Image sensor and its manufacturing method

Abstract

The present invention provides an image sensor comprising a photosensing layer for receiving incident light in a wavelength range, detecting the incident light, and generating an optical signal representing the incident light, wherein the photosensing layer has a first surface and a second surface opposite to the first surface; a redistribution layer RDL disposed on the first surface of the photosensing layer, the redistribution layer including a plurality of conductive traces for receiving an electrical signal representing the optical signal; and a protective layer disposed on the redistribution layer and opposite to the photosensing layer, the protective layer being configured to reflect incident light passing through the photosensing layer and the redistribution layer, and to direct the reflected light to the second surface of the photosensing layer and away from the second surface, wherein the protective layer is opaque and reflective to light in the wavelength range.

Description

Technical Field

[0001] This invention generally relates to image sensors, and more specifically to image sensors that reduce or eliminate ghosting caused by light reflection. Background Technology

[0002] Image sensors with visible and near-infrared (NIR) capabilities have been widely used in digital still cameras, cellular phones, security cameras, and in medical, automotive, and other applications. Image sensors comprise pixel arrays with photosensitive elements (e.g., photodiodes) that absorb a portion of incident image light and immediately generate an image charge after absorption. These sensors can operate in dual modes, allowing them to function in both daytime (visible spectrum applications) and nighttime vision (infrared applications). This incorporation of infrared capability has been made possible through the development and implementation of processes that extend the sensor's spectral sensitivity to approximately 1050 nm (fitting the 750-1400 nm near-infrared range).

[0003] One drawback of this dual-mode capability is that the new sensitivity in the near-infrared range has led to constructed infrared ghosting. In some cases, infrared radiation can be reflected, for example, through the redistribution layer (RDL) of the image sensor and then detected by the image sensor. This introduces noise into the image sensor, thus reducing its sensitivity.

[0004] The technology used to manufacture image sensors continues to advance rapidly. The demand for higher resolution and lower power consumption has spurred further miniaturization and integration of these devices. As the demand for image sensors continues to increase, the high packing density and isolation of pixel units within image sensors, as well as low-noise performance, have become increasingly challenging. Summary of the Invention

[0005] To address the noise problem caused by ghosting due to reflections detected by image sensors, this invention provides an improved sensor element. The invention primarily improves the stacked structure by using an opaque protective layer to reduce reflections from the redistribution layer (RDL), thereby reducing ghosting detected by the image sensor. This simplifies the manufacturing process, reduces stress issues in the multilayer stack, and ultimately lowers the risk of element failure.

[0006] In one or more embodiments, according to one aspect of the invention, an image sensor includes a photosensing layer for receiving incident light in a wavelength range, detecting the incident light, and generating an optical signal representing the incident light, wherein the photosensing layer has a first surface and a second surface opposite to the first surface; a redistribution layer (RDL) disposed on the first surface of the photosensing layer, the redistribution layer including a plurality of conductive traces for receiving an electrical signal representing the optical signal; and a protective layer disposed on the redistribution layer and opposite to the photosensing layer, the protective layer being configured to reflect incident light passing through the photosensing layer and the redistribution layer, and to direct the reflected light away from the second surface of the photosensing layer, wherein the protective layer is opaque to light in the wavelength range.

[0007] According to one aspect of the invention, a method for manufacturing an image sensor includes providing a substrate; forming a photosensitive layer on the substrate for receiving optical signals in a wavelength range, wherein the photosensitive layer has a first surface and a second surface opposite to the first surface; forming a redistribution layer on the first surface of the photosensitive layer, wherein the redistribution layer includes a plurality of conductive traces for receiving electrical signals representing the optical signals; and forming a protective layer on the redistribution layer and opposite to the photosensitive layer, the protective layer being configured to reflect incident light passing through the photosensitive layer and the redistribution layer, and to direct the reflected light away from the second surface of the photosensitive layer, wherein the protective layer is opaque and reflective to light in the wavelength range. Attached Figure Description

[0008] Non-limiting and non-exhaustive embodiments of the invention are illustrated with reference to the following figures, wherein, unless otherwise specified, similar element symbols refer to similar parts.

[0009] Figure 1 A cross-sectional view of an image sensor according to some embodiments of the present invention is shown.

[0010] Figure 2 A bottom view of an image sensor according to some embodiments of the present invention is shown.

[0011] Figure 3 A cross-sectional view of an image sensor according to some embodiments of the present invention is shown.

[0012] Figure 4 A bottom view of an image sensor according to some embodiments of the present invention is shown.

[0013] Figure 5 yes Figure 4 A cross-sectional view cut along line AA.

[0014] Figure 6 A perspective view of an image sensor according to some embodiments of the present invention is shown.

[0015] Figure 7 A perspective view of an image sensor according to some embodiments of the present invention is shown.

