A back-illuminated photodetector preparation method and a security inspection equipment with the same

Abstract

The application discloses a preparation method of a back-illumination photoelectric detector, and the preparation steps comprise the following steps: depositing an anti-reflection layer on the front surface of a substrate silicon wafer, bonding with a supporting substrate, thinning the substrate silicon wafer and performing CMP polishing, doping a front N+ region, doping a front P+ region, depositing a front medium layer and preparing an electrode, depositing a surface passivation layer and etching a lead hole, and removing the back supporting substrate. In the implementation process of the application, the back surface is thinned to below 200 microns as a whole, and the application has the advantage of small crosstalk. In the implementation process, the strength of the back surface can be increased, the occurrence of fragments of the back surface can be reduced, and the subsequent passivation step can be normally performed. When the extension plate needs to be used and is pulled out, the first supporting leg is moved downwards to make the universal wheel be suspended, so that the stability of the device in use is ensured. The position of the extension plate is not changed in the use process of the device.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric detector technology, specifically a method for preparing a back-illuminated photoelectric detector and a security inspection device having the detector. Background Technology

[0002] Semiconductor photodiodes (detectors) are core components in photoelectric detection for security inspection, industrial inspection, and medical imaging. Based on the location of the light receiver, detectors can be divided into front-illuminated detectors and back-illuminated detectors. Compared to front-illuminated detectors, back-illuminated detectors have improved light reception efficiency because their light-receiving surface lacks metal leads and pads. They can also be mounted on four sides, reducing package size and making them suitable for manufacturing large-size detector modules.

[0003] However, back-illuminated detectors suffer from high crosstalk. To address this, the back surface is typically thinned to less than 200 micrometers. However, thinning the back surface can cause contamination, and the thin sheet is prone to fragmentation, which is not conducive to the implementation of the back surface passivation step after thinning.

[0004] In summary, there is a need to provide a method for fabricating a back-illuminated photodetector that can solve the above problems. Summary of the Invention

[0005] In view of the above situation and to overcome the defects of the prior art, the present invention provides a method for preparing a back-illuminated photodetector and a security inspection device having the detector, which effectively solves the problems in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for fabricating a back-illuminated photodetector, the fabrication steps of which include:

[0007] Anti-reflection layer (ARC) is deposited on the front side of the substrate silicon wafer.

[0008] Bonded to the supporting substrate,

[0009] Substrate silicon wafer thinning and CMP polishing

[0010] The front N+ region is doped.

[0011] Front-side P+ region doping,

[0012] Front dielectric layer deposition and electrode fabrication,

[0013] Surface passivation layer deposition and lead hole etching

[0014] Backside support substrate removal.

[0015] Furthermore, the silicon substrate is an N-type silicon wafer, or it can be an N-type silicon epitaxial wafer with a thickness of 300~800μm.

[0016] The anti-reflective layer (ARC) is made of SiO2, SiN, or SiO2 / SiN, with a thickness of 50-100 nm, and is used to reduce light reflection, decrease surface recombination, and reduce dark current.

[0017] The supporting substrate can be silicon or glass, wherein the silicon is a resistive N-type silicon wafer with a thickness of 300~800μm.

[0018] The bonding process employs surface activation bonding technology, which reduces the heat treatment temperature and increases the bonding strength.

[0019] The silicon wafer is thinned and CMP polished, resulting in a silicon substrate thickness of 100-200 μm and a surface roughness of less than 1 nm.

[0020] The front dielectric layer is SiO2, SiN, or SiO2 / SiN, used to reduce surface recombination, decrease dark current, and provide insulation and passivation.

[0021] The electrode material is Al or Ti / Ni / Ag.

[0022] The surface passivation layer is SiO2 or SiO2 / SiN.

[0023] The back support substrate removal process involves first thinning the support substrate to 20-50 μm through grinding, followed by selective etching until the anti-reflection layer is formed.

[0024] Furthermore, it also includes the first step of N+ doping on the front side of the substrate silicon wafer.

[0025] To achieve the above objectives, the present invention provides the following technical solution: a security inspection device with a back-illuminated photoelectric detector, comprising a device body, a front fixed frame fixed to one side of the device body, and a rear fixed frame fixed to the other side of the device body, an opening on one side of the device body, and a rotatable conveyor belt disposed within the front fixed frame, the conveyor belt extending rearward through the opening and into the rear fixed frame, a caster wheel and a first support leg mounted on the lower end of the device body, the first support leg being located on one side of the caster wheel and capable of moving up and down, an extension plate capable of moving horizontally disposed on the side of the rear fixed frame away from the device body, and the first support leg being capable of moving downward when the extension plate moves away from the device body.

