Photoelectric signal conversion device and preparation method thereof

Abstract

The invention relates to a photoelectric signal conversion device and a preparation method thereof. A first wafer and a second wafer are respectively provided with a first photoelectric conversion unit and a second photoelectric conversion unit; the first wafers and the second wafers are arranged in a manner that the first photoelectric conversion unit of each first wafer corresponds to the second photoelectric conversion unit of one second wafer, and the second photoelectric conversion unit of each first wafer corresponds to the first photoelectric conversion unit of one second wafer; and after each first photoelectric conversion unit and the corresponding second photoelectric conversion unit form a sensor unit, the wafer assembly is segmented, so that a plurality of photoelectric signal conversion devices can be formed. According to the preparation method, a supporting device required by the photoelectric signal conversion device in the application process can be removed, and the temperature measurement precision can be improved while the production cost is reduced.

Description

Technical Field

[0001] The present application relates to the field of infrared detection technology, and in particular to a photoelectric signal conversion device and a preparation method thereof. Background Art

[0002] Two-color temperature measurement will not affect the accuracy of temperature measurement even if the surface state of the object changes. It determines the temperature by measuring the ratio of the radiation energy of the object in two specific bands. Therefore, two-color temperature measurement detectors are generally encapsulated with two layers of photoelectric signal conversion units.

[0003] Traditional two-color temperature detectors generally use microstructures to support the upper photoelectric signal conversion unit. This method not only generates high production costs, but also causes poor coaxiality between the stacked photoelectric signal conversion units due to the setting of the support structure, which in turn affects the temperature measurement accuracy of the two-color temperature detector. Summary of the invention

[0004] The present application provides a method for preparing a photoelectric signal conversion device, which comprises:

[0005] Providing a first wafer, the first wafer comprising a plurality of first photoelectric conversion units and a plurality of second photoelectric conversion units; wherein the first photoelectric conversion unit has a first functional surface, the second photoelectric conversion unit has a second functional surface, and an area of ​​the first functional surface is greater than an area of ​​the second functional surface;

[0006] Providing a second wafer, wherein the second wafer includes a plurality of first photoelectric conversion units and a plurality of second photoelectric conversion units;

[0007] Bonding the first wafer and the second wafer to form a wafer assembly; wherein each first photoelectric conversion unit of the first wafer corresponds to a second photoelectric conversion unit of the second wafer, and each second photoelectric conversion unit of the first wafer corresponds to a first photoelectric conversion unit of the second wafer; each first photoelectric conversion unit is connected to the corresponding second photoelectric conversion unit by welding bumps, and each first photoelectric conversion unit and a corresponding second photoelectric conversion unit form a sensor unit;

[0008] The wafer assembly is cut into pieces to form a plurality of the optoelectronic signal conversion devices.

[0009] In some embodiments, the first wafer includes a first surface, the first photoelectric conversion units included in the first wafer correspond to the second photoelectric conversion units one by one, and the orthographic projections of each of the first photoelectric conversion units and the corresponding second photoelectric conversion units on the plane where the first surface is located are symmetrical about the same straight line;

[0010] The second wafer includes a third surface, the first photoelectric conversion units included in the second wafer correspond one to one with the second photoelectric conversion units, and the orthographic projections of each first photoelectric conversion unit and the corresponding second photoelectric conversion unit on the plane where the third surface is located are symmetrical about the same straight line.

[0011] In some embodiments, in the first wafer, the orthographic projections of each of the first photoelectric conversion units and the corresponding second photoelectric conversion unit on the plane where the first surface is located are symmetrical about a first straight line, and the size of each of the first photoelectric conversion units perpendicular to the first straight line is larger than the size of the corresponding second photoelectric conversion unit perpendicular to the first straight line;

[0012] In the second wafer, the orthographic projections of each of the first photoelectric conversion units and the corresponding second photoelectric conversion unit on the plane where the third surface is located are symmetrical about a second straight line, and the size of each of the first photoelectric conversion units perpendicular to the second straight line is larger than the size of the corresponding second photoelectric conversion unit perpendicular to the second straight line.

[0013] In some embodiments, in each sensor unit, the second photoelectric conversion unit is arranged as an orthographic projection on the corresponding first photoelectric conversion unit along the direction in which the first wafer and the second wafer are stacked, and is partially staggered with the corresponding first photoelectric conversion unit;

[0014] A first external pad for electrically leading out the first photoelectric conversion unit is provided in an area on the first photoelectric conversion unit that is staggered from the orthographic projection of the second photoelectric conversion unit.

[0015] In some embodiments, the first wafer includes a first surface, and the first functional surfaces of all first photoelectric conversion units and the second functional surfaces of all second photoelectric conversion units included in the first wafer are located on the first surface; the second wafer includes a third surface, and the first functional surfaces of all first photoelectric conversion units and the second functional surfaces of all second photoelectric conversion units included in the second wafer are located on the third surface;

[0016] Bonding the first wafer and the second wafer to form a wafer assembly includes:

[0017] The first surface of the first wafer is placed toward the third surface of the second wafer, and the first wafer and the second wafer are bonded to form a wafer assembly.

[0018] In some embodiments, a second external pad for electrically leading out the second photoelectric conversion unit is further provided in an area of ​​the first photoelectric conversion unit that is offset from the orthographic projection of the second photoelectric conversion unit.

[0019] In some embodiments, the first wafer includes a first surface and a second surface which are opposite to each other, and functional surfaces of at least some of the plurality of first photoelectric conversion units and the plurality of second photoelectric conversion units included in the first wafer are located on the first surface, and functional surfaces of another portion of the photoelectric conversion units are located on the second surface; the second wafer includes a third surface, and first functional surfaces of all first photoelectric conversion units and second functional surfaces of all second photoelectric conversion units included in the second wafer are located on the third surface;

[0020] Bonding the first wafer and the second wafer to form a wafer assembly includes:

[0021] The first surface of the first wafer is placed toward the third surface of the second wafer, and the first wafer and the second wafer are bonded to form a wafer assembly.

[0022] In some embodiments, the first wafer includes a plurality of first photoelectric conversion units and a plurality of second photoelectric conversion units arranged into a plurality of groups of photoelectric conversion units, and the second wafer includes a plurality of first photoelectric conversion units and a plurality of second photoelectric conversion units arranged into a plurality of groups of photoelectric conversion units, each group of photoelectric conversion units includes a first photoelectric conversion unit and a second photoelectric conversion unit adjacent to each other; before providing the first wafer and providing the second wafer, the method includes forming the first wafer and forming the second wafer; wherein

[0023] The forming of the first wafer comprises: loading the first wafer into a photolithography machine;

[0024] The photolithography machine exposes the plurality of first exposure areas on the first wafer respectively to form a first wafer having the plurality of groups of photoelectric conversion units;

[0025] The forming of the second wafer comprises: loading the second wafer into a photolithography machine;

[0026] The photolithography machine exposes the multiple second exposure areas on the second wafer respectively to form a second wafer having the multiple groups of photoelectric conversion units; and the first exposure area and the second exposure area are equal in shape and size.

[0027] In some embodiments, after providing a first wafer and providing a second wafer, and before bonding the first wafer and the second wafer, the method includes:

[0028] Solder bumps are provided on at least one of the first wafer and the second wafer.

[0029] In some embodiments, bonding the first wafer and the second wafer comprises:

[0030] The first wafer and the second wafer are bonded by cold compression bonding; or

[0031] The first wafer and the second wafer are bonded by thermocompression bonding; or

[0032] The first wafer and the second wafer are bonded by ultrasonic bonding.

