An ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on light-transmitting auxiliary materials and its preparation method and processing method

Abstract

The present invention provides a photoelectrocatalytic-assisted CMP processing device for ultrathin wafers using a light-transmitting auxiliary material, as well as a preparation and processing method. The device comprises a body, a light source, and a polishing head. The body includes a base, a frame, a rotating shaft, a polishing disc, a polishing pad, and a polishing load application device. The polishing head comprises a coupling sleeve, a conductive slip ring, a fixed frame, a base plate, a conductive electrode, and conductive glass. The polishing head is provided with a polishing liquid buffer tank and evenly distributed arc-shaped through-holes. During processing, the polishing liquid passes through the polishing liquid buffer tank, the arc-shaped through-holes, and the holes in the conductive glass. Finally, a solution layer of a certain thickness is formed between the conductive glass and the polishing disc. A narrow-bandgap photoelectrocatalytic semiconductor composite material thin film is deposited on the surface of the conductive glass to continuously generate hydroxyl radicals. The device has high photoelectrocatalytic efficiency, excellent light energy absorption, wide applicability, simple structure, and low cost, enabling high-quality and efficient processing.

Description

Technical Field

[0001] The present invention relates to the technical field of thin-sheet ultra-thin wafer polishing, and in particular to an ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on a light-transmitting auxiliary material, a preparation method, and a processing method. Background Art

[0002] Thin-disk laser crystals are mainly used in the development of compact thin-disk solid-state lasers and have advantages such as high pumping efficiency and low wavefront distortion. As the core component inside the laser, the material properties and surface quality of the ultra-thin wafer have a significant impact on the laser output performance. In addition, to avoid damage to the laser itself by the high-power laser beam, very high requirements are placed on the material properties and processing surface quality of the ultra-thin wafer (surface accuracy PV ≤ λ / 6, surface roughness Ra ