Dark scene full-color function image sensor and its manufacturing method

Abstract

The present invention provides an image sensor with a dark scene full-color function, comprising: a plurality of photosensitive elements disposed in a semiconductor substrate; a plurality of filter films disposed on the light-receiving surfaces of the photosensitive units, the plurality of filter films including color filter films with different light responses and a white filter film with a full-spectrum response; and an infrared suppression film disposed between the color filter films and the photosensitive elements to suppress infrared light from entering the photosensitive elements. By providing an infrared cut-off film below the color filter films and changing the color filter array pattern to introduce a white color filter with a full-spectrum response in the present invention, a full-color effect in a low-light scene can be achieved using only one image sensor chip. The present invention also provides a method for manufacturing the above-mentioned image sensor.

Description

Technical Field

[0001] The present invention relates to an image sensor, and more particularly to an image sensor with a dark scene full-color function and a method for manufacturing the same. Background Art

[0002] An image capturing device includes an image sensor and an imaging lens. The imaging lens focuses light onto the image sensor to form an image, and the image sensor converts the light signal into an electrical signal. The image capturing device outputs the electrical signal to other components of the host system. The image capturing device and other components of the host system form an image sensor system or an imaging system. The applications of image sensors have been very common and can be applied in various electronic systems, such as mobile devices, digital cameras, medical devices, or computers. The technologies for manufacturing image sensors, especially the technologies for manufacturing complementary metal oxide semiconductor (“CMOS”) image sensors, have been continuously and rapidly developing.

[0003] A typical image sensor includes a plurality of photosensitive elements (“pixels”) arranged in a two-dimensional array. Such an image sensor can be configured to generate a color image by forming a color filter array (CFA) on the pixels. Existing image sensor chips are generally designed in a Bayer array. However, in an environment with weak light intensity at night, when infrared light supplementation is required to achieve sufficient brightness, colors cannot be restored because infrared light can pass through the RGB three color filters, resulting in the same signal intensity for all colors passing through. In fields such as security monitoring and machine vision that have high requirements for dark scenes, there are two existing technical solutions: one is a Bayer-mode CMOS image sensor, which needs to turn off the infrared cut-off filter (IR-CUT) and supplement infrared light in a very dark scene, and the image becomes black and white, completely losing color information; the second is to use two CMOS image sensor chips, as Figure 1A and Figure 1B shown, in a very dark scene, the Bayer-mode chip is responsible for collecting color information, and the other chip has a full-spectrum response, without an infrared cut-off filter, and can receive actively supplemented infrared light to obtain brightness information with a higher signal-to-noise ratio, and then use an algorithm to fuse the two, but this requires two chips and two lenses, resulting in a high cost. Summary of the Invention

[0004] The following description presents the contributions made by the present invention.

[0005] The present invention provides an image sensor with a dark scene full-color function and a method for manufacturing the same, which can achieve the full-color effect in a dark scene with only one image sensor chip.

[0006] An image sensor with a dark scene full-color function includes:

[0007] A plurality of photosensitive elements, disposed in a semiconductor substrate;

[0008] A plurality of filter films, disposed on a light-receiving surface of the photosensitive unit, the plurality of filter films including color filter films with different light responses and a white filter film with a full-spectrum response; and

[0009] An infrared suppression film, disposed between the color filter film and the photosensitive element to suppress infrared light from entering the photosensitive element.

[0010] A method for manufacturing an image sensor as described above, comprising the following steps:

[0011] Providing a semiconductor substrate, in which a pixel region and an isolation region are provided, the pixel region including a color pixel region and a white pixel region;

[0012] Disposing an infrared suppression film above the color pixel region;

[0013] Disposing a color filter above the infrared suppression film;

[0014] Disposing a white filter above the white pixel region, the white filter and the color filter being located on the same layer.

[0015] The image sensor with a dark scene full-color function and its manufacturing method of the present invention achieve the full-color effect in a low-light scene by disposing an infrared cut-off film below the color filter film and changing the filter array pattern to introduce a white filter film with a full-spectrum response. In particular, it can receive infrared signals in a night environment, improve the sensitivity of the chip in different environments, and enable the chip to accurately restore images and colors in an extremely dark scene. Description of the Drawings

[0016] Figure 1A 、 1B Is a schematic structural diagram of a Bayer pattern color filter array and a full-spectrum response filter in the prior art;

[0017] Figure 2 Is a schematic structural diagram of an image sensor according to an embodiment of the present invention.

[0018] Figure 3 Is a schematic structural diagram of an image sensor according to another embodiment of the present invention.

[0019] Figure 4 Is a schematic structural diagram of an image sensor according to another embodiment of the present invention.

[0020] Figure 5 Is a schematic structural diagram of an image sensor according to another embodiment of the present invention.

[0021] Figure 6Flow chart of the preparation method of the image sensor according to an embodiment of the present invention.

[0022] Figure 7 Flow chart of the preparation method of the image sensor according to another embodiment of the present invention.

[0023] Figure 8 Schematic diagram of the wavelength and transmittance of the image sensor of the present invention. Detailed implementation manners

[0024] The above-mentioned drawings illustrate the present invention, an image sensor with a dark scene full-color function and its preparation method. Different embodiments of the image sensor are disclosed herein. In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, those skilled in the relevant art should know that the technical content described in the present invention can be implemented without one or more specific details, or other methods, components, materials, etc. In other examples, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring specific content.

[0025] The present invention achieves the full-color effect in a low-light scene by setting an infrared cut-off film under the color filter and changing the color filter array pattern to introduce a white color filter with full-spectrum response, so that only one image sensor chip is used.

[0026] Figure 2 Schematic structural diagram of the image sensor according to an embodiment of the present invention. The image sensor includes a plurality of photosensitive elements 110, a plurality of color filters 410 / 420, a transparent film 330, and an infrared suppression film 310. The plurality of photosensitive elements 110 are disposed in a semiconductor substrate 100. The plurality of color filters are disposed on the light-receiving surface of the photosensitive unit 110. The plurality of color filters include color filters 410 with different light responses and a white color filter 420 with full-spectrum response. The photosensitive elements under the color filters 410 are used to collect the color signals of the image, and the photosensitive elements under the white color filter are used to collect the luminance signals of the image. The transparent film 330 is disposed between the white color filter 420 and the photosensitive elements 110. The infrared suppression film 310 is disposed between the color filters 410 and the photosensitive elements 110 to suppress infrared light from entering the photosensitive elements 110.

[0027] Figure 2The image sensor shown is a back-illuminated (BSI) image sensor. The image sensor includes a metal wiring layer 200 disposed on the backlight surface of the photosensitive element 110. The metal wiring layer 200 is provided with a metal wiring structure 210 to achieve the connection of circuit components. In one embodiment, the image sensor further includes a plurality of microlenses 500 disposed on the color filter 410 and the white filter 420 to focus incident light onto the photosensitive element 110. In one embodiment, the microlenses 500 are made of the same clear material as the transparent film 330 and the white color filter 420, such as quartz, glass, or any other suitable transparent material. Therefore, the transparent film 330 can be the white color filter 420, that is, a double-layer or double-thickness white color filter 420 is disposed on the corresponding photosensitive element.

[0028] In one embodiment, an isolation structure 120 is disposed between adjacent photosensitive elements 110. The photosensitive element 110 includes a photoelectric conversion portion for converting incident light into photoelectric charges and a charge transfer portion for reading and transferring out signal charges from the photoelectric conversion portion, such as a photodiode and a plurality of transistors. Figure 2 Transistors are not shown, but the gate 212 of the transistor is shown in the metal wiring layer 200 to indicate the presence of the transistor. The isolation structure 120 is an oxidation region. In one embodiment, the isolation structure 120 is STI isolation (Shallow Trench Isolation), and in another embodiment, the isolation structure 120 is LOCOS isolation (Local Oxidation of Silicon). The isolation structure 120 is used to reduce problems such as signal crosstalk and leakage current between pixel regions 222.

[0029] The infrared suppression film 310 is a material that allows visible light to pass through while suppressing infrared light. Placing it under the color filter 410 ensures that normal color information can be obtained without the need for optical components such as an infrared cut-off filter (IR-CUT), and it is not affected by infrared, enabling accurate color reproduction even when using infrared supplementary lighting at night. This material is not required under the white filter 420. In one embodiment, the infrared suppression film is an infrared cut-off material with a light transmittance of 0.1% - 2%. In one embodiment, the material of the infrared suppression film 310 is an organic substance. In one embodiment, the material of the infrared suppression film 310 is polyurethane or polyimide. In other ways, the material of the infrared suppression film can also be an inorganic substance. In one embodiment, the thickness of the infrared suppression film 310 is 0.6 - 1.5 um, and preferably, the thickness of the infrared suppression film is 1 um. In one embodiment, the width of the infrared suppression film 310 is 0.5 - 10 um, and preferably, the width of the infrared suppression film 310 is 2 um.