[0016] Figure 8A The image contains images in which ghosting occurs.

[0017] Figure 8B It contains a clear image, that is, a contrasting image in which no ghosting occurs.

[0018] Figure 9 A flowchart illustrating a method for manufacturing an image sensor according to the present invention is shown.

[0019] Throughout the various drawings and detailed descriptions, common reference numerals are used to indicate the same or similar components. The invention can be best understood from the following detailed description taken in conjunction with the accompanying drawings. Detailed Implementation

[0020] In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. However, those skilled in the art will recognize that the techniques described herein can be practiced without one or more of the specific details or using other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring certain aspects.

[0021] Throughout this specification, references to "an example" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that example is included in at least one example of the invention. Therefore, the phrases "in an example" or "in an embodiment" appearing in various places throughout this specification do not necessarily all refer to the same example or embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more examples and embodiments.

[0022] For ease of explanation, spatially relative terms such as “below,” “under,” “lower,” “below,” “above,” “upper,” and similar terms may be used herein to describe the relationship between one element or feature illustrated in the figures and another element(s). It will be understood that, in addition to the orientation shown in the figures, these spatially relative terms are also intended to cover different orientations of the device during use or operation. For example, if the device in the figures is rotated, then an element described as “below,” “below,” or “below” other elements or features will then be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “below” may cover both the above and below orientations. The device may be oriented in other ways (rotated 90 degrees or otherwise) and the spatially relative descriptive terms used herein will be interpreted accordingly. Furthermore, it will be understood that when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or there may be one or more intervening layers.

[0023] Several terms are used throughout this specification. These terms will be given their general meaning in the field of their origin, unless otherwise specifically defined herein or the context in which they are used will clearly imply otherwise. It should be noted that in this document, the names of chemical elements and their symbols are used interchangeably (e.g., Si and silicon); however, they have the same meaning.

[0024] Figure 1 A cross-sectional view of an image sensor 1 according to some embodiments of the present invention is shown. Figure 1 As shown, the image sensor 1 may have a multi-layer structure. In some embodiments, the image sensor 1 may include a photosensing layer 12, a color filter 14, a lens 16, an insulating layer 18, a redistribution layer (RDL) 20, a protective layer 22, and an electrical contact 24.

[0025] See Figure 1 The image sensor 1 may include a photosensing layer 12, which may include a photosensitive element (e.g., a photosensor). The photosensing layer 12 can receive and detect light signals containing incident light of a specific wavelength incident on the surface 121. In some embodiments, the photosensing layer 12 can detect visible light, infrared light (IR), or near-infrared light (NIR), etc. The photosensing layer 12 can be used to receive light with wavelengths in the range of 400 nm to 1000 nm. The photosensing layer 12 can generate and output an electrical signal representing the detected light properties (e.g., the intensity of the detected light) based on the detected incident light. The photosensing layer 12 may have a surface 121 (also referred to as a second surface) and a surface 122 (also referred to as a first surface) opposite to the surface 121.

[0026] In some embodiments, a redistribution layer (RDL) 20 is disposed on a surface 122 of a photosensing layer 12. The redistribution layer 20 may have a surface 201 and a surface 202 opposite to the surface 201.

[0027] In some embodiments, the redistribution layer 20 is a patterned conductive layer containing traces. The redistribution layer 20 may comprise a patterned conductive metal layer, the material of which may include, for example, gold (Au), silver (Ag), copper (Cu), nickel (Ni), palladium (Pd), solder alloys, or combinations of two or more thereof. The redistribution layer 20 can be used to conduct electrical signals as needed, for example, electrical signals generated by the photosensing layer 12 can communicate electrically with electrical contacts 24 via the redistribution layer 20, and can also communicate electrically with external electronic components via electrical contacts 24.

[0028] In some embodiments, the image sensor 1 may further include an isolation layer 18 disposed between the photosensing layer 12 and the redistribution layer 20. The isolation layer 18 may be formed on the surface 122 of the photosensing layer 12 and in contact with the redistribution layer 20. In some embodiments, the isolation layer 18 is light-transmitting.

[0029] A protective layer 22 may be formed on one side of the surface 122 of the photosensing layer 12. The protective layer 22 may be formed on and in contact with the insulating layer 18. The protective layer 22 may be formed on the redistribution layer 20 and relative to the photosensing layer 12. The protective layer 22 may be disposed on the surface 202 of the redistribution layer 20 to protect the conductive traces from external environmental interference, such as moisture or electrical interference. In some embodiments, the protective layer 22 may be formed within the redistribution layer 20, i.e., between the conductive traces. The protective layer 22 may laterally cover the redistribution layer 20 to protect the conductive traces from open circuits or short circuits.