[0026] Furthermore, a bracket is fixedly connected to the lower end of the extension plate, and a second leg is fixedly connected to the lower end of the bracket, with the lower end of the second leg and the lower end of the caster wheel located in the same plane.

[0027] Furthermore, a plug-in plate is fixedly connected to the extension plate, and a groove is formed on the surface of the rear fixing frame. The plug-in plate passes through the groove and extends into the main body of the equipment. A connecting frame is fixedly connected to the upper end of the first support leg, and a threaded rod is fixedly connected to the upper end of the connecting frame. The threaded rod passes through a gear, and when the gear rotates, the threaded rod can move up and down. The surface of the plug-in plate is provided with teeth, which mesh with the gear. When the plug-in plate slides in the horizontal direction, the gear can rotate.

[0028] Furthermore, the plug-in plate is provided with a limiting block, and the rear fixing frame is provided with a rotatable locking block. The limiting block has a locking groove, and the locking block can be embedded in the locking groove. One end of the limiting block is inserted into the fixing rod, and the fixing rod is fixedly connected to the plug-in plate. A spring is provided between the limiting block and the fixing rod. The rear fixing frame has a limiting hole, and the limiting block can be inserted into the limiting hole.

[0029] Furthermore, one end of the locking block is fixedly connected to a rotating shaft, and a torsion spring is provided on the outer sleeve of the rotating shaft. A toggle rod is also fixedly connected to the locking block, and the toggle rod extends upward and extends out of the rear fixing frame.

[0030] Furthermore, a fixing block is fixedly connected to the actuating lever.

[0031] Furthermore, a ball groove is provided inside the rear fixing frame, the upper end of the ball groove is connected to the groove, and a ball that can rotate freely is provided inside the ball groove.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1) When implementing this invention, the back side is thinned to less than 200 micrometers, which has the advantage of low crosstalk. In addition, during the implementation process, the strength of the back side can be increased, the occurrence of fragmentation can be reduced, and the subsequent passivation steps can be carried out normally.

[0034] 2) By setting up a plug-in plate, gears and threaded rods, when the extension plate is pulled out when the device needs to be used, the first leg can move downwards and the caster wheel can be suspended in the air, thus ensuring the stability of the device during use.

[0035] 3) By setting a limit block, the position of the extension plate can be fixed when the extension plate is pulled out, thus ensuring that the position of the extension plate will not change during the use of this device;

[0036] 4) By incorporating a sphere and a groove, the extension plate can move more smoothly when it is pulled out. Attached Figure Description

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0038] Figure 1 This is a schematic diagram of the fabrication process of a back-illuminated photodetector according to the present invention.

[0039] Figure 2 This is a schematic diagram of the structure of the product obtained by the back-illuminated photodetector fabrication method of the present invention.

[0040] Figure 3 This is a schematic diagram of the structure of the product structure two obtained by the method for fabricating a back-illuminated photodetector according to the present invention.

[0041] Figure 4 This is a schematic diagram of the overall structure of a security inspection device with a back-illuminated photoelectric detector according to the present invention.

[0042] Figure 5 This is a schematic diagram of the combined structure of an extension plate and a threaded rod in a security inspection device with a back-illuminated photoelectric detector according to the present invention.

[0043] Figure 6 This invention relates to a security inspection device with a back-illuminated photoelectric detector. Figure 2 A top-view structural diagram;

[0044] Figure 7 This invention relates to a security inspection device with a back-illuminated photoelectric detector. Figure 4 A top-view structural diagram;

[0045] Figure 8 This is a schematic diagram of the connection structure between the rear fixing frame and the plug-in plate of a security inspection device with a back-illuminated photoelectric detector according to the present invention.

[0046] Figure 9 This invention relates to a security inspection device with a back-illuminated photoelectric detector. Figure 8 Enlarged structural diagram at point A;

[0047] Figure 10 This is an enlarged structural schematic diagram of the card block of a security inspection device with a back-illuminated photoelectric detector according to the present invention;

[0048] Figure 11 This is a schematic diagram of the connection structure between the limiting block and the fixing rod of a security inspection device with a back-illuminated photoelectric detector according to the present invention.

