filter unit 104 can be improved separately, thereby improving the color accuracy of the collected image, avoiding color imbalance, improving the signal-to-noise ratio of the image, and avoiding the problem of imbalance in brightness and contrast of the image.

[0062] Another embodiment of the present application also provides an image sensor. Figure 5 The first photosensitive element 1022 is a second green light photosensitive element G2, and the second photosensitive element 1023 includes a red light photosensitive element R, a first green light photosensitive element and a blue light photosensitive element.

[0063] In this embodiment, the first filter unit is the second green filter unit 105, which is used to transmit green light. The second filter unit includes the first green filter unit 104, a red filter unit and a blue filter unit. The red filter unit is used to transmit red light, the blue filter unit is used to transmit blue light, and the first green filter unit 104 is used to transmit green light.

[0064] In this embodiment, the second green filter unit 105 is located above the second green light sensing element G2 , and the anti-reflection layer 108 is located above the second green filter unit 105 .

[0065] In this embodiment, the optical efficiency of the second green filter unit 105 can be improved, and the anti-reflection layer 108 can be specifically prepared above a certain one or a certain part of the second green filter unit 105 in the filter layer of the image sensor, and the optical efficiency of the second green filter unit 105 can be improved separately, thereby improving the color accuracy of the collected image, avoiding color imbalance, improving the signal-to-noise ratio of the image, and avoiding the problem of imbalance in brightness and contrast of the image.

[0066] Another exemplary embodiment of the present application also provides a method for preparing an image sensor. The method for preparing an image sensor in this embodiment is used to prepare Figure 2 The image sensor shown. Figure 6 As shown, in this embodiment, the method for preparing the image sensor may include the following steps S601 to S606: Step S601, providing a semiconductor device, the semiconductor device comprising a substrate, array-arranged photosensitive elements, a filter layer and a microlens layer, the photosensitive elements are located above the substrate, the filter layer is located above the photosensitive elements, the filter layer comprises a first filter unit and a second filter unit, the first filter unit is used to transmit light within a first wavelength range, the second filter unit is used to transmit light within a second wavelength range, and the microlens layer is located above the filter layer; the microlens layer comprises a first microlens and a second microlens, the first microlens is located above the first filter unit, and the second microlens is located above the second filter unit.

[0067] In one embodiment, the first filter unit is adjacent to the second filter unit, and there is no overlapping interval between the first wavelength band range and the second wavelength band range.

[0068] In this step, if Figures 7 and 8 As shown, a semiconductor device is provided, which includes a substrate 1021, a first photosensitive element 1022, a second photosensitive element 1023, a filter layer CF and a microlens layer ML, wherein the first photosensitive element 1022 is a red light photosensitive element R, the second photosensitive element 1023 includes a green light photosensitive element G and a blue light photosensitive element B, and the green light photosensitive element G includes a first green light photosensitive element G1 and a second green light photosensitive element G2.

[0069] like Figures 7 and 8As shown, the filter layer CF is located above the first photosensitive element 1022 and the second photosensitive element 1023. The filter layer CF includes a red filter unit 106, green filter units 104, 105 and a blue filter unit 103 arranged in an array. The green filter units 104, 105 include a first green filter unit 104 and a second green filter unit 105. The blue filter unit 103 is located above the blue light photosensitive element, and the red filter unit 106 is located above the red light photosensitive element R. The first green filter unit 104 is located above the first green light photosensitive element, and the second green filter unit 105 is located above the second green light photosensitive element.

[0070] like Figures 7 and 8 As shown, the microlens layer ML is located above the filter layer CF. The microlens layer ML includes a microlens array formed by a plurality of microlenses 107. The microlenses 107 correspond to the photosensitive elements one by one. One microlens 107 is located above one photosensitive element. The microlens 107 is a convex lens used for focusing light to improve the light efficiency of the photosensitive element.

[0071] In one embodiment, step S601 may include the following steps: first, providing an image sensor 102 with a filter layer CF to be processed, that is, an image sensor with a filter layer CF and a microlens layer ML to be processed. Then, forming the filter layer CF and the microlens layer ML by coating, photolithography, developing, baking, and etching processes.