[0030] In some embodiments, the protective layer 22 may be a passivation layer. In some embodiments, the protective layer 22 may be insulating and may comprise a polymer. The protective layer 22 may comprise a black solder mask film (BSMF). The protective layer 22 has a thickness of less than or equal to 3 micrometers (µm). In some embodiments, the protective layer 22 has a transmittance of less than 1% for light with wavelengths in the range of 400 nm to 1000 nm. Preferably, the protective layer 22 has a transmittance of less than 0.5% for light with wavelengths in the range of 400 nm to 1000 nm. More preferably, the protective layer 22 has a transmittance of less than 0.3% for light with wavelengths in the range of 400 nm to 1000 nm.

[0031] The protective layer 22 is substantially opaque to light within a specific wavelength range and is reflective in some embodiments. Incident light of a specific wavelength is incident on the surface 121 of the photosensitive layer 12, passes through the redistribution layer 20, is incident on the protective layer 22, is reflected by the protective layer 22, and the reflected light passes through the redistribution layer 20 and is directed toward the surface 121 of the photosensitive layer 12 before leaving the image sensor 1.

[0032] In some embodiments, the protective layer 22 is substantially opaque to light within a specific wavelength range and has low reflectivity, and absorbs light within that specific wavelength range. In some embodiments, the reflectivity of the protective layer 22 to light with wavelengths from 400 nm to 1000 nm is less than 5%, preferably less than 3%. Light with a specific wavelength, incident on the protective layer 22 via the photosensing layer 12 and the redistribution layer 20, and / or incident on the protective layer 22 from the external environment, can be absorbed by the protective layer 22.

[0033] Incident light passing through the photosensitive layer 12 and reaching the RDL layer and / or protective layer 22 may be reflected back to the photosensitive layer 12, resulting in ghosting due to reflection. A protective layer that is substantially opaque to light within a specific wavelength range and has low reflectivity will effectively reduce ghosting caused by reflection.

[0034] In the image sensor 1, incident light 31 (e.g., ambient light) is incident from the outside towards the image sensor 1. The incident light 31 can be reflected by the protective layer 22 and become reflected light 32, which leaves the image sensor 1.

[0035] In some embodiments, the protective layer 22 is substantially opaque to light of a specific wavelength and has the characteristics of partial absorption and partial reflection. In some embodiments, the protective layer 22 is an infrared light absorbing layer or an infrared light reflecting layer.

[0036] The protective layer 22 may be an insulating material. In one embodiment, the protective layer 22 may be an organic polymer material. In some embodiments, the protective layer 22 may comprise organic materials, solder mask, polyimide (PI), epoxy resin, one or more molding materials, borosilicate glass (BPSG), silicon oxide, silicon nitride, silicon oxynitride, any combination thereof, etc. Examples of molding materials may include, but are not limited to, epoxy resin containing fillers dispersed therein. In some embodiments, the protective layer 22 may comprise inorganic materials such as silicon, ceramics, etc. In some embodiments, the protective layer 22 may comprise the same or similar materials as the insulating layer 18.

[0037] One or more electrical contacts 24 may be formed on the surface 202 of the redistribution layer 20 and penetrate the protective layer 22 to make electrical contact with the redistribution layer 20. (Refer to...) Figure 1Electrical contact 24 can be in the form of a conductive solder bump. That is, electrical contact 24 can be a conductive input / output (I / O) pad. Electrical contact 24 can be formed in the protective layer 22 to contact the redistribution layer 20 and provide electrical connection between external components and the redistribution layer 20. In some embodiments, electrical contact 24 may be partially laterally covered by the protective layer 22. The redistribution layer 20 is a patterned metal layer of lines that can power various locations inside the image sensor 1 through electrical connections to the outside via electrical contacts 24.

[0038] The photosensing layer 12 may have a side surface 12s that may be aligned with the side surface 18s of the insulating layer 18. The protective layer 22 may have a side surface 22s that may be aligned with the side surface 18s of the insulating layer 18. In some embodiments, the side surface 22s of the protective layer 22 may be aligned with the side surface 12s of the photosensing layer 12. In some embodiments, the side surface 22s of the protective layer 22 may be coplanar with the side surface 12s of the photosensing layer 12. In another embodiment, the side surface 12s of the photosensing layer 12, the side surface 18s of the insulating layer 18, and the side surface 22s of the protective layer 22 may be coplanar.

[0039] The color filter 14 may comprise various patterns formed on the side of the surface 121 of the photosensing layer 12. In some embodiments, the color filter 14 may be arranged in an array. For example, a Bayer pattern RGB (red, green, and blue) filter. The color filter 14 may comprise a panchromatic filter, i.e., a clear filter.

[0040] In some embodiments, the lens 16 may be disposed on the color filter 14 and relative to the photosensing layer 12. The color filter 14 may be disposed between the pixel lens 16 and the photosensing layer 12. Each lens 16 may be formed on a corresponding color filter 14 to guide incident light through the corresponding color filter 14 to reach the photosensing layer 12. In some embodiments, the lens 16 may be a microlens or a pixel lens. Corresponding to the color filter 14, the lenses 16 may be arranged in an array. Figure 1 As shown, incident light 28 enters the photosensitive layer 12 of image sensor 1 through lens 16 and filter 14 in window 26, and is sensed by photosensitive layer 12.

[0041] In the present implementation, incident light 31 (e.g., infrared or near-infrared light) may enter the image sensor 1 via the back side of the image sensor 1 (i.e., the side opposite to where the color filter 14 is located). It may pass through the protective layer 22, the redistribution layer 20, and the insulating layer 18 to enter the photosensing layer 12, thereby producing a ghosting of the redistribution layer 20.

[0042] However, the protective layer 22 disposed on the back (or bottom) side of the image sensor 1 provided in this application is reflective of infrared or near-infrared light. Therefore, incident light 31 (e.g., infrared light, near-infrared light, or other light in a specific wavelength range that can cause ghosting) incident from the back side is reflected by the protective layer 22 and becomes reflected light 32, thereby preventing light from penetrating into the image sensor 1. In this way, the incident light 31 on the back side cannot cause ghosting.

[0043] According to the present invention, the protective layer 22 may have the function of protecting conductive traces (e.g., redistribution layer 20) from interference by the external environment, and may have the function of reflecting and / or absorbing unwanted light. The protective layer 22 having at least these two functions allows the image sensor 1 to avoid the need for additional layer structures, simplifies the manufacturing process, and avoids stress problems caused by multilayer films, such as warping or deformation of the element due to thermal stress during manufacturing or operation.

[0044] In some embodiments, the material of the protective layer 22 and the insulating layer 18 may be substantially the same. In some embodiments, the coefficient of thermal expansion (CTE) of the protective layer 22 and the insulating layer 18 may be close to or substantially the same, thereby reducing deformation or warping during the image sensor manufacturing process and / or operation.

[0045] Figure 2 A bottom view of an image sensor 1 according to some embodiments of the present invention is shown. Figure 2 It is illustrated Figure 1 The image sensor 1 is shown in the bottom view, and the image sensor 1 is shown in the top view, specifically the side with the electrical contact 24. (Refer to...) Figure 2 The image sensor 1 includes a plurality of electrical contacts 24 disposed on a protective layer 22. For detailed descriptions of the protective layer 22 and the electrical contacts 24, please see [link to relevant documentation]. Figure 1 Relevant paragraphs.

[0046] Electrical contacts 24 can be arranged in an array, which can have one or more columns or one or more rows. For example... Figure 2As shown, the array of electrical contacts 24 may have ten columns. In some embodiments, the array of electrical contacts 24 may have fewer or more than ten columns. The array of electrical contacts 24 may have seven rows. In some embodiments, the array of electrical contacts 24 may have fewer or more than seven rows. In some embodiments, each column may have the same or different number of electrical contacts 24. For example, a column may have 1, 2, 3, 4, 5, 6, or 7 electrical contacts 24. Each row may have the same or different number of electrical contacts 24. For example, a column may have 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 electrical contacts 24. In some embodiments, because the protective layer 22 is opaque, the orientation of the image sensor 1 may not be confirmed. An asymmetrical array of electrical contacts 24 can be used to confirm the orientation of the image sensor 1, thereby improving production yield in subsequent processes.

[0047] Figure 3 A cross-sectional view of an image sensor 2 according to some embodiments of the present invention is shown. See also Figure 3 The various components of image sensor 2 are the same as those of image sensor 2. Figure 1 and 2 The corresponding elements of the image sensor 1 illustrated above are shown. These similar elements are represented by similar reference numerals. Detailed descriptions of these similar elements will not be repeated. Figure 1 Compared to image sensor 1, image sensor 2 includes a back side metal grid (BSMG) layer 40.

[0048] Reference Figure 3 The back-side metal grid layer 40 may be disposed on one side of the photosensing layer 12, relative to the redistribution layer 20. In some embodiments, the back-side metal grid layer 40 may be disposed within the photosensing layer 12. In some embodiments, the back-side metal grid layer 40 may be disposed adjacent to the color filter 14. The back-side metal grid layer 40 may be disposed between the photosensing layers 12. That is, after the incident light 28 passes through the lens 16 and the color filter 14, it penetrates through the gaps in the back-side metal grid layer 40 and is received by the photosensing layer 12.

[0049] In some embodiments, the back metal grid layer 40 may include multiple vertical lines and multiple horizontal lines (viewed from above) that intersect each other perpendicularly. Therefore, the back metal grid layer 40 may include multiple gaps defined by the mutually perpendicular vertical and horizontal lines. In some embodiments, each gap in the back metal grid layer 40 corresponds to a respective color filter 14. That is, the gaps in the back metal grid layer 40 may be aligned with the color filters 14.

