Device and method for photoelectrochemical mechanical polishing of semiconductor substrate aiming at uniform arrangement of electric field and mutual coordination of light field

Abstract

The invention relates to a device and a method for photoelectrochemical mechanical polishing of a semiconductor substrate aiming at electric field uniform arrangement and light field intercoordination, and the device comprises a rack, a machine body unit, a polishing disc assembly, a conductive base, an LED ultraviolet light source, an electrochemical workstation and a moving assembly, the machine body unit is used for loading and unloading the polishing disc assembly; the electrochemical workstation and the LED light source power supply respectively supply power to the conductive base and the LED ultraviolet light source in the machining process, the LED ultraviolet light source is fixed on the polishing disc and acts on a semiconductor substrate workpiece in machining together with the polishing disc in the workpiece polishing process, and the semiconductor substrate workpiece is bonded on the conductive base. The LED light source directly irradiates the surface of a machined workpiece, the distance between the light source and a polishing solution is effectively shortened, the effect of a light field is improved, meanwhile, the intensity of the light field in different directions along the radius is adjusted, the light field and an electric field applied to the workpiece act together to guarantee uniform oxidation of the surface of the workpiece, and the flatness of the machined workpiece is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor polishing technology, and in particular to a device and method for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field. Background Art

[0002] As electronic information technology enters the post-Moore era, people are seeking new materials and technologies to promote the further development of semiconductor science and technology. As a new generation of strategic electronic materials, wide bandgap semiconductor materials have excellent characteristics such as large bandgap width, high power, high carrier mobility, fast saturated electron velocity, and resistance to high temperature and high pressure, which has attracted widespread attention. These materials not only promote the development of the LED lighting industry (from Mini-LED to Micro-LED), but also play an important role in high-power lasers, ultraviolet sterilization and detection. Wide bandgap semiconductor technology is also one of the key technologies supporting the electronics industry, covering a wide range of applications from new energy vehicles to 5G / 6G communications, AR / VR and digital humans. In the current environment of technological competition and cooperation, the international community is paying more and more attention to the field of wide bandgap semiconductor materials.

[0003] The third generation of semiconductor materials are particularly suitable for manufacturing high voltage and high frequency power devices due to their excellent electrical and chemical properties, such as wide energy band gap, excellent thermal conductivity, high breakdown voltage, and excellent chemical stability. In these devices, the surface roughness of the semiconductor substrate has a significant impact on the performance. It has been proven that by reducing the surface roughness, the breakdown electric field strength and breakdown charge can be increased, thereby improving the transconductance of the MOS transistor. Therefore, it is crucial to achieve an ultra-smooth surface with no surface damage and atomic-level smoothness.

[0004] Chemical mechanical polishing (CMP) is currently a common method for ultra-precision processing of third-generation semiconductor substrate materials. This process uses chemical action to generate a modified soft oxide layer on the surface, and then uses mechanical removal to achieve efficient surface processing. Since third-generation semiconductor materials are chemically inert and have high hardness, they are difficult to react with acid and alkali solutions at room temperature. It is difficult to simultaneously improve the overall surface flatness and obtain a high material removal rate. Therefore, achieving high-quality and efficient processing of third-generation semiconductor substrate materials remains a challenge.

[0005] So far, only the patent application publication numbers CN116038440A, CN115415857A, CN106141900A, CN109465739A, etc. disclose devices and schemes for realizing photoelectrochemical mechanical polishing by combining chemical mechanical action field with photoelectric coupling. However, the uniformity of oxidation of the anode wafer and the optical field-electric field coupling in the above-mentioned devices make it impossible to intermittently monitor the surface quality and material removal rate at different positions on the wafer surface, resulting in incompleteness in the processing process.