[0049] In the diagram: 1. Main body of the equipment; 2. Casters; 3. First support leg; 4. Front fixed frame; 5. Conveyor belt; 6. Opening; 7. Rear fixed frame; 8. Extension plate; 9. Bracket; 10. Second support leg; 11. Threaded rod; 12. Connecting frame; 13. Gear; 14. Tooth; 15. Limiting block; 16. Actuating rod; 17. Torsion spring; 18. Locking block; 19. Locking groove; 20. Rotating shaft; 21. Ball groove; 22. Ball; 23. Insertion plate; 24. Fixing rod; 25. Spring; 26. Fixing block. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0051] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0052] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0053] In the above description of the present invention, it should be noted that the terms "one side," "the other side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use. These terms are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0054] Furthermore, terms such as "identical" do not imply that components must be absolutely identical; minor differences are permissible. The term "perpendicular" simply means that the positional relationship between components is more perpendicular than "parallel," not that the structure must be perfectly perpendicular; a slight tilt is acceptable.

[0055] Depend on Figure 1-3 This invention discloses a method for fabricating a back-illuminated photodetector, the fabrication steps of which include:

[0056] The front side of the silicon substrate is N+ doped;

[0057] Anti-reflection layer (ARC) is deposited on the front side of the substrate silicon wafer;

[0058] Bonded to the supporting substrate;

[0059] Substrate silicon wafer thinning and CMP polishing;

[0060] Front-side N+ region doping;

[0061] Front-side P+ region doping;

[0062] Front dielectric layer deposition and electrode fabrication;

[0063] Surface passivation layer deposition and lead hole etching;

[0064] Backside support substrate removal.

[0065] The silicon substrate is an N-type silicon wafer, or an N-type silicon epitaxial wafer, with a thickness of 300~800μm.

[0066] The anti-reflective layer (ARC) is made of SiO2, SiN, or SiO2 / SiN, with a thickness of 50~100nm. It is used to reduce light reflection, reduce surface recombination, and reduce dark current.

[0067] The supporting substrate can be silicon or glass, preferably a resistive N-type silicon wafer with a thickness of 300~800μm.

[0068] The bonding process preferably employs surface activation bonding technology to reduce the heat treatment temperature and improve the bonding strength.

[0069] The silicon wafer is thinned and CMP polished, resulting in a silicon substrate thickness of 100-200 μm and a surface roughness of less than 1 nm.

[0070] The front dielectric layer is SiO2, SiN, or SiO2 / SiN, used to reduce surface recombination and dark current, and to provide insulation and passivation.

[0071] The electrode material is Al or Ti / Ni / Ag.

[0072] The surface passivation layer is SiO2 or SiO2 / SiN.

[0073] The back support substrate removal process involves first thinning the support substrate to 20-50 μm by grinding, and then selectively etching it down to the anti-reflection layer (SiN).

[0074] This fabrication method is adapted to the semiconductor structures of the back-illuminated photodetector and its array shown in Structure 1 and Structure 2, wherein Structure 1 does not require the first step (N+ doping on the front side of the substrate silicon wafer).

[0075] like Figure 4-11 As shown, the present invention also discloses a security inspection device with a back-illuminated photoelectric detector, including a device body 1. A front fixed frame 4 is fixed to one side of the device body 1, and a rear fixed frame 7 is fixed to the other side. An opening 6 is provided on one side of the device body 1, and a rotatable conveyor belt 5 is provided in the front fixed frame 4. The conveyor belt 5 extends backward, passes through the opening 6, and extends into the rear fixed frame 7. When the device is in use, the user places his personal belongings on the conveyor belt 5. As the conveyor belt 5 moves, the belongings enter the device body 1 through the opening 6. After being detected by the back-illuminated photoelectric detector, the belongings are transported to the other side of the device body 1 and fall onto the extension plate 8. A caster wheel 2 and a first support leg 3 are installed at the lower end of the device body 1. The first support leg 3 is located on one side of the caster wheel 2 and can move up and down. An extension plate 8 that can move horizontally is provided on the side of the rear fixed frame 7 away from the device body 1, and the first support leg 3 can move downward when the extension plate 8 moves away from the device body 1.

[0076] When this device is needed, the extension plate 8 is located below the rear fixed frame 7. The user pushes the main body 1. The universal wheels 2 make it easy for the user to push the main body 1. When the main body 1 moves to the predetermined position, the user pulls the extension plate 8 outward. At this time, the first leg 3 moves downward and makes the universal wheels 2 suspended in the air, so that the first leg 3 provides support for the device. This ensures that the device will not move during use.

