An apparatus and method for photoelectrochemical mechanical polishing of semiconductor substrates with uniform electric field distribution and light field coordination

Abstract

The application relates to a device and method for photoelectrochemical mechanical polishing of semiconductor substrates, which are characterized by uniform electric field distribution and mutual coordination with light field, and the device comprises a frame, 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 provide power for the conductive base and the LED ultraviolet light source during the machining process; the LED ultraviolet light source is fixed on the polishing disc and acts on the semiconductor substrate workpiece in the machining process together with the polishing disc during polishing of the workpiece; and the semiconductor substrate workpiece is bonded on the conductive base. The LED light source directly irradiates on the machining workpiece surface, effectively shortens the distance between the light source and the polishing liquid, improves the action of the light field, adjusts the light field intensity in different directions along the radius, and guarantees the oxidation uniformity of the workpiece surface together with the electric field applied on the workpiece, so that the flatness of the machined workpiece is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor polishing, in particular, especially relates to a device and method for photoelectrochemical mechanical polishing of semiconductor substrates with uniform electric field distribution and coordinated light field. BACKGROUND

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

[0003] The third generation semiconductor material is particularly suitable for manufacturing high-voltage and high-frequency power devices due to its excellent electrical and chemical properties, such as wide energy bandgap, 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 performance. It has been proven that by reducing surface roughness, the breakdown electric field strength and breakdown charge can be increased, thereby increasing the transconductance of MOS transistors. Therefore, it is crucial to achieve a surface without damage and with atomic-level smoothness.

[0004] Chemical mechanical polishing (CMP) is currently a common method for achieving ultra-precision processing of third-generation semiconductor substrate materials. This process generates a modified soft oxide layer on the surface through chemical action, and then uses mechanical removal to achieve efficient processing of the surface. Due to the strong chemical inertness and high hardness of third-generation semiconductor materials, it is difficult to react with acid or base solution at room temperature, making it difficult to simultaneously improve the overall surface flatness and achieve high material removal rate. Therefore, achieving high-quality and efficient processing of third-generation semiconductor substrate materials remains a challenge.

[0005] So far, only patent application publication numbers CN116038440A, CN115415857A, CN106141900A, CN109465739A, etc. disclose devices and schemes for combining chemical and mechanical effects with photoelectric coupling to realize photoelectrochemical mechanical polishing. However, the above-mentioned scheme devices do not monitor the uniformity of the anode wafer oxidation and the photoelectric field coupling effect, which makes the surface quality and material removal rate at different positions on the wafer surface not be monitored intermittently, resulting in the incompleteness of the processing process.

[0006] Specifically, patent application publication number CN116038440A discloses "a photoelectric combined chemical mechanical polishing equipment and method thereof", which involves two accommodation grooves, one of which contains a light-emitting lamp, and the other of which contains a conductive body electrically connected to a power supply. The efficiency is improved by photoelectricity. The light source applied to the upper surface of the wafer is embedded in the accommodation groove. In the actual processing process, such design will be affected by the pressure applied to the workpiece and the vibration generated during processing, etc., which will cause the light applied to the wafer surface to be attenuated to some extent, thereby affecting the processing of the wafer. Specifically, patent application publication number CN115415857A discloses "a photoelectrochemical mechanical polishing device and a material efficient removal adjustment method", which involves using an electrochemical workstation to measure the voltage applied and the current during wafer polishing. The wafer oxidation rate is achieved by adjusting the electric field voltage, and the mechanical removal effect is used 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 make the electric field distribution applied to the wafer uneven, thereby causing uneven oxidation of the wafer surface, resulting in poor flatness of the processed wafer, and affecting the subsequent application as a device.

[0007] Patent application publication number CN106141900A discloses the use of photoelectrochemical method to corrode the surface of GaN wafer, and the mechanical method to remove the corrosion layer. Only the type of light and the device for providing light source are specified. In the actual processing process, the distance between the light and the workpiece is too far, or the non-uniformity of the light on the wafer surface will make the oxidation of the surface at different positions different, which will affect the flatness of the processed surface, especially for larger size wafers.

