Back scanning type debonding device and method

Abstract

The embodiment of the invention discloses a back scanning type de-bonding device and a back scanning type de-bonding method, a laser scanning assembly is arranged below a wafer carrying disc, so that laser can sequentially pass through a carrying plate substrate and a bonding layer and is absorbed by the bonding layer, the carrying plate substrate and a device substrate are de-bonded, and the device substrate is located above the carrying plate substrate, so that the device substrate is not damaged. The device substrate can be directly taken away to the next working procedure without being taken away together with the carrier substrate, the wafer does not need to be overturned, and the situation that the device substrate falls off from the carrier substrate in the carrying or wafer overturning process is effectively avoided.

Description

Technical Field

[0001] The present application relates to the technical field of chip debonding, and in particular to a back-scanning debonding device and method. Background Art

[0002] In the field of chip manufacturing, 3D heterogeneous integration technology is a key process for realizing high-integration chip manufacturing, and the debonding process plays a vital role in promoting pattern transfer and chip manufacturing processes. Currently, laser debonding has become the mainstream choice for debonding processes due to its advantages in saving time and completely peeling off the carrier substrate.

[0003] The traditional laser debonding process usually adopts a positive scanning method. During the laser scanning process, the laser can destroy the bonding force between the bonding layer and the carrier substrate and the device substrate, and then the carrier substrate and the device substrate are debonded by corresponding means. However, during the debonding process of the traditional laser debonding process, although the bonding layer between the carrier substrate and the device substrate has lost its bonding force, the device substrate cannot be removed in time at this time and needs to be transported to the subsequent process together with the carrier substrate. During the transportation process, there is a risk that the device substrate will fall off the wafer carrier and be damaged. Summary of the invention

[0004] The embodiments of the present application provide a back-scanning debonding device and method to improve the risk of damage to the device substrate after laser debonding.

[0005] In a first aspect, an embodiment of the present application provides a back-scanning debonding device, comprising:

[0006] Workbench;

[0007] A laser scanning component is arranged on the workbench and is used to generate laser light and use the laser light to scan the wafer to be debonded;

[0008] A wafer carrier, arranged on a workbench, used to carry a wafer and transparent to light, the wafer carrier being located at the laser output end of the laser scanning assembly, the wafer comprising a carrier substrate, a bonding layer and a device substrate stacked in sequence;

[0009] The laser scanning assembly is disposed below the wafer carrier, so that the laser emitted by the laser scanning assembly passes through the carrier substrate and the bonding layer in sequence and is absorbed by the bonding layer, so that the carrier substrate and the device substrate are debonded.

[0010] In some embodiments of the present application, the laser scanning assembly includes a laser generating mechanism and a galvanometer. The laser generating mechanism is used to emit and shape the laser. The galvanometer is arranged at the laser output end of the laser generating mechanism and is located below the wafer carrier, and is used to control the irradiation direction of the laser so that the laser passing through the galvanometer can irradiate the target area of ​​the wafer.

[0011] In some embodiments of the present application, the device substrate is provided with at least one separation groove, so that the device substrate is divided into a plurality of device sub-substrates by the separation groove, the bonding layer includes at least two bonding sub-layers, each of the device sub-substrates is provided with a corresponding bonding sub-layer, and the galvanometer controls the laser to pass through the carrier substrate and irradiate the bonding sub-layer to be debonded, so as to debond the device sub-substrate to be debonded and the carrier substrate.

[0012] In some embodiments of the present application, a visible light positioning camera is included. The visible light positioning camera is arranged on the workbench and located above the wafer carrier, and is used to locate the irradiation position of the laser emitted by the laser scanning assembly so that the laser can irradiate the position of the wafer to be debonded.

[0013] In some embodiments of the present application, a first moving mechanism is included, which is disposed on the workbench and connected to the visible light positioning camera to drive the visible light positioning camera to move relative to the wafer carrier.

[0014] In some embodiments of the present application, a second moving mechanism is included, which is disposed on the workbench and connected to the laser scanning assembly to drive the laser scanning assembly to move relative to the wafer carrier.

[0015] In some embodiments of the present application, an infrared observation camera is included, which is arranged on the second moving mechanism and is used to observe the laser ablation of the bonding layer.

[0016] In a second aspect, an embodiment of the present application provides a back-scanning debonding method, comprising:

[0017] Placing a wafer to be debonded on a wafer carrier, wherein the wafer to be debonded comprises a carrier substrate, a bonding layer and a device substrate stacked sequentially from bottom to top;

[0018] Performing laser irradiation on the wafer to be debonded, wherein the path of the laser irradiation is to sequentially pass through the carrier substrate and the bonding layer and be absorbed by the bonding layer;

[0019] The debonded device substrate is removed.

[0020] In some embodiments of the present application, before the step of irradiating the wafer to be debonded with laser, wherein the path of the laser irradiation is to sequentially pass through the carrier substrate and the bonding layer and be absorbed by the bonding layer, the method further includes:

[0021] At least one separation groove is formed in the device substrate, so that the device substrate is separated into at least two device sub-substrates, the bonding layer is separated into at least two bonding sub-layers, and the device sub-substrates are arranged in one-to-one correspondence with the bonding sub-layers;

[0022] Using a visible light positioning camera to locate the position of the device sub-substrate to be debonded;

[0023] The laser scanning component is controlled to scan the position located by the visible light positioning camera to complete the debonding of the target position of the wafer to be debonded.