[0077] The lower end of the extension plate 8 is fixedly connected to a bracket 9, and a second support leg 10 is fixedly connected to the lower end of the bracket 9. When the extension plate 8 is pulled out, the use of the second support leg 10 can support the extension plate 8, thereby ensuring that the extension plate 8 can be stably positioned on the ground during use.

[0078] A connector plate 23 is fixedly connected to the extension plate 8. A groove is formed on the surface of the rear fixing frame 7. The connector plate 23 passes through the groove and extends into the main body 1 of the equipment. A connecting frame 12 is fixedly connected to the upper end of the first support leg 3. There are multiple first support legs 3; preferably, there are four. The four first support legs 3 are connected together by the connecting frame 12, ensuring that the four first support legs 3 can rise or fall synchronously. A threaded rod 11 is fixedly connected to the upper end of the connecting frame 12. The threaded rod 11 passes through the gear 13, meaning that a through hole is coaxially formed inside the gear 13. The threaded rod 11 is located inside the through hole and is threadedly connected to the inner wall of the through hole. The gear 13 is installed inside the main body 1. The wheel 13 can rotate within the main body 1 of the device, but during its rotation, the vertical height of the gear 13 will not change (there is a mounting groove in the main body 1 of the device that is adapted to the gear 13). When the gear 13 rotates, the threaded rod 11 can move up and down. The surface of the plug plate 23 is provided with teeth 14, which mesh with the gear 13. When the plug plate 23 slides in the horizontal direction, the gear 13 can rotate. When the user pulls the extension plate 8 outward, the plug plate 23 engages with the gear 13. At this time, the gear 13 can rotate, and the threaded rod 11 inside the gear 13 can move downward, thereby allowing the first leg 3 to extend downward and the caster wheel 2 to be suspended in the air, thus ensuring the stability of the device during use.

[0079] The plug-in plate 23 is provided with a limiting block 15, and the rear fixing frame 7 is provided with a rotatable locking block 18. The limiting block 15 has a locking groove 19, and the locking block 18 can be embedded in the locking groove 19. One end of the limiting block 15 is inserted into the fixing rod 24, and the fixing rod 24 is fixedly connected to the plug-in plate 23. A spring 25 is provided between the limiting block 15 and the fixing rod 24. The rear fixing frame 7 has a limiting hole, and the limiting block 15 can be inserted into the limiting hole. When the extension plate 8 is pulled outward, the end of the limiting block 15 slides against the inner wall of the groove. When the extension plate 8 is pulled out to the limit position, the limiting block 15 can enter the limiting hole, and the locking block 18 is locked into the locking groove 19, thus ensuring that the locking block 18 will not separate from the locking groove 19 in this state, that is, the extension plate 8 can be in a stable state.

[0080] One end of the locking block 18 is fixedly connected to a rotating shaft 20. The locking block 18 can rotate around the rotating shaft 20. A torsion spring 17 is sleeved on the rotating shaft 20. When the torsion spring 17 is in a free state, the locking block 18 is locked in the slot 19. A toggle rod 16 is also fixedly connected to the locking block 18. The toggle rod 16 extends upward and extends outside the rear fixed frame 7. When the user needs to retract the extension plate 8 into the main body of the device 1 (i.e., when the position of the device needs to be moved), the user first pulls the toggle rod 16 upward, which can then separate the locking block 18 from the slot 19. At this time, the extension plate 18 can be retracted into the main body of the device 1.

[0081] A fixing block 26 is fixedly connected to the toggle lever 16, and the fixing block 26 makes it convenient for the user to pick up the end of the toggle lever 16.

[0082] The rear fixing frame 7 is also provided with a ball groove 21. The upper end of the ball groove 21 is connected to the groove. A ball 22 that can rotate freely is provided in the ball groove 21, which makes the sliding of the plug plate 23 in the groove smoother. The ball groove 21 and the ball 22 form a sliding member. Multiple sliding members can be provided in the groove.