[0050] The back-side metal grid layer 40 can be made of various types of metal to reflect light. For example, the back-side metal grid layer 40 can be made of aluminum (Al), copper (Cu), tungsten (W), or other metals. In some embodiments, the vertical and horizontal lines of the back-side metal grid layer 40 can have a width of about 0.1 micrometers to 0.3 micrometers.

[0051] Incident light 28 incident on image sensor 2 can be reflected by redistribution layer 20 or protective layer 22, and further reflected by back metal grid layer 40 in photosensitive layer 12 to become reflected light 38. Reflected light 38 can be reflected again at any interface between layers and terminated by being collected by neighboring pixels. Image sensor 2 with back metal grid layer 40 can improve reflection problems in image sensors. The reflected light 38 reduces ghosting problems by consuming light intensity through the light path.

[0052] Figure 4 A bottom view of an image sensor 3 according to some embodiments of the present invention is shown. See also Figure 4 The various components of image sensor 3 are the same as those of image sensor 3. Figure 1 and 2 The corresponding elements of the image sensor 1 illustrated above are shown. These similar elements are indicated by similar reference numerals. Detailed descriptions of these similar elements will not be repeated. The image sensor 3 may include a plurality of electrical contacts 24 disposed on the protective layer 22.

[0053] In some embodiments, the protective layer 22 may be patterned to form a recess 22a at a first location and one or more recesses 22b at a second location, wherein the recess 22a and / or one or more recesses 22b may be used to indicate the orientation of the image sensor. In some embodiments, the recess 22a may be formed at a location corresponding to the element working area of ​​the image sensor 3, and the recess 22 may be formed at a corner location of the element working area of ​​the image sensor.

[0054] Figure 5 yes Figure 4A cross-sectional view cut along line AA. The protective layer 22 is patterned to form a notch 22a near the center, exposing the exposed portion 205 of the redistribution layer 20. Because the etchant has different etching rates for the redistribution layer 20 containing conductive material (e.g., metal) and the protective layer 22, the depth of the notch 22a may vary. The etching of the protective layer 22 may stop within the protective layer 22, or at the interface between the protective layer 22 and the insulating layer 18, or even at the insulating layer 18. In some embodiments, the notch 22a may expose a portion of the insulating layer 18. Given that the exposed portion 205 has been etched, its thickness may be less than the thickness of other conductive traces of the redistribution layer 20. In some embodiments, based on the selectivity of the etchant used for conductive material, the exposed portion 205 may have substantially the same thickness as the other conductive traces of the redistribution layer 20.

[0055] In some embodiments, the protective layer 22 is substantially opaque to visible light, while the redistribution layer 20 is reflective to visible light. Therefore, when the notch 22a is viewed from the direction of the electrical contact 24, the reflection of the exposed portion 205 of the redistribution layer 20 can be seen, and the orientation of the image sensor 3 is determined by the exposed portion 205.

[0056] For a protective layer 22 that is opaque to a specific wavelength (e.g., visible light), not only can the redistribution layer 20 with conductive traces be isolated from interference from the environment (e.g., moisture), but the image sensor can also be protected from unwanted light interference. In known device structures, the protective layer that isolates the redistribution layer from moisture is a different layer from the light-shielding layer that isolates ambient light. Conversely, in this invention, the protective layer 22 has both moisture-isolating and light-shielding functions, which can reduce the stacking process, reduce the complexity of etching to form notches, and further reduce warping and deformation due to stress, thereby reducing the risk of device failure.

[0057] In some embodiments, the width of the notch 22a may be substantially equal to the width of the exposed portion 205 of the redistribution layer 20. In some embodiments, the width of the notch 22a may be greater than the width of the exposed portion 205 of the redistribution layer 20.

[0058] The notch 22a may be located within the active area of ​​the image sensor 3. In some embodiments, the notch 22a may be located substantially at or near the center of the image sensor 3.

[0059] refer to Figure 4The notch 22a can be patterned into an L-shaped notch. In some embodiments, the L-shaped notch 22a has two substantially perpendicular arms, including a first arm 22a1 and a second arm 22a2. The two arms are substantially parallel to the columns and rows of the electrical contacts 24 forming the array, for example, the first arm 22a1 is substantially parallel to the X direction of the electrical contact array, and the second arm 22a2 is substantially parallel to the Y direction of the electrical contact array.

[0060] To facilitate directional interpretation, the two substantially perpendicular arms of the L-shaped notch 22a may have different lengths; for example, the first arm 22a1 may be longer than the second arm 22a2, and vice versa. In some embodiments, the two substantially perpendicular arms of the L-shaped notch 22a may have different widths; for example, the first arm 22a1 may be wider than the second arm 22a2, and vice versa.

