Light sensing chip and preparation method thereof, laser radar and electronic equipment

Abstract

The present application relates to the field of semiconductor packaging technology, and provides a photosensitive chip and a preparation method thereof, a laser radar and an electronic device; the preparation method includes the following steps: providing a wafer; the wafer includes a plurality of cores that can be cut and separated, and the cores include a substrate and a light detection module arranged on the substrate; providing a light-transmitting body; the light-transmitting body is adapted to the wafer; a dielectric layer for shading is arranged on at least one of the wafer or the light-transmitting body; the dielectric layer is respectively formed with light-transmitting holes in the area corresponding to the light detection module; bonding the wafer and the light-transmitting body to form a chip board group; forming the dielectric layer between the wafer and the light-transmitting body to form a cavity for accommodating the light detection module through the light-transmitting holes; cutting the chip board group to obtain a plurality of photosensitive chips. A reliable packaging structure is formed by stacking the core, the dielectric layer and the light-transmitting body, and the packaging structure is streamlined; the manufacturing steps are simplified, and the manufacturing efficiency of the photosensitive chip can be greatly improved.

Description

Technical Field

[0001] The present application relates to the field of chip packaging technology, and in particular provides a light sensing chip and a preparation method thereof, a laser radar and an electronic device. Background Art

[0002] The Time of Flight (TOF) device obtains the three-dimensional information of an object, such as the distance information or surface depth information of an object, by measuring the flight time of the light signal emitted by the light sensing chip in space. Due to its advantages such as long sensing distance and large measurement range, it is widely used in consumer electronics, autonomous driving, AR / VR and other fields.

[0003] The packaging structure of the light sensing chip of the TOF device currently on the market usually includes a packaging substrate and a cover body. The cover body and the packaging substrate are accurately aligned to package the chip. Some light sensing chips even require plastic sealing during the packaging process. The packaging structure is relatively complex, which increases the difficulty of the packaging process, resulting in increased costs and low packaging efficiency. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a light sensing chip and a method for preparing the same, a laser radar and an electronic device, aiming to solve the problem that the existing light sensing chip packaging is difficult and the packaging efficiency is low.

[0005] To achieve the above purpose, the technical solution adopted in this application is:

[0006] In the first aspect, an embodiment of the present application provides a method for preparing a light sensing chip, comprising the following steps: providing a wafer; the wafer comprises a plurality of cores that can be cut and separated, the cores comprising a substrate and a light detection module arranged on the substrate; providing a light-transmitting body; the light-transmitting body is adapted to the wafer; a dielectric layer for shading is arranged on at least one of the wafer or the light-transmitting body; the dielectric layer is respectively provided with light-transmitting holes in the areas corresponding to the light detection modules; the wafer and the light-transmitting body are bonded to form a chip board group; the dielectric layer is formed between the wafer and the light-transmitting body to form a cavity for accommodating the light detection module through the light-transmitting holes; the chip board group is cut to obtain a plurality of the light sensing chips.

[0007] In a possible design, a dielectric layer is provided on at least one of the wafer or the light-transmitting body, and light-transmitting holes are formed in the dielectric layer in areas corresponding to the light detection modules, including:

[0008] A first dielectric layer is formed on the wafer; a first light-transmitting hole is opened on the first dielectric layer to expose the light detection module on each of the cores; and / or a second dielectric layer is set on one side of the light-transmitting body; a second light-transmitting hole is opened on the second dielectric layer, and the first light-transmitting hole corresponds to the second light-transmitting hole one by one.

[0009] In a possible design, the light detection module includes a first light receiving element and a second light receiving element which are spaced apart from each other; the first light-transmitting hole is opened on the first dielectric layer to expose the light detection module on each of the cores, including:

[0010] A first sub-light-transmitting hole and a second sub-light-transmitting hole are provided in the first dielectric layer at intervals, so that the first light receiving element is exposed in the first sub-light-transmitting hole, and the second light receiving element is exposed in the second sub-light-transmitting hole.

[0011] In a possible design, the core further includes a light source bonding area, and the first light receiving element is closer to the light source bonding area than the second light receiving element; after the first sub-light-transmitting holes and the second sub-light-transmitting holes are provided at intervals on the first dielectric layer, the following steps are included:

[0012] A light source component is provided and arranged in the light source bonding area; the light source component and the first light receiving element are exposed to the first sub-light-transmitting hole.

[0013] In a possible design, the second light-transmitting hole is opened on the second medium layer; comprising:

[0014] A third sub-light-transmitting hole matching the first sub-light-transmitting hole and a fourth sub-light-transmitting hole matching the second sub-light-transmitting hole are provided on the second medium layer; wherein the third sub-light-transmitting hole is used to form a first chamber with the first sub-light-transmitting hole, and the fourth sub-light-transmitting hole is used to form a second chamber with the second sub-light-transmitting hole.

[0015] In a possible design, bonding the wafer and the light-transmitting body to form a chip-on-board assembly includes:

[0016] The first dielectric layer and the second dielectric layer are bonded by photocuring; or,

[0017] The first dielectric layer and the second dielectric layer are bonded by thermal compression.

[0018] In a possible design, a light-transmitting body is provided; comprising:

[0019] The light-transmitting body is made of a material that is transparent to infrared rays and blocks visible light; and / or, a light-filtering film layer is arranged on a side of the light-transmitting body that is away from the wafer.

[0020] In a possible design, after bonding the wafer and the light-transmitting body to form a chip board group and before cutting the chip board group to obtain a plurality of light-sensing chips, the method includes:

[0021] The wafer is thinned on a side of the wafer away from the light-transmitting body; a plurality of through-silicon vias penetrating the wafer are formed in the wafer; and a redistribution layer is formed on a side of the wafer away from the light-transmitting body.