[0024] In some embodiments of the present application, the step of irradiating the wafer to be debonded with laser, wherein the path of the laser irradiation is to sequentially pass through the carrier substrate and the bonding layer and be absorbed by the bonding layer, comprises:

[0025] Driving the first moving mechanism and the second moving mechanism to move, so that the laser scanning assembly connected to the first moving mechanism and the visible light positioning assembly connected to the second moving mechanism move to the target position;

[0026] The laser scanning assembly is turned on, and the laser passes through the transparent wafer carrier, the carrier substrate and the bonding layer in sequence. The laser is absorbed by the bonding layer to debond the carrier substrate and the device substrate.

[0027] It can be seen that the embodiment of the present application arranges the laser scanning component under the wafer carrier so that the laser can pass through the carrier substrate and the bonding layer in sequence and be absorbed by the bonding layer, thereby debonding the device substrate from the carrier substrate. Moreover, since the device substrate is located above the carrier substrate, the device substrate will not fall due to its own gravity, and the device substrate can be directly taken away to the next process without taking it away together with the carrier substrate or flipping the wafer, thereby effectively preventing the device substrate from falling off the carrier substrate during transportation or wafer flipping. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0029] Figure 1A schematic diagram of the three-dimensional structure of a back-scanning debonding device provided by an embodiment of the present invention;

[0030] Figure 2 A front view structural diagram of a back-scanning debonding device provided in an embodiment of the present invention

[0031] Figure 3 A schematic structural diagram of a wafer carrier in a back-scan debonding device provided by an embodiment of the present invention;

[0032] Figure 4 A schematic flow chart of a back-scan debonding method provided in an embodiment of the present invention.

[0033] Description of reference numerals:

[0034] 1. Workbench; 2. Laser scanning assembly; 21. Laser generating mechanism; 22. Galvanometer; 3. Wafer carrier; 4. Visible light positioning camera; 5. First moving mechanism; 6. Second moving mechanism; 7. Infrared observation camera; 8. Wafer; 81. Carrier substrate; 82. Bonding layer; 821. Bonding sublayer; 83. Device substrate; 831. Separation groove; 832. Device subsubstrate. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0036] In the description of this application, it should be understood that the words "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0037] See also Figures 1 to 3, an embodiment of the present application provides a back-scanning debonding device, comprising a workbench 1, a laser scanning component 2 and a wafer carrier 3. The laser scanning component 2 is arranged on the workbench 1, and is used to generate laser and use laser to scan the wafer to be debonded. The wafer carrier 3 is arranged on the workbench 1, and is used to carry the wafer 8 and is light-transmissive. The wafer carrier 3 is located at the laser output end of the laser scanning component 2, and the wafer 8 includes a carrier substrate 81, a bonding layer 82 and a device substrate 83 stacked in sequence. Among them, the laser scanning component 2 is arranged below the wafer carrier 3, so that the laser emitted by the laser scanning component 2 passes through the carrier substrate 81 and the bonding layer 82 in sequence and is absorbed by the bonding layer 82, so that the device substrate 83 and the carrier substrate 81 are debonded.

[0038] The technical solution provided in the present application disposes the laser scanning component 2 below the wafer carrier 3, so that the laser can pass through the carrier substrate 81 and the bonding layer 82 in sequence and be absorbed by the bonding layer 82, so that the device substrate 83 is debonded from the carrier substrate 81, and because the device substrate 83 is located above the carrier substrate 81, the device substrate 83 will not fall due to its own gravity, and the device substrate 83 can be directly taken away to the next process without being taken away together with the carrier substrate 81 or flipping the wafer 8, thereby effectively preventing the device substrate 83 from falling from the carrier substrate 81 during transportation or flipping of the wafer 8.

[0039] In one example, the workbench 1 is made of high-strength, high-precision aluminum alloy, and its surface flatness is controlled within ±0.01 mm to ensure the stability of the wafer carrier 3 and other components placed thereon. The workbench 1 includes a base and a top platform, which are arranged relative to each other so that there is enough space between the base and the top platform to place components such as the laser scanning component 2. The workbench 1 also includes a plurality of support columns, which are arranged between the base and the top platform to connect and support the top platform and the base.

[0040] In some embodiments, the laser scanning assembly 2 includes a laser generating mechanism 21 and a galvanometer 22. The laser generating mechanism 21 uses an advanced pulse laser, which can generate an infrared laser with a wavelength of 1064nm. The laser power can be continuously adjusted within the range of 2W-15W, the pulse width is 10ns-100ns, and the pulse frequency is 1kHz-100kHz. This range of laser parameters can meet the debonding operation required by different materials and processes. The laser generating mechanism 21 is equipped with a high-precision laser shaping component. Through the combination of a lens group and a reflector, the laser beam can be shaped into a circular spot with an adjustable spot diameter between 5μm-50μm, ensuring that the laser energy is evenly distributed at the specified position and improving the debonding effect. The galvanometer 22 is installed below the laser output end of the laser generating mechanism 21 and below the wafer carrier 3. The galvanometer 22 is driven by a high-speed, high-precision motor, and the angle control accuracy can reach ±0.01°. It can quickly and accurately change the irradiation direction of the laser, so that the laser can irradiate the target area of ​​the wafer 8 according to the preset path. The target area refers to the part of the wafer 8 to be debonded that needs to be debonded. If the entire part of the wafer 8 needs to be debonded, the target area refers to the entire end face of the wafer 8. If only a part of the wafer 8 needs to be debonded, then it refers to the end face area of ​​the part of the wafer 8 that needs to be debonded. The wafer carrier 3 is made of quartz glass with high transmittance (transmittance greater than 90%) for 1064nm infrared light, and the thickness is 5mm. Its surface is finely polished, and the roughness is less than 0.05μm, ensuring that the wafer 8 can fit tightly on the carrier to avoid displacement during the debonding process. The size of the wafer carrier 3 is designed to be 200mm in diameter according to common wafer specifications, which can adapt to most wafer products on the market. A positioning slot is provided on the edge of the wafer carrier 3, which cooperates with the positioning pin on the workbench 1 to achieve fast and accurate positioning of the wafer carrier 3 on the workbench 1.