[0006] Specifically, the patent application publication number CN116038440A discloses "a photoelectric combined chemical mechanical polishing device and method thereof", which involves two containing tanks, a light-emitting lamp is placed in one tank, and a conductor electrically connected to a power source is placed in the other tank, and the efficiency is improved by photoelectric means. The light source applied to the upper surface of the wafer is embedded in the containing tank. In the actual processing process, such a design will cause a certain impact on the light source applied to the processing surface due to the pressure applied to the workpiece and the vibration generated by the processing, etc., which will cause the light applied to the wafer surface to be attenuated to a certain extent, thereby affecting the processing of the wafer. Specifically, the patent application publication number CN115415857A discloses "a photoelectric chemical mechanical polishing device and a material efficient removal adjustment method", which involves the use of an electrochemical workstation to apply voltage and measure current during wafer polishing, and the wafer oxidation rate is achieved by adjusting the electric field voltage, and the mechanical removal effect is coordinated to improve the material removal rate of the wafer. The voltage applied to the wafer will affect the overall oxidation degree of the wafer. The use of a conductive column-shaped structure will cause the electric field applied to the wafer to be unevenly distributed, which in turn causes uneven oxidation of the wafer surface, resulting in poor flatness of the processed wafer, affecting subsequent applications as a device.

[0007] Patent application publication number CN106141900A discloses the use of photoelectrochemical methods to corrode the surface of GaN wafers and mechanical methods to remove the corrosion layer. It only stipulates certain requirements for the type of light and the device that provides the light source. In the actual processing process, the distance between the light and the workpiece is too far or the unevenness of the light on the wafer surface will cause different oxidation effects on the surface at different positions, resulting in the inability to guarantee the flatness of the processed surface, which is particularly evident for larger wafers.

[0008] Patent application publication number CN109465739A discloses "a semiconductor wafer photoelectrochemical mechanical polishing processing device". This patent uses a polishing plate with through holes and a polishing pad that cooperates with it to allow droplets to drip onto the wafer surface through distributed through holes for photoelectrochemical mechanical polishing. In this process, the device for dripping polishing liquid cannot be fixed and is limited by the limitations of the dripping device, making it impossible to drip polishing liquid to multiple holes at the same time.

[0009] In addition, the existing photoelectrochemical mechanical polishing device cannot detect the morphology of the polished workpiece processed in different time periods to provide feedback on the coordination between photoelectricity during the processing process, which affects the surface quality after processing and increases the complexity of the process. Summary of the invention

[0010] In response to the technical problems raised above, a device and method for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field are provided.

[0011] The technical means adopted by the present invention are as follows:

[0012] A device for photoelectrochemical mechanical polishing of semiconductor substrates for uniform electric field arrangement and coordinated light field comprises: a frame, a body unit, a polishing disc assembly, a conductive base, an LED ultraviolet light source, an electrochemical workstation and a moving assembly. The body unit is used for loading and unloading the polishing disc assembly. The body unit, the electrochemical workstation, the LED light source power supply and the moving assembly are all installed on the frame. The electrochemical workstation and the LED light source power supply are respectively used to provide power for the conductive base and the LED ultraviolet light source during the processing. The LED ultraviolet light source is fixed on the polishing disc and acts on the semiconductor substrate workpiece being processed during the polishing process of the polishing disc. The semiconductor substrate workpiece is fixed on the conductive base by bonding, and the position of the body unit and the workpiece to be processed is adjusted by the moving assembly.

[0013] Furthermore, the polishing disc assembly includes a polishing disc, a polishing pad, the LED ultraviolet light source, a water cooling disc, a conductive column and a hexagonal nut. The polishing disc is provided with an annular groove of a preset radius near the center position, and the added polishing liquid is dripped onto the semiconductor substrate workpiece based on the annular groove. A plurality of holes arranged radially are provided on the disc surface, so that the LED ultraviolet light source can directly irradiate the processed semiconductor substrate, and through holes are distributed between the holes along the radial direction, so that the polishing liquid dripped into the groove can drip onto the processed semiconductor substrate through the through holes along the radial direction, thereby realizing an electrical path between the anode and cathode. The polishing pad is fixed to the working surface of the polishing disc by bonding. The LED ultraviolet light source and the water cooling disc are an integrated structure. The water cooling disc is used to solve the problem of overheating of light during the processing, wherein the distribution mode of the LED ultraviolet light source is consistent with the distribution mode of the holes on the polishing disc. The three conductive columns on the water cooling disc are connected to the middle hexagonal nut, which provides a stable power supply for the LED lamp during the processing and controls the intensity of the light along the radial direction. The hexagonal nut is fixed to the polishing disc by bolts to ensure coaxial rotation with the polishing disc.

