TW202401804A - Image sensor and method for manufacturing the same - Google Patents

Abstract

The subject disclosure provides an image sensor, including a photo sensing layer for receiving and detecting an incident light in a wavelength range and generating an optical signal indicative of the incident light, wherein the photo sensing 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 photo sensing layer, the redistribution layer including a plurality of conductive traces for receiving an electrical signal indicative of the optical signal; and a protection layer disposed on the redistribution layer and opposite to the photo sensing layer, the protection layer configured to reflect the incident light passing through the photo sensing layer and the redistribution layer and to direct a reflected light toward the second surface of the photo sensing layer to depart from the second surface, wherein the protection layer is opaque and reflective with respect to the optical signal within the wavelength range

Description

Image sensor and manufacturing method thereof

The present invention relates generally to image sensors, and in particular to image sensors that reduce or eliminate ghost images caused by light reflection.

Image sensors with visible and near-infrared (NIR) capabilities are used in a wide range of digital still cameras, cellular phones, security cameras, and medical, automotive, and other applications. The image sensor includes a pixel array having photosensitive elements (eg, photodiodes) that absorb a portion of the incident image light and generate image charges immediately after absorbing the image light. The sensors can operate in dual modes, which allows them to perform dual functions for daytime (visible spectrum applications) and night vision (infrared applications). This incorporated infrared capability is made possible by the development and implementation of several process enhancements that expand the spectral light sensitivity of the sensor to approximately 1050nm (adapted to the near-infrared range of 750-1400nm).

One drawback of this dual-mode capability is that the new sensitivity in the near-infrared range has resulted in the creation of infrared ghosts. In some cases, infrared radiation may be reflected, such as by a redistribution layer (RDL) of the image sensor, and then detected by the image sensor. This generates noise entering the image sensor, thereby reducing the sensitivity of the image sensor.

The technology used to manufacture image sensors continues to advance rapidly. The demand for higher resolution and lower power consumption has driven further miniaturization and consolidation of these devices. As the demand for image sensors continues to rise, high packing density and isolation of pixel units in image sensors and low noise performance have become increasingly challenging.

In order to solve the problem of image sensors detecting noise caused by ghost images caused by reflections, the present invention provides an improved sensor element. The present invention mainly improves the laminate structure. It uses an opaque protective layer to reduce the reflection caused by the redistribution layer (RDL), thereby reducing the ghost detected by the image sensor, simplifying the manufacturing process and reducing the need for multi-layer lamination. stress issues, thereby reducing the risk of component failure.

In one or more embodiments, according to an aspect of the present invention, an image sensor includes a light sensing layer for receiving an incident light in a wavelength range, detecting the incident light, and generating a signal representing the incident light. An optical signal of incident light, wherein the light sensing layer has a first surface and a second surface opposite to the first surface; a redistribution layer (RDL) disposed on the third surface of the light sensing layer On one surface, the redistribution layer includes a plurality of conductive traces for receiving an electrical signal representative of the optical signal; and a protective layer disposed above the redistribution layer and relative to the light sensing layer, the The protective layer is configured to reflect incident light passing through the light sensing layer and the redistribution layer, and to direct a reflected light away from the second surface of the light sensing layer, wherein the protective layer is configured for Light in this wavelength range is opaque.

According to an aspect of the present invention, a method for manufacturing an image sensor includes providing a substrate; forming a light sensing layer on the substrate for receiving an optical signal in a wavelength range, wherein the The light sensing layer has a first surface and a second surface opposite to the first surface; a redistribution layer is formed on the first surface of the light sensing layer, wherein the redistribution layer includes a a plurality of conductive traces of an electrical signal of the optical signal; and forming a protective layer over the redistribution layer and relative to the optical sensing layer, the protective layer configured to reflect through the optical sensing layer and the optical sensing layer Incident light of the layer is redistributed and a reflected light is directed away from the second surface of the light sensing layer, wherein the protective layer is opaque and reflective to light in the wavelength range.

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

Reference throughout this specification to "an example" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the invention. Therefore, the phrases "in one instance" or "in one embodiment" appearing in various places throughout this specification are not necessarily all referring 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.