[0022] In a possible design, the wavelength infrared transmittance of the first dielectric layer and the wavelength infrared transmittance of the second dielectric layer are both configured to be less than or equal to 1%; and / or, the thickness range of the first dielectric layer and the thickness range of the second dielectric layer are both set to 90um-150um.

[0023] In the second aspect, the present application also provides a light sensing chip, which is obtained by the preparation method described above, and the light sensing chip includes a core body, a dielectric layer and a light transmissive body which are stacked in sequence; the core body has a light source bonding area and a light detection module, and the light source bonding area is provided with a light source assembly; the light detection module includes a first light receiving element and a second light receiving element which are arranged at intervals, and the first light receiving element is closer to the light source assembly than the second light receiving element; the dielectric layer is opaque, and the light sensing chip has a first chamber and a second chamber formed in the dielectric layer which are connected between the light transmissive body and the core body, the light source assembly and the first light receiving element are located in the first chamber, and the second light receiving element is located in the second chamber.

[0024] In a possible design, the dielectric layer includes a first dielectric layer formed on the core and a second dielectric layer formed on the light-transmitting body; the first cavity and the second cavity penetrate the first dielectric layer and the second dielectric layer respectively.

[0025] In a third aspect, the present application also provides a laser radar, including a processing circuit and the light sensing chip, wherein the processing circuit is electrically connected to the light sensing chip and is used to control the light sensing chip to sense three-dimensional information of objects in space.

[0026] In a fourth aspect, the present application also provides an electronic device, including the above-mentioned laser radar.

[0027] The beneficial effect of the preparation method of the light sensing chip provided in the embodiment of the present application is that: by forming a dielectric layer with a light-shielding effect between the wafer and the light-transmitting body, and making a light-transmitting hole on the dielectric layer, after the wafer is bonded to the light-transmitting body, the dielectric layer forms a first chamber for accommodating the light source assembly and the first light receiving element and a second chamber for accommodating the second light receiving element at the light-transmitting hole, and a reliable packaging structure is formed only by stacking the core body, the dielectric layer, and the light-transmitting body. The overall packaging structure is streamlined, which is beneficial to cost saving; and, a plurality of finished light sensing chips forming an effective packaging structure can be obtained directly by cutting the bonded chip board group, and there is no need to perform packaging operations on the core body after cutting; simplifying the production steps, reducing the difficulty of light sensing chip packaging, and can greatly improve the production efficiency of light sensing chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 A flowchart of the steps of a method for preparing a light sensing chip provided in one embodiment of the present application;

[0030] Figure 2 A schematic diagram of a structure for providing a first dielectric layer on a wafer according to an embodiment of the present application;

[0031] Figure 3 A schematic diagram of a structure in which a first light-transmitting hole is provided on a first dielectric layer according to an embodiment of the present application;

[0032] Figure 4 for Figure 3 A magnified view of the part A in the middle;

[0033] Figure 5 A schematic diagram of the structure of a single core provided in one embodiment of the present application;

[0034] Figure 6 A schematic diagram of a three-dimensional structure in which a wafer and a light-transmitting body are prepared to be bonded together according to an embodiment of the present application;

[0035] Figure 7 A schematic diagram of a three-dimensional structure of a specific bonding structure of a first dielectric layer on a core body and a second dielectric layer on a light-transmitting body in a wafer provided in an embodiment of the present application;

[0036] Figure 8A schematic diagram of a three-dimensional structure of a specific bonding structure of a core body and a light-transmitting body in a wafer provided in an embodiment of the present application, wherein only a dielectric layer is provided on the wafer;

[0037] Fig. 9 A cross-sectional view of a light sensing chip provided in one embodiment of the present application;

[0038] Fig.10 A schematic diagram of the three-dimensional structure of a light sensing chip provided in one embodiment of the present application;

[0039] Fig.11 A schematic diagram of a three-dimensional structure of a groove formed on a light sensing chip provided in an embodiment of the present application.

[0040] Among them, the reference numerals in the figure are:

[0041] 1000, wafer;

[0042] 1. light sensing chip; 2. core body; 201. substrate; 202. light source bonding area;

[0043] 3. Dielectric layer; 301. first dielectric layer; 302. second dielectric layer;

[0044] 4. light-transmitting body; 5. light detection module; 501. first light receiving element; 502. second light receiving element;

[0045] 6. Light source assembly; 7. First chamber; 8. Second chamber;

[0046] 9. Light transmission hole;

[0047] 901, first light-transmitting hole; 9011, first sub-light-transmitting hole; 9012, second sub-light-transmitting hole;

[0048] 902, second light-transmitting hole; 9021, third sub-light-transmitting hole; 9022, third sub-light-transmitting hole;

[0049] 10. Chamber;

[0050] 11. Through silicon via; 12. Solder ball; 13. Redistribution layer; 14. Solder mask; 15. Grooving. DETAILED DESCRIPTION

[0051] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0052] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0053] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0054] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0055] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0056] The Time of Flight (TOF) device obtains the three-dimensional information of an object, such as the distance information or surface depth information of the object, by measuring the flight time of the light signal emitted by the light sensing chip in space. Due to its advantages such as long sensing distance and large measurement range, it is widely used in consumer electronics, autonomous driving, AR / VR and other fields. The packaging structure of the light sensing chip of the current TOF device on the market usually adopts a packaging substrate and a cover body, and the cover body and the packaging substrate are accurately aligned to package the chip. In the packaging process of some light sensing chips, the chip even needs to be further injection molded in the mold; the packaging structure is relatively complex, which will increase the difficulty of the packaging process, resulting in increased costs and low packaging efficiency.

[0057] Based on this, in order to solve the above problems, the first aspect of the present application designs a method for preparing a light sensing chip, by forming a dielectric layer with a light-shielding effect between a wafer and a light-transmitting body, and making a light-transmitting hole on the dielectric layer; after the wafer is bonded to the light-transmitting body, the dielectric layer forms a first chamber for accommodating a light source assembly and a first light receiving element and a second chamber for accommodating a second light receiving element at the light-transmitting hole, and a packaging structure is formed only by stacking a core body, a dielectric layer, and a light-transmitting body. The overall packaging structure is streamlined, which is beneficial to cost saving; and, a plurality of finished light sensing chips forming an effective packaging structure are obtained by directly cutting the bonded chip board group, and there is no need to perform packaging operations on the core body after cutting; simplifying the production steps can improve the production efficiency of light sensing chips.

[0058] Please refer to Fig. 9 , Fig.10 , Fig.11 The embodiment of the present application provides a light sensing chip 1, which includes a core body 2, a dielectric layer 3 and a light transmissive body 4 stacked in sequence; the core body has a light source bonding area 202 and a light detection module 5, and the light source bonding area 202 is provided with a light source assembly 6; the light detection module 5 includes a first light receiving element 501 and a second light receiving element 502 arranged at intervals, and the first light receiving element 501 is closer to the light source assembly 6 than the second light receiving element 502; the dielectric layer 3 is opaque, and the light sensing chip 1 is formed with a first cavity 7 and a second cavity 8 connected between the light transmissive body 4 and the core body 2 in the dielectric layer 3, the light source assembly 6 and the first light receiving element 501 are located in the first cavity 7, and the second light receiving element 502 is located in the second cavity 8.

[0059] The light sensing chip 1 is used to sense the three-dimensional information of objects in space, and the three-dimensional information includes but is not limited to the distance information of the object, the depth information of the surface of the object, and the proximity information of the object. Specifically, the light source assembly 6 is configured to emit a sensing light signal outward in the first chamber 7, wherein at least part of the sensing light signal can be projected into the space outside the light sensing chip 1 through the light-transmitting body 4, and part of the sensing light signal projected into the external space will be reflected back by the object in the space, and this part of the sensing light signal reflected back by the object can be used to sense the three-dimensional information of the object. The second light receiving element 502 is configured to receive the light signal returned from the outside of the light sensing chip 1 and output the corresponding light sensing signal. It can be understood that the light signal returned from the outside of the light sensing chip 1 includes the sensing light signal reflected back by the object, and also includes the ambient light signal of the external space. The first light receiving element 501 is arranged at a position closer to the light source assembly 6 than the second light receiving element 502. A portion of the sensing light signal is emitted from the light source assembly 6 and then transmitted inside the light sensing chip 1 to the first light receiving element 501 to be received as a reference light signal. The first light receiving element 501 is configured to receive the reference light signal and output a corresponding reference signal. The reference signal can be used to determine the emission time of the sensing light signal and / or to correct deviations caused by changes in environmental conditions such as temperature.

[0060] Optionally, the sensing light signal emitted by the light source assembly 6 may be visible light, infrared light or near infrared light, with a wavelength range of, for example, 390-780 nm, 700-1400 nm, 800-1000 nm, etc. In some embodiments, the sensing light signal may be a periodic light pulse signal.

[0061] It can be understood that the dielectric layer 3 is opaque and can provide a shading effect between the first chamber 7 and the second chamber 8, thereby preventing the light emitted by the light source assembly 6 from being transmitted through the inside of the light sensing chip 1, so that the second light receiving element 502 located in the second chamber 8 can only receive light reflected from the outside of the light sensing chip 1, thereby improving product reliability.

[0062] The dielectric layer 3 is made of resin and can be formed on at least one of the core 2 and the light-transmitting body 4 by coating, which is convenient to process and manufacture.

[0063] In some embodiments, the dielectric layer 3 is a colloid that can bond the core 2 and the light-transmitting body 4 , that is, the dielectric layer 3 can not only play a light-shielding role, but also a bonding role. The structural design is ingenious, which is conducive to simplifying the overall structure of the light-sensing chip 1 .

[0064] Here, the specific structure of the dielectric layer 3 is not limited, as long as it is formed between the core 2 and the light-transmitting body 4 and forms the first cavity 7 and the second cavity 8 .

[0065] For example, refer to Fig. 9and Fig.10 The dielectric layer 3 may be a double-layer structure, and the dielectric layer 3 includes a first dielectric layer 301 formed on the core 2 and a second dielectric layer 302 formed on the light-transmitting body 4; that is, the first dielectric layer 301 is pre-arranged on the core 2, and the second dielectric layer 302 is pre-arranged on the light-transmitting body 4, and the core 2 and the light-transmitting body 4 are bonded by connecting the first dielectric layer 301 and the second dielectric layer 302. The first cavity 7 and the second cavity 8 penetrate the first dielectric layer 301 and the second dielectric layer 302, respectively.

[0066] Alternatively, the dielectric layer 3 can be a single-layer structure, and the dielectric layer 3 is pre-arranged on one of the core 2 or the light-transmitting body 4. During bonding, the dielectric layer 3 is connected to the other of the core 2 or the light-transmitting body 4; the first cavity 7 and the second cavity 8 respectively penetrate the dielectric layer 3 of the single-layer structure.

[0067] The light sensing chip of the present application forms a first chamber 7 and a second chamber 8 in the dielectric layer 3 for accommodating the light source component 6 and the light detection module 5, so that the light source component 6 can directly emit a sensing light signal through the light-transmitting body 4, and the first light receiving element 501 and the second light receiving element 502 can directly receive external light signals through the light-transmitting body 4; and the dielectric layer 3 is also opaque, which can shield the interior of the light sensing chip 1, avoid light from penetrating the interior of the light sensing chip 1, and improve product stability; a light sensing chip product with a good packaging structure is formed by only stacking the core 2, the dielectric layer 3, and the light-transmitting body 4, and the overall packaging structure is concise and reliable, which is conducive to cost saving.

[0068] Furthermore, the light emitted from the light sensing chip 1 and the light entering the light sensing chip 1 from the outside only need to pass through a layer of light-transmitting body 4, thereby improving the light transmittance and reducing the refraction loss of light.

[0069] refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 According to a second aspect of an embodiment of the present application, there is provided a method for preparing a light sensing chip, the method comprising the following steps:

[0070] S101 , providing a wafer 1000 ; the wafer 1000 comprises a plurality of cores 2 that can be cut and separated, and the cores 2 comprise a substrate 201 and a light detection module 5 disposed on the substrate 201 .

[0071] It can be understood that a wafer refers to a silicon chip used in the manufacture of silicon semiconductor integrated circuits. Because of its round shape, it is called a wafer; various circuit component structures can be processed on the silicon wafer to become an integrated circuit product with specific electrical functions. Figure 3 and Figure 4The wafer 1000 includes a plurality of cores 2 arranged in an array and capable of being cut and separated.

[0072] The thickness range of wafer 1000 is 725-750um. The specific thickness of wafer 1000 can be any value among 725um, 730um, 735um, 740um, 745um and 750um, and the specific selection should be made according to the preparation requirements of different chips.

[0073] refer to Figure 5 A single core 2 includes a substrate 201 and a light detection module 5 arranged on the substrate 201. The light detection module 5 includes a first light receiving element 501 and a second light receiving element 502 which are spaced apart on the substrate 201. The first light receiving element 501 and the second light receiving element 502 are two photosensitive areas formed at different positions of the core 2 and can be used to receive light signals and convert them into corresponding electrical signals.

[0074] Specifically, the first light receiving element 501 and the second light receiving element 502 respectively include photosensitive pixels (not shown) capable of converting the received light signals into corresponding electrical signals, and the photosensitive pixels are, for example, single photon avalanche diodes (SPAD), avalanche photodiodes (APD), silicon photomultipliers (SiPM) formed by connecting multiple SPADs in parallel, and / or other suitable photoelectric conversion elements. Optionally, the photosensitive pixel can be single or multiple. In some embodiments, each photosensitive pixel can, for example, include a single SPAD and / or a combination of multiple SPADs.

[0075] The core 2 also includes a light source bonding area 202 disposed on the substrate 201 , and the first light receiving element 501 is closer to the light source bonding area 202 than the second light receiving element 502 ; the light source bonding area 202 is used to set the light source assembly 6 and make the light source assembly 6 form an electrical connection with the core 2 .

[0076] S102, providing a light-transmitting body 4; the light-transmitting body 4 is adapted to the wafer 1000;

[0077] Specifically, the shape of the light-transmitting body 4 matches the wafer 1000, and the light-transmitting body 4 can be stacked with the wafer and completely cover the wafer 1000. The light-transmitting body 4 is made of a light-transmitting material with good light-transmitting properties, such as glass, acrylic plate, etc., preferably glass.

[0078] In some embodiments, the sensing light signal emitted by the light source assembly 6 selected in the present application is infrared light, and the first light receiving element 501 and the second light receiving element 502 can receive infrared light. In order to improve the transmittance of infrared light in the light-transmitting body 4, so that the product can receive and emit infrared light in a targeted manner; the light-transmitting body 4 can be made of a material that transmits infrared light and isolates visible light, so that only infrared light can pass through the light-transmitting body 4.

[0079] Alternatively, a filter film (not shown) may be provided on the side of the light-transmitting body 4 away from the wafer 1000, so that the light-filter film enables the light-transmitting body 4 to filter visible light other than infrared light and allows only infrared light to penetrate the light-transmitting body 4; the thickness of the filter film ranges from 1 to 10 um, and specifically may be 1 um, 2 um, 3 um, 4 um, 5 um, 6 um, 7 um, 8 um, 9 um, 10 um, etc.

[0080] Optionally, an anti-reflection film (not shown) may be provided on the side of the light-transmitting body 4 close to the wafer 1000, which can reduce or eliminate the reflected light on the surface of the light-transmitting body 4, thereby increasing the light transmittance of the light-transmitting body 4, reducing or eliminating stray light, and improving the light transmittance. The thickness of the anti-reflection film ranges from 1 to 10 um, and specifically can be 1 um, 2 um, 3 um, 4 um, 5 um, 6 um, 7 um, 8 um, 9 um, 10 um, etc.

[0081] It can be understood that the wafer 1000 is cut after the transparent body 4 is bonded to the wafer 1000, and the transparent body 4 can also provide structural support for the wafer 1000 to ensure stable structural cutting. Therefore, the transparent body 4 should not be too thin, and the thickness of the transparent body 4 ranges from 200 to 600 um. Specifically, the thickness of the transparent body 4 can be 200 um, 300 um, 400 um, 500 um, 600 um, etc.

[0082] S103 , disposing a dielectric layer 3 for shielding light on at least one of the wafer 1000 or the light-transmitting body 4 ; the dielectric layer 3 is provided with light-transmitting holes 9 in regions corresponding to the light detection modules 5 .

[0083] refer to Figure 2 , Figure 5-Figure 7 In some embodiments, a first dielectric layer 301 is coated on the wafer 1000 so that the first dielectric layer 301 covers the first light receiving element 501 and the second light receiving element 502 of the core 2; the first dielectric layer 301 is made of resin and can be formed on at least one of the core 2 and the light-transmitting body 4 by coating, which is convenient for processing and manufacturing.

[0084] Specifically, the light-transmitting holes 9 include first light-transmitting holes 901 formed on the first dielectric layer 301 ; the first light-transmitting holes 901 are formed on the first dielectric layer 301 of each core 2 on the wafer 1000 by performing exposure and development processes on the first dielectric layer 301 on the wafer 1000 .

[0085] The first light-transmitting hole 901 specifically includes a first sub-light-transmitting hole 9011 and a second sub-light-transmitting hole 9012 spaced apart from each other; and, with reference to Figure 7 The first light receiving element 501 and the light source bonding area 202 are exposed to the outside of the core 2 through the first sub-light-transmitting hole 9011 , and the second light receiving element 502 is exposed to the outside of the core 2 through the second sub-light-transmitting hole 9012 .

[0086] A second dielectric layer 302 is coated on one side of the light-transmitting body 4, and the light-transmitting hole 9 also includes a second light-transmitting hole 902 formed on the second dielectric layer 302 and corresponding to the first light-transmitting hole 901 one by one; the second dielectric layer 302 on the light-transmitting body 4 is exposed and developed to form a second light-transmitting hole 902 on the second dielectric layer 302 on the light-transmitting body 4.

[0087] The second light-transmitting hole 902 specifically includes a third sub-light-transmitting hole 9021 and a fourth sub-light-transmitting hole 9022 which are spaced apart from each other; wherein the third sub-light-transmitting hole 9021 on the second dielectric layer 302 corresponds one-to-one to the first sub-light-transmitting hole 9011 on the first dielectric layer 301; and the fourth sub-light-transmitting hole 9022 on the second dielectric layer 302 corresponds one-to-one to the second sub-light-transmitting hole 9012 on the first dielectric layer 301.

[0088] In some embodiments, the first dielectric layer 301 and the second dielectric layer 302 are both made of photoresist, which is also called photoresist and has photochemical sensitivity. It is possible to produce a high-precision photolithography pattern on the photoresist by optical processing; and the photoresist has high heat resistance, chemical stability and easy processing. Specifically, the first dielectric layer 301 and the second dielectric layer 302 are exposed and developed to form the first light-transmitting hole 901 and the second light-transmitting hole 902, which is convenient to process and manufacture, and the optical processing method of exposure and development is used to realize the patterning of the surface of the first dielectric layer 301 and the second dielectric layer 302, and the manufacturing precision is higher. Among them, the exposure and development process is a conventional technical means in the prior art, and will not be described in detail here.

[0089] In some embodiments, the infrared transmittance of the wavelength of the first dielectric layer 301 and the infrared transmittance of the wavelength of the second dielectric layer 302 are both configured to be less than or equal to 1%. It can be understood that the sensing light signal emitted and received by the light sensing chip 1 of the present application is infrared light. By setting the infrared transmittance of the first dielectric layer 301 and the second dielectric layer 302 to a lower value, the light sensing chip 1 can be effectively shielded, so that the first dielectric layer 301 and the second dielectric layer 302 can shield the light crosstalk between the light source assembly 6 and the second light receiving element 502, thereby improving the sensing accuracy and ensuring product reliability.

[0090] In some embodiments, the first dielectric layer 301 and the second dielectric layer 302 are both black colloids.

[0091] In some embodiments, the thickness range of the first dielectric layer 301 and the thickness range of the second dielectric layer 302 are both set to 90um-150um. Specifically, the thickness of the first dielectric layer 301 and the thickness of the second dielectric layer 302 can be: 90um, 100um, 110um, 120um, 130um, 140um, 150um, etc.

[0092] It is understandable that the first dielectric layer 301 and the second dielectric layer 302 are made of colloidal material, and the thickness of the first dielectric layer 301 and the second dielectric layer 302 should not be designed to be too thick. Too thick first dielectric layer 301 and second dielectric layer 302 will cause the side walls at the light-transmitting hole to be non-vertical, affecting subsequent bonding and other processing techniques.

[0093] In some embodiments, reference Figure 8 Alternatively, the dielectric layer 3 may be provided on only one of the wafer 1000 or the light-transmitting body 4, and it is only necessary to make light-transmitting holes 9 corresponding to the light detection module 5 on the dielectric layer 3, so that the processing and manufacturing are simpler.

[0094] refer to Figure 5 , Figure 7 In some embodiments, after a first sub-light-transmitting hole 9011 and a second sub-light-transmitting hole 9012 are provided on the first dielectric layer 301 and spaced apart from each other, a light source assembly 6 is provided and the light source assembly 6 is disposed in the light source bonding area 202 on the core 2; the light source assembly 6 and the first light receiving element 501 are exposed in the first sub-light-transmitting hole 9011.

[0095] The light source assembly 6 and the first light receiving element 501 are both exposed to the first sub-light-transmitting hole 9011, so that after the sensing light signal is emitted from the light source assembly 6, part of the sensing light signal can be transmitted inside the light sensing chip 1 to the first light receiving element 501 and received as a reference light signal, which is conducive to more accurately determining the emission time of the sensing light signal.

[0096] Specifically, the light source assembly 6 is a light emitting element for emitting a sensing light signal, and the sensing light signal emitted by the light emitting element is infrared light. The light source assembly 6 can adopt, but is not limited to, a light source in the form of a vertical cavity surface emitting laser (Vertical Cavity Surface Emitting Laser, referred to as VCSEL, which can also be translated as a vertical resonant cavity surface emitting laser), an edge emitting laser (Edge Emitting Laser, EEL), a light emitting diode (Light Emitting Diode, LED), a laser diode (Laser Diode, LD), etc. Among them, the edge emitting laser can be a Fabry Perot (Fabry Perot, FP) laser, a distributed feedback (Distribute Feed back, DFB) laser, an electro-absorption modulated laser (Electro-absorption Modulated, EML), etc. Optionally, the light emitting element can be single or multiple. In the case of multiple light emitting elements, the multiple light emitting elements can be arranged regularly, for example, in an array arrangement, and the multiple light emitting elements can also be arranged irregularly and randomly. The light emitting elements can be of the same type or of different types.

[0097] The bottom surface of the light source assembly 6 is cured to the light source bonding area 202 of the core 2 through a conductive adhesive and electrically connected. The conductive adhesive is, for example, conductive silver paste; the top surface of the light source assembly 6 serves as the light emitting surface. If the positive and negative electrodes of the light source assembly 6 are located on the bottom and top surfaces respectively, the electrodes of the light source assembly 6 on the top surface need to be electrically connected to the light source bonding area 202 of the core 2 by wire bonding (not shown); if the positive and negative electrodes of the light source assembly 6 are both located on the bottom surface, no wire bonding operation is required; if the positive and negative electrodes of the light source assembly 6 are both located on the top surface, wire bonding is required for both electrodes of the light source assembly 6 on the top surface to electrically connect to the light source bonding area 202 of the core 2.

[0098] Specifically, the thickness of the light source assembly 6 is in the range of 80um-150um. The thickness of the light source assembly 6 may be greater than the thickness of the first dielectric layer 301. If the light source assembly 6 is first arranged on the core 2 and then the first dielectric layer 301 is arranged, the thickness of the first dielectric layer 301 is not enough to cover the light source assembly 6; therefore, refer to Figure 7 After the first light-transmitting hole 901 is pre-opened on the first dielectric layer 301, the light source assembly 6 is then disposed on the core 2, so that the manufacturing is more orderly and reasonable.

[0099] S104 , bonding the wafer 1000 and the light-transmitting body 4 to form a chip board assembly; forming a dielectric layer 3 between the wafer 1000 and the light-transmitting body 4 , so as to form a chamber 10 for accommodating the light detection module 5 through the light-transmitting hole 9 .

[0100] refer to Figure 6-Figure 9 After the wafer 1000 and the light-transmitting body 4 are stacked and bonded, the first dielectric layer 301 and the second dielectric layer 302 will be formed between the wafer 1000 and the light-transmitting body 4; the chamber 10 includes a first chamber 7 and a second chamber 8 that are spaced apart.

[0101] refer to Fig. 9 The first sub-light-transmitting hole 9011 on the first dielectric layer 301 and the third sub-light-transmitting hole 9021 on the second dielectric layer 302 form a first chamber 7 , and the light source assembly 6 and the first light receiving element 501 are both located in the first chamber 7 .

[0102] The second sub-light-transmitting hole 9012 on the first dielectric layer 301 and the fourth sub-light-transmitting hole 9022 on the second dielectric layer 302 form a second chamber 8, and the second light receiving element 502 is located in the second chamber 8. The first dielectric layer 301 and the second dielectric layer 302 between the first chamber 7 and the second chamber 8 can play a light-shielding role, so that the first chamber 7 and the second chamber 8 are not light-transmitting, thereby preventing the light emitted by the light source assembly 6 from being directly received by the second light receiving element 502 in the second chamber 8, thereby ensuring product reliability.

[0103] Here, the specific bonding method of the first dielectric layer 301 and the second dielectric layer 302 is not limited, as long as the bonding between the two is stable. For example, the first dielectric layer 301 and the second dielectric layer 302 can be photocured and bonded by utilizing the self-photocuring properties of the first dielectric layer 301 and the second dielectric layer 302 to bond the wafer 1000 to the light-transmitting body 4. Alternatively, the first dielectric layer 301 and the second dielectric layer 302 can be bonded by hot pressing by utilizing the self-thermal curing properties of the first dielectric layer 301 and the second dielectric layer 302. Alternatively, if the first dielectric layer 301 and the second dielectric layer 302 do not have photocuring or thermal curing properties themselves, new colloids with photocuring or thermal curing properties can be introduced into the first dielectric layer 301 and the second dielectric layer 302 for bonding.

[0104] In some embodiments, after bonding the wafer 1000 and the light-transmitting body 4 to form a chip board assembly, the wafer 1000 is thinned on a side of the wafer 1000 away from the light-transmitting body 4; specifically, the wafer 1000 needs to be thinned to 100um-200um, and the specific thickness can be selected according to the design requirements of the chip.

[0105] Understandably, reference Fig. 9, subsequently, the wafer 1000 needs to be processed with a through silicon via 11 process, namely, a TSV (Through Silicon Via) process. By making a through silicon via 11 in the wafer 1000 and filling it with conductive materials such as copper, tungsten, and polysilicon, the vertical electrical interconnection of the through silicon via 11 is realized, and the aluminum / copper welding area of ​​the core 2 can be led to the side of the wafer 1000 away from the light-transmitting body 4, which can greatly shorten the length of the circuit wiring; it is beneficial to reduce the geometric dimensions and packaging weight of the light-sensing chip 1 package. However, there is a limitation on the aspect ratio when making the through silicon via 11, so the thickness of the wafer 1000 cannot be too thick, and the thickness of the wafer 1000 needs to be thinned. Therefore, before making the through silicon via 11, the wafer 1000 needs to be thinned in advance. Here, the specific thinning operation can be performed by physical grinding and / or chemical etching.

[0106] In some embodiments, after the through silicon via 11 is manufactured, a redistribution layer 13 is further formed on the side of the wafer 1000 away from the light-transmitting body 4. Specifically, by manufacturing the redistribution layer 13 (Re-Distributed Layer, RDL), the aluminum / copper soldering area of ​​the through silicon via 11 can be rearranged to form a new soldering area, and the spacing between each new soldering area can be adjusted so that the new soldering area is in a reasonable position, thereby improving space utilization and avoiding too dense local leads during electrical connection, resulting in limited connection.

[0107] Continue to refer Fig. 9 In some embodiments, after the redistribution layer 13 is formed, a solder mask 14 is formed on the side of the wafer 1000 away from the light-transmitting body 4 to protect the wafer 1000 from oxidation.

[0108] After the solder resist layer 14 is manufactured, solder balls 12 are disposed on the solder resist layer 14 , and the solder balls 12 are connected to the new soldering areas of the redistribution layer 13 , so as to facilitate electrical connection.

[0109] S105 , cutting the chip board group to obtain a plurality of light sensing chips 1 .

[0110] It can be understood that the finished photosensitive chip 1 with an effective packaging structure can be obtained by directly cutting the chip board group. After cutting, there is no need to perform packaging operations on the core 2. The processing and manufacturing steps are streamlined, which can greatly improve the manufacturing efficiency of the photosensitive chip 1 and also achieve smaller core packaging.

[0111] refer to Fig.10 , Fig.11 In some embodiments, after obtaining the light sensing chip 1 , a groove 15 is provided on the light-transmitting body 4 , and the groove 15 passes through the light-transmitting body 4 ; and the groove 15 is located between the first cavity 7 and the second cavity 8 .

[0112] It can be understood that the depth of the groove 15 is the thickness of the light-transmitting body 4, that is, the groove 15 will not be formed on the second dielectric layer 302; the groove 15 can separate the light-transmitting body 4, making the light-transmitting body 4 discontinuous between the first chamber 7 and the second chamber 8, which can reduce the light transmission phenomenon between the first chamber 7 and the second chamber 8, which is conducive to more accurate reception of optical signals and improved product stability.

[0113] The preparation method of the light sensing chip of the present application forms a dielectric layer 3 with a light-shielding effect between a wafer 1000 and a light-transmitting body 4, and makes a light-transmitting hole 9 on the dielectric layer 3; after the wafer 1000 is bonded to the light-transmitting body 4, the dielectric layer 3 forms a first chamber 7 for accommodating a light source assembly 6 and a first light receiving element 501 and a second chamber 8 for accommodating a second light receiving element 502 at the light-transmitting hole 9. The packaging structure is formed only by stacking the core 2, the dielectric layer 3, and the light-transmitting body 4. The overall packaging structure is streamlined, which is conducive to cost saving. Moreover, a plurality of finished light sensing chips 1 forming an effective packaging structure can be obtained by directly cutting the bonded chip board group, and there is no need to perform packaging operation on the core 2 after cutting. The simplified production steps can improve the production efficiency of the light sensing chip 1.

[0114] The third aspect of the embodiment of the present application also provides a laser radar, including a processing circuit and the above-mentioned light sensing chip 1, the processing circuit is electrically connected to the light sensing chip 1, and is used to control the light sensing chip to sense three-dimensional information of objects in space.

[0115] Optionally, in some embodiments, the laser radar may further include a scanning unit, which may be configured to adjust the sensing direction of the light sensing chip to expand the sensing range of the light sensing chip.

[0116] The fourth aspect of the embodiment of the present application also provides an electronic device, which includes the above-mentioned laser radar. The laser radar is used to sense the three-dimensional information of objects in space, and the three-dimensional information includes but is not limited to the distance information of the object, the depth information of the surface of the object, and the proximity information of the object. The three-dimensional information is used, for example, in 3D modeling, face recognition, intelligent driving, machine vision, monitoring, drone control, augmented reality (AR) / virtual reality (VR), simultaneous localization and mapping (SLAM) and other fields, and the present application does not limit this. The electronic device is configured to implement corresponding functions according to the three-dimensional information of the surrounding environment obtained by the light sensing chip or the laser radar, for example: it can be determined whether an object appears within a preset range in front of the electronic device according to the proximity information of the object; or, the electronic device can be controlled to avoid obstacles according to the distance information of the object; or, 3D modeling, face recognition, machine vision, etc. can be implemented according to the depth information of the surface of the object. The electronic device can be a consumer electronic product, a home electronic product, a vehicle, a production device, etc. Among them, consumer electronic products include mobile phones, laptops, tablet computers, e-books, monitors, televisions, wearable devices, etc. Home electronic products include smart door locks, televisions, refrigerators, etc. Transportation tools include cars, motorcycles, electric skateboards, balance bikes, etc. Production equipment includes automatic CNC machine tools, robots, etc.

[0117] In the description of this specification, the description with reference to the terms "one embodiment", "certain embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0118] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a light sensing chip, characterized in that: The steps include: A wafer is provided; the wafer comprises a plurality of cores that can be cut and separated, the cores comprising a substrate and a light detection module and a light source bonding area arranged on the substrate; the light detection module comprises a first light receiving element and a second light receiving element that are arranged at intervals from each other; Providing a light-transmitting body; the light-transmitting body is adapted to the wafer; Disposing a dielectric layer for shielding light on at least one of the wafer or the light-transmitting body; The dielectric layer is formed with a light-transmitting hole in the area corresponding to the light detection module; the light source bonding area and the first light receiving element are located in the same light-transmitting hole, and the second light receiving element is located in another light-transmitting hole, and the light-transmitting hole is formed by an exposure and development process; Providing a light source assembly, and arranging the light source assembly in the light source bonding area; Bonding the wafer and the light-transmitting body to form a chip board assembly; The dielectric layer is formed between the wafer and the light-transmitting body, so as to form a cavity for accommodating the light detection module through the light-transmitting hole; Cutting the chip board group to obtain a plurality of light sensing chips; After obtaining the light sensing chip, a groove is provided on the light-transmitting body, wherein the groove passes through the light-transmitting body; and the groove is located between the two light-transmitting holes.

2. The method for preparing a light sensing chip according to claim 1, characterized in that: The method of disposing a dielectric layer on at least one of the wafer or the light-transmitting body, wherein the dielectric layer is provided with light-transmitting holes in areas corresponding to the light detection modules, comprises: forming a first dielectric layer on the wafer; A first light-transmitting hole is formed on the first dielectric layer to expose the light detection module on each of the cores; Disposing a second dielectric layer on one side of the light-transmitting body; A second light-transmitting hole is opened on the second medium layer, and the first light-transmitting hole corresponds to the second light-transmitting hole one by one.

3. The method for preparing a light sensing chip according to claim 2, characterized in that: The first light-transmitting hole is opened on the first dielectric layer to expose the light detection module on each of the cores, including: A first sub-light-transmitting hole and a second sub-light-transmitting hole are provided in the first dielectric layer at intervals, so that the first light receiving element is exposed in the first sub-light-transmitting hole, and the second light receiving element is exposed in the second sub-light-transmitting hole.

4. The method for preparing a light sensing chip according to claim 3, characterized in that: The first light receiving element is closer to the light source bonding area than the second light receiving element; After the first light-transmitting sub-holes and the second light-transmitting sub-holes are provided in the first dielectric layer and are spaced apart from each other, the method comprises: The light source assembly and the first light receiving element are both exposed to the first sub-light-transmitting hole.

5. The method for preparing a light sensing chip according to claim 4, characterized in that: The second light-transmitting hole is opened on the second medium layer; comprising: A third sub-light-transmitting hole matching the first sub-light-transmitting hole and a fourth sub-light-transmitting hole matching the second sub-light-transmitting hole are provided on the second medium layer; wherein the third sub-light-transmitting hole is used to form a first chamber with the first sub-light-transmitting hole, and the fourth sub-light-transmitting hole is used to form a second chamber with the second sub-light-transmitting hole.

6. The method for preparing a light sensing chip according to claim 2, characterized in that: The step of bonding the wafer and the light-transmitting body to form a chip-on-board assembly comprises: The first dielectric layer and the second dielectric layer are bonded by photocuring; or, The first dielectric layer and the second dielectric layer are bonded by thermal compression.

7. The method for preparing a light sensing chip according to any one of claims 1 to 6, characterized in that: The invention provides a light-transmitting body; comprising: The light-transmitting body is made of a material that is transparent to infrared rays and blocks visible light; and / or, a filter film layer is arranged on a side of the light-transmitting body that is away from the wafer.

8. The method for preparing a light sensing chip according to claim 1, characterized in that: After bonding the wafer and the light-transmitting body to form a chip board group, and before cutting the chip board group to obtain a plurality of light-sensing chips, the method includes: Performing a thinning process on the wafer at a side of the wafer away from the light-transmitting body; forming a plurality of through silicon vias (TSVs) in the wafer and penetrating the wafer; A redistribution layer is formed on a side of the wafer away from the light-transmitting body.

9. The method for preparing a light sensing chip according to any one of claims 2 to 6, characterized in that: The infrared transmittance of the first dielectric layer at a wavelength and the infrared transmittance of the second dielectric layer at a wavelength are both configured to be less than or equal to 1%; and / or, The thickness range of the first dielectric layer and the thickness range of the second dielectric layer are both set to 90um-150um.

10. A light sensing chip, obtained by the preparation method according to any one of claims 1 to 9, characterized in that: The light sensing chip comprises a core body, a dielectric layer and a light-transmitting body which are stacked in sequence; the core body has a light source bonding area and a light detection module, and the light source bonding area is provided with a light source assembly; The light detection module comprises a first light receiving element and a second light receiving element which are arranged at intervals, and the first light receiving element is closer to the light source assembly than the second light receiving element; The dielectric layer is opaque, and the light sensing chip forms a first cavity and a second cavity in the dielectric layer that are connected between the light-transmitting body and the core body. The light source assembly and the first light receiving element are located in the first cavity, and the second light receiving element is located in the second cavity.

11. The light sensing chip according to claim 10, characterized in that: The dielectric layer includes a first dielectric layer formed on the core and a second dielectric layer formed on the light-transmitting body; the first cavity and the second cavity penetrate the first dielectric layer and the second dielectric layer respectively.

12. A laser radar, characterized in that: include: A processing circuit and a light sensing chip as claimed in claim 10 or 11, wherein the processing circuit is electrically connected to the light sensing chip and is used to control the light sensing chip to sense three-dimensional information of objects in space.

13. An electronic device, characterized in that: Comprising a laser radar as described in claim 12.

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