[0014] Furthermore, the body unit includes a conductive slip ring, a coupling, a polishing disc motor and a motor holder, the polishing disc motor is fixed on the motor holder, the polishing disc motor is connected to the shaft of the polishing disc through a coupling, and the conductive slip ring is fixed on the polishing disc assembly to connect the power supply to the conductive slider.

[0015] Furthermore, the conductive base specifically includes a conductive adhesive disk, an adapter flange, a support shaft joint, a conductive slip ring, a support shaft and a support shaft seat. The support shaft is installed on the support shaft seat. The conductive adhesive disk cooperates with the adapter flange through the hole thereon. The adapter flange is threadedly engaged with the support shaft joint to ensure that it can be disassembled when needs change. The chip is fixed to the conductive adhesive disk by bonding.

[0016] Furthermore, the moving component includes a body unit moving mechanism, which includes a first standard cylinder, a second standard cylinder, a cross slide and a linkage frame, and a cylinder slide is arranged on the linkage frame, and the first standard cylinder and the second standard cylinder are respectively connected to the lateral sliding end and the vertical sliding end of the cross slide, the lateral sliding end of the cross slide can move on the cylinder slide, and the vertical sliding end can move along the lateral sliding end, and the front side of the cross slide is connected to the motor holder.

[0017] Furthermore, a 3D surface optical profiler is included. During the processing, the surface processing quality of the semiconductor substrate workpiece is detected by the 3D surface optical profiler.

[0018] Furthermore, the moving assembly includes a detector slide plate laterally arranged on the inner side wall of the frame, and the end of the 3D surface optical profiler can slide on the detector slide plate, and the end of the 3D surface optical profiler can be connected to a third standard cylinder.

[0019] Furthermore, it also includes a polishing liquid collection pool, which is movably installed on the frame and is used to collect waste liquid during the polishing process. The bottom of the polishing liquid collection pool is connected to the collection pool base through a collection pool support column. The collection pool base can slide on the water tank slide. The bottom of the polishing liquid collection pool is provided with a collection pool outlet.

[0020] Furthermore, the moving component includes a support shaft slide plate arranged at the bottom of the frame, the support shaft slide plate is provided with a slide rail, the bottom of the support shaft seat is connected to the slide plate base, and through the cooperation of the slide rail and the slide plate base, the workpiece to be processed is moved to the bottom of the 3D surface optical profiler.

[0021] The present invention also discloses a polishing method for a semiconductor substrate by photoelectrochemical mechanical polishing based on the uniform arrangement of the electric field and the coordination of the light field of the above device, which comprises the following steps:

[0022] S1. Configuration of electrochemical polishing liquid: SiO2 suspension (mass concentration of 5wt%) with a particle size of 20-30nm + K2SO4 (0.1mol / L) aqueous solution is selected. The suspension at this mass concentration can ensure light transmittance while ensuring processing quality;

[0023] S2. Wafer cleaning: First, the wafer is completely immersed in anhydrous ethanol for ultrasonic cleaning for 10 minutes, and then repeatedly cleaned with deionized water for 3 minutes, then immersed in a concentrated HF solution for 10 minutes, and then cleaned with deionized water for 3 minutes, and finally blown dry with nitrogen;

[0024] S3, using a conductive adhesive, bonding the wafer to the conductive bonding pad to ensure that it is fully fastened;

[0025] S4. Fix the conductive adhesive plate and the adapter flange plate on the spindle joint to ensure that they are fully tightened;

[0026] S5. Use the catheter of the peristaltic pump to first drop a certain amount of polishing liquid on the surface of the wafer to form a liquid film that completely covers the wafer;

[0027] S6, moving the polishing plate and adjusting it so that the polishing pad on its processing surface just contacts the surface of the wafer, and the liquid film is in full contact with the polishing pad. At this time, the wafer as the anode and the polishing plate as the cathode form a closed loop;

[0028] S7, turning on the LED ultraviolet light source so that the light source can directly irradiate the surface of the wafer, and the voltage applied by the electrochemical workstation is applied to the wafer through the conductive block directly in contact with the wafer, so as to separate the electron-hole pairs generated by the ultraviolet light irradiating the wafer surface, so that a modified soft layer is generated on the wafer surface;

[0029] S8, turn on the polishing disc motor to drive the polishing disc to start rotating, the speed can be controlled between 60rpm-120rpm; 100rpm;

[0030] S9, the polishing liquid is steadily dripped into the annular groove in the center of the polishing disc at a flow rate of 150 ml / min, and as the polishing disc rotates, the polishing liquid is continuously dripped onto the surface of the workpiece through the through holes between the holes. At this time, the surface oxidation-mechanical removal reciprocating cycle is carried out to achieve high-quality and efficient polishing of the wafer surface;

[0031] S10, soaking the wafer on the conductive adhesive pad in a toluene solution to separate the wafer from the conductive adhesive pad;

[0032] S11, using acetone, alcohol, 2wt% hydrofluoric acid, and deionized water to clean the surface of the chip in sequence, and then blowing the chip dry with nitrogen.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1. The LED light source can be directly irradiated on the surface of the workpiece, which effectively shortens the distance between the light source and the polishing liquid, improves the effect of the light field, and adjusts the light field intensity in different directions along the radius. It works together with the electric field applied to the workpiece to ensure uniform oxidation of the workpiece surface and the flatness of the workpiece after processing.

[0035] 2. A conductive block that meets the working conditions is used in the conductive base to achieve controllable electric field acting on the workpiece. The interaction with the light field makes the oxidation of the workpiece uniform, and the flatness of the workpiece after processing is guaranteed.

[0036] 3. A groove is designed in the center of the polishing disk to prevent splashing of polishing liquid during processing, and holes are designed between the through holes of the polishing disk so that the added polishing liquid can be evenly distributed on the surface of the workpiece to ensure the electrical circuit path during processing.

[0037] 4. A movable base is designed for the workpiece to be processed. The workpiece can be withdrawn after a period of processing, and its surface can be cleaned and dried. The surface processing quality can be tested and fed back to the photoelectric coupling process in the polishing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0039] Figure 1 It is a schematic structural diagram of a device for photoelectrochemical mechanical polishing of a semiconductor substrate for the present invention with uniform arrangement of electric field and coordination of optical field;

[0040] Figure 2 is a schematic diagram of the polishing disc assembly structure;

[0041] Figure 3 Schematic diagram of the polishing disc structure (top view, cross-sectional view);

[0042] Figure 4 It is a schematic diagram of the body unit structure;

[0043] Figure 5 is a schematic diagram of the conductive base structure;

[0044] Figure 6 It is a schematic diagram of the structure of the polishing liquid collection pool;

[0045] Figure 7 Schematic diagram of the structure of conductive adhesive pads with different shapes.

[0046] In the figure: 1-body unit; 2-polishing disc assembly; 3-conductive base; 4-electrochemical workstation; 5-lateral slide; 6-LED light source power supply; 7-3D surface optical profiler; 8-polishing liquid collection tank; 9-polishing disc motor; 10-motor holder; 11-coupling; 12-conductive slip ring; 13-hexagonal nut; 14-conductive column; 15-LED ultraviolet light source; 16-polishing disc; 17-cross slide; 18-linkage mechanism frame; 19-cylinder Slide plate; 20-first standard cylinder; 21-second standard cylinder; 22-detector slide plate; 23-third standard cylinder; 24-water tank slide plate; 25-wafer; 26-conductive adhesive disk; 27-adapter flange; 28-support shaft joint; 29-conductive slip ring; 30-support shaft; 31-support shaft seat; 32-slide rail; 33-slide plate base; 34-support shaft slide plate; 35-collection pool support; 36-collection pool base; 37-collection pool drain outlet. DETAILED DESCRIPTION

[0047] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0050] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0051] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0052] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0053] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0054] like Figures 1 to 7As shown, an embodiment of the present invention discloses a device for photoelectrochemical mechanical polishing of a semiconductor substrate for uniform electric field arrangement and coordinated light field, comprising: a frame, a body unit 1, a polishing disc assembly 2, a conductive base 3, an LED ultraviolet light source 15, an electrochemical workstation 4 and a moving component, wherein the body unit 1 is used for loading and unloading the polishing disc assembly 2, the body unit 1, the electrochemical workstation 4, the LED light source power supply 6 and the moving component are all installed on the frame, the electrochemical workstation 4 and the LED light source power supply 6 are respectively used to provide power to the conductive base 3 and the LED ultraviolet light source 15 during the processing, the LED ultraviolet light source 15 is fixed on the polishing disc 16, and acts on the semiconductor substrate workpiece (wafer) 25 being processed during the polishing process of the polishing disc 16, the semiconductor substrate workpiece is fixed on the conductive base 3 by bonding, and the position of the body unit 1 and the workpiece to be processed is adjusted by the moving component.

[0055] The polishing disc assembly 2 includes a polishing disc 16, a polishing pad, the LED ultraviolet light source 15, a water cooling disc, a conductive column 14 and a hexagonal nut 13. The polishing disc is provided with an annular groove B with a preset radius near the center. The added polishing liquid is dripped on the semiconductor substrate workpiece based on the annular groove B, so that the processed substrate workpiece as the anode is connected to the polishing disc 16 as the cathode to form an electrical circuit. Under the action of the LED ultraviolet light source 15, the photoelectrochemical mechanical processing of the substrate workpiece is realized. A plurality of holes arranged radially are provided on the disc surface to realize the light transmission effect, so that the LED ultraviolet light source 15 can directly irradiate the processed semiconductor substrate, and through holes are distributed between the holes along the radial direction, so that the polishing liquid dripped in the groove can drip on the processed semiconductor substrate through the through holes along the radial direction, realizing the electrical path between the cathode and cathode. The polishing pad is fixed to the working surface of the polishing disc 16 by bonding, and the semiconductor substrate is processed by it. The LED ultraviolet light source 15 and the water cooling disc are an integrated structure, and the water cooling disc is used to solve the problem of overheating of the LED ultraviolet light source 15 during the processing. The distribution of the LED ultraviolet light source 15 is consistent with the distribution of the holes on the polishing disk 16. The three vertical conductive columns 14 on the water cooling disk are connected to the hexagonal nut 13 in the middle. There is a wired path between the hexagonal nut 13 and the conductive slip ring 12 to ensure the electrical path between the conductive column 14, provide a stable power supply for the LED lamp during the processing, and indirectly control the power on the conductive column 14 by controlling the LED light source power supply, so as to realize the control of the light intensity along the radial direction. The hexagonal nut 13 is fixed together with the polishing disk 16 by bolts to ensure the coaxial rotation with the polishing disk. In the figure, the circular groove is located at B above the polishing disk 16. The polishing liquid drips from here during the processing. During the rotation of the polishing disk, it drips on the workpiece through the through holes. The polishing liquid drips at b.

[0056] The above-mentioned radially distributed through holes can also be in the shape of leaf flocs, spirals, etc., and their distribution shape is determined according to specific working conditions.

[0057] The body unit includes a conductive slip ring 12, a coupling 11, a polishing disc motor 9 and a motor holder 10. The polishing disc motor 9 is fixed on the motor holder 10. The shafts of the polishing disc motor 9 and the polishing disc 12 are connected via the coupling 11. The conductive slip ring 12 is fixed on the polishing disc assembly 2 and is used to connect the power supply to the conductive electrode.

[0058] The conductive base 3 specifically includes a conductive adhesive disk 26, an adapter flange 27, a support shaft joint 28, a conductive slip ring 29, a support shaft 30 and a support shaft seat 31. The support shaft 30 is installed on the support shaft seat 31. The conductive adhesive disk 26 cooperates with the adapter flange 27 through the hole thereon. The adapter flange 27 is threadedly engaged with the support shaft joint 28 to ensure that it can be disassembled when the demand changes. The conductive slip ring is used for power supply. The chip 25 is fixed on the conductive adhesive disk 26 by bonding.

[0059] The bottom of the conductive adhesive plate 26 is provided with conductive blocks. The distribution and shape of the conductive blocks are adjusted according to the actual situation and can be the same or different. The conductive blocks provide a uniformly distributed power supply to the bottom of the conductive adhesive plate 26, so that the surface of the conductive adhesive plate is subjected to a uniform electric field. Figure 7 As shown, the conductive blocks on the back of the conductive bonding pad 26 are designed as a hexagonal distribution structure here, and the structure is not unique, and different shapes can be set according to the required working conditions to meet the processing conditions. Figure 7 As shown, the hole array pattern on the polishing disk 16 is not unique. The distribution in Figure B is radial, and the through holes between the holes can be clearly observed from the planed surface on the right. The distribution in Figure C is spiral, and the arrangement is determined according to the specific working conditions.