[0083] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0084] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A security inspection device with a back-illuminated photoelectric detector, characterized in that: This includes a back-illuminated photodetector, the fabrication steps of which include: depositing an anti-reflection layer on the front side of a silicon substrate. The process involves bonding to a supporting substrate, thinning and CMP polishing of the silicon wafer, doping of the front-side N+ and P+ regions, deposition of the front-side dielectric layer and electrode fabrication, deposition of the surface passivation layer and etching of lead holes, and removal of the back-side supporting substrate. The silicon substrate is an N-type silicon wafer with a thickness of 300-800 μm. The anti-reflection layer is SiO2, SiN, or SiO2 / SiN with a thickness of 50-100 nm, used to reduce light reflection, surface recombination, and dark current. The supporting substrate can be silicon or glass, wherein the silicon is a resistive N-type silicon wafer with a thickness of 300-800 μm. The bonding employs surface activation bonding technology to reduce... Heat treatment temperature to improve bonding strength; silicon wafer thinning and CMP polishing, the thinned silicon substrate thickness is 100~200μm, and the surface roughness is less than 1nm; the front dielectric layer is SiO2, SiN, or SiO2 / SiN, used to reduce surface recombination and dark current, and to provide insulation and passivation; the electrode material is Al, or Ti / Ni / Ag; the surface passivation layer is SiO2 or SiO2 / SiN; the back support substrate removal, this step first thins the support substrate to 20~50μm by grinding, and then selectively etches it down to the anti-reflection layer; the first step is N+ doping on the front side of the silicon wafer. It also includes a main body (1), a front fixed frame (4) is fixed to one side of the main body (1), and a rear fixed frame (7) is fixed to the other side. An opening (6) is provided on one side of the main body (1), and a rotatable conveyor belt (5) is provided in the front fixed frame (4). The conveyor belt (5) extends backward and passes through the opening (6) and extends into the rear fixed frame (7). A caster wheel (2) and a first support leg (3) are installed at the lower end of the main body (1). The first support leg (3) is located on one side of the caster wheel (2), and the first support leg (3) can move up and down. An extension plate (8) that can move horizontally is provided on the side of the rear fixed frame (7) away from the main body (1). When the extension plate (8) moves away from the main body (1), the first support leg (3) can move downward, thereby suspending the caster wheel (2).

2. The security inspection equipment with a back-illuminated photoelectric detector according to claim 1, characterized in that: The lower end of the extension plate (8) is fixedly connected to a bracket (9), and a second leg (10) is fixedly connected to the lower end of the bracket (9), and the lower end of the second leg (10) is in the same plane as the lower end of the caster wheel (2).

3. A security inspection device with a back-illuminated photoelectric detector according to claim 2, characterized in that: A plug plate (23) is fixedly connected to the extension plate (8). A groove is provided on the surface of the rear fixing frame (7). The plug plate (23) passes through the groove and extends into the main body (1) of the equipment. A connecting frame (12) is fixedly connected to the upper end of the first support leg (3). A threaded rod (11) is fixedly connected to the upper end of the connecting frame (12). The threaded rod (11) passes through the gear (13). When the gear (13) rotates, the threaded rod (11) can move up and down. The surface of the plug plate (23) is provided with teeth (14). The teeth (14) mesh with the gear (13). When the plug plate (23) slides in the horizontal direction, the gear (13) can rotate.

4. A security inspection device with a back-illuminated photoelectric detector according to claim 3, characterized in that: The plug plate (23) is provided with a limiting block (15), and the rear fixing frame (7) is provided with a rotatable locking block (18). The limiting block (15) is provided with a locking groove (19), and the locking block (18) can be embedded into the locking groove (19). One end of the limiting block (15) is inserted into the fixing rod (24), and the fixing rod (24) is fixedly connected to the plug plate (23). A spring (25) is provided between the limiting block (15) and the fixing rod (24). The rear fixing frame (7) is provided with a limiting hole, and the limiting block (15) can be inserted into the limiting hole.

5. A security inspection device with a back-illuminated photoelectric detector according to claim 4, characterized in that: One end of the locking block (18) is fixedly connected to a rotating shaft (20), and a torsion spring (17) is provided on the rotating shaft (20). A toggle rod (16) is also fixedly connected to the locking block (18), and the toggle rod (16) extends upward and extends out of the rear fixing frame (7).

6. A security inspection device with a back-illuminated photoelectric detector according to claim 5, characterized in that: A fixing block (26) is fixedly connected to the actuating lever (16).

7. A security inspection device with a back-illuminated photoelectric detector according to claim 6, characterized in that: The rear fixing frame (7) is also provided with a ball groove (21), the upper end of the ball groove (21) is connected to the groove, and a ball (22) that can rotate freely is provided in the ball groove (21).

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