[0008] Patent application publication number CN109465739A discloses "a semiconductor wafer photoelectrochemical mechanical polishing processing device", which uses a polishing disc with through holes and a polishing pad matched therewith to make liquid droplets drip on the wafer surface through the well-distributed through holes for photoelectrochemical mechanical polishing. In this process, the device for dripping polishing liquid cannot be fixed and is limited by the dripping device, and cannot drip at multiple holes at the same time.

[0009] In addition, the existing photoelectrochemical mechanical polishing device cannot detect the morphology processed by the polishing workpiece in different time periods to feedback the cooperation between the photoelectricity in the processing process, thereby affecting the surface quality after processing and increasing the complexity of the process. SUMMARY

[0010] According to the technical problems described above, a device and method for photoelectrochemical mechanical polishing of semiconductor substrates are provided, which are coordinated with the uniform arrangement of the electric field and the light field.

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

[0012] A device for photoelectrochemical mechanical polishing of semiconductor substrates, which is coordinated with the uniform arrangement of the electric field and the light field, comprises a rack, 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 rack. 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 processing. The LED ultraviolet light source is fixed on the polishing disc and acts together on the semiconductor substrate workpiece being processed during polishing of the workpiece by the polishing disc. The semiconductor substrate workpiece is fixed on the conductive base by bonding. The position adjustment of the body unit and the workpiece to be processed is realized by the moving assembly.

[0013] Further, the polishing disc assembly comprises a polishing disc, a polishing pad, the LED ultraviolet light source, a water-cooled disc, a conductive column and a hexagonal nut. The polishing disc is provided with an annular groove of a predetermined radius near the center position. The polishing liquid added is dripped on the semiconductor substrate workpiece based on the annular groove. A plurality of holes arranged in a radial direction are provided on the disc surface, so that the LED ultraviolet light source can directly irradiate on the processed semiconductor substrate. The through holes are distributed between the holes in the radial direction, so that the polishing liquid dripped in the groove can drop on the processed semiconductor substrate through the through holes in the radial direction to realize the electrical path between the anode and the cathode. The polishing pad is fixed on the working surface of the polishing disc by bonding. The LED ultraviolet light source and the water-cooled disc are an integral structure. The water-cooled disc is used to solve the problem of overheating of light emission during processing. The distribution mode of the LED ultraviolet light source is consistent with the distribution of the holes on the polishing disc. The three conductive columns on the water-cooled disc are connected with the hexagonal nut in the middle. A stable power supply is provided for the LED lamp during processing, and the intensity of the light irradiation in the radial direction is controlled. The hexagonal nut and the polishing disc are fixed together by bolts to ensure coaxial rotation with the polishing disc.

[0014] Further, the machine body unit comprises a conductive slip ring, a shaft 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 with the shaft of the polishing disc through the shaft coupling, and the conductive slip ring is fixed on the polishing disc assembly and used for connecting the power supply with the conductive sliding block.

[0015] Further, the conductive base comprises a conductive adhesive disc, 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 disc is matched with the adapter flange through the hole thereof, the adapter flange is matched on the support shaft joint through threads, the detachability is ensured when the demand changes, and the wafer is fixed on the conductive adhesive disc through the adhesive mode.

[0016] Further, the moving assembly comprises a machine body unit moving mechanism, the machine body unit moving mechanism comprises a first standard air cylinder, a second standard air cylinder, a cross slide and a linkage mechanism frame, a cylinder sliding plate is arranged on the linkage mechanism frame, the first standard air cylinder and the second standard air cylinder are connected with the horizontal sliding end and the vertical sliding end of the cross slide respectively, the horizontal sliding end of the cross slide can move on the cylinder sliding plate, the vertical sliding end can move along the horizontal sliding end, and the front surface of the cross slide is connected with the motor holder.