[0060] The adapter flange 27 is fixed to the conductive adhesive plate 26 by bolts, and a sealing ring is fixed between the two to ensure that the liquid in the polishing process will not affect the conductive effect. The adapter flange 27 is fixed to the support shaft joint 28 and is set as a detachable mechanism to ensure the convenience of bonding and separating the wafer 25. The conductive slip ring 29 is fixed on the support shaft 30 and connected to the power supply of the electrochemical workstation 4 to provide power for workpiece processing.

[0061] The mobile assembly includes a body unit mobile mechanism, which includes a first standard cylinder 20, a second standard cylinder 21, a cross slide 17 and a linkage frame 18. The linkage frame 18 is provided with a cylinder slide 19. The first standard cylinder 20 and the second standard cylinder 21 are respectively connected to the lateral sliding end and the vertical sliding end of the cross slide 17. The lateral sliding end of the cross slide 17 can move on the cylinder slide, and the vertical sliding end can move along the lateral sliding end. The front of the cross slide is connected to the motor holder. The motor holder 10 is connected to the cross slide 17 in a sliding manner, and its longitudinal (vertical) movement is guaranteed when the second standard cylinder 21 is loaded, and the loading and unloading of the workpiece are realized at the same time. The cross slide 17 is fixed together with the linkage frame 18 connected to the first standard cylinder 20 by bolts, ensuring that the first standard cylinder 20 provides power for the lateral movement of the polishing disc assembly as a whole. In this embodiment, the first standard cylinder 20 is fixed to the side of the body by bolts.

[0062] It also includes a 3D surface optical profiler 7. During the processing, the 3D surface optical profiler 7 is used to detect the surface processing quality of the semiconductor substrate workpiece.

[0063] The moving assembly includes a detector slide 22 disposed transversely on the inner side wall of the frame, and the end of the 3D surface optical profiler 7 can slide on the detector slide 22, and the end of the 3D surface optical profiler 7 can be connected to a third standard cylinder 23. During the processing, the conductive base can be moved to the bottom of the lens to scan the surface morphology of the workpiece, intermittently monitor the processing quality, and feedback the interaction between the electric field and the optical field to achieve better processing of the workpiece.

[0064] It also includes a polishing liquid collection pool 8, which is movably mounted on the frame and is used to collect waste liquid during the polishing process. The bottom of the polishing liquid collection pool 8 is connected to the collection pool base 36 through the collection pool support column 35. The collection pool base 36 can slide on the water storage tank slide 24. The bottom of the polishing liquid collection pool 8 is provided with a collection pool outlet 37. Waste liquid during the polishing process is collected in the polishing liquid collection pool 8 and directly flows out from the collection pool outlet 37 at the bottom of the pool. The waste liquid is recycled to avoid polluting the environment. The conductive base can be moved laterally during the processing to perform intermittent surface processing morphology detection on the workpiece by cooperating with the mobile component and the water storage tank slide 24.

[0065] The moving component includes a support shaft slide 34 arranged at the bottom of the frame, and a slide rail 32 is arranged on the support shaft slide 34. The bottom of the support shaft seat 31 is connected to the slide base 33. Through the cooperation of the slide rail 32 and the slide base 33, the workpiece to be processed is moved to the bottom of the 3D surface optical profiler.

[0066] The present invention also discloses a polishing method for a semiconductor substrate by photoelectrochemical mechanical polishing based on the uniform arrangement of the electric field and the coordination of the light field of the above device, which comprises the following steps:

[0067] S1. Configuration of electrochemical polishing liquid: SiO2 suspension (mass concentration of 5wt%) with a particle size of 20-30nm + K2SO4 (0.1mol / L) aqueous solution is selected. The suspension at this mass concentration can ensure light transmittance while ensuring processing quality;

[0068] S2. Wafer cleaning: First, the wafer is completely immersed in anhydrous ethanol for ultrasonic cleaning for 10 minutes, and then repeatedly cleaned with deionized water for 3 minutes, then immersed in a concentrated HF solution for 10 minutes, and then cleaned with deionized water for 3 minutes, and finally blown dry with nitrogen;

[0069] S3, using a conductive adhesive, bonding the wafer to the conductive bonding pad to ensure that it is fully fastened;