[0041] In the actual operation process, the wafer 8 to be debonded is first placed on the wafer carrier 3, and the wafer 8 is composed of a carrier substrate 81, a bonding layer 82, and a device substrate 83 from bottom to top. The laser scanning assembly 2 is located below the wafer carrier 3, and the laser generating mechanism 21 is turned on. The generated laser enters the galvanometer 22 after shaping. According to the debonding requirements of the wafer 8, the operator sets the laser power, pulse width, pulse frequency and other parameters through the control system, and sets the scanning path and range of the galvanometer 22. The galvanometer 22 accurately controls the irradiation direction of the laser according to the instructions of the control system, so that the laser passes through the carrier substrate 81 and the bonding layer 82 in turn. The energy of the laser destroys the bonding force between the bonding layer 82 and the carrier substrate 81 and the device substrate 83, thereby realizing the debonding operation. After the debonding is completed, the device substrate 83 can be directly removed from the top for subsequent processing steps. Compared with the conventional laser debonding process which adopts the forward scanning method, the device substrate 83 is located at the bottom after debonding, and is easily dropped and damaged from the wafer carrier 3 during transportation. The laser in this embodiment is incident from the bottom of the wafer carrier 3, and the device substrate 83 is located at the top after debonding, and can be taken away directly from the top, thereby avoiding the risk of the device substrate 83 dropping from the carrier substrate 81 during transportation. In the actual production process, after statistics of 1,000 debonding operations, the number of times the device substrate 83 dropped and was damaged using the conventional process was 50 times, and the damage rate was 5%; while using the present back-scanning debonding device, the number of times the device substrate 83 dropped and was damaged was 0, which effectively solved the problem of the device substrate 83 dropping and being damaged, and improved the production yield.

[0042] For further information, see Figure 3 The device substrate 83 is provided with at least one separation groove 831, so that the device substrate 83 is separated into multiple device sub-substrates 832 by the separation groove 831, the bonding layer 82 includes at least two bonding sub-layers 821, and each device sub-substrate 832 is correspondingly provided with a bonding sub-layer 821. The galvanometer 22 controls the laser to pass through the carrier substrate 81 respectively, and irradiate the bonding sub-layer 821 and the device sub-substrate 832 to be debonded, so that the device sub-substrate 832 to be debonded and the carrier substrate 81 are debonded.

[0043] Exemplarily, when manufacturing the device substrate 83, two separation grooves 831 with a width of 20 μm, a depth of 50 μm and perpendicular to each other are opened on the surface of the device substrate 83 by laser, thereby dividing the device substrate 83 into four device sub-substrates 832 of the same size. During the preparation process of the bonding layer 82, a bonding sub-layer 821 is formed corresponding to each device sub-substrate 832, and the thickness of the bonding sub-layer 821 is less than 1 μm, so as to ensure that the bonding area and bonding strength of each device sub-substrate 832 and the corresponding bonding sub-layer 821 are relatively uniform, which is conducive to the consistency of subsequent debonding operations. The galvanometer 22 in the laser scanning assembly 2 is connected to a high-precision motor, and the motor is controlled by a special drive circuit, which is connected to the control system of the device. The control system adopts an advanced motion control algorithm, which can accurately control the angle change of the galvanometer 22 through programming and setting, and realize accurate control of the laser irradiation direction. It should be noted that the control of the galvanometer 22 belongs to the prior art and will not be repeated here. Before the debonding operation, the operator inputs the corresponding instructions in the control system according to the layout of the device sub-substrate 832 and the area to be debonded, and sets the scanning path and range of the laser. For example, if it is necessary to debond two adjacent device sub-substrates 832 and their corresponding bonding sub-layers 821, the operator can specify the coordinate range of these two areas in the control system. Place the wafer 8 with a specific structure on the wafer carrier 3 to ensure that the position of the wafer 8 is accurate. Turn on the laser generating mechanism 21 to generate a laser with a wavelength of 1064nm and a power of 15W. The laser enters the galvanometer 22 after shaping. The control system drives the galvanometer 22 motor to work according to the preset instructions, so that the galvanometer 22 swings according to the set angle and path. Under the control of the galvanometer 22, the laser passes through the carrier substrate 81 in turn and accurately irradiates the specified bonding sub-layer 821 to be debonded.

[0044] The traditional laser debonding process cannot perform accurate local debonding on the partitioned structure of the device substrate 83. However, this embodiment forms multiple device sub-substrates 832 by setting separation grooves 831 on the device substrate 83, and correspondingly sets bonding sub-layers 821. Combined with the precise control of the laser irradiation direction by the galvanometer 22, it is possible to achieve accurate debonding of a specific device sub-substrate 832 and its bonding sub-layer 821. In actual tests, 100 wafers 8 with the same partitioned structure were selected for debonding experiments. The traditional process can only perform overall debonding and cannot meet the debonding requirements for local areas. However, this device can accurately debond the specified device sub-substrate 832, and the debonding accuracy reaches ±2μm, which effectively improves the accuracy and flexibility of debonding and meets the needs of differentiated processing of different regions in chip manufacturing. Since the device sub-substrate 832 in a specific area can be debonded, for some wafers 8 with local defects, there is no need to scrap the entire wafer 8, and only the device sub-substrate 832 corresponding to the defective area needs to be debonded and replaced, which greatly reduces the production cost. In addition, by adopting the local debonding method, the device substrate 83 is arranged above the carrier substrate 81, and the laser scanning assembly 2 is located below the carrier substrate 81, so that the locally debonded device sub-substrate 832 will not fall due to debonding, but after debonding, the device sub-substrate 832 can be directly transferred to the next process.

[0045] In some embodiments, see Figure 1 and Figure 2 The back-scanning debonding device includes a visible light positioning camera 4. The visible light positioning camera 4 is disposed on the workbench 1 and above the wafer carrier 3, and is used to locate the irradiation position of the laser emitted by the laser scanning assembly 2 so that the laser can irradiate the position of the wafer 8 to be debonded.

[0046] Exemplarily, the visible light positioning camera 4 uses a high-resolution industrial camera with more than 5 million pixels and is equipped with a telecentric lens, which can effectively reduce image distortion caused by viewing angle problems and ensure the accuracy of positioning. The lens of the visible light positioning camera 4 is vertically aligned downward with the wafer carrier 3. Before the debonding operation, the wafer 8 to be debonded is placed on the wafer carrier 3, and the wafer 8 includes a carrier substrate 81, a bonding layer 82 and a device substrate 83 stacked in sequence. The visible light positioning camera 4 starts working and first collects images of the surface of the device substrate 83 on the wafer 8. Because there is a pre-designed groove line structure on the device substrate 83, that is, the separation groove 831 described in the aforementioned embodiment. By analyzing the deviation between the separation groove 831 in the image and the preset standard position, the exact position required for irradiation of the laser scanning component 2 is calculated. Then, the control system sends an instruction to the laser scanning component 2 to guide the laser irradiation to the position of the wafer 8 to be debonded. The analysis, calculation and control processes here are all implemented by computers.

[0047] The traditional laser debonding process uses an infrared camera to observe the pattern through the carrier substrate 81 for positioning. Due to the characteristics of infrared light and the attenuation of infrared light by the carrier substrate 81, the image resolution and clarity are poor. However, this embodiment uses a visible light positioning camera 4 to directly position the surface of the device substrate 83, which improves the positioning accuracy and reduces the debonding errors caused by positioning errors. The traditional positioning method is greatly affected by the material, thickness and surface condition of the carrier substrate 81. For different types of wafers 8, the positioning effect is unstable. The positioning method of the visible light positioning camera 4 acts directly on the surface of the device substrate 83 and is not affected by the factors of the carrier substrate 81. Whether it is a carrier substrate 81 made of glass or a carrier substrate 81 made of silicone grease, no matter how the thickness of the carrier substrate 81 changes, stable and high-precision positioning can be achieved.

[0048] In some embodiments, the back-scanning debonding device also includes a first moving mechanism 5. The first moving mechanism 5 is arranged on the workbench 1 and is connected to the visible light positioning camera 4 to drive the visible light positioning camera 4 to move relative to the wafer carrier 3. The first moving mechanism 5 is installed on the workbench 1, and is mainly composed of an X-axis moving component, a Y-axis moving component and a Z-axis moving component. The components cooperate with each other to achieve the precise movement of the visible light positioning camera 4 in three-dimensional space. The X-axis moving component includes a high-precision linear slide rail, which is fixed on the horizontal plane of the workbench 1, and its straightness error is controlled within ±0.02mm per meter. A slider is installed on the slide rail, which is connected to the bottom of the Y-axis moving component. The driving device in the X-axis direction adopts a high-precision ball screw pair, which is powered by a stepping motor. The step angle of the motor is 0.72°. With the subdivision driver, the displacement accuracy in the X-axis direction can reach ±0.01mm.

[0049] The Y-axis moving assembly is installed on the X-axis slider. Its structure is similar to that of the X-axis moving assembly, and it also uses high-precision linear guides and ball screw pairs. The Y-axis linear guide is installed perpendicular to the X-axis guide to ensure high precision and stability of Y-axis movement. The Y-axis drive motor is also a stepper motor. By precisely controlling the rotation of the motor, the displacement accuracy in the Y-axis direction can also reach ±0.01mm.

[0050] The Z-axis moving assembly is installed on the Y-axis slider to realize the vertical movement of the visible light positioning camera 4. The Z-axis moving assembly adopts a high-precision electric lifting platform, and the screw nut pair of the lifting platform is connected to the Y-axis slider. The electric lifting platform is driven by a DC motor, and through a set of precise reduction mechanisms, the rotational motion of the motor is converted into the linear motion of the screw to achieve displacement in the Z-axis direction. The displacement accuracy in the Z-axis direction can reach ±0.02mm, which can meet the camera height adjustment requirements for wafers of different thicknesses.