[0017] Further, the 3D surface optical profiler is further arranged, and the surface machining quality of the semiconductor substrate workpiece is detected by the 3D surface optical profiler during the machining process.

[0018] Further, the moving assembly comprises a detector sliding plate arranged on the inner side wall of the rack in the transverse direction, the tail end of the 3D surface optical profiler can slide on the detector sliding plate, and the tail end of the 3D surface optical profiler can be connected with a third standard air cylinder.

[0019] Further, the polishing liquid collecting pool is further arranged, the polishing liquid collecting pool is movably installed on the rack and used for collecting waste liquid in the polishing process, the bottom of the polishing liquid collecting pool is connected with a collecting pool support column and a collecting pool base, the collecting pool base can slide on a water storage groove sliding plate, and the bottom of the polishing liquid collecting pool is provided with a collecting pool water outlet.

[0020] Further, the moving assembly comprises a support shaft sliding plate arranged at the bottom of the rack, the support shaft sliding plate is provided with a sliding rail, the bottom of the support shaft seat is connected with a sliding plate base, and through the cooperation of the sliding rail and the sliding plate base, the workpiece to be machined can be moved to the lower side of the 3D surface optical profiler.

[0021] The application further discloses a polishing method for photoelectrochemical mechanical polishing of a semiconductor substrate based on the uniform arrangement of the electric field and the mutual coordination of the optical field of the device, and the polishing method comprises the following steps.

[0022] S1, configuration of electrochemical polishing solution: SiO2 suspension (mass concentration of 5wt%) with particle size of 20-30nm + K2SO4 (0.1mol / L) aqueous solution is selected, the suspension with the mass concentration can ensure the processing quality and also ensure the light transmittance;

[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 concentrated HF solution for 10 minutes, and then cleaned with deionized water for 3 minutes, and finally dried with nitrogen;

[0024] S3, using conductive adhesive, the wafer is adhered to the conductive bonding disc to ensure complete fastening;

[0025] S4, the conductive bonding disc and the adapter flange are fixed on the main shaft joint to ensure complete fastening;

[0026] S5, using the catheter of the peristaltic pump, a certain amount of polishing solution is first added on the surface of the wafer to form a liquid film completely covering the wafer;

[0027] S6, the position of the polishing disc is moved and adjusted so that the polishing pad on the processing surface is in contact with the surface of the wafer, the above-mentioned liquid film is in complete contact with the polishing pad, and the wafer as the anode and the polishing disc as the cathode form a closed loop;

[0028] S7, the LED ultraviolet light source is turned on so that the light source can directly irradiate the surface of the wafer, the voltage applied by the electrochemical workstation is applied to the wafer through the conductive block directly contacting the wafer, and the electron-hole pairs generated by the ultraviolet irradiation of the wafer surface are separated, so that a modified soft layer is generated on the surface of the wafer;

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

[0030] S9, the polishing solution is steadily added in the annular groove at the center of the polishing disc at a flow rate of 150ml / min, and with the rotation of the polishing disc, the polishing solution is continuously added on the workpiece surface through the through holes between the holes, at this time, the surface oxidation-mechanical removal is reciprocatingly carried out, and high-quality and efficient polishing of the wafer surface is realized;

[0031] S10, the wafer on the conductive bonding disc is soaked in toluene solution to separate it from the conductive bonding disc;

[0032] S11, the wafer surface is cleaned with acetone, alcohol and 2wt% hydrofluoric acid, deionized water in turn, and then the wafer is dried with nitrogen.

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

[0034] 1. The LED light source can directly irradiate on the surface of the workpiece, effectively shortening the distance between the light source and the polishing liquid, improving the action of the light field, and adjusting the light field intensity in different directions along the radius, which together with the electric field applied to the workpiece ensures the uniform oxidation of the workpiece surface, and the flatness of the processed workpiece is guaranteed.

[0035] 2. The conductive block in the conductive base is used to realize the controllable electric field acting on the workpiece, which interacts with the light field to make the oxidation of the workpiece uniform, and the flatness of the processed workpiece is guaranteed.