[0061] The orientation of the image sensor can be determined based on the direction of the support arm of the L-shaped notch 22a. Figure 4 For example, taking the intersection of the first arm 22a1 and the second arm 22a2 as a reference, the first arm 22a1 extends along the -X direction, and the second arm 22a2 extends along the -Y direction. In other embodiments, the first arm 22a1 may extend along the X direction. In some embodiments, the second arm 22a2 may extend along the Y direction.

[0062] In some embodiments, the notch 22a is arranged between adjacent electrical contacts 24. The notch 22a may be aligned with a row of electrical contacts 24. For example, the notch 22a may be aligned with the electrical contacts 24 in the X direction. In some embodiments, the notch 22a may be aligned with the electrical contacts 24 in the Y direction. In some embodiments, the notch 22a may not be aligned with the electrical contacts 24 (in the horizontal or vertical direction).

[0063] Because the protective layer 22 is opaque, its orientation is difficult to determine from the appearance of the image sensor. The conductive traces of the RDL layer are not visible from the image sensor's exterior, potentially causing errors in subsequent manufacturing processes when electrically coupling electrical contacts to external components. We can determine the orientation of the image sensor through the reflection from the RDL layer via the specially patterned notches 22a, thereby ensuring the correct connection of each electrical contact.

[0064] In some embodiments, the notch 22b may be located around the element working area of ​​the image sensor 3. In some embodiments, the notch 22b may be formed at a corner position of the element working area.

[0065] refer to Figure 4The image sensor 3 includes four notches 22b. The protective layer 22 forms notches 22b at the four corners of the element's active area of ​​the image sensor 3 through etching. In some embodiments, the number of notches 22b may be greater than four. For example, the notches 22b may be located at at least one edge of the image sensor 3, thereby defining the edge of the image sensor 3. In some embodiments, the notches 22b may surround the element's active area of ​​the image sensor 3.

[0066] The notch 22b can be patterned into a rectangular notch. In some embodiments, the notch 22b can be patterned into an elongated notch. In some embodiments, asymmetrically patterning the notch 22b around the active area of ​​the image sensor 3 can help determine the orientation of the image sensor 3.

[0067] Because the protective layer 22 is opaque, the conductive traces of the RDL layer cannot be seen from the appearance of the image sensor, making it difficult to determine the extent of the active area of ​​the image sensor 3. With the arrangement of the notch 22b, the extent of the active area of ​​the image sensor 3 can be observed and confirmed under visible light, which facilitates subsequent processes (e.g., singulation).

[0068] In some embodiments, the depth of notch 22a may be the same as the depth of notch 22b. In some embodiments, the depth of notch 22a may be different from the depth of notch 22b. In some embodiments, the depth of notch 22b may penetrate the protective layer 22 via etching. In some embodiments, etching is performed using an etchant, causing the etching to stop at the protective layer 22. In some embodiments, etching stops at the insulating layer 18, or etching stops at the interface between the protective layer 22 and the insulating layer 18, exposing the insulating layer 18. In some embodiments, etching stops at the redistribution layer 20, exposing the conductive material of the redistribution layer 20.

[0069] In some embodiments, a notch 22b is formed at the outermost periphery of the element, such that the protective layer 22 may have an outer surface 22s1 that is recessed from the outer surface 18s of the insulating layer 18. That is, the protective layer 22 may have a width smaller than the width of the insulating layer 18. In some embodiments, the side surface 22s1 of the protective layer 22 may be recessed from the side surface 12s of the photosensitive layer 12.

[0070] Figure 6 A perspective view of an image sensor 6 according to some embodiments of the present invention is shown. Figure 6 The conductive circuit pattern of the redistribution layer 20 shown is merely an example and is not intended to limit the scope of the invention. Figure 6The protective layer 22 is omitted to clearly show the redistribution layer 20. The image sensor 6 includes an RDL layer 20 and electrical contacts 24 overlapping the conductive traces of the RDL 20. L-shaped notches 22a, formed in the element's active region, help determine the orientation of the image sensor 6, exposing a portion of the RDL layer. Notches 22b1, 22b2, and 22b3, located at the corners of the element's active region, help determine the extent of the element's active region of the image sensor 6. In some embodiments, notches 22b1 and 22b2 may be formed adjacent to the conductive material of the redistribution layer 20 without exposing the conductive material of the redistribution layer 20. In some embodiments, notch 22b3 may at least partially expose the conductive material of the redistribution layer 20. The asymmetrical arrangement of notches 22b1, 22b2, and 22b3 also helps determine the orientation of the image sensor 6.

[0071] Electrical contact 24 is formed on and electrically coupled to redistribution layer 20. In some embodiments, electrical contact 24 is in electrical contact with redistribution layer 20. Electrical contact 24 is used to provide an electrical connection between an external component and redistribution layer 20.