[0070] S4. Fix the conductive adhesive plate and the adapter flange plate on the spindle joint to ensure that they are fully tightened;

[0071] S5. Use the catheter of the peristaltic pump to first drop a certain amount of polishing liquid on the surface of the wafer to form a liquid film that completely covers the wafer;

[0072] S6, moving the polishing plate and adjusting it so that the polishing pad on its processing surface just contacts the surface of the wafer, and the liquid film is in full contact with the polishing pad. At this time, the wafer as the anode and the polishing plate as the cathode form a closed loop;

[0073] S7, turning on the LED ultraviolet light source so that the light source can directly irradiate the surface of the wafer, and the voltage applied by the electrochemical workstation is applied to the wafer through the conductive block directly in contact with the wafer, so as to separate the electron-hole pairs generated by the ultraviolet light irradiating the wafer surface, so that a modified soft layer is generated on the wafer surface;

[0074] S8, turn on the polishing disc motor to drive the polishing disc to start rotating at a speed of 100 rpm;

[0075] S9, dripping polishing liquid with a flow rate of 150ml / min into the annular groove in the center of the polishing disk, and as the polishing disk rotates, the polishing liquid is continuously dripped onto the surface of the workpiece through the through holes between the holes, at this time, the surface oxidation-mechanical removal reciprocating cycle is carried out to achieve high-quality and efficient polishing of the wafer surface;

[0076] S10, soaking the wafer on the conductive adhesive pad in a toluene solution to separate the wafer from the conductive adhesive pad;

[0077] S11, using acetone, alcohol, 2wt% hydrofluoric acid, and deionized water to clean the surface of the chip in sequence, and then blowing the chip dry with nitrogen.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field, characterized in that: include: A frame, a body unit, a polishing disc assembly, a conductive base, an LED ultraviolet light source, an electrochemical workstation and a moving assembly. The body unit is used for loading and unloading the polishing disc assembly. The body unit, the electrochemical workstation, the LED light source power supply and the moving assembly are all installed on the frame. The electrochemical workstation and the LED light source power supply are respectively used to provide power to the conductive base and the LED ultraviolet light source during the processing. The LED ultraviolet light source is fixed on the polishing disc and acts on the semiconductor substrate workpiece being processed during the polishing process of the polishing disc. The semiconductor substrate workpiece is fixed on the conductive base by bonding, and the position of the body unit and the workpiece to be processed is adjusted by the moving assembly.

2. The device for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field according to claim 1, characterized in that: The polishing disc assembly includes a polishing disc, a polishing pad, the LED ultraviolet light source, a water cooling disc, a conductive column and a hexagonal nut. The polishing disc is provided with an annular groove with a preset radius near the center position. The added polishing liquid is dripped onto the semiconductor substrate workpiece based on the annular groove. A plurality of holes arranged radially are provided on the disc surface, so that the LED ultraviolet light source can directly irradiate the processed semiconductor substrate, and through holes are distributed between the holes along the radial direction, so that the polishing liquid dripped into the groove can drip onto the processed semiconductor substrate through the through holes along the radial direction, so as to realize the electrical path between the cathode and anode. The polishing pad is fixed to the working surface of the polishing disc by bonding. The LED ultraviolet light source and the water cooling disc are an integrated structure. The water cooling disc is used to solve the problem of overheating of light during the processing, wherein the distribution mode of the LED ultraviolet light source is consistent with the distribution mode of the holes on the polishing disc. The three conductive columns on the water cooling disc are connected to the middle hexagonal nut, which provides a stable power supply for the LED lamp during the processing and controls the intensity of the light along the radial direction. The hexagonal nut is fixed to the polishing disc by bolts to ensure coaxial rotation with the polishing disc.

3. The device for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field according to claim 1, characterized in that: The body unit includes a conductive slip ring, a coupling, a polishing disc motor and a motor holder. The polishing disc motor is fixed on the motor holder. The polishing disc motor is connected to the shaft of the polishing disc through a coupling. The conductive slip ring is fixed on the polishing disc assembly and is used to connect the power supply to the conductive electrode.

4. The device for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field according to claim 1, characterized in that: The conductive base specifically includes a conductive adhesive disk, an adapter flange, a support shaft joint, a conductive slip ring, a support shaft and a support shaft seat. The support shaft is installed on the support shaft seat. The conductive adhesive disk cooperates with the adapter flange through a hole thereon. The adapter flange is threadedly engaged with the support shaft joint. The chip is fixed on the conductive adhesive disk by bonding.

