Photoelectric sensor and manufacturing method thereof

Abstract

The invention belongs to the technical field of sensors, and particularly relates to a photoelectric sensor and a manufacturing method thereof, the photoelectric sensor comprises an integrated circuit, the integrated circuit comprises an integrated circuit main body and a wiring layer formed on the surface of the integrated circuit main body; a mixed bonding layer, a photoelectric detector layer and a passivation layer are vertically stacked on the wiring layer in sequence; the manufacturing method comprises the following steps: S1, forming a photoelectric detector layer; s2, forming a dielectric material butt joint layer; s3, forming a bonding material layer; s4, forming a first-order through hole and a second-order through hole; s5, realizing electrical connection between the other surface of the photoelectric detector layer and the wiring layer; s6, forming a passivation layer; and S7, forming an external electrode. Through the stacking design of the sensor detection material and the integrated circuit, the length of a lead can be reduced, the anti-electromagnetic interference capability is improved, the size of a packaging body is reduced, the integration degree of stacking is improved through the semiconductor technology, and the endurance capability of the sensor to severe working conditions is improved through the passivation layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and in particular relates to a photoelectric sensor and a manufacturing method thereof. Background Art

[0002] Photoelectric sensors use photodetectors to convert light signals into current or voltage signals, which are then converted into digital or analog electrical signals by integrated circuits to sense the intensity of light in the environment.

[0003] Traditional photoelectric sensors connect photodetectors to data processing circuits in three main ways: through wiring harnesses or circuit board leads, through leads inside the package, through flip-chip packaging, and through hybrid bonding interconnection.

[0004] However, harsh electromagnetic interference may add a time-varying voltage to both ends of the wiring harness or circuit board leads, causing errors in the photoelectric signal measurement. Common packaging processes have poor tolerance to harsh working conditions such as high temperature and high humidity, making the photoelectric sensor unstable and short-lived. Vacuum packaging, hermetic packaging and other solutions can improve the sensor's tolerance to harsh working conditions, but these two packaging solutions are relatively expensive. Summary of the invention

[0005] The purpose of the present invention is to provide a photoelectric sensor and a method for manufacturing the same. By stacking the sensor detection material with the integrated circuit, the lead length can be reduced, the anti-electromagnetic interference capability can be improved, the package size can be reduced, the stacking integration can be improved through semiconductor technology, and the sensor's tolerance to harsh working conditions can be improved through the passivation layer.

[0006] The technical solution adopted by the present invention is as follows: A photoelectric sensor includes an integrated circuit, wherein the integrated circuit includes an integrated circuit body and a wiring layer formed on a surface of the integrated circuit body; A hybrid bonding layer, a photodetector layer and a passivation layer are vertically stacked in sequence on the wiring layer; The hybrid bonding layer includes a bonding material layer combining the photodetector layer and the wiring layer and a metal conducting column electrically connecting one side of the two.

[0007] As a preferred solution, a metal column is provided between the bonding material layer and the photodetector layer to electrically connect the wiring layer with the other side of the photodetector layer, and an insulating layer is formed on the side wall of the through hole between the bonding material layer and the photodetector layer using a semiconductor process.

[0008] As a preferred solution, an external electrode for electrically connecting the wiring layer to the outside is provided between the hybrid bonding layer and the passivation layer.

[0009] As a preferred embodiment, the photodetector layer is made of semiconductor materials, and the semiconductor materials include one or an alloy of silicon, germanium, gallium arsenide, indium phosphide, gallium phosphide, indium arsenide, indium antimonide or gallium antimonide materials.

[0010] As a preferred solution, when multiple materials are selected for the photodetector layer, they are combined by stacking, and the stacking method includes molecular beam epitaxy, metal compound vapor phase epitaxy, hydride vapor phase epitaxy and liquid phase epitaxy process.

[0011] As a preferred solution, the passivation layer is made of one or more of styrene-cyclobutene polymer, polyimide or SU-8 formula polymer materials.

[0012] As a preferred solution, the bonding material layer is made of dielectric material, and the dielectric material includes one or more of silicon dioxide, silicon nitride or polyimide materials.