[0072] Figure 7 A perspective view of an image sensor 7 according to some embodiments of the present invention is shown. Figure 7 The protective layer 22 is omitted to clearly show the redistribution layer 20. (See reference...) Figure 7 The image sensor 7 may include a redistribution layer 20 having a conductive circuit pattern, a plurality of electrical contacts 24, a notch 22a, and a notch 22b. In some embodiments, the electrical contacts 24 are disposed on and in contact with the redistribution layer 20 to provide an electrical connection between an external element and the redistribution layer 20.

[0073] refer to Figure 7 In one embodiment, the notch 22a is positioned near the center of the image sensor element, exposing the redistribution layer 20. In some embodiments, the exposed portion of the redistribution layer 20 exposed by the notch 22a is an electrical signal communication line. In some embodiments, the redistribution layer 20 exposed by the notch 22a is independent of the electrical signal communication line, not electrically connected to the photosensing layer 12, and / or not electrically connected to the electrical contact 24.

[0074] The notch 22b may be disposed at the edge (e.g., a corner location) of the image sensor 7. In some embodiments, the notch 22b may be formed adjacent to the conductive material of the redistribution layer 20 without exposing the conductive material of the redistribution layer 20. In some embodiments, the notch 22b may at least partially expose the conductive material of the redistribution layer 20.

[0075] Figure 8AThe image contains ghosting, such as ghosting caused by reflections from the RDL layer or by ambient light. Figure 8B Includes a clear image, that is, a comparison image in which no ghosting occurs. For example... Figure 8A The image of the redistribution layer 20, which clearly shows its conductive lines and solder pads, is generated within a clear image of the area being viewed. For example, the incident light 31 incident from the back side carries information about the shape of the redistribution layer 20 and adds it to the image used to generate... Figure 8A The image information. As mentioned above, this result is highly undesirable because it reduces the sensitivity of the image sensor and degrades the quality of the images produced by the image sensor. In Figure 8B and 8A The images are generated by an image sensor operating in the wavelength range of λ = 400–1000 nm. In some embodiments, other wavelength ranges may also be applicable and fall within the scope of this disclosure.

[0076] Figure 9 A flowchart illustrating a method for manufacturing an image sensor according to the present invention is shown. In step 91, a substrate is provided. In step 92, a photosensitive layer is formed on the substrate. In some embodiments, the photosensitive layer can be used to receive light signals within a specific wavelength range. The photosensitive layer (e.g., photosensitive layer 12) has a first surface (e.g., surface 122) and a second surface (e.g., surface 121) opposite the first surface. In step 93, an insulating layer (e.g., insulating layer 18) is formed on the photosensitive layer and relative to the substrate. In step 94, a redistribution layer (e.g., redistribution layer 20) is formed on the photosensitive layer, wherein the redistribution layer includes a plurality of conductive traces for receiving an electrical signal representing the light signal. In step 95, a protective layer (e.g., protective layer 22) is formed on the redistribution layer and relative to the photosensitive layer. The protective layer is opaque and reflective to light within the specific wavelength range. In operation 96, the protective layer is patterned such that a first notch (e.g., notch 22a or notch 22b) is formed at a first location. In step 97, a plurality of electrical contacts (e.g., electrical contact 24) are formed on the redistribution layer and through the protective layer. A detailed description of the image sensor manufactured by these steps is similar to... Figures 1 to 7 The descriptions in the text have been omitted for the sake of brevity.

[0077] The above description of the illustrated examples of the invention, including the content set forth in the abstract, is not intended to be exhaustive or to limit the precise forms disclosed. While specific embodiments and examples of the invention have been set forth herein for illustrative purposes, various equivalent modifications may be made without departing from the broader spirit and scope of the invention. In fact, it should be understood that the voltage, current, frequency, power range values, time, etc., in the specific examples are provided for illustrative purposes, and other values ​​may be used in other embodiments and examples according to the teachings of the invention.

[0078] Based on the detailed description above, these modifications can be made to the embodiments of the invention. The terminology used in the appended claims should not be construed as limiting the invention to the specific embodiments disclosed in the specification and claims. Rather, the scope will be determined entirely by the appended claims, which will be understood as establishing the principles as interpreted by the claims. Therefore, this specification and the figures should be considered illustrative rather than limiting.