[0036] 3. The groove is designed in the center of the polishing disc to prevent the splashing of the polishing liquid during processing, and the hole is designed between the through holes of the polishing disc, so that the added polishing liquid can be uniformly distributed on the surface of the workpiece, and the electric circuit path during processing is ensured.

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

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0039] Figure 1 The structure schematic diagram of the photoelectrochemical mechanical polishing semiconductor substrate device of the present application is for the uniform arrangement of electric field and the mutual coordination of light field.

[0040] Figure 2 The structure schematic diagram of the polishing disc assembly is shown.

[0041] Figure 3 The structure schematic diagram of the polishing disc is shown (top view, sectional view).

[0042] Figure 4 The structure schematic diagram of the machine body unit is shown.

[0043] Figure 5 The structure schematic diagram of the conductive base is shown.

[0044] Figure 6 The structure schematic diagram of the polishing liquid collecting pool is shown.

[0045] Figure 7 The structure schematic diagram of the conductive adhesive disc with different shapes is shown.

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

[0047] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0048] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0049] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of a feature, step, operation, device, component and / or combination thereof.

[0050] The foregoing is considered as illustrative only of the principles of the application. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and practice described. Accordingly, all suitable modifications and equivalents can be resorted to falling within the scope of the application. Unless otherwise indicated herein, the contents of all patents, patent applications, publications, and test methods cited herein are hereby incorporated by reference in their entirety for all purposes.

[0051] In the description of the present application, it is to be understood that the orientation or positional relationships indicated by terms such as "front", "back", "up", "down", "left", "right", "lateral", "vertical", "horizontal", "top", "bottom", and the like are generally based on the orientation or positional relationships shown in the drawings, and are merely intended to facilitate the description and simplify the description, and do not indicate or imply that the device or element must have a particular orientation or be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the scope of protection of the present application. The orientation terms "inner", "outer" refer to the inner and outer relative to the contour of the components themselves.

[0052] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper", and the like can be used herein to describe the spatial positional relationship of one device or feature with respect to other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device as described in the drawings. For example, if the device in the drawings is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0053] In addition, it should be noted that the use of the terms "first", "second", and the like, to describe various components, do not necessarily indicate any special significance, and are merely used to distinguish the corresponding components, and therefore cannot be construed as limiting the scope of protection of the present application.

[0054] As Figures 1-7As shown, the embodiment of the present application discloses a device for photoelectrochemical mechanical polishing semiconductor substrate, which is coordinated with uniform electric field and light field, comprising: a rack, a machine body unit 1, a polishing disc assembly 2, a conductive pedestal 3, an LED ultraviolet light source 15, an electrochemical workstation 4 and a moving assembly, the machine body unit 1 is used for loading and unloading the polishing disc assembly 2, the machine body unit 1, the electrochemical workstation 4, the LED light source power supply 6 and the moving assembly are all installed on the rack, the electrochemical workstation 4 and the LED light source power supply 6 are respectively used for providing power supply for the conductive pedestal 3 and the LED ultraviolet light source 15 during processing, the LED ultraviolet light source 15 is fixed on the polishing disc 16, and acts on the semiconductor substrate workpiece (wafer) 25 in the processing together during polishing of the workpiece by the polishing disc 16, the semiconductor substrate workpiece is fixed on the conductive pedestal 3 by means of bonding, and the position adjustment of the machine body unit 1 and the workpiece to be processed is realized by the moving assembly.