[0013] A method for manufacturing a photoelectric sensor, used to manufacture the above-mentioned photoelectric sensor, comprises the following steps: S1, forming a photodetector layer by depositing a metal organic compound epitaxial process on a substrate material of the photodetector layer; S2. Forming a metal column for docking on the interface between the photodetector layer and the wiring layer by a semiconductor process and covering the dielectric material, and then improving the surface flatness of the dielectric material and reducing the roughness by grinding and chemical mechanical polishing processes, and making the height of the metal column lower than the dielectric material; S3, connecting the dielectric material and the metal pillars on the surface of the photodetector layer and the wiring layer to form a gap between the metal pillars on both sides, and then bonding the metal pillars on both sides of the photodetector layer and the wiring layer to form an integrated metal conductive pillar, and electrically connecting one side between the two through the metal conductive pillar, and at the same time, the dielectric materials on both sides are bonded to form a bonding material layer; S4, removing excess substrate material by grinding and chemical etching processes, and removing part of the photodetector layer by semiconductor processes on the photodetector layer to form a first-order through hole, and then aligning a part of the first-order through hole with a semiconductor process on the bonding material layer to form a second-order through hole; S5. Using semiconductor technology, forming an insulating layer on the sidewalls of the first-order through hole and the second-order through hole, and filling the first-order through hole and the second-order through hole with metal pillars in the insulating layer by semiconductor technology to achieve electrical connection between the other side of the photodetector layer and the wiring layer; S6, coating the surface of the photodetector layer with a layer of passivation material precursor by a spin coating process, and forming a passivation layer after curing; S7. Part of the passivation layer is removed through a semiconductor process to form a passivation layer through hole aligned with another part of the first-order through hole, and the first-order through hole and the passivation layer through hole are filled with a conductive metal using photolithography, magnetron sputtering, and electroplating processes to form an external electrode on the surface of the passivation layer for electrical connection between the wiring layer and the outside world.

[0014] As a preferred solution, the semiconductor processes in S2, S4, S5 and S7 are one or more of photolithography, etching, deposition and electroplating processes.

[0015] As a preferred solution, the bonding process in S3 is one or more of anodic bonding or thermal compression bonding processes.

[0016] The technical effects achieved by the present invention are: The present invention places the signal processing integrated circuit and the photodetector layer in the same package and uses shorter metal conductive columns for interconnection, which can reduce the impact of the electromagnetic environment on the sampling of the sensor signal. Compared with flip chip packaging, the present invention does not need to be filled with resin, avoiding the stress and failure risk caused by resin curing. Compared with general hybrid bonding interconnection, the present invention uses through holes and metal columns to connect one side of the detector, reducing the process difficulty of the photodetector and avoiding the etching process and failure risk required for the same-side electrode of the photodetector.

[0017] The present invention adopts a design of stacking a photodetector layer and an integrated circuit, which can reduce the lead length, improve the anti-electromagnetic interference capability, reduce the package size, and save production costs. At the same time, the integration of the stack is improved through semiconductor technology, and the sensor's tolerance to harsh working conditions is improved through a passivation layer, thereby improving the stability and accuracy of the sensor under harsh working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of the structure of a photoelectric sensor in an embodiment of the present invention; Figure 2 is a schematic cross-sectional view of a photoelectric sensor in an embodiment of the present invention; Figure 3 1 is a manufacturing flow chart of the photoelectric sensor in an embodiment of the present invention.

[0019] In the accompanying drawings, the components represented by the reference numerals are listed as follows: 100, photodetector layer; 101, hybrid bonding layer; 102, bonding material layer; 103, metal conductive pillar; 104, integrated circuit; 105, wiring layer; 106, integrated circuit body; 107, insulating layer; 108, metal pillar; 109, passivation layer; 110, external electrode; 300, gallium arsenide substrate; 301, stop layer; 302, gallium arsenide photodetector layer; 303, copper metal bonding column; 304, silicon dioxide material layer; 305, integrated circuit one; 306, wiring layer one; 307, integrated circuit body one; 308, gap; 309, copper metal conductive column; 310, silicon dioxide hybrid bonding layer; 311, detector through hole; 312, silicon dioxide through hole; 313, silicon nitride insulating layer; 314, copper metal column; 315, styrene-propylcyclobutene polymer passivation layer; 316, styrene-propylcyclobutene polymer through hole; 317, metal external electrode. DETAILED DESCRIPTION

[0020] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or several specific embodiments of the present invention, and does not strictly limit the scope of protection of the specific claims of the present invention.

[0021] like Figure 1-Figure 2 As shown, a photoelectric sensor includes an integrated circuit 104, which includes an integrated circuit body 106 and a wiring layer 105 formed on the surface of the integrated circuit body 106; and a hybrid bonding layer 101, a photodetector layer 100 and a passivation layer 109 are vertically stacked in sequence on the wiring layer 105, and the hybrid bonding layer 101 is used to mechanically and electrically connect the photodetector layer 100 and the wiring layer 105. At the same time, the passivation layer 109 isolates the entire sensor area except the external electrode 110 from the air environment, so as to improve the sensor's tolerance to harsh working conditions and ensure its working stability.

[0022] Among them, the hybrid bonding layer 101 includes a bonding material layer 102 that combines the photodetector layer 100 and the wiring layer 105, and a metal conductive column 103 that electrically connects one side of the photodetector layer 100 to the wiring layer 105. The bonding material in the hybrid bonding layer 101 is used to form a mechanical connection between the photodetector layer 100 and the wiring layer 105, thereby improving the connection strength between the layers to ensure its tolerance to harsh working conditions. At the same time, the metal conductive column 103 is used to realize the electrical connection between one side of the photodetector layer 100 and the wiring layer 105, and several through holes passing through the bonding material layer 102 and the photodetector layer 100 and the metal column 108 establish an electrical connection between the other side of the photodetector layer 100 and the wiring layer 105, thereby reducing the lead length, improving the anti-electromagnetic interference capability, and reducing the package size.

[0023] In some embodiments, an insulating layer 107 is formed on the sidewalls of the through holes between the bonding material layer 102 and the photodetector layer 100 using a semiconductor process to wrap the metal pillar 108 to enhance its anti-electromagnetic interference capability.

[0024] It should be noted that the bonding material layer 102 is formed by combining two bonding material layers 102 belonging to the photodetector layer 100 and the wiring layer 105 on both sides during the manufacturing process through an anodic bonding or a hot pressing bonding process. At the same time, the metal conductive column 103 is also formed by joining two parts belonging to the photodetector layer 100 and the wiring layer 105 on both sides. Selecting a bonding process instead of a packaging process such as soldering, a ball grid array (BGA) or a flip-chip to achieve the joining of the two layers can improve the alignment accuracy of the photodetector layer 100 and the integrated circuit 104, which is higher than the packaging process and can achieve a smaller, thinner and more compact joint.

[0025] Furthermore, the bonding material layer 102 is made of dielectric materials such as silicon dioxide, silicon nitride or polyimide materials, and the metal conductive pillar 103 is made of conductive metals such as aluminum, silver, copper, and iron.

[0026] In this embodiment, the bonding material layer 102 is made of silicon dioxide material, and the metal conductive column 103 is made of copper metal material. The excellent thermal stability, insulation and optical properties of silicon dioxide are used to prevent current leakage and electromagnetic interference. At the same time, the excellent conductivity of copper metal is used to achieve electrical connection between the photodetector layer 100 and the wiring layer 105.

[0027] In some embodiments, the photodetector layer 100 is made of semiconductor materials such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), gallium phosphide (GaP), indium arsenide (InAs), indium antimonide (InSb), and gallium antimonide (GaSb). When the photodetector layer 100 uses a combination of multiple materials, they are combined by stacking, and the stacking method includes processes such as molecular beam epitaxy, metal compound vapor phase epitaxy, hydride epitaxy, and liquid phase epitaxy.

[0028] It should be noted that the photodetector layer 100 may use a photoconductive photodetector to achieve light detection by measuring the resistance change caused by the light signal, or a photovoltaic detector to achieve light detection by measuring the current or voltage change caused by the light signal. The selection is made according to production needs during actual production.

[0029] In this embodiment, the photodetector layer 100 is made of a gallium arsenide substrate material, and its excellent physical and electrical properties are used to ensure the accuracy of the sensor.

[0030] In order to make electrical connection with the outside world, an external electrode 110 is provided between the hybrid bonding layer 101 and the passivation layer 109 to electrically connect the wiring layer 105 to the outside world. At the same time, the passivation layer 109 isolates the entire sensor except for the protruding part of the external electrode 110 from the air environment, and can cover the photodetector layer 100, the integrated circuit 104, the hybrid bonding layer 101, the through hole and the metal column 108, which are prone to failure in a high temperature and high humidity environment, and isolate the latter from the air in the working environment of the sensor, so as to improve the sensor's tolerance to harsh working conditions and ensure its working stability.

[0031] In some embodiments, the passivation layer 109 is made of materials such as styrene-cyclobutene polymer, polyimide or SU-8 formula polymer.