For ease of description, spatially relative terms such as "bottom,""below,""lower,""lower,""upper,""upper," and the like may be used herein to describe an element or feature illustrated in the figures. relationship with another component(s) or feature(s) . It will be understood that these spatially relative terms are intended to cover different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the illustrative terms "below" and "below" may encompass both an orientation above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted differently. In addition, it will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

Throughout this specification, several terms are used. Such terms are to be given their ordinary meaning in the art from which they are derived, unless otherwise specifically defined herein or the context in which they are used would clearly imply otherwise. It should be noted that in this document, chemical element names and their symbols are used interchangeably (eg, Si versus silicon); however, both have the same meaning.

FIG. 1 shows a cross-sectional view of an image sensor 1 according to some embodiments of the present invention. As shown in FIG. 1 , the image sensor 1 may have a multi-layer structure. In some embodiments, the image sensor 1 may include a light sensing layer 12, a color filter 14, a lens 16, an isolation layer 18, a redistribution layer (RDL) 20, and a protective layer 22 and electrical contacts 24.

Referring to FIG. 1 , the image sensor 1 may include a photosensitive layer 12 , which may include photosensitive elements (eg, photodetectors). The light sensing layer 12 can receive and detect an optical signal including incident light of a specific wavelength incident on the surface 121 . In some embodiments, the light sensing layer 12 can detect visible light, infrared light (IR), near-infrared light (NIR), etc. The light sensing layer 12 can be used to receive light with wavelengths from 400n to 1000nm. The light sensing layer 12 can generate an electrical signal representing the detected light attribute (eg, the intensity of the detected light) according to the detected incident light and output the electrical signal. The light sensing layer 12 may have a surface 121 (also called a second surface) and a surface 122 (also called a first surface) opposite to the surface 121.

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

In some embodiments, redistribution layer 20 is a patterned conductive layer containing traces. The redistribution layer 20 may include a patterned conductive metal layer, the material of which may include, for example, gold (Au), silver (Ag), copper (Cu), nickel (Ni), palladium (Pd), a solder alloy, or two thereof. one or a combination of two or more. The redistribution layer 20 may be used to conduct electrical signals as needed. For example, the electrical signals generated by the light sensing layer 12 may be in electrical communication with the electrical contacts 24 via the redistribution layer 20 , and may be in electrical communication with external electronic components via the electrical contacts 24 . .

In some embodiments, the image sensor 1 may further include an isolation layer 18 disposed between the light sensing layer 12 and the redistribution layer 20 . The isolation layer 18 may be formed on the surface 122 of the light sensing layer 12 and in contact with the redistribution layer 20 . In some embodiments, barrier layer 18 is light transmissive.

A protective layer 22 may be formed on one side of the surface 122 of the light sensing layer 12 . The protective layer 22 may be formed on the isolation layer 18 and in contact with the isolation layer 18 . A protective layer 22 may be formed on the redistribution layer 20 and opposite the light sensing 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 and electrical interference. In some embodiments, protective layer 22 may be formed within redistribution layer 20, ie, between conductive traces. A protective layer 22 may laterally wrap the redistribution layer 20 to protect the conductive traces from opening or shorting the conductive traces.

In some embodiments, the protective layer 22 may be a passivation layer. In some embodiments, the protective layer 22 may be insulating and may include a high molecular weight polymer. The protective layer 22 may include a black solder mask film (BSMF). The protective layer 22 has a thickness less than or equal to 3 microns (um). In some embodiments, the transmittance of the protective layer 22 for light with wavelengths between 400 nm and 1000 nm is less than 1%. Preferably, the transmittance of the protective layer 22 for light with wavelengths between 400 nm and 1000 nm is less than 0.5%. Furthermore, preferably, the transmittance of the protective layer 22 for light with a wavelength between 400 nm and 1000 nm is less than 0.3%.

The protective layer 22 is substantially opaque, and in some embodiments reflective, to light in a specific wavelength range. Incident light with a specific wavelength is incident on the surface 121 of the light sensing 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 light sensing layer 12 The direction of the surface 121 is away from the image sensor 1 .