[0055] The polishing disc assembly 2 comprises a polishing disc 16, a polishing pad, the LED ultraviolet light source 15, a water-cooled 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 a central position, polishing liquid added is dropped on the semiconductor substrate workpiece based on the annular groove B, so that the processing substrate workpiece as an anode is connected with the polishing disc 16 as a cathode to form an electric circuit, and photoelectrochemical mechanical processing of the substrate workpiece is realized under the action of the LED ultraviolet light source 15. A plurality of holes arranged in a radial manner are arranged on the disc surface, the light transmission effect is realized, the LED ultraviolet light source 15 can directly irradiate on the processed semiconductor substrate, and through holes are distributed between the holes in the radial direction, so that the polishing liquid dropped in the groove can drop on the processed semiconductor substrate through the through holes in the radial direction, the electric path between the anode and the cathode is realized, the polishing pad is fixed on the working surface of the polishing disc 16 by means of bonding, the semiconductor substrate is processed through the polishing pad, the LED ultraviolet light source 15 and the water-cooled disc are an integral structure, the water-cooled disc is used for solving the problem of overheat of the LED ultraviolet light source 15 during processing, the distribution mode of the LED ultraviolet light source 15 is consistent with the distribution of the holes on the polishing disc 16, the three vertical conductive columns 14 on the water-cooled disc are connected with the middle hexagonal nut 13, there is a wire path between the hexagonal nut 13 and the conductive slip ring 12, the electric path between the conductive column 14 is guaranteed, a stable power supply is provided for the LED lamp during processing, the power on the conductive column 14 is indirectly controlled by controlling the LED light source power supply, the control of the light intensity in the radial direction is realized, the hexagonal nut 13 and the polishing disc 16 are fixed together through bolts, and coaxial rotation with the polishing disc is guaranteed. In the figure, the B place above the polishing disc 16 is a circular groove, the polishing liquid is dropped from here during processing, and is dropped on the processed workpiece through the through holes between the holes during the rotation of the polishing disc, and b is the polishing liquid drop inlet.

[0056] The radial distribution of the through holes can also be in the form of a leaflet, a spiral, etc., and the distribution shape is determined according to the specific working condition.

[0057] The body unit comprises a conductive slip ring 12, a shaft 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 polishing disc motor 9 is connected with the shaft of the polishing disc 12 through the shaft coupling 11, and the conductive slip ring 12 is fixed on the polishing disc assembly 2 and used for connecting the power supply and the conductive electrode.

[0058] The conductive base 3 comprises a conductive bonding disc 26, an adapter flange disc 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 bonding disc 26 is matched with the adapter flange disc 27 through the hole on the conductive bonding disc 26, the adapter flange disc 27 is matched on the support shaft joint 28 through threads, and the detachability when the demand changes is ensured, the conductive slip ring is used for power supply, and the wafer 25 is fixed on the conductive bonding disc 26 in a bonding mode.

[0059] The bottom of the conductive bonding disc 26 is provided with conductive blocks, the distribution and shape of the conductive blocks are adjusted according to the actual situation, and the conductive blocks can be the same or different. The conductive blocks provide the conductive bonding disc 26 with uniformly distributed power supply below the conductive bonding disc 26, so that the surface of the conductive bonding disc 26 is subjected to a uniform electric field. Figure 7 As shown in the figure, the conductive blocks on the back of the conductive bonding disc 26 are designed in a hexagonal shape distribution structure, the structure is not unique, and different shapes can be set according to the required working condition to meet the processing conditions. Figure 7 As shown in the figure, the hole array mode on the polishing disc 16 is not unique, and the distribution is radial. From the right side planar view, the through holes between the holes can be clearly observed, and the distribution is spiral, and the arrangement mode is determined according to the specific working condition.

[0060] The adapter flange disc 27 is fixed on the conductive bonding disc 26 through bolts, a sealing ring is fixed between the two, the liquid in the polishing process cannot affect the conductive effect, the adapter flange disc 27 is fixed on the support shaft joint 28 and is set as a detachable mechanism, the convenience of bonding and separating the wafer 25 is ensured, the conductive slip ring 29 is fixed on the support shaft 30 and is connected with the power supply of the electrochemical workstation 4, and the power supply for workpiece processing is provided.