[0032] In this embodiment, the passivation layer 109 is made of styrene cyclobutene polymer material, which has excellent electrical insulation properties, low dielectric constant, low water absorption, excellent thermal stability and low thermal expansion coefficient, and can better isolate the sensor body from the air and improve its tolerance to harsh working conditions.

[0033] like Figure 3 As shown, a method for manufacturing a photoelectric sensor is used to manufacture the above-mentioned photoelectric sensor. The integrated circuit 305 is manufactured using a mature standard logic circuit process. The wafer size of the integrated circuit is 8 inches. At the same time, the substrate material is a gallium arsenide substrate 300.

[0034] The specific steps include the following (see also attached Figure 3 Serial number in ): Step 1: (1) A GaInP stop layer 301 and a GaAs photodetector layer 302 are sequentially deposited on the surface of a GaAs substrate 300 by a metal organic compound epitaxial process; the GaAs photodetector layer 302 specifically comprises a p-type conductive layer on the upper surface, an n-type conductive layer on the lower surface, and an intrinsic photosensitive layer therebetween.

[0035] Step 2: (2) On the surface of the gallium arsenide photodetector layer 302, a portion of the copper metal bonding column 303 is formed through a series of processes such as photolithography and metal deposition.

[0036] (3) A silicon dioxide material layer 304 is deposited on the surface of the gallium arsenide photodetector layer 302 to cover a portion of the copper metal bonding pillar 303 .

[0037] (4) Through grinding and chemical mechanical polishing processes, the surface flatness of the silicon dioxide material layer 304 is improved, the roughness is reduced, and the height of the copper metal bonding column 303 is made slightly lower than the silicon oxide layer.

[0038] (5) Repeat the processes (3) and (4) on the surface of the wiring layer 1 306 to form another portion of the copper metal bonding column 303 and the silicon dioxide material layer 304.

[0039] Step 3: (6) Align the copper metal bonding pillars 303 on the surface of the wiring layer 1 306 with the surface of the gallium arsenide photodetector layer 302. At this time, the copper metal bonding pillars 303 on both sides have not yet been bonded and there is still a gap 308 between them.

[0040] (7) Specific pressure and temperature are applied to both sides of the wiring layer 306 and the gallium arsenide photodetector layer 302, so that the copper metal bonding pillars 303 on both sides are bonded to form an integrated copper metal conductive pillar 309, thereby electrically connecting the back side of the gallium arsenide photodetector layer 302 with the wiring layer 306 on the integrated circuit body 307; at the same time, the silicon dioxide material layers 304 on both sides are also bonded together to form an integrated silicon dioxide hybrid bonding layer 310.

[0041] In some embodiments, the thermal compression bonding process in (7) can be replaced by a bonding process, which can be selected according to production requirements during the actual production process.

[0042] Step 4: (8) Remove the excess GaAs substrate 300 through grinding and chemical etching processes.

[0043] (9) Remove the excess stop layer 301 through a chemical etching process.

[0044] (10) Part of the GaAs photodetector layer 302 is removed by photolithography and etching to form a GaAs photodetector layer 302 including a detector through hole 311.

[0045] (11) Form a silicon dioxide through hole 312 in the silicon dioxide material layer 304 by photolithography and etching.

[0046] Step 5: (12) Using photolithography and chemical vapor deposition, a silicon nitride insulating layer 313 is formed on the side wall of the detector through hole 311.

[0047] (13) Through photolithography and electroplating processes, copper metal pillars 314 are used to fill the detector through holes 311 and realize electrical connection between the upper surface of the gallium arsenide photodetector layer 302 and the wiring layer 306 on the integrated circuit body 307.

[0048] Step 6: (14) A layer of styrene cyclobutene polymer precursor is coated on the surface of the sensor by a spin coating process, and a styrene cyclobutene polymer passivation layer 315 is formed after curing.

[0049] Step 7: (15) A portion of the SAB polymer passivation layer 315 is removed by photolithography and etching processes to form a SAB polymer through hole 316 aligned with the silicon dioxide through hole 312.

[0050] (16) Using photolithography, magnetron sputtering and electroplating processes, a conductive metal is used to fill the silicon dioxide through hole 312 and the styrene-cyclobutene polymer through hole 316, and a metal external electrode 317 is formed on the upper surface of the sensor, which is used for the integrated circuit 305 to form an electrical connection with the outside world through the wiring layer 306.

[0051] The above is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention shall be implemented according to the conventional means in the art unless otherwise specified and limited.