In some embodiments, the protective layer 22 is substantially opaque and low-reflective to light in a specific wavelength range, and can absorb light in the specific wavelength range. In some embodiments, the reflectivity of the protective layer 22 for light with a wavelength of 400 nm to 1000 nm is less than 5%. Preferably, the reflectivity of the protective layer 22 for light with a wavelength of 400 nm to 1000 nm is less than 3%. Light with a specific wavelength is incident on the protective layer 22 through the light sensing layer 12 and the redistribution layer 20 , and/or the incident light incident on the protective layer 22 from the external environment can be absorbed by the protective layer 22 .

The incident light entering the RDL layer and/or the protective layer 22 through the photo-sensing layer 12 may be reflected back to the photo-sensing layer 12 , resulting in ghost images caused by reflection. A protective layer that is substantially opaque to light in a specific wavelength range and has low reflectivity will effectively reduce ghosting caused by reflections.

In another direction of the image sensor 1 , incident light 31 (eg, ambient light) is incident from the outside toward the image sensor 1 . The incident light 31 may be reflected by the protective layer 22 to become reflected light 32 and leave the image sensor 1 .

In some embodiments, the protective layer 22 is substantially opaque to light of a specific wavelength and has partially absorbing and partially reflective properties. In some embodiments, the protective layer 22 is an infrared light absorbing layer or an infrared light reflecting layer.

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, protective layer 22 may include organic materials, solder mask, polyimide (PI), epoxy resin, one or more molding materials, borophosphosilicate glass (BPSG), silicon oxide , silicon nitride, silicon oxynitride, any combination thereof, etc. Examples of molding materials may include, but are not limited to, epoxy resins containing fillers dispersed therein. In some embodiments, the protective layer 22 may include inorganic materials such as silicon, ceramics, and the like. In some embodiments, protective layer 22 may include the same or similar material as isolation layer 18 .

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 . Referring to Figure 1, electrical contacts 24 may be in the form of conductive solder bumps. That is, electrical contact 24 may be a conductive input/output (I/O) pad. Electrical contacts 24 may be formed in protective layer 22 in contact with redistribution layer 20 and provide electrical connections between external components and redistribution layer 20 . In some embodiments, electrical contacts 24 may be partially laterally covered by protective layer 22 . The redistribution layer 20 is a patterned metal layer circuit that can electrically connect various locations inside the image sensor 1 to the outside through the electrical contacts 24 to supply power to the image sensor 1 .

The light sensing layer 12 may have one side surface 12s, which may be aligned with one side surface 18s of the isolation layer 18. The protective layer 22 may have a side surface 22s that may be aligned with the side surface 18s of the isolation layer 18 . In some embodiments, the side surface 22s of the protective layer 22 may be aligned with the side surface 12s of the light sensing layer 12. In some embodiments, the side surface 22s of the protective layer 22 may be coplanar with the side surface 12s of the light sensing layer 12. In another embodiment, the side surface 12s of the light sensing layer 12, the side surface 18s of the isolation layer 18 and the side surface 22s of the protective layer 22 may be coplanar.

The color filter 14 may be configured in various patterns and formed on the side of the surface 121 of the light sensing layer 12 . In some embodiments, color filters 14 may be configured as an array. For example, Bayer pattern RGB (red, green and blue) filters. Color filter 14 may comprise a panchromatic filter, that is, a clear filter.

In some embodiments, lens 16 may be disposed on color filter 14 and relative to light sensing layer 12 . The color filter 14 may be disposed between the pixel lens 16 and the light sensing layer 12 . Each lens 16 may be formed on a respective color filter 14 to guide incident light to pass through the respective color filter 14 and reach the light sensing layer 12 . In some embodiments, lens 16 may be a microlens or pixel lens. Corresponding to the color filter 14, the lenses 16 may be configured in an array. As shown in FIG. 1 , the incident light 28 enters the light sensing layer 12 of the image sensor 1 through the lens 16 and the filter 14 in the window hole 26 , and is sensed by the light sensing layer 12 .

In the current implementation, the incident light 31 (eg, infrared light or near-infrared light) can enter the image through the back side of the image sensor 1 (ie, the other side relative to the side where the color filter 14 is located) Sensor 1. It may pass through the protective layer 22 , the redistribution layer 20 and the isolation layer 18 and enter the light sensing layer 12 , thereby generating a ghost in the redistribution layer 20 .