5. The device for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field according to claim 1, characterized in that: The moving assembly includes a body unit moving mechanism, which includes a first standard cylinder, a second standard cylinder, a cross slide and a linkage frame. A cylinder slide is provided on the linkage frame. The first standard cylinder and the second standard cylinder are respectively connected to the lateral sliding end and the vertical sliding end of the cross slide. The lateral sliding end of the cross slide can move on the cylinder slide, and the vertical sliding end can move along the lateral sliding end. The front side of the cross slide is connected to the motor holder.

6. The device for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field according to claim 1, characterized in that: It also includes a 3D surface optical profiler. During the processing, the surface processing quality of the semiconductor substrate workpiece is detected by the 3D surface optical profiler.

7. The device for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field according to claim 1, characterized in that: The moving assembly comprises a detector slide plate arranged transversely on the inner side wall of the frame, the end of the 3D surface optical profiler can slide on the detector slide plate, and the end of the 3D surface optical profiler can be connected to a third standard cylinder.

8. The device for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field according to claim 1, characterized in that: It also includes a polishing liquid collection pool, which is movably mounted on a frame and is used to collect waste liquid during the polishing process. The bottom of the polishing liquid collection pool is connected to a collection pool base via a collection pool support column. The collection pool base can slide on a water tank slide. A collection pool water outlet is provided at the bottom of the polishing liquid collection pool.

9. The device for photoelectrochemical mechanical polishing of a semiconductor substrate with uniform electric field arrangement and coordinated light field according to claim 1, characterized in that: The moving component includes a support shaft slide plate arranged at the bottom of the frame, the support shaft slide plate is provided with a slide rail, the bottom of the support shaft seat is connected to the slide plate base, and the workpiece to be processed is moved to the bottom of the 3D surface optical profiler through the cooperation of the slide rail and the slide plate base.

10. A method for polishing a semiconductor substrate by photoelectrochemical mechanical polishing based on the uniform arrangement of the electric field and the coordination of the optical field of the device according to any one of claims 1 to 9, characterized in that: The steps include: S1. Configuration of electrochemical polishing solution: SiO2 suspension with a particle size of 20-30nm + K2SO4 aqueous solution; S2. Wafer cleaning: First, the wafer is completely immersed in anhydrous ethanol for ultrasonic cleaning, and repeatedly cleaned with deionized water, then immersed in a concentrated HF solution, and then cleaned with deionized water, and finally blown dry with nitrogen; S3, using a conductive adhesive, bonding the wafer to the conductive bonding pad to ensure that it is fully fastened; S4. Fix the conductive adhesive plate and the adapter flange plate on the spindle joint to ensure that they are fully tightened; S5. Use the catheter of the peristaltic pump to first drop a certain amount of polishing liquid on the surface of the wafer to form a liquid film that completely covers the wafer; S6, moving the polishing plate and adjusting it so that the polishing pad on its processing surface just contacts the surface of the wafer, and the liquid film is in full contact with the polishing pad. At this time, the wafer as the anode and the polishing plate as the cathode form a closed loop; S7, turning on the LED ultraviolet light source so that the light source can directly irradiate the surface of the wafer, and the voltage applied by the electrochemical workstation is applied to the wafer through the conductive block directly in contact with the wafer, so as to separate the electron-hole pairs generated by the ultraviolet light irradiating the wafer surface, so that a modified soft layer is generated on the wafer surface; S8, turning on the polishing disc motor to drive the polishing disc to start rotating; S9. During the processing, a certain amount of polishing liquid is dripped into the circular groove in the center of the polishing disc, and as the polishing disc rotates, the polishing liquid is continuously dripped onto the surface of the workpiece through the through holes between the holes. At this time, the surface oxidation-mechanical removal reciprocating cycle is carried out to achieve high-quality and efficient polishing of the wafer surface; S10, soaking the wafer on the conductive adhesive pad in a toluene solution to separate the wafer from the conductive adhesive pad; S11, using acetone, alcohol, 2 wt% hydrofluoric acid, and deionized water to clean the surface of the chip in sequence, and then blowing the chip dry with nitrogen.

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