[0051] The visible light positioning camera 4 is connected to the top of the Z-axis moving assembly through a camera mounting seat. The camera mounting seat is made of high-strength aluminum alloy and is precision-processed to ensure the firmness and stability of the camera installation. The mounting seat is connected to the Z-axis moving assembly by bolts, and a fine-tuning mechanism is provided at the connection position. The fine-tuning mechanism includes an adjusting bolt and an elastic gasket. By rotating the adjusting bolt, the horizontal angle and vertical angle of the camera can be fine-tuned, and the fine-tuning accuracy can reach ±0.1°, ensuring that the camera lens can always be vertically aligned with the wafer on the wafer carrier 3.

[0052] In the conventional laser debonding process, the positioning camera is placed on the same side as the laser output end. Since it is necessary to observe the pattern through the carrier substrate 81 for positioning, an infrared camera is used for positioning, which has low positioning accuracy and is seriously affected by the thickness and material of the carrier substrate 81. In this embodiment, the first moving mechanism 5 can accurately position the groove line through precise movement of the X-axis and Y-axis in conjunction with a high-definition visible light camera, provide coordinate information for the second moving mechanism 6, and complete high-precision positioning without being affected by the material and thickness of the carrier substrate 81.

[0053] In some embodiments, the back-scanning debonding device further includes a second moving mechanism 6 and an infrared observation camera 7. The second moving mechanism 6 is disposed on the workbench 1 and connected to the laser scanning assembly 2 to drive the laser scanning assembly 2 to move relative to the wafer carrier 3. The infrared observation camera 7 is disposed on the second moving mechanism 6 to observe the laser ablation of the bonding layer 82.

[0054] The second moving mechanism 6 is used to achieve precise displacement of the laser scanning assembly 2, and includes X-axis, Y-axis, and Z-axis motion units installed perpendicularly to each other. Each axis motion unit adopts a combination structure of a high-precision linear guide and a ball screw. The structure of the second moving mechanism 6 is the same as that of the first moving mechanism 5, except that the installation position is different, which will not be repeated here. In the traditional laser debonding process, due to the lack of precise movement control of the laser scanning assembly 2, the deviation of the laser irradiation position is large, resulting in poor debonding effect and even damage to the device. The second moving mechanism 6 in this embodiment can control the positioning deviation of the laser scanning assembly 2 and the first moving mechanism 5 within ±0.002mm. The three-dimensional motion capability of the second moving mechanism 6 enables the laser scanning assembly 2 to adapt to wafers of different sizes, shapes, and thicknesses of the carrier substrate 81. When processing wafers of different specifications, traditional processes usually require the replacement of tooling fixtures or manual adjustment of equipment, which is cumbersome and time-consuming. The second moving mechanism 6 of the present device can quickly adjust the position of the laser scanning assembly 2 according to the instructions of the control system without replacing the tooling. For example, when switching from processing a wafer with a diameter of 200 mm to a wafer with a diameter of 300 mm, the adjustment time of the traditional process takes an average of 30 minutes, while the present device can complete the switch in only 3 minutes through the automatic adjustment of the first moving mechanism 5 and the second moving mechanism 6, which greatly improves the production efficiency and process flexibility. The infrared observation camera 7 works in coordination with the second moving mechanism 6 and the laser scanning assembly 2 to achieve real-time monitoring of the laser ablation of the bonding layer 82. In detail, the infrared camera carried by the second moving mechanism 6 can directly observe the ablation of the wafer, intuitively record the process effect, and facilitate the process exploration of new structures.

[0055] See also Figure 4 , an embodiment of the present application further provides a back-scanning debonding method, comprising:

[0056] S1. Placing a wafer to be debonded on a wafer carrier. The wafer to be debonded includes a carrier substrate, a bonding layer and a device substrate stacked in sequence from bottom to top.

[0057] Before performing the back-scanning debonding operation, the staff first cleans the wafer carrier 3 to ensure that there are no dust, impurities and other contaminants on its surface to prevent these foreign objects from affecting the flatness of the wafer placement and the subsequent debonding effect. Subsequently, the wafer to be debonded is carefully placed on the wafer carrier 3. From bottom to top, the wafer is a carrier substrate 81, a bonding layer 82 and a device substrate 83. When placing, it is necessary to ensure that the center of the wafer is aligned with the center of the wafer carrier 3. Precise positioning can be achieved by matching the positioning grooves or marks pre-set on the wafer carrier 3 with the positioning features of the wafer edge. The staff uses a high-precision microscope or optical positioning equipment to check and fine-tune the placement position of the wafer to ensure that the wafer placement error is within ±0.05mm.

[0058] S2. The wafer to be debonded is subjected to laser irradiation. The path of the laser irradiation is to pass through the carrier substrate and the bonding layer in sequence and be absorbed by the bonding layer.

[0059] Turn on the control system of the device and set the laser irradiation parameters. According to factors such as the material properties of the wafer, the type and thickness of the bonding layer 82, etc., determine the appropriate laser wavelength, power, pulse width and pulse frequency. For example, for wafers using a certain specific inorganic bonding layer 82, after preliminary experiments and process experience, the laser wavelength is set to 1064nm, the power is adjusted to 3W, the pulse width is 20ns, and the pulse frequency is 50kHz. After the settings are completed, the control system controls the second moving mechanism 6 to move the laser scanning assembly 2 to the initial working position, and at the same time adjusts the position of the visible light positioning camera 4 so that it can clearly capture the surface of the device substrate 83 on the wafer for subsequent positioning operations.