[0061] The moving assembly comprises a machine body unit moving mechanism, the machine body unit moving mechanism comprises a first standard air cylinder 20, a second standard air cylinder 21, a cross slide 17 and a linkage mechanism frame 18, the linkage mechanism frame 18 is provided with an air cylinder sliding plate 19, the first standard air cylinder 20 and the second standard air cylinder 21 are connected with the transverse sliding end and the vertical sliding end of the cross slide 17 respectively, the transverse sliding end of the cross slide 17 can move on the air cylinder sliding plate, the vertical sliding end can move along the transverse sliding end, and the front surface of the cross slide is connected with a motor holder. The motor holder 10 and the cross slide 17 are connected in a sliding mode, the vertical (vertical direction) movement of the second standard air cylinder 21 is ensured when the second standard air cylinder 21 is loaded, and the loading and unloading of the workpiece are realized. The cross slide 17 and the linkage mechanism frame 18 connected on the first standard air cylinder 20 are fixed by bolts, so that the first standard air cylinder 20 provides power for the transverse movement of the polishing disc assembly as a whole. In the embodiment, the first standard air cylinder 20 is fixed on the side of the machine body by bolts.

[0062] The 3D surface optical profiler 7 is further included, and the surface machining quality of the semiconductor substrate workpiece is detected by the 3D surface optical profiler 7 during the machining process.

[0063] The moving assembly comprises a detector sliding plate 22 transversely arranged on the inner side wall of the rack, the tail end of the 3D surface optical profiler 7 can slide on the detector sliding plate 22, and the tail end of the 3D surface optical profiler 7 can be connected with a third standard air cylinder 23. During the machining process, the surface topography of the workpiece can be scanned by moving the conductive base directly below the lens, the machining quality is intermittently monitored, the interaction between the electric field and the optical field is fed back, and better machining of the workpiece is realized.

[0064] The polishing liquid collecting pool 8 is further included, the polishing liquid collecting pool 8 is movably installed on the rack and used for collecting waste liquid in the polishing process, the bottom of the polishing liquid collecting pool 8 is connected with a collecting pool support column 35 and a collecting pool base 36, the collecting pool base 36 can slide on a water storage tank sliding plate 24, and the bottom of the polishing liquid collecting pool 8 is provided with a collecting pool water outlet 37. The waste liquid in the polishing process is collected in the polishing liquid collecting pool 8 and directly flows out from the collecting pool water outlet 37 at the bottom of the pool, the waste liquid is recycled, the environment is avoided from being polluted, the conductive base can be moved transversely in the machining process by cooperation of the moving assembly and the water storage tank sliding plate 24, and the surface machining topography of the workpiece is intermittently detected.

[0065] The moving assembly comprises a support shaft sliding plate 34 arranged at the bottom of the rack, the support shaft sliding plate 34 is provided with a sliding rail 32, the bottom of a support shaft seat 31 is connected with a sliding plate base 33, and the cooperation of the sliding rail 32 and the sliding plate base 33 realizes the movement of the workpiece to be machined to the lower side of the 3D surface optical profiler.

[0066] The application also discloses a polishing method for photoelectrochemical mechanical polishing of a semiconductor substrate based on the above-mentioned device.

[0067] S1, configuration of an electrochemical polishing solution: SiO2 suspension (mass concentration of 5 wt%) with a particle size of 20-30 nm + K2SO4 (0.1 mol / L) aqueous solution, the suspension with the mass concentration can ensure light transmission under the premise of ensuring processing quality;

[0068] S2, wafer cleaning: first, immerse the wafer in anhydrous ethanol for ultrasonic cleaning for 10 minutes, repeatedly clean with deionized water for 3 minutes, then immerse in concentrated HF solution for 10 minutes, then clean with deionized water for 3 minutes, and finally blow dry with nitrogen;

[0069] S3, use conductive adhesive to bond the wafer to the conductive bonding disc to ensure complete fastening;

[0070] S4, fix the conductive bonding disc and the adapter flange disc on the main shaft joint to ensure complete fastening;

[0071] S5, use the conduit of the peristaltic pump to first drop a certain amount of polishing solution on the wafer surface to form a liquid film completely covering the wafer;