[0030] In one embodiment, a gap 320 is provided between the infrared suppression film 310 and the transparent film 330. The gap 320 is used to prevent light crosstalk between the photosensitive elements 110, thereby ensuring the best brightness signal-to-noise ratio. The gap 320 is made of a material with a low refractive index. In one embodiment, the gap 320 can be made of metals such as AL, W, etc., or inorganic thin film materials such as SiO2, SiN, etc. to prevent infrared light from crosstalking with each other. In one embodiment, the refractive index of the gap 320 is 1.3 - 1.5, and preferably, the refractive index of the gap 320 is 1.4. In one embodiment, the thickness of the gap 320 is 0.75 - 1 um, and preferably, the thickness of the gap 320 is 0.8 um. In one embodiment, the width of the gap 320 is 0.3 - 1 um, and preferably, the width of the gap 320 is 0.3 um. In one embodiment, the infrared suppression film 310 and the transparent film 330 have the same width, and the gap 320 is located in the middle of the infrared suppression film 310 and the transparent film 330 and below the junction of the color filter 410 and the white filter 420.

[0031] In one embodiment, the color filter 410 includes a first light-responsive color filter, a second light-responsive color filter, and a third light-responsive color filter. In one embodiment, the first light-responsive color filter is a green filter, the second light-responsive color filter is a blue filter, and the third light-responsive color filter is a red filter.

[0032] Figure 3 This is a schematic structural diagram of an image sensor according to another embodiment of the present invention. In Figure 3In the illustrated embodiment, the transparent film 330 is narrower than the infrared suppression film 310, and the gap 330 is offset toward the transparent film 320 and is completely located below the white filter 420, thereby better preventing light crosstalk. Figure 2 The structures with the same reference numerals as those in FIG. 1 have the same functions and will not be described herein again.

[0033] Figure 4 and Figure 5 FIG. [ID] is a schematic structural diagram of an image sensor according to another embodiment of the present invention. Figure 4 and Figure 5 The illustrated image sensor is a front-side illuminated (FSI) image sensor. The metal wiring layer 200 is disposed on the light-receiving surface of the photosensitive element 110. Figure 4 、 Figure 5 and Figure 2 The structures with the same reference numerals as those in FIG. 1 have the same functions and will not be described herein again.

[0034] The present invention also provides a method for manufacturing the above image sensor, including the following steps:

[0035] Provide a semiconductor substrate, and form a pixel region and an isolation region therein, the pixel region including a color pixel region and a white pixel region;

[0036] Dispose an infrared suppression film above the color pixel region;

[0037] Dispose a color filter above the infrared suppression film;

[0038] Dispose a white filter above the white pixel region, the white filter and the color filter being located on the same layer.

[0039] In one embodiment, as Figure 6 illustrated, the method 600 for manufacturing the image sensor provided by the present invention includes the following steps:

[0040] Step 610: Provide a semiconductor substrate, and form a pixel region and an isolation region therein, the pixel region including a color pixel region and a white pixel region;

[0041] Step 620: Dispose an infrared suppression film above the color pixel region, dispose a transparent film above the white pixel, and dispose a gap layer between the infrared suppression film and the transparent film;

[0042] Step 630: Dispose a color filter above the infrared suppression film;

[0043] Step 640: Dispose a white filter above the transparent film, the white filter and the color filter being located on the same layer.

[0044] In one embodiment, the preparation method 600 further includes the step of disposing a microlens above the color filter and the white filter, wherein the microlens is formed synchronously with the white filter.

[0045] In one embodiment, the step 620 specifically includes: first disposing the gap layer, then disposing the infrared suppression film, and then disposing the transparent film.

[0046] In another embodiment, as Figure 7 shown, the preparation method 700 of the image sensor provided by the present invention includes the following steps:

[0047] Step 710: Provide a semiconductor substrate, and dispose a pixel region and an isolation region therein, wherein the pixel region includes a color pixel region and a white pixel region;

[0048] Step 720: Dispose an infrared suppression film above the color pixel region, and dispose a gap layer beside the infrared suppression film;

[0049] Step 730: Dispose a color filter above the infrared suppression film;

[0050] Step 740: Dispose a transparent film above the white pixel region, and dispose a white filter above the transparent film. The transparent film is in the same layer as the infrared suppression film and the gap layer, and the white filter is in the same layer as the color filter.