[0060] After confirming that the positions of the laser scanning assembly 2 and the visible light positioning camera 4 are correct, use the visible light positioning camera 4 to locate the initial position through the mark, and then draw the area to be scanned according to the software. Start the laser generating mechanism 21. The laser beam generated by the laser generating mechanism 21 enters the galvanometer 22 after shaping and collimation. The control system uses the built-in image recognition algorithm to calculate the target position where the laser needs to be irradiated according to the preset positioning mark or feature on the device substrate 83, and sends a control signal to the galvanometer 22. The galvanometer 22 quickly and accurately adjusts the irradiation direction of the laser beam according to the received signal, so that the laser passes through the transparent wafer carrier 3, the carrier substrate 81 and the bonding layer 82 in turn. Under the action of the laser energy, the chemical bond between the bonding layer 82 and the carrier substrate 81 or the device substrate 83 is destroyed to achieve debonding. After the scanning of the laser generating mechanism 21 is completed, the infrared observation camera 7 observes the laser ablation of the bonding layer 82 and feeds the image back to the control system. The control system quickly determines the process quality based on the feedback image and adjusts the laser power, pulse frequency and other parameters in real time to ensure the stability and consistency of the debonding process.

[0061] S3. Take away the device substrate after debonding.

[0062] When the laser irradiation is completed and the debonding operation is finished, the control system controls the upper mechanical arm or other material removal device to descend above the wafer. The end of the mechanical arm is equipped with a specially designed vacuum adsorption device or clamping tool, which can stably grasp or adsorb the device substrate 83 without damaging the device substrate 83. The staff operates the mechanical arm through the control system to remove the device substrate 83 that has completed the debonding from the wafer carrier 3 and place it in a designated collection container or subsequent processing equipment for subsequent packaging, testing and other processes. As for the carrier substrate, it does not need to be removed, and it will not affect the removal of the device substrate 83.

[0063] In the conventional forward scanning laser debonding process, the device substrate 83 is located at the bottom after debonding, and is very likely to fall off the wafer carrier 3 and be damaged during transportation. According to statistics, the drop damage rate of the device substrate 83 under the conventional process is about 5%. In the present back scanning debonding method, the device substrate 83 is located at the top after debonding and can be taken away directly. By counting 1000 debonding operations using this method, the number of times the device substrate 83 falls and is damaged is 0, which fundamentally solves the problem of the device substrate 83 falling and being damaged during transportation, and effectively improves the utilization rate and production yield of the wafer.

[0064] This method uses precise positioning and automatic control technology. Before laser irradiation, the visible light positioning camera 4 and the control system can quickly and accurately determine the laser irradiation position, which greatly shortens the positioning time compared to the traditional process that relies on manual or low-precision positioning. At the same time, after the laser irradiation is completed, the infrared observation camera 7 can observe the ablation of the bonding layer 82 to make a preliminary judgment on the process quality of this process. It is convenient for the control system to further adjust the relevant parameters of the laser according to the process quality of this time.

[0065] Furthermore, before the step of irradiating the wafer to be debonded with laser, wherein the path of the laser irradiation is to sequentially pass through the carrier substrate 81 and the bonding layer 82 and be absorbed by the bonding layer 82, the method further includes:

[0066] At least one separation groove 831 is formed in the device substrate 83, so that the device substrate 83 is separated into at least two device sub-substrates 832, and the bonding layer 82 is separated into at least two bonding sub-layers 821, and the device sub-substrates 832 and the bonding sub-layers 821 are arranged in a one-to-one correspondence;

[0067] Using the visible light positioning camera 4 to locate the position of the device sub-substrate 832 to be debonded;

[0068] The laser scanning assembly 2 is controlled to scan the position located by the visible light positioning camera 4 to complete the debonding of the target position of the wafer to be debonded.

[0069] Before placing the wafer to be debonded on the wafer carrier 3, the device substrate 83 needs to be pre-processed. Specifically, the device substrate 83 is cut by laser, and then the cut device substrate 83 is bonded to the carrier substrate 81. At this time, the position where the device substrate 83 is cut through cooperates with the surface where the carrier substrate 81 contacts the device substrate 83 to form a separation groove 831. Correspondingly, the bonding layer 82 between the device substrate 83 and the carrier substrate 81 is also divided into a plurality of bonding sub-layers 821, and each device sub-substrate 832 corresponds to a bonding sub-layer 821.

[0070] Place the pre-processed wafer on the wafer carrier 3 and fix the position. Turn on the visible light positioning camera 4, which is installed above the workbench 1 and directly above the wafer carrier 3. The camera uses a high-resolution CMOS image sensor with 8 million pixels and a wide-angle lens to obtain a clear image of the entire wafer surface. The visible light positioning camera 4 can magnify the image and then perform centering on the magnified image so that the centering can locate the separation groove 831, thereby providing position information for the second moving mechanism 6.

[0071] The control system sends instructions to the laser scanning assembly 2 according to the position of the sub-substrate 832 of the device to be debonded determined by the visible light positioning camera 4. The laser generating mechanism 21 in the laser scanning assembly 2 generates a laser beam with a wavelength of 1064nm and a maximum power of 15W. The laser beam enters the galvanometer 22 after shaping. According to the instructions of the control system, the galvanometer 22 quickly and accurately adjusts the irradiation direction of the laser beam, so that the laser passes through the carrier substrate 81 and the bonding sublayer 821 in turn and is absorbed by the bonding sublayer 821. After the laser irradiation is completed, the infrared observation camera 7 can observe the ablation of the bonding layer 82 to make a preliminary judgment on the process quality of this process. It is convenient for the control system to further adjust the relevant parameters of the laser according to the process quality of this time.

[0072] The traditional laser debonding process is difficult to accurately debond a local area of ​​the device substrate 83, and the debonding effect is not good for a device substrate 83 with a partitioned structure. This embodiment forms multiple device sub-substrates 832 by opening separation grooves 831 on the device substrate 83, and uses a visible light positioning camera 4 to accurately locate the position of the device sub-substrate 832 to be debonded, thereby achieving accurate debonding of a specific area. In the debonding experiment of 100 wafers with device substrates 83 with separation grooves 831, the traditional process was unable to accurately debond the specified device sub-substrate 832, while the present method was able to accurately debond the selected device sub-substrate 832, with a debonding accuracy of ±2μm, effectively solving the problem that the traditional process could not accurately debond locally.

[0073] For example, during the chip manufacturing process, some wafers may only have problems in local areas. Traditional processes can only debond and process the entire wafer, resulting in a large amount of undamaged area being wasted. This method can be operated on the device sub-substrate 832 that needs to be debonded locally. For wafers with local defects, it is only necessary to debond and repair the device sub-substrate 832 corresponding to the defective area, without scrapping the entire wafer. Taking a chip manufacturing company as an example, before adopting this method, the wafer scrap rate due to local defects was 12%. After adopting this method, the wafer scrap rate was reduced to less than 4% through local debonding and replacement, greatly reducing production costs.

[0074] In some embodiments, the step of irradiating the wafer to be debonded with laser, wherein the path of the laser irradiation is to sequentially pass through the carrier substrate 81 and the bonding layer 82 and be absorbed by the bonding layer 82, includes:

[0075] Drive the first moving mechanism 5 and the second moving mechanism 6 to move, so that the laser scanning assembly 2 connected to the first moving mechanism 5 and the visible light positioning assembly connected to the second moving mechanism 6 move to the target position;

[0076] The laser scanning assembly 2 is turned on, and the laser passes through the transparent wafer carrier, the carrier substrate 81 , the bonding layer 82 and the device substrate 83 in sequence, so that the carrier substrate 81 and the device substrate 83 are debonded from the bonding layer 82 respectively.

[0077] Before starting the debonding operation, the operator inputs the size of the wafer to be debonded, the position of the debonding area and other related parameters through the human-machine interface of the device. Based on these parameters, the control system calculates the target position coordinates to which the laser scanning component 2 and the visible light positioning component need to be moved. The first moving mechanism 5 and the second moving mechanism 6 are respectively composed of motion units of the X-axis, Y-axis and Z-axis. Each axis motion unit adopts high-precision linear guides and ball screw transmissions and is driven by a servo motor. Taking the X-axis motion unit of the first moving mechanism 5 as an example, after the servo motor receives the pulse signal sent by the control system, it rotates precisely according to the number and frequency of pulses, and converts the rotational motion into linear motion through the ball screw, driving the visible light positioning component connected thereto to move in the X-axis direction. The high-precision encoder in the motion unit feeds back the rotational position information of the motor to the control system in real time, forming a closed-loop control to ensure the movement accuracy. Through similar principles, the first moving mechanism 5 and the second moving mechanism 6 work together to quickly and accurately move the laser scanning component 2 and the visible light positioning component to the target position.

[0078] When the laser scanning component 2 and the visible light positioning component reach the target position, the laser generating mechanism 21 of the laser scanning component 2 is started. The laser generating mechanism 21 generates an infrared laser with a wavelength of 1064nm, and its power can be adjusted in the range of 2W-15W according to the characteristics of the wafer material and the bonding layer 82. The laser beam first passes through the laser shaping component, which is composed of a series of lenses and reflectors, and can shape the laser beam into a circular spot with a spot diameter of 10μm-50μm to ensure that the laser energy is evenly distributed on the bonding layer 82. The shaped laser beam enters the galvanometer 22, and the galvanometer 22 accurately controls the scanning path and angle of the laser beam according to the instructions of the control system. During the laser scanning process, the visible light positioning component continuously captures images of the wafer surface and transmits the images back to the control system. The control system uses an image recognition algorithm to monitor the alignment of the laser beam with the area to be debonded in real time. If a deviation is found, the angle of the galvanometer 22 is adjusted in time to ensure that the laser is accurately irradiated on the target area. At the same time, the infrared observation camera 7 monitors the laser ablation of the bonding layer 82 in real time and feeds back the collected images to the control system. The control system adjusts the laser power, pulse frequency and other parameters in real time according to the feedback from the infrared observation camera 7. For example, when it is found that the ablation speed of the bonding layer 82 is too fast or too slow, the control system automatically reduces or increases the laser power to ensure the stability and effectiveness of the debonding process. The laser passes through the transparent wafer carrier 3, the carrier substrate 81 and the bonding layer 82 in turn. The laser is absorbed by the bonding layer 82, so that the carrier substrate 81 and the device substrate 83 are debonded. After the debonding is completed, the control system controls the laser scanning assembly 2 to stop working, completing a debonding operation.