[0079] Symbol Explanation

[0080] 1: Image sensor

[0081] 2: Image sensor

[0082] 3: Image sensor

[0083] 6: Image sensor

[0084] 7: Image sensor

[0085] 12: Photosensitive layer

[0086] 12s: Side surface

[0087] 14: Color Filter

[0088] 16: Lens

[0089] 18: Insulation layer

[0090] 18s: Side surface

[0091] 20: Reassignment Layer

[0092] 22: Protective layer

[0093] 22a: Notch

[0094] 22a1: First arm

[0095] 22a2: Second arm

[0096] 22b: Notch

[0097] 22b1: Notch

[0098] 22b2: Notch

[0099] 22b3: Notch

[0100] 22s: Side surface

[0101] 22s1: Side surface

[0102] 24: Electrical contacts

[0103] 26: Window opening

[0104] 28: Incident light

[0105] 31: Incident light

[0106] 32: Reflected light

[0107] 38: Reflected light

[0108] 40: Backside Metal Grille (BSMG) Layer

[0109] 91: Steps

[0110] 92: Steps

[0111] 93: Steps

[0112] 94: Steps

[0113] 95: Steps

[0114] 96: Steps

[0115] 97: Steps

[0116] 121: Surface

[0117] 122: Surface

[0118] 201: Surface

[0119] 202: Surface

[0120] 205: Exposed portion.

[0121] Translation of attached images

[0122] Figure 9

[0123] 91. Provide substrate

[0124] 92. A photosensitive layer is formed on the substrate.

[0125] 93 An insulating layer is formed on the photosensitive layer and relative to the substrate.

[0126] 94. A redistribution layer is formed on the photosensitive layer.

[0127] 95. A protective layer is formed on top of the redistribution layer and relative to the photosensing layer.

[0128] 96. Pattern the protective layer such that a first notch is formed at a first location.

[0129] 97. Multiple electrical contacts are formed on the redistribution layer and penetrating the protective layer.

Claims

1. An image sensor comprising: A photosensitive layer is used to receive incident light in a wavelength range, detect the incident light, and generate an optical signal representing the incident light, wherein the photosensitive layer has a first surface and a second surface relative to the first surface; A redistribution layer RDL is disposed on the first surface of the photosensitive layer, the redistribution layer comprising a plurality of conductive traces for receiving electrical signals representing the optical signal; and A protective layer is disposed on top of the redistribution layer and relative to the photosensing layer. The protective layer is in contact with and laterally covers the redistribution layer. The protective layer is configured to reflect incident light passing through the photosensing layer and the redistribution layer, and to guide the reflected light to the second surface of the photosensing layer and exit from the second surface. The protective layer is opaque to light within the specified wavelength range.

2. The image sensor according to claim 1, wherein the protective layer is patterned such that a first notch is formed at a first location to expose the redistribution layer.

3. The image sensor according to claim 1, wherein the protective layer has a thickness greater than or equal to 3 micrometers (µm).

4. The image sensor according to claim 1, wherein the protective layer comprises an organic polymer material.

5. The image sensor according to claim 2, wherein the first position is located in the element's active area.

6. The image sensor of claim 2, wherein the protective layer is further patterned to form a second notch at a second location.

7. The image sensor of claim 6, wherein the second notch extends into the RDL.

8. The image sensor of claim 6, wherein the second notch is located around the element's functional area.

9. The image sensor according to claim 2, wherein the first notch is patterned into an L-shaped notch.

10. The image sensor of claim 6, wherein the second notch is patterned as a rectangular notch.

11. The image sensor of claim 6, wherein the first notch has a first depth, the second notch has a second depth, and the second depth is greater than or equal to the first depth.

12. The image sensor of claim 6, wherein the image sensor has at least two second notches, and the at least two second notches are located at the corner positions of the element's active area.

13. The image sensor of claim 1, wherein the protective layer has a transmittance of less than 1% for light with wavelengths in the range of 400 nm to 1000 nm.

14. The image sensor of claim 2, wherein the first notch is arranged between adjacent electrical contacts and aligned with a row of electrical contacts.

15. The image sensor of claim 14, wherein the first notch is further arranged to align with a row of electrical contacts.

16. The image sensor of claim 1, further comprising an insulating layer disposed between the photosensitive layer and the RDL.

17. The image sensor of claim 1, further comprising a back-side metal grid layer located on a second side of the photosensitive layer, opposite to the redistribution layer.

18. The image sensor of claim 17, wherein the optical signal is reflected by the protective layer toward the second surface of the photosensitive layer, and further reflected in the photosensitive layer by the back-side metal grid layer.

19. A method for manufacturing an image sensor, comprising: Provide substrate; A photosensitive layer is formed on the substrate for receiving light signals in a wavelength range, wherein the photosensitive layer has a first surface and a second surface relative to the first surface; A redistribution layer is formed on the first surface of the photosensitive layer, wherein the redistribution layer includes a plurality of conductive traces for receiving an electrical signal representing the optical signal; and A protective layer is formed on top of the redistribution layer and relative to the photosensing layer. The protective layer is in contact with and laterally covers the redistribution layer. The protective layer is configured to reflect incident light passing through the photosensing layer and the redistribution layer, and to direct the reflected light to the second surface of the photosensing layer and away from the second surface. The protective layer is opaque to light in the wavelength range.

20. The method of claim 19, further comprising patterning the protective layer such that a first notch is formed at a first location.

Images