However, in the image sensor 1 provided in this case, the protective layer 22 disposed on the backside (or bottom side) of the image sensor 1 may be reflective to infrared light or near-infrared light. Therefore, the incident light 31 (for example, infrared light, near-infrared light or other light in a specific wavelength range that can cause ghosting) incident from the back side will be reflected by the protective layer 22 and become reflected light 32, thereby preventing the light from penetrating into image sensor 1. In this way, the incident light 31 from the back side cannot cause ghosting.

In accordance with the present invention, the protective layer 22 may have conductive traces (eg, redistribution layer 20 ) that are protected from interference by the external environment, and may reflect and/or absorb undesired light. The protective layer 22 with at least these two functions eliminates the need to add additional layer structures to the image sensor, simplifies the manufacturing process, and avoids stress problems caused by multi-layer films, such as during the manufacturing process of the component, or during operation. Warping or deformation due to thermal stress.

In some embodiments, the material of the protective layer 22 and the material of the isolation layer 18 may be substantially the same. In some embodiments, the coefficient of thermal expansion (CTE) of the protective layer 22 and the CTE of the isolation layer 18 may be close to or substantially the same, so that deformation during the manufacturing process and/or operation of the image sensor or Warpage is reduced.

FIG. 2 shows a bottom view of an image sensor 1 according to some embodiments of the present invention. FIG. 2 shows a bottom view of the image sensor 1 in FIG. 1 , that is, a top view of the side with the electrical contacts 24 . Referring to FIG. 2 , the image sensor 1 includes a plurality of electrical contacts 24 disposed on the protective layer 22 . Please refer to the relevant paragraphs of Figure 1 for detailed description of the protective layer 22 and the electrical contacts 24.

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

FIG. 3 shows a cross-sectional view of the image sensor 2 according to some embodiments of the present invention. Referring to FIG. 3 , various components of the image sensor 2 are the same as the corresponding components of the image sensor 1 described above in FIGS. 1 and 2 . These similar elements are designated by similar reference numerals. Detailed descriptions of these similar elements will not be repeated. Compared with the image sensor 1 of FIG. 1 , the image sensor 2 includes a back side metal grid (BSMG) layer 40 .

Referring to FIG. 3 , the backside metal barrier layer 40 may be disposed on one side of the light sensing layer 12 relative to the redistribution layer 20 . In some embodiments, the backside metal barrier layer 40 may be disposed in the light sensing layer 12 . In some embodiments, the backside metal barrier layer 40 may be disposed proximate the color filter 14 . The backside metal barrier layer 40 may be disposed between the light sensing layers 12 . That is to say, after the incident light 28 passes through the lens 16 and the color filter 14 , it penetrates through the gap of the back metal barrier layer 40 and is received by the light sensing layer 12 .

In some embodiments, the backside metal barrier layer 40 may include a plurality of vertical lines and a plurality of horizontal lines perpendicularly intersecting each other (in plan view). Therefore, the backside metal barrier layer 40 may include a plurality of voids, which are defined by mutually perpendicular vertical lines and horizontal lines. In some embodiments, each void in the backside metal barrier layer 40 corresponds to each color filter 14 . That is to say, the gaps of the backside metal barrier layer 40 can be aligned with the color filter 14 .

The backside metal barrier layer 40 can be made of various types of metals to reflect light. For example, the backside metal barrier layer 40 can be made of aluminum (Al), copper (Cu), tungsten (W) or other metals. In some embodiments, the vertical lines and horizontal lines of the backside metal barrier layer 40 may have a width of about 0.1 microns to 0.3 microns.

The incident light 28 incident on the image sensor 2 may be reflected by the redistribution layer 20 or the protective layer 22 , and further reflected in the light sensing layer 12 through the backside metal barrier layer 40 to become reflected light 38 . Reflected light 38 may be re-reflected at any interface between layers and end up being collected by a neighboring pixel. The image sensor 2 with the backside metal barrier layer 40 can improve the reflection problem in the image sensor. Reflected light 38 reduces ghosting problems by consuming light intensity through the light path.