[0051] In one embodiment, the preparation method 700 further includes the step of disposing a microlens above the color filter and the white filter, wherein the microlens is formed synchronously with the transparent film and the white filter. Wherein, in one embodiment, the microlens, the transparent film and the white filter are made of the same clear material, such as quartz, glass or any other suitable transparent material.

[0052] In one embodiment, the step 720 specifically includes: first disposing the gap layer, and then disposing the infrared suppression film.

[0053] The difference between the preparation method 700 and the preparation method is that after the steps of fabricating the infrared cut-off film and the gap layer are completed in the preparation method 700, the transparent film is not made first, but the color filter part is made first, and then the filling of the materials of the microlens, the white filter and the transparent film is completed synchronously, which can reduce the intermediate interface and improve the sensitivity.

[0054] In one embodiment, the color filter includes a first light-responsive color filter, a second light-responsive color filter, and a third light-responsive color filter. The first light-responsive color filter is a green filter, the second light-responsive color filter is a blue filter, and the third light-responsive color filter is a red filter. In step 630 or step 730, it specifically includes: first setting the green filter, then setting the red filter, and then setting the blue filter.

[0055] In one embodiment, it further includes the step of: setting a metal wiring layer on the backlight surface of the semiconductor substrate. In another embodiment, a metal wiring layer is set on the light-receiving surface of the semiconductor substrate and below the infrared suppression film.

[0056] Figure 8 It is a schematic diagram of the wavelength and transmittance of the image sensor of the present invention. According to the content of the present invention, using infrared suppression films with different thicknesses has a near-zero transmittance for infrared light around 850 nm wavelength, while having a relatively high transmittance for other visible lights. Therefore, visible light can pass through while infrared light is suppressed, and the white filter can ensure brightness information. Therefore, it can ensure that the image sensor has the best brightness signal-to-noise ratio.

[0057] The image sensor with the dark scene full-color function and its manufacturing method of the present invention set an infrared cut-off film below the color filter and change the color filter array pattern, introducing a white color filter with full-spectrum response. Thus, with only one image sensor chip, the full-color effect in the low-light scene can also be achieved. Especially in the night environment, it receives infrared signals, improves the sensitivity of the chip in different environments, and enables the chip to accurately restore images and colors in extremely dark scenes.

[0058] References throughout the specification to "one embodiment", "an embodiment", "one example" or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. Or an example of the present invention. Thus, the phrases such as "in one embodiment" or "in one example" that appear throughout the specification do not necessarily all refer to the same embodiment or example. Additionally, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments or examples. Directional terms such as "top", "downward", "above", "below" are used with reference to the orientation of the described drawings. Furthermore, unless otherwise specifically stated, the terms "having", "including", "containing" and similar terms are defined to mean "comprising". The particular features, structures, or characteristics may be included in an integrated circuit, an electronic circuit, a combinational logic circuit, or other suitable components that provide the described functionality. Additionally, it should be understood that the drawings provided herein are for the purpose of explaining to those of ordinary skill in the art and the drawings are not necessarily drawn to scale.

[0059] The foregoing description of the illustrated embodiments of the invention (including what is described in the abstract) is not intended to be exhaustive or to be limited to the precise forms disclosed. Although specific embodiments and examples of the invention are described herein for illustrative purposes, various equivalent modifications can be made without departing from the broader spirit and scope of the invention. Indeed, it should be understood that the specific example structures and materials are provided for purposes of explanation and that other structures and materials can be used in other embodiments and examples in accordance with the teachings of the invention. These modifications to the embodiments of the invention can be made in light of the foregoing detailed description. The terms used in the following claims should not be construed as limiting the invention to the specific embodiments disclosed in the specification and claims. Instead, the scope is determined entirely by the following claims, which are to be construed in accordance with established principles of claim interpretation.

[0060] Each of the embodiments given in the embodiments of the present invention includes, but is not limited to, the explanation and illustration of the inventive concept proposed by the present invention. The above embodiments are only for the purpose of explanation and do not constitute a limitation to the present invention. Reasonable revisions to each of the embodiments of the present invention.

Claims

1. An image sensor with a dark scene full-color function, characterized in that, Comprising: A plurality of photosensitive elements disposed in a semiconductor substrate; A plurality of filter films disposed on the light-receiving surfaces of the photosensitive elements, the plurality of filter films including color filter films with different light responses and a white filter film with full-spectrum response; And an infrared suppression film disposed below the color filter film and between the color filter film and the photosensitive element to suppress infrared light from entering the photosensitive element corresponding to the color filter film; It further includes a transparent film disposed below the white filter film and between the white filter film and the photosensitive element; Wherein, the color filter film and the white filter film are on the same layer, and the infrared suppression film and the transparent film are on the same layer; A gap is provided between the infrared suppression film and the transparent film; The transparent film is narrower than the infrared suppression film, and the gap is offset toward the transparent film and is completely below the white filter film; Wherein, the gap is used to prevent light crosstalk between adjacent filter films.