Claims

1. A photoelectric sensor, characterized in that: include: Integrated Circuits (104); The integrated circuit (104) comprises an integrated circuit body (106) and a wiring layer (105) formed on a surface of the integrated circuit body (106); A hybrid bonding layer (101), a photodetector layer (100) and a passivation layer (109) are vertically stacked in sequence on the wiring layer (105); The hybrid bonding layer (101) comprises a bonding material layer (102) that combines the photodetector layer (100) and the wiring layer (105), and a metal conductive column (103) that electrically connects one side of the two.

2. A photoelectric sensor according to claim 1, characterized in that: A metal column (108) is provided between the bonding material layer (102) and the photodetector layer (100) to electrically connect the wiring layer (105) to the other side of the photodetector layer (100), and an insulating layer (107) is formed on the side wall of the through hole between the bonding material layer (102) and the photodetector layer (100) using a semiconductor process.

3. A photoelectric sensor according to claim 1, characterized in that: An external electrode (110) for electrically connecting the wiring layer (105) to the outside is provided between the hybrid bonding layer (101) and the passivation layer (109).

4. A photoelectric sensor according to claim 1, characterized in that: The photodetector layer (100) is made of semiconductor material, which includes one or an alloy of silicon, germanium, gallium arsenide, indium phosphide, gallium phosphide, indium arsenide, indium antimonide or gallium antimonide.

5. A photoelectric sensor according to claim 4, characterized in that: When multiple materials are selected for the photodetector layer (100), they are combined in a stacking manner, wherein the stacking manner includes molecular beam epitaxy, metal compound vapor phase epitaxy, hydride vapor phase epitaxy and liquid phase epitaxy processes.

6. A photoelectric sensor according to claim 1, characterized in that: The passivation layer (109) is made of one or more of styrene-cyclobutene polymer, polyimide or SU-8 formula polymer materials.

7. The photoelectric sensor according to claim 1, characterized in that: The bonding material layer (102) is made of a dielectric material, wherein the dielectric material includes one or more of silicon dioxide, silicon nitride or polyimide materials.

8. A method for manufacturing a photoelectric sensor, used for manufacturing the photoelectric sensor according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, forming a photodetector layer (100) by depositing a metal organic compound epitaxial process on a substrate material of the photodetector layer (100); S2, forming a metal column for docking on the docking surface between the photodetector layer (100) and the wiring layer (105) by a semiconductor process, and covering the dielectric material, and then performing grinding and chemical mechanical polishing processes to improve the surface flatness of the dielectric material, reduce the roughness, and make the height of the metal column lower than the dielectric material; S3, connecting the dielectric material and the metal pillars on the surface of the photodetector layer (100) and the wiring layer (105) to form a gap between the metal pillars on both sides, and then bonding the metal pillars on both sides of the photodetector layer (100) and the wiring layer (105) to form an integrated metal conductive pillar (103), and electrically connecting one side between the two through the metal conductive pillar (103), and at the same time, the dielectric materials on both sides are bonded to form a bonding material layer (102); S4, removing excess substrate material by grinding and chemical etching processes, and removing part of the photodetector layer (100) by semiconductor processes on the photodetector layer (100) to form a first-order through hole, and then aligning a part of the first-order through hole with a semiconductor process on the bonding material layer (102) to form a second-order through hole; S5. Using semiconductor technology, forming an insulating layer (107) on the sidewalls of the first-order through hole and the second-order through hole, and using a semiconductor process to fill the first-order through hole and the second-order through hole in the insulating layer (107) with a metal column (108), thereby achieving electrical connection between the other side of the photodetector layer (100) and the wiring layer (105); S6, coating the surface of the photodetector layer (100) with a layer of passivation material precursor by a spin coating process, and forming a passivation layer (109) after curing; S7. A portion of the passivation layer (109) is removed by a semiconductor process to form a passivation layer through hole aligned with another portion of the first-order through hole, and the first-order through hole and the passivation layer through hole are filled with a conductive metal using photolithography, magnetron sputtering, and electroplating processes to form an external electrode (110) on the surface of the passivation layer (109) for electrical connection between the wiring layer (105) and the outside world.

9. A photoelectric sensor and a method for manufacturing the same according to claim 8, characterized in that: The semiconductor processes in S2, S4, S5 and S7 are one or more of photolithography, etching, deposition and electroplating processes.

10. A photoelectric sensor and a method for manufacturing the same according to claim 8, characterized in that: The bonding process in S3 is one or more of anodic bonding or thermal compression bonding processes.

Images