FIG. 4 shows a bottom view of the image sensor 3 according to some embodiments of the present invention. Referring to FIG. 4 , various components of the image sensor 3 are the same as the corresponding components of the image sensor 1 described above in FIGS. 1 and 2 . These similar elements are designated 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 .

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. Each notch 22b can be used to indicate the orientation of the image sensor. In some embodiments, the notch 22a may be formed at a position corresponding to the element active area of the image sensor 3, and the notch 22 may be formed at a corner position of the element active area of the image sensor.

Figure 5 is a cross-sectional view taken along line A-A in Figure 4 . The protective layer 22 is patterned such that a notch 22a is formed near the middle to expose an exposed portion 205 of the redistribution layer 20 . Since the etchant has different etching speeds for the redistribution layer 20 and the protective layer 22 including conductive material (eg, metal), the depth of the recess 22a may be different. The etching of the protective layer 22 by the etchant may stop in the protective layer 22 , or may stop at the interface between the protective layer 22 and the isolation layer 18 , or may stop in the isolation layer 18 . In some embodiments, the notch 22a may expose a portion of the isolation layer 18 . Since the exposed portion 205 is exposed to the etchant, the thickness of the exposed portion 205 may be smaller than the thickness of other conductive traces of the redistribution layer 20 . In certain embodiments, exposed portion 205 may have substantially the same thickness as other conductive traces of redistribution layer 20 based on the selectivity of the etchant used for conductive materials.

In some embodiments, the protective layer 22 is substantially opaque to visible light, and the redistribution layer 20 is reflective to visible light, so that the exposure of the redistribution layer 20 is visible when viewing the recess 22a from the direction of the electrical contact 24 The portion 205 reflects light, and the orientation of the image sensor 3 is determined by exposing the portion 205 .

The protective layer 22 that is opaque to a specific wavelength (e.g., visible light) not only isolates the redistribution layer 20 with conductive traces from environmental interference (e.g., moisture) and protects the image sensor from undesired light interference, For example. In known device structures, the protective layer that isolates the redistribution layer from moisture and the light-shielding layer that isolates the ambient light are separate layers. On the contrary, in the present invention, the protective layer 22 has the function of isolating moisture and having the function of shielding light, which can reduce the lamination process, reduce the complexity of etching to form the notches, and further reduce warpage caused by stress. and deformation, thereby reducing the risk of component failure.

In some embodiments, the width of the notch 22 a 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.

The notch 22a may be located in an element active area of the image sensor 3 . In some embodiments, the notch 22 a may be substantially located at or close to the middle position of the image sensor 3 .

Referring to FIG. 4, the notch 22a may be patterned into an L-shaped notch. In some embodiments, the patterned L-shaped recess 22a has two substantially mutually perpendicular arms, including a first arm 22a1 and a second arm 22a2. The two arms are respectively substantially parallel to the rows and columns 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 electrical contacts. The Y direction of the contact array.

In order to make the directional interpretation more convenient, the lengths of the two substantially mutually perpendicular arms of the L-shaped notch 22a may be different. For example, the length of the first arm 22a1 may be longer than the length of the second arm 22a2, and vice versa. Of course. In some embodiments, the widths of the two substantially mutually perpendicular arms of the L-shaped notch 22a may be different. For example, the width of the first arm 22a1 may be greater than the width of the second arm 22a2, and vice versa.

The orientation of the image sensor can be determined based on the arm direction of the L-shaped notch 22a. Taking FIG. 4 as an example, based on the intersection of the first arm 22a1 and the second arm 22a2, 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 in the X direction. In some embodiments, the second arm 22a2 may extend in the Y direction.

In some embodiments, notches 22a are configured between adjacent electrical contacts 24. Notches 22a may be aligned with an array of electrical contacts 24. For example, notch 22a may be aligned with electrical contact 24 in the X direction. In some embodiments, notches 22a may be aligned with electrical contacts 24 in the Y direction. In some embodiments, notches 22a may be misaligned (horizontally or vertically) with electrical contacts 24 .

Since the protective layer 22 is opaque, it is difficult to know the orientation of the image sensor from its appearance. The conductive trace layout of the RDL layer cannot be seen from the appearance of the image sensor, which may cause errors in the subsequent manufacturing process when the electrical contacts are electrically coupled to external components. We can determine the orientation of the image sensor through the reflection of the RDL layer through the specially patterned notch 22a, and then determine the correct connection of each electrical contact.