2. The image sensor according to claim 1, characterized in that, It further includes a metal wiring layer disposed on the backlight surface of the photosensitive element, on which a metal wiring structure is provided to realize the connection of circuit components.

3. The image sensor according to claim 1, wherein It further includes a metal wiring layer disposed on the light-receiving surface of the photosensitive element and below the infrared suppression film, on which a metal wiring structure is provided to realize the connection of circuit components.

4. The image sensor according to claim 1, characterized in that, It further includes a plurality of microlenses disposed on the plurality of filter films to focus incident light onto the photosensitive element.

5. The image sensor according to claim 1, characterized in that, An isolation structure is provided between adjacent photosensitive elements.

6. The image sensor according to claim 1, wherein The thickness of the gap is 0.75 - 1um.

7. The image sensor according to claim 1, characterized in that, The thickness of the gap is 0.8um.

8. The image sensor according to claim 1, characterized in that, The width of the gap is 0.3 - 1um.

9. The image sensor according to claim 1, wherein The width of the gap is 0.3um.

10. The image sensor according to claim 1, wherein, The gap is selected to have a refractive index of 1.3 - 1.

5.

11. The image sensor according to claim 10, wherein, The gap is selected to have a refractive index of 1.

4.

12. The image sensor according to claim 1, wherein, The thickness of the infrared suppression film is 0.6 - 1.5um.

13. The image sensor according to claim 12, wherein The thickness of the infrared suppression film is 1um.

14. The image sensor according to claim 1, wherein The width of the infrared suppression film is 0.5 - 10um.

15. The image sensor according to claim 14, wherein, The width of the infrared suppression film is 2um.

16. The image sensor according to claim 1, wherein The infrared suppression film is selected from infrared cut-off materials with a light transmittance of 0.1% - 2%.

17. The image sensor according to claim 16, wherein The material of the infrared suppression film is polyurethane or polyimide.

18. The image sensor according to claim 1, characterized in that, The color filter film includes a first light-response color filter film, a second light-response color filter film, and a third light-response color filter film.

19. The image sensor according to claim 18, wherein The first light-response color filter film is a green filter film, the second light-response color filter film is a blue filter film, and the third light-response color filter film is a red filter film.

20. A method for manufacturing an image sensor according to any one of claims 1-19, characterized in that, Including the following steps: Providing a semiconductor substrate, in which a pixel region and an isolation region are provided, the pixel region including a color pixel region and a white pixel region; Providing an infrared suppression film above the color pixel region; Providing a color filter above the infrared suppression film; Providing a white filter above the white pixel region, the white filter being on the same layer as the color filter; 21. The preparation method according to claim 20, wherein, It further includes: Providing microlenses above the color filter and the white filter, wherein the microlenses are formed synchronously with the white filter; 22. The preparation method according to claim 20, characterized in that, It further includes: A transparent film is disposed above the white pixel region, and the transparent film is located between the white color filter and the white pixel region. The transparent film and the infrared suppression film are on the same layer, and the white color filter and the color filter are on the same layer.

23. The preparation method according to claim 22, characterized in that, Further included is: A microlens is disposed above the color filter and the white color filter, wherein the microlens is formed synchronously with the transparent film and the white color filter.

24. The preparation method according to claim 22, characterized in that, Further included is: A gap layer is disposed between the infrared suppression film and the transparent film.

25. The preparation method according to claim 24, wherein, The gap layer is disposed first, then the infrared suppression film is disposed, and then the transparent film is disposed.

26. The preparation method according to claim 20, wherein The color filter includes a green color filter, a blue color filter, and a red color filter; the step of "disposing a color filter above the infrared suppression film" means: first disposing the green color filter, then disposing the red color filter, and finally disposing the blue color filter.

27. The preparation method according to claim 20, characterized in that, Further included is a metal wiring layer disposed on the backlight surface of the photosensitive element, and a metal wiring structure is disposed in the metal wiring layer to realize the connection of circuit components.

28. The preparation method according to claim 20, characterized in that, Further included is a metal wiring layer disposed on the light-receiving surface of the photosensitive element and below the infrared suppression film, and a metal wiring structure is disposed in the metal wiring layer to realize the connection of circuit components.

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