[0072] In related technologies, such as Fig. 9 As shown, the conventional chemical vapor deposition process is used to prepare the anti-reflection coating 208, and only a whole layer of anti-reflection coating 208 can be prepared in the entire pixel area 100, covering all the filter layers CF, and cannot selectively cover one or part of the filter unit. In the present application, Figures 2 to 5 As shown, it is necessary to prepare an anti-reflection layer 108 that covers the first filter unit but does not cover the second filter unit. The specific preparation method is shown in steps S602 to S606.

[0073] Step S602 : forming an adhesive layer on the microlens layer, wherein the adhesive layer comprises a first adhesive film, and the first adhesive film is located on the first microlens.

[0074] In this embodiment, the material of the adhesion layer 109 may include resin.

[0075] In this step, if Fig.10 As shown, a spin coating process may be used to form an adhesion layer 109 on the microlens layer ML, and the adhesion layer 109 covers the entire pixel region 100. The adhesion layer 109 is used to increase adhesion and cannot be photolithographically processed.

[0076] In the present embodiment, the thickness of the adhesion layer 109 is less than or equal to 10 nanometers. For example, the thickness of the adhesion layer 109 is 6 nanometers, 8 nanometers, or 10 nanometers.

[0077] In one embodiment, the adhesion layer may not be formed on the microlens layer.

[0078] Step S603 , forming a sacrificial material layer on the adhesion layer.

[0079] In this embodiment, the material of the sacrificial material layer includes photoresist. In one embodiment, the material of the sacrificial material layer may include positive photoresist. The positive photoresist may include a mixture of methyl amyl ketone (miscible in most organic solvents), propylene glycol methyl ether acetate and phenolic numerical derivatives, but is not limited thereto. In another embodiment, the material of the sacrificial material layer may include negative photoresist.

[0080] In this embodiment, the distance is described by taking the example that the material of the sacrificial material layer includes positive photoresist.

[0081] In this embodiment, a sacrificial material layer may be formed on the adhesion layer 109 by a spin coating process, and the sacrificial material layer covers the entire pixel region 100 .

[0082] In this embodiment, the thickness of the sacrificial material layer is 4-8 micrometers. For example, the thickness of the sacrificial material layer can be 4 micrometers, 5 micrometers, 7 micrometers or 8 micrometers.

[0083] In another embodiment, if the adhesion layer is not formed over the microlens layer, a sacrificial material layer may be formed over the microlens layer.

[0084] Step S604 , forming a sacrificial layer opening on the sacrificial material layer to obtain a sacrificial layer; the sacrificial layer opening is used to expose the first adhesive film of the adhesive layer.

[0085] In this embodiment, if Fig.11As shown, a sacrificial layer opening 111 can be formed on the sacrificial material layer by a photolithography process to obtain a sacrificial layer 110. For example, a mask is placed on the side of the sacrificial material layer away from the substrate 1021, and the mask includes a shielding portion and a mask opening, wherein the shielding portion is located above the second microlens ML2, and the mask opening is located above the first microlens ML1, and the mask opening is used to expose the sacrificial material layer above the first microlens ML1. An exposure process is used to expose the sacrificial material layer exposed by the mask opening, that is, ultraviolet light is irradiated to the mask, and the sacrificial material layer exposed by the mask opening is irradiated by ultraviolet light, and the sacrificial material layer irradiated by ultraviolet light undergoes molecular cleavage. Then, a development process is used to remove the sacrificial material layer irradiated by ultraviolet light, that is, the sacrificial material layer that has undergone molecular cleavage is removed by dissolving the sacrificial material layer that has undergone molecular cleavage with a developer, and the unexposed sacrificial material layer is retained, thereby obtaining a sacrificial layer 110 having a sacrificial layer opening 111. The unexposed sacrificial material layer covers the second adhesive film 1092. The sacrificial layer opening 111 is used to expose the first adhesive film 1091 of the adhesive layer 109 . The first adhesive film 1091 is located above the first microlens ML1 , and the second adhesive film 1092 is located above the second microlens ML2 .

[0086] In another embodiment, if a sacrificial material layer is formed above the microlens layer, after a sacrificial layer opening is formed on the sacrificial material layer, the sacrificial layer opening is used to expose the first microlens ML1.

[0087] Step S605 , forming an anti-reflection material layer, the anti-reflection material layer includes an anti-reflection layer and an anti-reflection film layer to be removed, the anti-reflection film layer to be removed is located above the sacrificial layer, and the anti-reflection layer is located above the first adhesive film.