In some embodiments, the notch 22b may be located around the element active area of the image sensor 3 . In some embodiments, the notch 22b may be formed at a corner of the active area of the component.

Referring to Figure 4, the image sensor 3 includes four notches 22b. Through etching, the protective layer 22 forms notches 22b at the four corners of the device active area of the image sensor 3 . In some embodiments, the number of notches 22b may be greater than four. For example, the notch 22b can be located on at least one edge of the image sensor 3 to delineate the edge of the image sensor 3 . In some embodiments, the notch 22b may surround the element active area of the image sensor 3 .

The notch 22b can be patterned into a rectangular notch. In some embodiments, notches 22b may be patterned into elongated notches. In some embodiments, the notches 22b may be formed by patterning asymmetrically around the device active area of the image sensor 3 to help determine the device orientation of the image sensor 3 .

Since the protective layer 22 is opaque, the conductive trace arrangement of the RDL layer cannot be seen from the appearance of the image sensor, so it is difficult to determine the range of the element active area of the image sensor 3 . Through the configuration of the notch 22b, the range of the element active area of the image sensor 3 can be observed and confirmed under a visible light environment, which is helpful for subsequent processes (for example, processes such as singulation).

In some embodiments, the depth of recess 22a may be the same as the depth of recess 22b. In some embodiments, the depth of recess 22a may be different than the depth of recess 22b. In some embodiments, the depth of the recess 22b may be etched through the protective layer 22 . In some embodiments, etching is performed using an etchant, so that the etching stops at the protective layer 22 . In some embodiments, the etching stops at the isolation layer 18 , or the etching stops at the interface between the protective layer 22 and the isolation layer 18 , so that the isolation layer 18 is exposed. In some embodiments, the etch stops at redistribution layer 20, leaving the conductive material of redistribution layer 20 exposed.

In some embodiments, the recess 22b is formed at the outermost periphery of the component, so that the protective layer 22 may have an outer surface 22s1 that is recessed from the outer surface 18s of the isolation layer 18 . That is, the protective layer 22 may have a width smaller than the width of the isolation layer 18 . In some embodiments, the side surface 22s1 of the protective layer 22 may be recessed from the side surface 12s of the light sensing layer 12.

Figure 6 shows a perspective view of an image sensor 6 according to some embodiments of the present invention. The conductive circuit pattern of the redistribution layer 20 shown in FIG. 6 is only an example and is not intended to limit the scope of the present invention. Protective layer 22 is omitted in Figure 6 to clearly illustrate redistribution layer 20. The image sensor 6 includes an RDL layer 20 and electrical contacts 24 overlapping the conductive traces of the RDL 20 . The notch 22a having an L-shaped pattern helps us determine the orientation of the image sensor 6. The notch 22a is formed in the device active area, and the notch 22a exposes part of the RDL layer. The notches 22b1, 22b2 and 22b3 are located at the corners of the device active area, which help determine the range of the device active area of the image sensor 6. In some embodiments, the recesses 22b1, 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 redistribution layer 20. The arrangement of the asymmetric notches 22b1, 22b2 and 22b3 also helps us determine the orientation of the image sensor 6.

The electrical contact 24 is formed on the redistribution layer 20 and is electrically coupled to the redistribution layer 20. In some embodiments, the electrical contact 24 is in electrical contact with the redistribution layer 20. Electrical contacts 24 are used to provide electrical connections between external components and the redistribution layer 20 .

Figure 7 shows a perspective view of an image sensor 7 according to some embodiments of the present invention. Protective layer 22 is omitted in Figure 7 to clearly illustrate redistribution layer 20. Referring to FIG. 7 , the image sensor 7 may include a redistribution layer 20 having a conductive circuit pattern, a plurality of electrical contacts 24 , notches 22 a and notches 22 b. In some embodiments, electrical contacts 24 are disposed on and in contact with redistribution layer 20 to provide electrical connections between external components and redistribution layer 20 .