[0072] S6, move the position of the polishing disc and adjust it so that the polishing pad on the processing surface is in contact with the wafer surface, the above-mentioned liquid film is in complete contact with the polishing pad, and the wafer as the anode and the polishing disc as the cathode form a closed loop;

[0073] S7, turn on the LED ultraviolet light source so that the light source can directly irradiate the wafer surface, the voltage applied by the electrochemical workstation is applied to the wafer through the conductive block directly contacting the wafer, and the electron-hole pairs generated by the ultraviolet irradiation of the wafer surface are separated, so that a modified soft layer is generated on the wafer surface;

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

[0075] S9, drop the polishing solution with a flow rate of 150 ml / min in the annular groove at the center of the polishing disc, and with the rotation of the polishing disc, the polishing solution is continuously dropped on the workpiece surface through the through holes between the holes, at this time, the surface oxidation-mechanical removal reciprocating cycle is carried out, and high-quality and efficient polishing of the wafer surface is realized;

[0076] S10, immerse the wafer on the conductive bonding disc in toluene solution to separate it from the conductive bonding disc;

[0077] S11, the wafer surface is cleaned with acetone, alcohol and 2wt% hydrofluoric acid, deionized water, and then the wafer is dried with nitrogen.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An apparatus for photoelectrochemical mechanical polishing of a semiconductor substrate in which the electric field is uniformly distributed and coordinated with the light field, characterized by, It includes: The rack, the machine body unit, the polishing disc assembly, the conductive base, the LED ultraviolet light source, the electrochemical workstation and the moving assembly, the machine body unit is used for loading and unloading the polishing disc assembly, the machine body unit, the electrochemical workstation, the LED light source power supply and the moving assembly are all installed on the rack, the electrochemical workstation and the LED light source power supply are used for providing power for the conductive base and the LED ultraviolet light source respectively during processing, the LED ultraviolet light source is fixed on the polishing disc and acts on the semiconductor substrate workpiece in processing during polishing of the workpiece by the polishing disc, the semiconductor substrate workpiece is fixed on the conductive base by bonding, and the position of the machine body unit and the workpiece to be processed is adjusted by the moving assembly; The polishing disc assembly includes the polishing disc, the polishing pad, the LED ultraviolet light source, the water-cooled disc, the conductive column and the hexagonal nut, the polishing disc is provided with an annular groove with a preset radius near the central position, the polishing liquid is added and dropped on the semiconductor substrate workpiece based on the annular groove, a plurality of holes are arranged in a radial manner on the disc surface, so that the LED ultraviolet light source can directly irradiate on the processed semiconductor substrate, and the through holes are distributed between the holes in the radial direction, so that the polishing liquid dropped in the groove is dropped on the processed semiconductor substrate through the through holes in the radial direction, to realize the electrical path between the anode and the cathode, the polishing pad is fixed on the working surface of the polishing disc by bonding, the LED ultraviolet light source and the water-cooled disc are an integral structure, and the water-cooled disc is used for solving the problem of light overheating during processing, wherein the distribution mode of the LED ultraviolet light source is consistent with the distribution of the holes on the polishing disc, the three conductive columns on the water-cooled disc are connected with the middle hexagonal nut, a stable power supply is provided for the LED lamp during processing, and the intensity of the light irradiation in the radial direction is controlled, the hexagonal nut and the polishing disc are fixed together through bolts, and coaxial rotation with the polishing disc is guaranteed.

2. The apparatus for photoelectrochemical mechanical polishing of a semiconductor substrate in accordance with claim 1, wherein, The machine body unit includes a conductive slip ring, a shaft 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 with the shaft of the polishing disc through the shaft coupling, and the conductive slip ring is fixed on the polishing disc assembly and is used for connecting the power supply with the conductive pole.

3. The apparatus for photoelectrochemical mechanical polishing of semiconductor substrates in accordance with claim 1, wherein, The conductive base specifically includes a conductive bonding disc, an adapter flange disc, 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 bonding disc is matched with the adapter flange disc through the holes thereon, the adapter flange disc is threadedly matched on the support shaft joint, and the wafer is fixed on the conductive bonding disc by bonding.