[0088] In this step, if Fig.12 As shown, the anti-reflection material layer 18 can be formed by chemical vapor deposition process. The anti-reflection material layer 18 includes an anti-reflection layer 108 and an anti-reflection film layer 112 to be removed. The anti-reflection film layer 112 to be removed is located above the sacrificial layer 110, and the anti-reflection layer 108 is located above the first adhesive film 1091.

[0089] In another embodiment, if a sacrificial material layer is formed above the microlens layer, after a sacrificial layer opening is formed on the sacrificial material layer, the sacrificial layer opening is used to expose the first microlens ML1, and after the anti-reflection material layer is formed, the anti-reflection material layer includes an anti-reflection layer and an anti-reflection film layer to be removed, the anti-reflection film layer to be removed is located above the sacrificial layer, and the anti-reflection layer is located above the first microlens ML1.

[0090] Step S606 , peeling off the sacrificial layer and the anti-reflection film layer to be removed to obtain an image sensor.

[0091] In this step, a stripping process can be used to strip off the sacrificial layer 110 and the anti-reflective film layer 112 to be removed to obtain an image sensor, that is, the sacrificial layer 110 in contact with the adhesion layer 109 is dissolved by a chemical reaction between the stripping liquid and the sacrificial layer 110, and then the dissolved substance is removed by pure water and dried by high-speed rotation, and then the remaining sacrificial layer 110 above the entire pixel area 100 and the anti-reflective film layer 112 to be removed thereon are stripped off.

[0092] In this embodiment, the stripping solution may be a mixture of DMSO (dimethyl sulfoxide) and NMP (N-methyl-2-pyrrolidone), which has the ability to dissolve a variety of compounds. In other embodiments, the stripping solution may also be other materials.

[0093] In the present embodiment, when the sacrificial layer 110 and the anti-reflection film layer 112 to be removed thereon are peeled off, the anti-reflection layer 108 above the first filter unit can be prevented from being peeled off due to the presence of the adhesion layer 109, and the anti-reflection layer 108 is successfully retained above the first filter unit, thereby achieving the purpose of increasing the optical efficiency of the first filter unit alone.

[0094] In this embodiment, a sacrificial material layer is formed above the adhesive layer, and a sacrificial layer opening is formed on the sacrificial material layer to obtain a sacrificial layer, wherein the sacrificial layer opening is used to expose the first adhesive film, and then an anti-reflection material layer is formed, wherein the anti-reflection material layer includes an anti-reflection layer and an anti-reflection film layer to be removed, the anti-reflection film layer to be removed is located above the sacrificial layer, and the anti-reflection layer is located above the first adhesive film, and finally, the anti-reflection film layer to be removed is peeled off together by peeling off the sacrificial layer, so that the anti-reflection layer is prepared only above the first filter unit, that is, the anti-reflection layer can be prepared specifically above one or part of the filter units in the filter layer, and the optical efficiency of one or part of the filter units can be improved separately, thereby improving the color accuracy of the collected image, avoiding color imbalance, improving the signal-to-noise ratio of the image, and avoiding the problem of imbalance in brightness and contrast of the image.

[0095] The above introduces Figure 2 The method for preparing the image sensor shown in the figure can be prepared by a similar method in other embodiments. Figures 3 to 5 The image sensor shown.

[0096] In addition, the preparation method of the image sensor in the present application is based on a color film process (a process for preparing the filter layer CF), and the materials used are mostly resin materials (for example, the microlens layer ML, the adhesion layer 109, and the sacrificial layer 110 all include resin). When the process parameters of the product-related film layers (microlens layer ML, adhesion layer 109, sacrificial layer 110) need to be changed, the relevant film layers can be removed on the same wafer through a simple, mature, and low-cost etching process and then reprocessed, which greatly improves the fault tolerance during product design and the cost of product development.

[0097] In the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. The term "plurality" refers to two or more than two, unless otherwise clearly defined.

[0098] The above description of the embodiments is to facilitate those skilled in the art to understand and apply the present application. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without having to pay creative labor. Therefore, the present application is not limited to the embodiments herein, and improvements and modifications made by those skilled in the art based on the contents disclosed in the present application without departing from the scope and spirit of the present application are within the scope of the present application.