Referring to the embodiment of FIG. 7 , the notch 22 a is disposed near the center of the component of the image sensor, and the notch 22 a exposes the redistribution layer 20 . In some embodiments, the exposed portions of redistribution layer 20 exposed by notch 22a are electrical signal communication lines. In some embodiments, the redistribution layer 20 exposed by the recess 22a is independent of the electrical signal communication circuit, is not electrically connected to the light sensing layer 12, and/or is not electrically connected to the electrical contact 24.

The notch 22b can be disposed at the edge (for example, a corner position) of the image sensor 7 . In some embodiments, the recess 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, notch 22b may at least partially expose the conductive material of redistribution layer 20 .

Figure 8A includes an image that contains ghosts, such as ghosts caused by reflections from the RDL layer, or ghosts caused by ambient light. Figure 8B contains a clear image, that is, a control image in which no ghosts are formed. As can be clearly seen in Figure 8A, an image of the redistribution layer 20 showing its conductive traces and pads is produced within a clear image of the area being viewed. For example, incident light 31 incident on the back side carries information about the shape of the redistribution layer 20 and adds this to the information used to produce the image of Figure 8A. As mentioned above, this result is highly undesirable because it reduces the sensitivity of the image sensor and degrades the quality of the image produced by the image sensor. The images in Figures 8B and 8A are generated by an image sensor operating in the wavelength range of λ=400~1000nm. In some embodiments, other wavelength ranges may be suitable and are within the scope of this disclosure.

FIG. 9 is a flowchart of a method of manufacturing an image sensor according to the present invention. In step 91, a substrate is provided. In step 92, a light sensing layer is formed on the substrate. In some embodiments, the light sensing layer can be used to receive optical signals in a specific wavelength range. The light-sensing layer (eg, light-sensing layer 12) has a first surface (eg, surface 122) and a second surface (eg, surface 121) opposite to the first surface. In step 93, an isolation layer (eg, isolation layer 18) is formed on the light sensing layer and opposite to the substrate. In step 94, a redistribution layer (eg, redistribution layer 20) is formed on the light sensing layer, wherein the redistribution layer includes a plurality of conductive traces for receiving an electrical signal representative of the light signal. In step 95, a protective layer (eg, protective layer 22) is formed over the redistribution layer and opposite to the light sensing layer. The protective layer is opaque and reflective to light in the specific wavelength range. In operation 96, the protective layer is patterned to form a first recess (eg, recess 22a or recess 22b) at a first location. In step 97, a plurality of electrical contacts (eg, electrical contacts 24) are formed on the redistribution layer and through the protective layer. The detailed description of the image sensor manufactured by these steps is similar to the description in FIGS. 1 to 7 and is omitted for the sake of brevity.

The above description of illustrative examples of the invention, including what is set forth in the Abstract, is not intended to be exhaustive or to be limiting to the precise forms disclosed. Although specific embodiments and examples of the invention are set forth 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 specific example voltages, currents, frequencies, power range values, times, etc. are provided for purposes of explanation and that other values may be employed in other embodiments and examples consistent with the teachings of this disclosure.

Such modifications may be made to examples of the invention in view of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and claims. Rather, the scope will be determined entirely by the following patent application scope, which will be understood in accordance with the principles established in the interpretation of the claims. Accordingly, this specification and the drawings are to be regarded as illustrative rather than restrictive.

1:Image sensor 2:Image sensor 3:Image sensor 6:Image sensor 7:Image sensor 12:Light sensing layer 12s: Side surface 14: Color filter 16: Lens 18: Isolation layer 18s: side surface 20:Reassign layers 22:Protective layer 22a: Notch 22a1: first arm 22a2:Second arm 22b: notch 22b1: Notch 22b2: Notch 22b3: Notch 22s: Side surface 22s1:Side surface 24: Electrical contacts 26: window hole 28: Incident light 31: Incident light 32: Reflected light 38:Reflected light 40: Backside metal barrier (BSMG) layer 91: Steps 92: Steps 93: Steps 94: Steps 95: Steps 96: Steps 97: Steps 121:Surface 122:Surface 201: Surface 202: Surface 205:Exposed part

Non-limiting and non-exhaustive embodiments of the present invention are illustrated with reference to the following drawings, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

FIG. 1 shows a cross-sectional view of an image sensor according to some embodiments of the invention.