[0033] In some embodiments, the method further comprises: filling optical glue between the first photoelectric conversion unit and the second photoelectric conversion unit;

[0034] The optical adhesive is a two-component epoxy potting adhesive.

[0035] In some embodiments, all the photoelectric conversion units included in the first wafer are arranged in an array, and the multiple first photoelectric conversion units of the first wafer are arranged in multiple rows, and the multiple second photoelectric conversion units of the first wafer are arranged in multiple rows; the multiple rows of first photoelectric conversion units and the multiple rows of second photoelectric conversion units included in the first wafer include at least one row of first photoelectric conversion units and one row of second photoelectric conversion units that are arranged correspondingly and adjacently, and the multiple photoelectric conversion units of the row of first photoelectric conversion units and the corresponding adjacent row of second photoelectric conversion units are aligned in a direction perpendicular to the row of photoelectric conversion units, and a first scribe groove is provided between the row of first photoelectric conversion units and the corresponding adjacent row of second photoelectric conversion units;

[0036] All the photoelectric conversion units included in the second wafer are arranged in an array, a plurality of first photoelectric conversion units of the second wafer are arranged in a plurality of rows, and a plurality of second photoelectric conversion units of the second wafer are arranged in a plurality of rows; among the plurality of rows of first photoelectric conversion units and the plurality of rows of second photoelectric conversion units included in the second wafer, at least one row of second photoelectric conversion units and a row of first photoelectric conversion units are arranged correspondingly and adjacently, a plurality of photoelectric conversion units in a row of second photoelectric conversion units and the corresponding adjacent row of first photoelectric conversion units are aligned in a direction perpendicular to the row of photoelectric conversion units, and a second scribe groove is provided between the row of second photoelectric conversion units and the corresponding adjacent row of first photoelectric conversion units;

[0037] When the row of first photoelectric conversion units and the corresponding adjacent row of second photoelectric conversion units of the first wafer respectively correspond to the row of second photoelectric conversion units and the corresponding adjacent row of first photoelectric conversion units of the second wafer, the first scribe line is staggered with the second scribe line.

[0038] The present application further provides a photoelectric signal conversion device, which includes:

[0039] A first photoelectric conversion unit; the first photoelectric conversion unit has a first functional surface;

[0040] a second photoelectric conversion unit, the second photoelectric conversion unit having a first functional surface;

[0041] A plurality of welding bumps are supported at intervals between the first photoelectric conversion unit and the second photoelectric conversion unit.

[0042] In some embodiments, the second photoelectric conversion unit is disposed with an orthographic projection on the corresponding first photoelectric conversion unit along the direction in which the first photoelectric conversion unit and the second photoelectric conversion unit are stacked, and is partially staggered with the corresponding first photoelectric conversion unit;

[0043] A first external pad for electrically leading out the first photoelectric conversion unit is provided in an area on the first photoelectric conversion unit that is staggered from the orthographic projection of the second photoelectric conversion unit.

[0044] In some embodiments, the first functional surface of the first photoelectric conversion unit faces the second functional surface of the second photoelectric conversion unit;

[0045] A second external pad for electrically leading out the second photoelectric conversion unit is also provided in an area of ​​the first photoelectric conversion unit that is staggered from the orthographic projection of the second photoelectric conversion unit.

[0046] In some embodiments, the second photoelectric conversion unit is provided with a lead-out pad for electrically leading out the second photoelectric conversion unit, and the first photoelectric conversion unit includes a connecting pad opposite to the lead-out pad, the connecting pad is electrically connected to the second external pad, the connecting pad is directly opposite to the lead-out pad, and is connected to the lead-out pad through at least partial welding of the multiple welding bumps.

[0047] In some embodiments, the second functional surface of the second photoelectric conversion unit faces away from the first functional surface of the first photoelectric conversion unit, and the plurality of welding bumps serve as supporting bumps.

[0048] In some embodiments, optical glue is filled between the first photoelectric conversion unit and the second photoelectric conversion unit; and / or,

[0049] The solder bump is a solder ball; and / or the cross-sectional size of the solder bump is less than or equal to 5 μm.

[0050] The photoelectric signal conversion device and the preparation method thereof provided in the embodiment of the present application are provided by respectively setting the first photoelectric conversion unit and the second photoelectric conversion unit on the first wafer and the second wafer, and setting the first wafer and the second wafer so that each first photoelectric conversion unit of the first wafer corresponds to a second photoelectric conversion unit of the second wafer, each second photoelectric conversion unit of the first wafer corresponds to a first photoelectric conversion unit of the second wafer, and each first photoelectric conversion unit and a correspondingly set second photoelectric conversion unit form a sensor unit, and then the wafer assembly is cut to form a plurality of photoelectric signal conversion devices. This preparation method can remove the supporting device required by the photoelectric signal conversion device during the application process, reduce the production cost and improve the temperature measurement accuracy.

[0051] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are 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 creative work.

[0053] Figure 1 A flow chart of a method for preparing a photoelectric signal conversion device provided in one embodiment of the present application.

[0054] Figure 2 A layout of a first surface of a first wafer is provided in accordance with an embodiment of the present application.

[0055] Figure 3 A layout of a third surface of a second wafer is provided in accordance with an embodiment of the present application.

[0056] Figure 4 A schematic structural diagram of a first wafer at a viewing angle is provided for one embodiment of the present application.

[0057] Figure 5 A schematic structural diagram of a second wafer at a viewing angle is provided for one embodiment of the present application.

[0058] Figure 6 A structural schematic diagram of a first wafer from another perspective is provided for one embodiment of the present application.

[0059] Figure 7 A schematic structural diagram of a second wafer from another perspective is provided for one embodiment of the present application.

[0060] Figure 8 A schematic structural diagram of a first wafer and a second wafer bonded together at a certain viewing angle provided in an embodiment of the present application.

[0061] Fig. 9 A schematic diagram of the structure of a photoelectric signal conversion device provided in one embodiment of the present application at a certain viewing angle.

[0062] Fig.10 A schematic structural diagram of a first wafer and a second wafer bonded together at a certain viewing angle is provided in accordance with an embodiment of the present application.

[0063] Fig.11 Another layout of a first surface of a first wafer is provided in accordance with an embodiment of the present application.

[0064] Fig.12 Another layout of the second surface of a second wafer is provided in accordance with an embodiment of the present application.

[0065] Description of reference numerals:

[0066] 1. a first wafer; 10. a first surface; 101. a group of first photoelectric conversion units; 11. a second surface.

[0067] 2. A second wafer; 20. A second surface; 201. A group of second photoelectric conversions; 21. A fourth surface.

[0068] 3. Wafer assembly; 30. First photoelectric conversion unit; 300. First functional surface; 301. First bump; 40. Second photoelectric conversion unit; 400. Second functional surface; 401. Second bump; 50. Optical adhesive. DETAILED DESCRIPTION

[0069] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0070] In traditional two-color temperature detectors, some support structures need to be prepared on the upper photoelectric signal conversion unit to ensure the stability of the device. However, the support structure will bring systematic errors during the assembly process of the two-color temperature detector, and the set support structure will affect the alignment accuracy between the photoelectric signal conversion units, thereby affecting the temperature measurement accuracy of the two-color temperature detector.

[0071] Reference Figure 1 as shown, and if necessary, combined Figures 2 to 12As shown, the present application provides a method for preparing a photoelectric signal conversion device, which includes the following steps S100, S200, S300 and S400:

[0072] In step S100, a first wafer is provided, wherein the first wafer includes a plurality of first photoelectric conversion units and a plurality of second photoelectric conversion units; wherein the first photoelectric conversion unit has a first functional surface, the second photoelectric conversion unit has a second functional surface, and an area of ​​the first functional surface is greater than an area of ​​the second functional surface;

[0073] In step S200, a second wafer is provided, wherein the second wafer includes a plurality of first photoelectric conversion units and a plurality of second photoelectric conversion units;

[0074] In step S300, the first wafer and the second wafer are bonded to form a wafer assembly; wherein each first photoelectric conversion unit of the first wafer corresponds to a second photoelectric conversion unit of the second wafer, and each second photoelectric conversion unit of the first wafer corresponds to a first photoelectric conversion unit of the second wafer; each first photoelectric conversion unit is connected to the corresponding second photoelectric conversion unit by welding bumps, and each first photoelectric conversion unit and a corresponding second photoelectric conversion unit form a sensor unit;

[0075] In step S400, the wafer assembly is cut into pieces to form a plurality of the optoelectronic signal conversion devices.

[0076] The method for preparing the above-mentioned photoelectric signal conversion device is to respectively arrange the first photoelectric conversion unit and the second photoelectric conversion unit on the first wafer and the second wafer, and arrange the first wafer and the second wafer so that each first photoelectric conversion unit of the first wafer corresponds to a second photoelectric conversion unit of the second wafer, and each second photoelectric conversion unit of the first wafer corresponds to a first photoelectric conversion unit of the second wafer, and each first photoelectric conversion unit and a corresponding second photoelectric conversion unit form a sensor unit, and then the wafer assembly is cut to form a plurality of photoelectric signal conversion devices. This preparation method can remove the supporting device required by the photoelectric signal conversion device during the application process, reduce the production cost, and improve the temperature measurement accuracy.

[0077] Combination Figures 4 to 12 As shown, in step 100, a first wafer 1 is provided. The first wafer 1 includes a plurality of first photoelectric conversion units 30 and a plurality of second photoelectric conversion units 40, wherein the first photoelectric conversion unit 30 has a first functional surface 300, the second photoelectric conversion unit 40 has a second functional surface 400, and the area of ​​the first functional surface 300 is greater than the area of ​​the second functional surface 400.

[0078] In step 200 , a second wafer 2 is provided. The second wafer 2 includes a plurality of first photoelectric conversion units 30 and a plurality of second photoelectric conversion units 40 .

[0079] In some embodiments, the first wafer 1 includes a first surface 10 and a second surface 11, the first photoelectric conversion units 30 included in the first wafer 1 correspond one to one with the second photoelectric conversion units 40, and the orthographic projections of each first photoelectric conversion unit 30 and the corresponding second photoelectric conversion unit 40 on the plane where the first surface 10 is located are symmetrical about the same straight line R1.

[0080] The straight line R1 may be a straight line passing through the center of the first surface 10 of the first wafer 1. Of course, it may also be other straight lines.

[0081] Correspondingly, the second wafer 2 includes a third surface 20 and a fourth surface 21 facing away from the third surface 20. The first photoelectric conversion units 30 and the second photoelectric conversion units 40 included in the second wafer 2 correspond to each other one by one, and the orthographic projections of each first photoelectric conversion unit 30 and the corresponding second photoelectric conversion unit 40 on the plane where the third surface 20 is located are symmetrical about the same straight line R2.

[0082] The straight line R2 may be a straight line passing through the center of the first surface 10 of the first wafer 1. Of course, it may also be other straight lines.

[0083] In this example, the first wafer 1 and the second wafer 2 can be made of the same two wafers, which is helpful in saving wafer preparation costs.

[0084] for example Figure 4 and Figure 5 As shown, in some embodiments, in the first wafer 1, the orthographic projections of each of the first photoelectric conversion units 30 and the corresponding second photoelectric conversion unit 40 on the plane where the first surface 10 is located are symmetrical about the first straight line R1, and the dimension d1 of each of the first photoelectric conversion units 30 perpendicular to the first straight line R1 is greater than the dimension d2 of the corresponding second photoelectric conversion unit 40 perpendicular to the first straight line R1.

[0085] Correspondingly, in the second wafer 2, the orthographic projections of each of the first photoelectric conversion units 30 and the corresponding second photoelectric conversion unit 40 on the plane where the third surface 20 is located are symmetrical about the second straight line R2, and the dimension d1 of each of the first photoelectric conversion units 30 perpendicular to the second straight line R2 is greater than the dimension d2 of the corresponding second photoelectric conversion unit perpendicular to the second straight line R2.

[0086] Such a configuration can prevent the second photoelectric conversion unit 40 from completely covering the first photoelectric conversion unit 30, so as to facilitate the configuration of structures such as pads for external connection. The specific pad configuration will be described in detail in the subsequent bonding steps and will not be repeated here.

[0087] Of course, in some other embodiments, the first photoelectric conversion unit and the plurality of second photoelectric conversion units of the first wafer and the second wafer may not be arranged in the above-mentioned symmetrical manner.

[0088] In some embodiments, the first wafer 1 includes a plurality of first photoelectric conversion units 30 and a plurality of second photoelectric conversion units 40 arranged into a plurality of groups of photoelectric conversion units 101. Each group of photoelectric conversion units 101 includes one first photoelectric conversion unit 30 and one second photoelectric conversion unit 40 adjacent to each other.

[0089] The plurality of first photoelectric conversion units 30 and the plurality of second photoelectric conversion units 40 included in the second wafer 2 are arranged into a plurality of groups of photoelectric conversion units 201 , and each group of photoelectric conversion units 201 includes one adjacent first photoelectric conversion unit 30 and one adjacent second photoelectric conversion unit 40 .

[0090] In some embodiments, before providing the first wafer 1, the method includes forming the first wafer 1; the forming the first wafer 1 includes: loading the first wafer 1 into a photolithography machine;

[0091] The photolithography machine exposes the plurality of first exposure regions S11 on the first wafer 1 respectively to form the first wafer 1 having the plurality of groups of photoelectric conversion units. The first exposure regions S11 are arranged in an array on the first wafer 1.

[0092] Specifically, the first wafer 1 may be loaded into a photolithography machine.

[0093] Combination Figure 2 , Figure 4 and Figure 6 As shown, the photolithography machine exposes a plurality of first exposure regions S11 on the first wafer 1 to form a plurality of groups of photoelectric conversion units 101. The first exposure region S11 has a first sub-region (not shown in the figure) for preparing a larger photoelectric signal conversion unit and a second sub-region (not shown in the figure) for preparing a smaller photoelectric signal conversion unit in the positive direction of the first direction X1. Therefore, the photolithography machine exposes the first sub-region to form the first photoelectric conversion unit 30, and exposes the second sub-region to form the second photoelectric conversion unit 40.

[0094] The first exposure regions S11 are arranged in an array, so the multiple groups of photoelectric conversion units 101 formed are also arranged in an array.

[0095] In one embodiment, the lithography machine is a stepper projection lithography machine. The stepper projection lithography machine can automatically perform stepping and exposure, and continuously complete the exposure process of the first wafer 1. That is, after exposing a first exposure area S11, the wafer stage on which the first wafer 1 is placed moves to the next position according to a predetermined stepping distance, and the exposure process is repeated until the entire surface of the first wafer 1 is exposed.

[0096] In this process, the predetermined step distance is the same as the spacing between the first exposure regions S11 , or can also be understood as the same as the spacing between the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 .

[0097] In some embodiments, the first wafer 1 is a silicon wafer.

[0098] Accordingly, before step S200, the method further includes forming a second wafer 2. The forming of the second wafer 2 includes: loading the second wafer 2 into a photolithography machine;

[0099] The photolithography machine exposes the plurality of second exposure areas S21 on the second wafer 2 respectively to form a second wafer 2 having the plurality of groups of photoelectric conversion units.

[0100] Combination Figure 3 , Figure 5 and Figure 7 As shown, the second exposure area S21 has a first sub-area (not shown in the figure) for preparing a larger photoelectric signal conversion unit and a second sub-area (not shown in the figure) for preparing a smaller photoelectric signal conversion unit in the positive direction of the second direction X2. The photolithography machine exposes the plurality of second exposure areas S21 on the second wafer 2 respectively to form a second wafer 2 having the plurality of groups of photoelectric conversion units 201.

[0101] It should be noted that the first exposure area S11 on the first wafer 1 and the second exposure area S21 on the second wafer 2 are equal in shape and size, so as to ensure the alignment accuracy of the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 when the first wafer 1 and the second wafer 2 are bonded, thereby ensuring the temperature measurement accuracy.

[0102] Before step 300 , the method includes: preparing a solder bump on at least one of the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 .

[0103] Combination Figure 6 and Figure 7 As shown, in some embodiments, the bumps prepared on the first photoelectric conversion unit 30 are first welding bumps 301 , and the welding bumps prepared on the second photoelectric conversion unit 40 are second welding bumps 401 .

[0104] In this step, the solder bumps prepared on the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 are generally metal balls. The material may be indium. In some other embodiments, it may also be other conductive materials such as copper, tin, and gold.

[0105] Please refer to Figure 6-Figure 8 The first bump 301 and the second bump 401 mentioned here are both the above-mentioned bumps. The reason for dividing the first bump 301 and the second bump 401 is to facilitate the understanding of the subsequent steps.

[0106] In some embodiments, several first welding bumps 301 may be disposed on the first photoelectric conversion unit 30 .

[0107] Likewise, several second solder bumps 401 may be disposed on the second photoelectric conversion unit 40 .

[0108] In some embodiments, the cross-sectional dimensions of the first welding bump 301 and the second welding bump 401 are both less than or equal to 5 μm.

[0109] In some embodiments, the shapes of the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 perpendicular to the thickness direction may be rectangular or square or similar shapes, and their length and width dimensions are generally several millimeters.

[0110] In step 300 , the first wafer 1 and the second wafer 2 are bonded to form a wafer assembly 3 , and the first photoelectric conversion units 30 and the second photoelectric conversion units 40 correspondingly arranged in the wafer assembly 3 form a plurality of sensor units.

[0111] In some embodiments, the wafer assembly 3 is formed by cold compression bonding.

[0112] The bonding device is used to absorb the first wafer 1, and the first surface 10 of the first wafer 1 is oriented toward the third surface 20 of the second wafer 2. The first photoelectric conversion unit 30 corresponds to the second photoelectric conversion unit 40. Each second soldering bump 401 on each second photoelectric conversion unit 40 corresponds to the first soldering bump 301 on the first photoelectric conversion unit 30 corresponding thereto. If the first wafer 1 and the second wafer 2 are both provided with multiple groups of photoelectric conversion units, each group of photoelectric conversion units 101 may correspond to a corresponding group of photoelectric conversion units 201.

[0113] A certain pressure is applied to the first wafer 1 and the second wafer 2 at room temperature, so that the first welding bump 301 and the second welding bump 401 are connected, thereby forming a wafer assembly 3 .

[0114] In some embodiments, the wafer assembly 3 is formed by thermocompression bonding.

[0115] The same as the cold press bonding method, the difference is that the connection between the first welding bump 301 and the second welding bump 401 needs to be completed under a certain temperature and pressure. The hot press bonding method can increase the contact area between the first welding bump 301 and the second welding bump 401 and enhance the bonding strength.

[0116] In some embodiments, the wafer assembly 3 is formed by combining cold compression bonding and hot compression bonding. Specifically, the first wafer 1 and the second wafer 2 are initially fixed by cold compression bonding, which can also be understood as pre-bonding, and the bonding strength is further enhanced by hot compression bonding.

[0117] Specifically, pre-bonding at room temperature allows the first wafer 1 and the second wafer 2, which are integrated with a plurality of first photoelectric conversion units 30 with high-density first welding bumps 301 and a plurality of second photoelectric conversion units 40 with high-density second welding bumps 401, to be well initially fixed to ensure the alignment accuracy of the first welding bumps 301 and the second welding bumps 401 during the subsequent hot pressing bonding of the first wafer 1 and the second wafer 2, thereby avoiding problems such as poor bonding caused by low alignment accuracy of the small-sized and high-density first welding bumps 301 and the second welding bumps 401.

[0118] In some embodiments, after the first wafer 1 is pre-bonded to the second wafer 2 at room temperature by a preset pressure, the following steps are also included:

[0119] A flat pressing piece with a first preset temperature is used to bond the first wafer 1 and the second wafer 2 for a first preset time to achieve corresponding connection between the first welding bump 301 and the second welding bump 401, so that the first welding bump 301 and the second welding bump 401 are connected more firmly, thereby improving the bonding strength between the two.

[0120] In some embodiments, the first preset temperature is 220° C.-260° C., and the first preset time is 1 hour to 1.5 hours.

[0121] The pressing piece may be a plate-shaped piece or a sheet-shaped piece with high flatness, and its size may be consistent with (equal to or substantially equal to) the first wafer 1 .

[0122] In one embodiment, the pressed part is a sapphire wafer or a silicon wafer, and its flatness is ≤ 2 μm.

[0123] During the specific bonding operation, the press piece is placed on the side where the second surface 11 of the first wafer 1 is located and pressed toward the side where the first wafer 1 is located. During the pressing process, the press piece can be given a first preset temperature so that the first welding bump 301 and the second welding bump 401 between the first wafer 1 and the second wafer 2 are in a molten state. This bonding method can better align the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40, and can well improve the bonding strength between the two, which is conducive to making the bonding force of the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 at different positions more uniform, which is conducive to improving the bonding effect.

[0124] It is understandable that the pressing piece can be heated to a first preset temperature by a heating device.

[0125] In some embodiments, the first wafer 1 and the second wafer 2 are connected by ultrasonic bonding. Ultrasonic bonding can achieve precise alignment between the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40, so as to improve the coaxiality of the photosensitive surface between the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40, thereby improving the temperature measurement efficiency.

[0126] It should be noted that, in the wafer assembly 3, the photoelectric conversion units of the first wafer 1 and the second wafer 2 are arranged as multiple groups of photoelectric conversion units, and by performing panelization on the first wafer 1 and the second wafer 2, that is, in the bonded wafer assembly 3, each group of photoelectric conversion units on the first wafer 1 and the corresponding group of photoelectric conversion units on the second wafer, the arrangement direction of the first photoelectric conversion units 30 and the second photoelectric conversion units 40 in the two groups of photoelectric conversion units are just opposite, when the first surface 10 of the first wafer 1 and the third surface 20 of the second wafer 2 are relatively bonded to form the wafer assembly 3, wherein the several sensor units formed by the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 are cut into pieces on the wafer assembly 3, and the several sensor units are separated from the wafer assembly 3 to form a plurality of photoelectric signal conversion devices.

[0127] The present application designs a first photoelectric conversion unit 30 and a second photoelectric conversion unit 40 with a certain arrangement order on the first wafer 1 and the second wafer 2, and the arrangement order of the photoelectric conversion units on the first wafer 1 can be designed to be opposite to the arrangement order of the photoelectric conversion units on the second wafer 2. When the first wafer 1 and the second wafer 2 are bonded, different photoelectric conversion units on the first wafer 1 and the second wafer 2 are connected to form a sensor unit in a semi-finished state of a photoelectric signal conversion device. The first wafer 1 and the second wafer 2 including a plurality of sensor units are cut, that is, the wafer assembly 3 is cut, to form a plurality of separate photoelectric signal conversion devices.

[0128] This preparation method ensures that the photoelectric signal conversion device required for the dual-color temperature measurement detector is formed after dicing through the panel design on the first wafer 1 and the second wafer 2, combined with the bonding of the first wafer 1 and the second wafer 2, thereby greatly improving the production efficiency of the photoelectric signal conversion device.

[0129] Secondly, the bonding method of connecting wafers through welding bumps can eliminate the supporting structure in the photoelectric signal conversion device, ensure the coaxiality of the photosensitive surfaces of the upper photoelectric signal conversion unit and the lower photoelectric signal conversion unit, improve the temperature measurement effect, and reduce the production cost of the dual-color temperature measurement detector by reducing the preparation steps of the supporting mechanism.

[0130] It should be noted that "paneling" refers to arranging multiple circuit designs in a larger wafer layout, which allows multiple circuits of different sizes to share one exposure area.

[0131] In one embodiment, the second photoelectric conversion unit 40 is configured as an orthographic projection on the corresponding first photoelectric conversion unit 30 along the stacking direction of the first wafer 1 and the second wafer 2 , and is staggered from a partial area of ​​the corresponding first photoelectric conversion unit 30 .

[0132] A first external pad (not shown) for electrically leading out the first photoelectric conversion unit 30 may be provided in a region of the first photoelectric conversion unit 30 that is offset from the orthographic projection of the second photoelectric conversion unit 40 .

[0133] In some embodiments, the first functional surfaces 300 of all first photoelectric conversion units 30 and the second functional surfaces 400 of all second photoelectric conversion units 40 included in the first wafer 1 are located on the first surface 10. The first functional surfaces 300 of all first photoelectric conversion units 30 and the second functional surfaces 400 of all second photoelectric conversion units 40 included in the second wafer 2 are located on the third surface 20.

[0134] In some embodiments, Fig.10 As shown, in step S300 , the first wafer 1 and the second wafer 2 are bonded to form a wafer assembly 3 , including: the first surface 10 of the first wafer 1 is facing the third surface 20 of the second wafer 2 , and the first wafer 1 and the second wafer 2 are bonded to form a wafer assembly 3 .

[0135] In some embodiments, a second external pad for electrically leading out the second photoelectric conversion unit is further provided in an area of ​​the first photoelectric conversion unit 30 that is offset from the orthographic projection of the second photoelectric conversion unit 40 .

[0136] Combination Fig.10As shown, the second external pad and the first external pad on the first photoelectric conversion unit 30 can be located on opposite sides of the positive projection of the second photoelectric conversion unit 40 on the third surface 20, such as the left and right sides of the positive projection of the second photoelectric conversion unit 40 on the third surface 20 in the figure.

[0137] For the second external pads provided on the first photoelectric conversion unit 30, in some embodiments, the second photoelectric conversion unit 40 may be provided with lead pads for electrically leading out the second photoelectric conversion unit 40, and the first photoelectric conversion unit 30 may include a connection pad opposite to the lead pad, the connection pad is electrically connected to the second external pad, the connection pad may be directly opposite to the lead pad, and is connected to the lead pad by welding at least part of the plurality of welding bumps. Of course, the second external pad may also be electrically connected to the second photoelectric conversion unit in other ways.

[0138] In some embodiments, the projection of the midpoint of the second photoelectric conversion unit 40 on the first photoelectric conversion unit 30 along the thickness direction of the photoelectric signal conversion device 1001 coincides with the midpoint of the first photoelectric conversion unit 30. It can also be understood that the second photoelectric conversion unit 40 is located in the middle of the first photoelectric conversion unit 30.

[0139] In one embodiment, referring to Fig. 9 The photoelectric conversion unit located at the upper layer of the photoelectric signal conversion device 1001 is the second photoelectric conversion unit 40, and the photoelectric conversion unit located at the lower layer is the first photoelectric conversion unit 30. The second photoelectric conversion unit 40 is located in the middle of the first photoelectric conversion unit 30. The photoelectric signal conversion device 1001 is assembled into a dual-color sensor detector in this structure.

[0140] Combination Fig.11 and Fig.12 As shown, in some other embodiments, the functional surfaces of at least some of the plurality of first photoelectric conversion units 30 and the plurality of second photoelectric conversion units 40 included in the first wafer 1' may be located on the first surface 10, and the functional surfaces of another portion of the photoelectric conversion units may be located on the second surface 11. The first functional surfaces of all the first photoelectric conversion units and the second functional surfaces of all the second photoelectric conversion units included in the second wafer are located on the third surface. The second wafer may be similar to Figure 3 The second wafer 2 is shown.

[0141] Accordingly, in step S300, bonding the first wafer and the second wafer to form a wafer assembly includes:

[0142] The first surface 10 of the first wafer 1 ′ is directed toward the third surface of the second wafer, and the first wafer and the second wafer are bonded to form a wafer assembly.

[0143] When preparing the first wafer 1', a photolithography process can be used to form a photoelectric conversion unit. In the process of preparing the wafer 1', the wafer 1' can be loaded into a photolithography machine, and the photolithography machine exposes the exposure area S51 on the first surface S1 of the wafer 1' and the exposure area S52 on the second surface S2 to form a first photoelectric conversion unit 30 and a second photoelectric conversion unit 40. Among them, the photoelectric conversion units on one surface of the wafer 1' can be prepared in sequence, and then the wafer can be turned over to sequentially prepare the photoelectric conversion units on the other side of the wafer 1'. For example, the first photoelectric conversion unit 30 on the first surface S1 of the wafer 1' can be prepared in sequence, and then the second photoelectric conversion unit 40 on the second surface S2 of the wafer can be prepared in sequence.

[0144] It should be noted that, in some embodiments, a first alignment mark O1 may be provided in the center area of ​​the first wafer 1. A second alignment mark O2 may be provided in the center area of ​​the second wafer to align the first wafer 1 and the second wafer 2 before bonding.

[0145] In some embodiments, the central area of ​​the first wafer is set to one of the first photoelectric conversion unit and the second photoelectric conversion unit, and correspondingly, the central area of ​​the second wafer is set to the other of the first photoelectric conversion unit and the second photoelectric conversion unit, the central area of ​​the photoelectric conversion unit located at the center of the first wafer is set with the first alignment mark, and the central area of ​​the photoelectric conversion unit located at the center of the second wafer is set with the second alignment mark.

[0146] The first alignment mark and the second alignment mark may be a cross mark or other marks that can be used for identification and alignment by a bonding machine or other machine.

[0147] Of course, in some other embodiments, the central areas of the first wafer and the second wafer may not be set as the photoelectric conversion unit, and the alignment mark may not be set in the central area of ​​the photoelectric conversion unit.

[0148] It should be noted that the wafer 1 ′ may be provided with a first alignment mark O3 or O4 .

[0149] In some embodiments, the method further includes filling an optical glue 50 between the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 .

[0150] Please combine Fig.10 As shown, preferably, in some embodiments, after step S300 and before step S400, the bonded wafer assembly may be filled with optical glue 50 to form a Fig.10 The wafer assembly 3 is shown filled with optical adhesive 50 .

[0151] Of course, in some other embodiments, the optical adhesive may also be applied after step S400 .

[0152] The optical glue 50 fills the hollow area between the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 , and can wrap the first welding bump 301 and the second welding bump 401 to fix the first welding bump 301 and the second welding bump 401 , and support the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 .

[0153] The filling of the optical glue 50 can not only play a supporting role, but also improve the response of the photoelectric conversion unit located at the lower layer to light when the independent photoelectric signal conversion device 1001 is formed later. Fig. 9 The filling of the optical glue 50 can improve the response of the first photoelectric conversion unit 30 to light, and further improve the temperature measurement accuracy of the dual-color temperature measurement detector.

[0154] In some embodiments, the optical adhesive 50 is a two-component epoxy potting adhesive.

[0155] In some embodiments, after the optical glue 50 is filled between the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 and before the sensor unit is cut, the method includes:

[0156] In one embodiment, the first wafer 1 is thinned from the second surface 11 of the first wafer 1 .

[0157] Specifically, the first wafer 1 is thinned from its second surface 11 to less than or equal to 100 μm to ensure that light can better enter from the first photoelectric conversion unit 30 or the second photoelectric conversion unit 40, thereby ensuring the sensing efficiency of the dual-color temperature measuring detector.

[0158] In one embodiment, the first wafer 1 is thinned from the fourth surface 21 of the second wafer 2 .

[0159] Specifically, the second wafer 2 is thinned from the fourth surface 21 of the second wafer 2 to less than or equal to 100 μm to ensure that light can better enter from the first photoelectric conversion unit 30 or the second photoelectric conversion unit 40, thereby ensuring the sensing efficiency of the dual-color temperature measuring detector.

[0160] In one embodiment, referring to Fig. 9By filling the optical glue 50 between the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40, it can be ensured that light can better enter from the second photoelectric conversion unit 40, so as to improve the response of the photosensitive surface on the first photoelectric conversion unit 30 to light, thereby ensuring the sensing efficiency of the dual-color temperature measurement detector.

[0161] Step 400 , cutting the wafer assembly 3 to form a plurality of optoelectronic signal conversion devices 1001 .

[0162] In some embodiments, Figure 8 In the optoelectronic signal conversion device 1001 formed after the wafer assembly is cut, the first functional surface 300 of the first optoelectronic conversion unit 30 faces the second functional surface 400 of the second optoelectronic device.

[0163] As for the use of Fig.11 and Fig.12 The first wafer 1' is bonded to the corresponding second wafer, and in the optoelectronic signal conversion devices formed by dicing, the first functional surface 300 of the first optoelectronic conversion unit 30 of a part of the optoelectronic signal conversion devices faces the second functional surface 400 of the second optoelectronic device. The second functional surface 400 of the other part of the second optoelectronic device faces away from the first functional surface 300 of the first optoelectronic conversion unit 30.

[0164] In some embodiments, all the photoelectric conversion units included in the first wafer 1 are arranged in an array, and the multiple first photoelectric conversion units 30 of the first wafer 1 are arranged in multiple rows, and the multiple second photoelectric conversion units 40 of the first wafer 1 are arranged in multiple rows; the multiple rows of first photoelectric conversion units 30 and the multiple rows of second photoelectric conversion units 40 included in the first wafer 1 include at least one row of first photoelectric conversion units 30 and a row of second photoelectric conversion units 40 that are arranged correspondingly and adjacently, and the multiple photoelectric conversion units of the row of first photoelectric conversion units 30 and the corresponding adjacent row of second photoelectric conversion units 40 are aligned in a direction perpendicular to the photoelectric conversion unit row, and a first scribe groove 1011 is provided between the row of first photoelectric conversion units 30 and the corresponding adjacent row of second photoelectric conversion units 40.

[0165] All the photoelectric conversion units included in the second wafer 2 are arranged in an array, and the multiple first photoelectric conversion units 30 of the second wafer 2 are arranged in multiple rows, and the multiple second photoelectric conversion units 40 of the second wafer 2 are arranged in multiple rows; the multiple rows of first photoelectric conversion units 30 and the multiple rows of second photoelectric conversion units 40 included in the second wafer 2 include at least one row of second photoelectric conversion units 40 and a row of first photoelectric conversion units 30 that are arranged correspondingly and adjacently, and the multiple photoelectric conversion units of the row of second photoelectric conversion units 40 and the corresponding adjacent row of first photoelectric conversion units 30 are aligned in a direction perpendicular to the photoelectric conversion unit row, and a second scribe groove 1012 is provided between the row of second photoelectric conversion units 40 and the corresponding adjacent row of first photoelectric conversion units 30.

[0166] When the row of first photoelectric conversion units 30 and the corresponding adjacent row of second photoelectric conversion units 40 of the first wafer 1 respectively correspond to the row of second photoelectric conversion units 40 and the corresponding adjacent row of first photoelectric conversion units 30 of the second wafer 2, the first scribe line 1011 and the second scribe line 1012 are staggered.

[0167] for example, Figure 8 As shown, two adjacent rows of first photoelectric conversion units 3001 and second photoelectric conversion units 4001 on the first wafer 1 correspond to two adjacent rows of second photoelectric conversion units 4002 and first photoelectric conversion units 3002 on the second wafer 2, respectively. The first scribe groove 1011 of the two adjacent rows of first photoelectric conversion units 3001 and second photoelectric conversion units 4001 on the first wafer 1 is staggered with the second scribe groove 1012 of the two adjacent rows of second photoelectric conversion units 4002 and first photoelectric conversion units 3002 on the second wafer 2.

[0168] Specifically, refer to Figure 4 , Figure 5 and Figure 8 In the first wafer 1, a first scribe groove 1011 is prepared between each two adjacent photoelectric conversion units. A first mark (not shown in the figure) corresponding to the first scribe groove 1011 is provided on the second surface 11. In the second wafer 2, a first scribe groove 1012 is prepared between each two adjacent photoelectric conversion units, and a second mark (not shown in the figure) corresponding to the second scribe groove 12 is provided on the fourth surface 21. The wafer assembly 3 is cut along the first mark and the second mark to obtain a plurality of photoelectric signal conversion devices 1001.

[0169] It should be particularly noted that the sensor unit in this step refers to the state of the photoelectric signal conversion device 1001 before dicing, that is, a number of undiced sensor units are still located in the wafer assembly 3.

[0170] In some embodiments, the method of cutting the first wafer 1 and the second wafer 2 along the first mark and the second mark specifically includes:

[0171] S501 , cutting the first wafer 1 according to the first mark on the second surface 11 .

[0172] During the bonding process between the first wafer 1 and the second wafer 2 , the first surface 10 of the first wafer 1 is aligned with the third surface 20 of the second wafer 2 by a bonding device until the bonding is completed.

[0173] In this process, the second surface 11 of the first wafer 1 is always facing upward, so in this step, the first wafer 1 and the second wafer 2 are directly moved to the cutting device, and the slicing operation is performed along the first mark on the second surface 11. Specifically, the cutting device generally adopts a backside exposure machine.

[0174] S502 , turning over the first wafer 1 and the second wafer 2 .

[0175] In this step, the adjacent sensor units on the first wafer 1 are separated. It is necessary to perform a dicing operation on the sensor units on the second wafer 2. The first wafer 1 and the second wafer 2 are flipped 180 degrees so that the second dicing of the second wafer 2 faces upward.

[0176] S503 , cutting the second wafer 2 according to the second mark on the fourth surface 21 .

[0177] The first wafer 1 and the second wafer 2 are moved to a cutting device, and a slicing operation is performed along the second mark on the fourth surface 21. Specifically, the cutting device generally adopts a backside exposure machine.

[0178] S504 , removing the two layers of photoelectric conversion units after slicing the second surface 11 and the fourth surface 21 , and completing the preparation of the photoelectric signal conversion device 1001 . Each photoelectric signal conversion device 1001 has a first photoelectric conversion unit 30 and a second photoelectric conversion unit 40 .

[0179] The present application also provides a wafer assembly 3, comprising a first wafer 1 and a second wafer 2 bonded to each other.

[0180] Reference Figure 4 and Figure 5 The bonding surfaces of the first wafer 1 and the second wafer 2 both have first photoelectric conversion units 30 and second photoelectric conversion units 40 arranged in an array, and the first photoelectric conversion units 30 and the second photoelectric conversion units 40 are alternately arranged in sequence.

[0181] The first photoelectric conversion unit 30 of each first wafer 1 faces the second photoelectric conversion unit 40 of each second wafer 2 , and the second photoelectric conversion unit 40 of each first wafer 1 faces the first photoelectric conversion unit 30 of each second wafer 2 .

[0182] By cutting the above-mentioned wafer assembly 3, a large number of photoelectric signal conversion devices 1001 can be formed. This production process can greatly improve the production efficiency of the photoelectric signal conversion devices, and further improve the production efficiency of the two-color temperature measurement detector.

[0183] Specifically, in the wafer assembly 3, the orthographic projection of the second photoelectric conversion unit 40 on the wafer where the corresponding first photoelectric conversion unit 30 is located along the stacking direction of the first wafer 1 and the second wafer 2 all falls into the corresponding first photoelectric conversion unit 30. It can also be understood that the size of the first photoelectric conversion unit 30 is larger than the size of the second photoelectric conversion unit 40.

[0184] Preferably, the orthographic projection of the midpoint of the second photoelectric conversion unit 40 on the first photoelectric conversion unit 30 coincides with the midpoint of the first photoelectric conversion unit 30. It can also be understood that the second photoelectric conversion unit 40 is located in the middle of the first photoelectric conversion unit 30.

[0185] Please refer to Fig. 9 As shown, and in combination with other drawings when necessary, the present application further provides a photoelectric signal conversion device 1001, which includes a first photoelectric conversion unit 30, a second photoelectric conversion unit 40 and a plurality of welding bumps 34. The photoelectric signal conversion device 1001 can be prepared by the above-mentioned photoelectric signal conversion device preparation method.

[0186] The first photoelectric conversion unit 30 has a first functional surface 300;

[0187] The second photoelectric conversion unit 40 has a second functional surface 400;

[0188] A plurality of solder bumps 34 are supported between the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 at intervals.

[0189] In some embodiments, the second photoelectric conversion unit 40 is disposed as an orthographic projection on the corresponding first photoelectric conversion unit along the stacking direction of the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 , and is partially staggered with the corresponding first photoelectric conversion unit 30 .

[0190] A first external pad for electrically leading out the first photoelectric conversion unit 30 is disposed in an area of ​​the first photoelectric conversion unit 30 that is offset from the orthographic projection of the second photoelectric conversion unit 40 .

[0191] In some embodiments, the first functional surface 300 of the first photoelectric conversion unit 30 faces the second functional surface 400 of the second photoelectric conversion unit 40 .

[0192] A second external pad for electrically leading out the second photoelectric conversion unit 40 is further provided in a region of the first photoelectric conversion unit 30 that is offset from the orthographic projection of the second photoelectric conversion unit 40 .

[0193] In some embodiments, the second photoelectric conversion unit 40 is provided with a lead-out pad for electrically leading out the second photoelectric conversion unit 40, and the first photoelectric conversion unit 30 includes a connecting pad opposite to the lead-out pad, the connecting pad is electrically connected to the second external pad, the connecting pad is directly opposite to the lead-out pad, and is connected to the lead-out pad through at least partial welding of the multiple welding bumps 34.

[0194] It should be noted that, in some other embodiments, the second functional surface of the second photoelectric conversion unit 40 may be away from the first functional surface of the first photoelectric conversion unit 30, and the plurality of welding bumps 34 serve as supporting bumps.

[0195] In some embodiments, an optical glue 50 is filled between the first photoelectric conversion unit 30 and the second photoelectric conversion unit 40 .

[0196] In some embodiments, the solder bumps 34 are solder balls.

[0197] In some embodiments, the cross-sectional size of the solder bump 34 is less than or equal to 5 μm.

[0198] The specific description of the photoelectric signal conversion device 1001 can refer to the relevant description in the above-mentioned preparation method, which will not be repeated here.

[0199] The functional surface referred to in this application is the entire surface of the photoelectric conversion unit where the photoelectric conversion structure (such as a photosensitive structure), pads, connecting wires, etc. are located. Figure 4 As shown, the first functional surface 300 may be the entire surface of the first photoelectric conversion unit 30 that is perpendicular to the paper and faces outwards, and the second functional surface 400 may be the entire surface of the second photoelectric conversion unit 40 that is perpendicular to the paper and faces outwards.

[0200] In the present application, the structural embodiments and the method embodiments can complement each other if they do not conflict.

[0201] In the present application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The terms "plurality" and "several" refer to two or more than two, unless otherwise clearly defined.

[0202] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for preparing a photoelectric signal conversion device, characterized in that: include: Providing a first wafer, the first wafer comprising a plurality of first photoelectric conversion units and a plurality of second photoelectric conversion units; wherein the first photoelectric conversion unit has a first functional surface, the second photoelectric conversion unit has a second functional surface, and an area of ​​the first functional surface is greater than an area of ​​the second functional surface; Providing a second wafer, wherein the second wafer includes a plurality of first photoelectric conversion units and a plurality of second photoelectric conversion units; Bonding the first wafer and the second wafer to form a wafer assembly; wherein each first photoelectric conversion unit of the first wafer corresponds to a second photoelectric conversion unit of the second wafer, and each second photoelectric conversion unit of the first wafer corresponds to a first photoelectric conversion unit of the second wafer; each first photoelectric conversion unit is connected to the corresponding second photoelectric conversion unit by welding bumps, and each first photoelectric conversion unit and a corresponding second photoelectric conversion unit form a sensor unit; The wafer assembly is cut into pieces to form a plurality of the optoelectronic signal conversion devices.

2. The method for preparing a photoelectric signal conversion device according to claim 1, characterized in that: The first wafer includes a first surface, the first photoelectric conversion units and the second photoelectric conversion units included in the first wafer are opposite to each other one by one, and the orthographic projections of each of the first photoelectric conversion units and the corresponding second photoelectric conversion units on the plane where the first surface is located are symmetrical about the same straight line; The second wafer includes a third surface, the first photoelectric conversion units included in the second wafer are opposite to the second photoelectric conversion units one by one, and the orthographic projections of each first photoelectric conversion unit and the corresponding second photoelectric conversion unit on the plane where the third surface is located are symmetrical about the same straight line.

3. The method for preparing a photoelectric signal conversion device according to claim 2, characterized in that: In the first wafer, the orthographic projections of each of the first photoelectric conversion units and the corresponding second photoelectric conversion unit on the plane where the first surface is located are symmetrical about a first straight line, and the size of each of the first photoelectric conversion units perpendicular to the first straight line is larger than the size of the corresponding second photoelectric conversion unit perpendicular to the first straight line; In the second wafer, the orthographic projections of each of the first photoelectric conversion units and the corresponding second photoelectric conversion unit on the plane where the third surface is located are symmetrical about a second straight line, and the size of each of the first photoelectric conversion units perpendicular to the second straight line is larger than the size of the corresponding second photoelectric conversion unit perpendicular to the second straight line.

4. The method for preparing a photoelectric signal conversion device according to any one of claims 1 to 3, characterized in that: In each sensor unit, the second photoelectric conversion unit is arranged as an orthographic projection on the corresponding first photoelectric conversion unit along the direction in which the first wafer and the second wafer are stacked, and is partially staggered with the corresponding first photoelectric conversion unit; A first external pad for electrically leading out the first photoelectric conversion unit is provided in an area on the first photoelectric conversion unit that is staggered from the orthographic projection of the second photoelectric conversion unit.

5. The method for preparing a photoelectric signal conversion device according to claim 4, characterized in that: The first wafer includes a first surface, and the first functional surfaces of all the first photoelectric conversion units and the second functional surfaces of all the second photoelectric conversion units included in the first wafer are located on the first surface; the second wafer includes a third surface, and the first functional surfaces of all the first photoelectric conversion units and the second functional surfaces of all the second photoelectric conversion units included in the second wafer are located on the third surface; Bonding the first wafer and the second wafer to form a wafer assembly includes: The first surface of the first wafer is placed toward the third surface of the second wafer, and the first wafer and the second wafer are bonded to form a wafer assembly.

6. The method for preparing a photoelectric signal conversion device according to claim 4, characterized in that: The first wafer comprises a first surface and a second surface which are opposite to each other, and the functional surfaces of at least some of the plurality of first photoelectric conversion units and the plurality of second photoelectric conversion units included in the first wafer are located on the first surface, and the functional surfaces of another portion of the photoelectric conversion units are located on the second surface; the second wafer comprises a third surface, and the first functional surfaces of all the first photoelectric conversion units and the first functional surfaces of all the second photoelectric conversion units included in the second wafer are located on the third surface; Bonding the first wafer and the second wafer to form a wafer assembly includes: The first surface of the first wafer is placed toward the third surface of the second wafer, and the first wafer and the second wafer are bonded to form a wafer assembly.

7. The method for preparing a photoelectric signal conversion device according to claim 4, characterized in that: A second external pad for electrically leading out the second photoelectric conversion unit is also provided in an area of ​​the first photoelectric conversion unit that is staggered from the orthographic projection of the second photoelectric conversion unit.

8. The method for preparing a photoelectric signal conversion device according to any one of claims 1 to 3, characterized in that: The plurality of first photoelectric conversion units and the plurality of second photoelectric conversion units included in the first wafer are arranged into a plurality of groups of photoelectric conversion units, and the plurality of first photoelectric conversion units and the plurality of second photoelectric conversion units included in the second wafer are arranged into a plurality of groups of photoelectric conversion units, each group of photoelectric conversion units includes a first photoelectric conversion unit and a second photoelectric conversion unit adjacent to each other; before providing the first wafer and providing the second wafer, the method includes forming the first wafer and forming the second wafer; in The forming of the first wafer comprises: loading the first wafer into a photolithography machine; The photolithography machine exposes the plurality of first exposure areas on the first wafer respectively to form a first wafer having the plurality of groups of photoelectric conversion units; The forming of the second wafer comprises: loading the second wafer into a photolithography machine; The photolithography machine exposes the multiple second exposure areas on the second wafer respectively to form a second wafer having the multiple groups of photoelectric conversion units; and the first exposure area and the second exposure area are equal in shape and size.

9. The method for preparing a photoelectric signal conversion device according to claim 1, characterized in that: After providing a first wafer and a second wafer, and before bonding the first wafer and the second wafer, the method includes: Solder bumps are provided on at least one of the first wafer and the second wafer.

10. The method for preparing a photoelectric signal conversion device according to claim 1, characterized in that: Bonding the first wafer and the second wafer comprises: The first wafer and the second wafer are bonded by cold compression bonding; or The first wafer and the second wafer are bonded by thermocompression bonding; or The first wafer and the second wafer are bonded by ultrasonic bonding.

11. The method for preparing a photoelectric signal conversion device according to claim 1, characterized in that: The method further includes: filling optical glue between the first photoelectric conversion unit and the second photoelectric conversion unit; The optical adhesive is a two-component epoxy potting adhesive.

12. The method for preparing a photoelectric signal conversion device according to claim 1, characterized in that: All the photoelectric conversion units included in the first wafer are arranged in an array, and the multiple first photoelectric conversion units of the first wafer are arranged in multiple rows, and the multiple second photoelectric conversion units of the first wafer are arranged in multiple rows; among the multiple rows of first photoelectric conversion units and the multiple rows of second photoelectric conversion units included in the first wafer, at least one row of first photoelectric conversion units and a row of second photoelectric conversion units are arranged correspondingly and adjacently, and the multiple photoelectric conversion units of the row of first photoelectric conversion units and the corresponding adjacent row of second photoelectric conversion units are aligned in a direction perpendicular to the row of photoelectric conversion units, and a first scribe groove is provided between the row of first photoelectric conversion units and the corresponding adjacent row of second photoelectric conversion units; All the photoelectric conversion units included in the second wafer are arranged in an array, a plurality of first photoelectric conversion units of the second wafer are arranged in a plurality of rows, and a plurality of second photoelectric conversion units of the second wafer are arranged in a plurality of rows; among the plurality of rows of first photoelectric conversion units and the plurality of rows of second photoelectric conversion units included in the second wafer, at least one row of second photoelectric conversion units and a row of first photoelectric conversion units are arranged correspondingly and adjacently, a plurality of photoelectric conversion units in a row of second photoelectric conversion units and the corresponding adjacent row of first photoelectric conversion units are aligned in a direction perpendicular to the row of photoelectric conversion units, and a second scribe groove is provided between the row of second photoelectric conversion units and the corresponding adjacent row of first photoelectric conversion units; When the row of first photoelectric conversion units and the corresponding adjacent row of second photoelectric conversion units of the first wafer respectively correspond to the row of second photoelectric conversion units and the corresponding adjacent row of first photoelectric conversion units of the second wafer, the first scribe line is staggered with the second scribe line.

13. A photoelectric signal conversion device, characterized in that: include: a first photoelectric conversion unit; The first photoelectric conversion unit has a first functional surface; a second photoelectric conversion unit, the second photoelectric conversion unit having a first functional surface; A plurality of welding bumps are supported at intervals between the first photoelectric conversion unit and the second photoelectric conversion unit.

14. The photoelectric signal conversion device according to claim 13, characterized in that: The second photoelectric conversion unit is disposed with an orthographic projection on the corresponding first photoelectric conversion unit along the direction in which the first photoelectric conversion unit and the second photoelectric conversion unit are stacked, and is partially staggered with the corresponding first photoelectric conversion unit; A first external pad for electrically leading out the first photoelectric conversion unit is provided in an area on the first photoelectric conversion unit that is staggered from the orthographic projection of the second photoelectric conversion unit.

15. The photoelectric signal conversion device according to claim 13, characterized in that: The first functional surface of the first photoelectric conversion unit faces the second functional surface of the second photoelectric conversion unit; A second external pad for electrically leading out the second photoelectric conversion unit is also provided in an area of ​​the first photoelectric conversion unit that is staggered from the orthographic projection of the second photoelectric conversion unit.

16. The photoelectric signal conversion device according to claim 13, characterized in that: The second photoelectric conversion unit is provided with a lead-out pad for electrically leading out the second photoelectric conversion unit, and the first photoelectric conversion unit includes a connecting pad opposite to the lead-out pad, the connecting pad is electrically connected to the second external pad, the connecting pad is directly opposite to the lead-out pad, and is connected to the lead-out pad through at least partial welding of the multiple welding bumps.

17. The photoelectric signal conversion device according to claim 13, characterized in that: The second functional surface of the second photoelectric conversion unit is away from the first functional surface of the first photoelectric conversion unit, and the plurality of welding bumps serve as supporting bumps.

18. The photoelectric signal conversion device according to claim 13, characterized in that: An optical glue is filled between the first photoelectric conversion unit and the second photoelectric conversion unit; and / or, The solder bump is a solder ball; and / or the cross-sectional size of the solder bump is less than or equal to 5 μm.

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