Claims

1. An image sensor, characterized in that: include: substrate; Photosensitive elements arranged in an array are located above the substrate; A filter layer is located above the photosensitive element; the filter layer includes a first filter unit and a second filter unit, the first filter unit is used to transmit light within a first wavelength range, and the second filter unit is used to transmit light within a second wavelength range; a microlens layer, located above the filter layer; the microlens layer comprises a first microlens and a second microlens, the first microlens is located above the first filter unit, and the second microlens is located above the second filter unit; The anti-reflection layer is located above the first microlens and is used to reduce the reflectivity of the light within the first wavelength band.

2. The image sensor according to claim 1, wherein: The first filter unit is adjacent to the second filter unit; and there is no overlapping interval between the first wavelength band range and the second wavelength band range.

3. The image sensor according to claim 1, wherein: Also includes: an adhesive layer, the adhesive layer being located above the microlens layer; The adhesive layer includes a first adhesive film and a second adhesive film, the first adhesive film is located above the first microlens, the second adhesive film is located above the second microlens, and the anti-reflection layer is located above the first adhesive film.

4. The image sensor according to claim 1, wherein: The material of the anti-reflection layer includes silicon dioxide.

5. The image sensor according to claim 4, wherein: The first filter unit is a red filter unit for transmitting red light, the second filter unit includes a green filter unit and a blue filter unit, the green filter unit is for transmitting green light, and the blue filter unit is for transmitting blue light; or The first filter unit is a green filter unit for transmitting green light, the second filter unit includes a red filter unit and a blue filter unit, the red filter unit is for transmitting red light, and the blue filter unit is for transmitting blue light; or The first filter unit is a blue filter unit for transmitting blue light. The second filter unit includes a red filter unit and a green filter unit. The red filter unit is for transmitting red light, and the green filter unit is for transmitting green light.

6. A method for preparing an image sensor, characterized in that: include: A semiconductor device is provided, the semiconductor device comprising a substrate, array-arranged photosensitive elements, a filter layer and a microlens layer, the photosensitive elements are located above the substrate, the filter layer is located above the photosensitive elements, the filter layer comprises a first filter unit and a second filter unit, the first filter unit is used to transmit light within a first wavelength range, and the second filter unit is used to transmit light within a second wavelength range; the microlens layer is located above the filter layer; the microlens layer comprises a first microlens and a second microlens, the first microlens is located above the first filter unit, and the second microlens is located above the second filter unit; forming a sacrificial material layer, wherein the sacrificial material layer is located above the microlens layer; forming a sacrificial layer opening on the sacrificial material layer to obtain a sacrificial layer; the sacrificial layer opening is used to expose the first microlens; forming an anti-reflection material layer, wherein the anti-reflection material layer comprises an anti-reflection layer and an anti-reflection film layer to be removed, wherein the anti-reflection film layer to be removed is located above the sacrificial layer, and the anti-reflection layer is located above the first microlens; The sacrificial layer and the anti-reflection film layer to be removed are peeled off to obtain the image sensor.

7. The method for preparing an image sensor according to claim 6, wherein: Before forming the sacrificial material layer, the method further comprises: forming an adhesive layer above the microlens layer; the adhesive layer comprises a first adhesive film, and the first adhesive film is located above the first microlens; The forming of the sacrificial material layer comprises: forming the sacrificial material layer above the adhesion layer; After forming a sacrificial layer opening on the sacrificial material layer, the sacrificial layer opening is used to expose the first adhesive film; After the anti-reflection material layer is formed, the anti-reflection layer is located above the first adhesive film, and the anti-reflection film layer to be removed is located above the sacrificial layer.

8. The method for preparing an image sensor according to claim 6, wherein: The material of the sacrificial material layer includes photoresist; The step of forming a sacrificial layer opening on the sacrificial material layer to obtain a sacrificial layer comprises: A sacrificial layer opening is formed on the sacrificial material layer by adopting a photolithography process to obtain the sacrificial layer.

9. The method for preparing an image sensor according to claim 8, wherein: The thickness of the sacrificial material layer is 4-8 microns.

10. The method for preparing an image sensor according to claim 8, wherein: The step of stripping the sacrificial layer and the anti-reflection film layer to be removed to obtain the image sensor comprises: The sacrificial layer and the anti-reflection film layer to be removed are stripped off by a film stripping process to obtain the image sensor.

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