FIG. 2 shows a bottom view of an image sensor according to some embodiments of the invention.

FIG. 3 shows a cross-sectional view of an image sensor according to some embodiments of the invention.

FIG. 4 shows a bottom view of an image sensor according to some embodiments of the invention.

Figure 5 is a cross-sectional view taken along line A-A in Figure 4 .

Figure 6 shows a perspective view of an image sensor according to some embodiments of the present invention.

Figure 7 shows a perspective view of an image sensor according to some embodiments of the present invention.

Figure 8A contains an image in which a ghost is formed.

Figure 8B contains a clear image, that is, a control image in which no ghosts are formed.

FIG. 9 is a flowchart of a method of manufacturing an image sensor according to the present invention.

Common reference numbers are used throughout the various drawings and detailed description to indicate the same or similar components. The present invention may be best understood from the following detailed description taken in conjunction with the accompanying drawings.

1:Image sensor

12:Light sensing layer

12s: Side surface

14: Color filter

16: Lens

18: Isolation layer

18s: side surface

20:Reassign layers

22:Protective layer

22s: Side surface

24: Electrical contacts

26: window hole

28: Incident light

31: Incident light

32: Reflected light

121:Surface

122:Surface

201: Surface

202: Surface

Claims (20)

An image sensor including: A light sensing layer for receiving an incident light in a wavelength range, detecting the incident light, and generating an optical signal representing the incident light, wherein the light sensing layer has a first surface and is relative to the first surface. one surface a second surface; A redistribution layer (RDL) disposed on the first surface of the light sensing layer, the redistribution layer including a plurality of conductive traces for receiving an electrical signal representative of the light signal; and A protective layer disposed above the redistribution layer and relative to the light sensing layer, the protective layer configured to reflect incident light passing through the light sensing layer and the redistribution layer, and to convert a reflected light directed toward the second surface of the light sensing layer away from the second surface, The protective layer is opaque to light in the wavelength range. As in the image sensor of claim 1, the protective layer is patterned so as to form a first notch at a first position to expose the redistribution layer. The image sensor of claim 1, wherein the protective layer has a thickness greater than or equal to 3 microns. The image sensor of claim 1, wherein the protective layer includes an organic polymer material. The image sensor of claim 2, wherein the first position is located in a component active area. The image sensor of claim 2, wherein the protective layer is further patterned to form a second notch at the second position. The image sensor of claim 6, wherein the second notch extends to the RDL. The image sensor of claim 6, wherein the second notch is located around the component active area. The image sensor of claim 2, wherein the first notch is patterned into an L-shaped notch. The image sensor of claim 6, wherein the second notch is patterned into a rectangular notch. 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. 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 corners of an active area of the element. The image sensor of claim 1, wherein the protective layer has a transmittance of less than 1% for light with a wavelength of 400 nm to 1000 nm. The image sensor of claim 2, wherein the first notch is disposed between adjacent electrical contacts and aligned with a row of electrical contacts. The image sensor of claim 14, wherein the first notch is further configured to be aligned with a row of electrical contacts. The image sensor of claim 1 further includes an isolation layer disposed between the light sensing layer and the RDL. For example, the image sensor of claim 1 further includes a back side metal grid (BSMG) layer located on the second side of the light sensing layer and redistributed The layers are opposite. The image sensor of claim 17, wherein the light signal is reflected by the protective layer toward the second surface of the light sensing layer, and is further reflected in the light sensing layer through the backside metal barrier layer. A method for manufacturing an image sensor, which includes: providing a substrate; Forming a light-sensing layer on the substrate for receiving optical signals in a wavelength range, wherein the light-sensing layer has a first surface and a second surface opposite to the first surface; forming a redistribution layer (RDL) on the first surface of the light sensing layer, wherein the redistribution layer includes a plurality of conductive traces for receiving an electrical signal representative of the light signal; and A protective layer is formed over the redistribution layer and opposite to the light sensing layer, the protective layer is configured to reflect incident light passing through the light sensing layer and the redistribution layer, and direct a reflected light to the The second surface of the light sensing layer is away from the second surface, wherein the protective layer is opaque to light in the wavelength range. The method of claim 19, further comprising patterning the protective layer to form a first notch at a first location.

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