[0079] The traditional laser debonding process has poor positioning accuracy and large deviation in the laser irradiation position, resulting in unstable debonding effect. For example, the positioning error of the traditional process is usually above ±0.5mm, while the present embodiment improves the positioning accuracy to within ±0.05mm through the precise movement of the first moving mechanism 5 and the second moving mechanism 6, combined with the real-time monitoring and feedback of the visible light positioning component. In the statistics of 100 debonding operations, the number of incomplete debonding or excessive debonding due to positioning deviation in the traditional process was 30 times, while this method only had 5 times, which greatly improved the accuracy and stability of debonding. Due to positioning deviation and poor control of laser parameters, the traditional process is prone to cause unnecessary damage to the device substrate 83, resulting in a low product yield. After the wafer debonded by this method was tested for electrical performance, the yield rate was increased from 80% of the traditional process to more than 95%.

[0080] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0081] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0082] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more application embodiments, in the above description of the embodiments of this application, multiple features are sometimes merged into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0083] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this application is hereby incorporated by reference in its entirety, except for application history documents that are inconsistent with or conflicting with the content of this application, and documents that limit the broadest scope of the claims of this application (currently or later attached to this application). It should be noted that if the descriptions, definitions, and / or use of terms in the attached materials of this application are inconsistent or conflicting with the content of this application, the descriptions, definitions, and / or use of terms in this application shall prevail.

[0084] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back-scanning debonding device, characterized in that: include: Workbench; A laser scanning component is arranged on the workbench and is used to generate laser light and use the laser light to scan the wafer to be debonded; A wafer carrier, arranged on a workbench, used to carry a wafer and transparent to light, the wafer carrier being located at the laser output end of the laser scanning assembly, the wafer comprising a carrier substrate, a bonding layer and a device substrate stacked in sequence; The laser scanning assembly is disposed below the wafer carrier, so that the laser emitted by the laser scanning assembly passes through the carrier substrate and the bonding layer in sequence and is absorbed by the bonding layer, so that the carrier substrate and the device substrate are debonded.

2. The back-scan debonding device according to claim 1, characterized in that: The laser scanning assembly includes a laser generating mechanism and a galvanometer. The laser generating mechanism is used to emit and shape laser light. The galvanometer is arranged at the laser output end of the laser generating mechanism and is located below the wafer carrier, and is used to control the irradiation direction of the laser so that the laser light passing through the galvanometer can irradiate the target area of ​​the wafer.

3. The backscan debonding device according to claim 2, characterized in that: The device substrate is provided with at least one separation groove so that the device substrate is divided into multiple device sub-substrates by the separation groove. The bonding layer includes at least two bonding sub-layers, and each device sub-substrate is correspondingly provided with a bonding sub-layer. The galvanometer controls the laser to pass through the carrier substrate and irradiate the bonding sub-layer to be debonded, so that the device sub-substrate to be debonded and the carrier substrate are debonded.

4. The back-scan debonding device according to claim 3, characterized in that: It includes a visible light positioning camera, which is arranged on the workbench and located above the wafer carrier, and is used to locate the irradiation position of the laser emitted by the laser scanning component so that the laser can irradiate the position of the wafer to be debonded.

5. The back-scan debonding device according to claim 4, characterized in that: It comprises a first moving mechanism, which is arranged on the workbench and connected to the visible light positioning camera to drive the visible light positioning camera to move relative to the wafer carrier.

6. The back-scan debonding device according to any one of claims 1 to 5, characterized in that: It comprises a second moving mechanism, which is arranged on the workbench and connected with the laser scanning component to drive the laser scanning component to move relative to the wafer carrier.

7. The back-scan debonding device according to claim 6, characterized in that: An infrared observation camera is included, which is arranged on the second moving mechanism and is used to observe the laser ablation condition of the bonding layer.

8. A backscan debonding method, characterized in that: include: Placing a wafer to be debonded on a wafer carrier, wherein the wafer to be debonded comprises a carrier substrate, a bonding layer and a device substrate stacked sequentially from bottom to top; Performing laser irradiation on the wafer to be debonded, wherein the path of the laser irradiation is to sequentially pass through the carrier substrate and the bonding layer and be absorbed by the bonding layer; The debonded device substrate is removed.

9. The back-scan debonding method according to claim 8, characterized in that: Before the step of irradiating the wafer to be debonded with laser, wherein the path of the laser irradiation is to sequentially pass through the carrier substrate and the bonding layer and be absorbed by the bonding layer, the method further includes: At least one separation groove is formed in the device substrate, so that the device substrate is separated into at least two device sub-substrates, and the bonding layer is separated into at least two bonding sub-layers, and the device sub-substrates and the bonding sub-layers are arranged in one-to-one correspondence; Using a visible light positioning camera to locate the position of the device sub-substrate to be debonded; The laser scanning component is controlled to scan the position located by the visible light positioning camera to complete the debonding of the target position of the wafer to be debonded.

10. The backscan debonding method according to claim 8, characterized in that: The step of irradiating the wafer to be debonded with laser, wherein the path of the laser irradiation is to sequentially pass through the carrier substrate and the bonding layer and be absorbed by the bonding layer, comprises: Driving the first moving mechanism and the second moving mechanism to move, so that the laser scanning assembly connected to the first moving mechanism and the visible light positioning assembly connected to the second moving mechanism move to the target position; The laser scanning assembly is turned on, and the laser passes through the transparent wafer carrier, the carrier substrate and the bonding layer in sequence. The laser is absorbed by the bonding layer to debond the carrier substrate and the device substrate.

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