4. The apparatus for photoelectrochemical mechanical polishing of semiconductor substrates in accordance with claim 1, wherein, The moving assembly includes a machine body unit moving mechanism, the machine body unit moving mechanism includes a first standard air cylinder, a second standard air cylinder, a cross slide and a linkage mechanism frame, a cylinder sliding plate is arranged on the linkage mechanism frame, the first standard air cylinder and the second standard air cylinder are connected with the horizontal sliding end and the vertical sliding end of the cross slide respectively, the horizontal sliding end of the cross slide can move on the cylinder sliding plate, the vertical sliding end can move along the horizontal sliding end, and the front surface of the cross slide is connected with the motor holder.

5. The apparatus for photoelectrochemical mechanical polishing of semiconductor substrates in accordance with claim 1, wherein, The 3D surface optical profiler is used to detect the surface processing quality of the semiconductor substrate workpiece during the processing.

6. The apparatus for photoelectrochemical mechanical polishing of semiconductor substrates in accordance with claim 1, wherein, The moving assembly comprises a detector slide plate transversely arranged on the inner side wall of the rack, and the tail end of the 3D surface optical profiler can slide on the detector slide plate.

7. The apparatus for photoelectrochemical mechanical polishing of semiconductor substrates in accordance with claim 1, wherein, The polishing liquid collecting pool is movably installed on the rack, and is used to collect waste liquid in the polishing process.

8. The apparatus for photoelectrochemical mechanical polishing of semiconductor substrates with uniform electric field distribution and light field coordination according to claim 3, wherein, The moving assembly comprises a support shaft slide plate arranged at the bottom of the rack, and the support shaft slide plate is provided with a slide rail.

9. A method for polishing semiconductor substrates based on the device according to any one of claims 1 to 8, wherein the electric field is uniformly arranged and the light field is coordinated, characterized in that, The method comprises the following steps: S1, configuration of electrochemical polishing liquid: SiO2 suspension with a particle size of 20-30 nm + K2SO4 aqueous solution is selected; S2, wafer cleaning: first, the wafer is completely immersed in anhydrous ethanol for ultrasonic cleaning, and then repeatedly cleaned with deionized water, then immersed in concentrated HF solution, and then cleaned with deionized water, and finally dried with nitrogen; S3, the wafer is adhered to the conductive bonding disc by using conductive adhesive, and the wafer is completely fastened; S4, the conductive bonding disc and the adapter flange are fixed on the main shaft joint, and the wafer is completely fastened; S5, using the conduit of the peristaltic pump, a certain amount of polishing liquid is first added on the surface of the wafer to form a liquid film completely covering the wafer; S6, the position of the polishing disc is moved and adjusted so that the polishing pad on the processing surface is in contact with the wafer surface, and the liquid film is in complete contact with the polishing pad, and at this time, the wafer as the anode and the polishing disc as the cathode form a closed circuit; S7, turn on the LED ultraviolet light source so that the light source can directly irradiate the wafer surface, and the voltage applied by the electrochemical workstation is applied to the wafer through the conductive block in direct contact with the wafer, so as to separate the electron-hole pairs generated by the ultraviolet irradiation of the wafer surface, and the wafer surface generates a modified soft layer; S8, start the polishing disc motor to drive the polishing disc to rotate; S9, during the processing, the polishing liquid is added in the annular groove at the center of the polishing disc, and with the rotation of the polishing disc, the polishing liquid is continuously added on the workpiece surface through the through holes between the holes, at this time, the surface oxidation-mechanical removal reciprocating cycle is carried out, and the high-quality and efficient polishing of the wafer surface is realized; S10, immerse the wafer on the conductive bonding disc in toluene solution to separate the wafer from the conductive bonding disc; S11, sequentially clean the wafer surface with acetone, alcohol and 2wt% hydrofluoric acid, deionized water, and then dry the wafer with nitrogen.

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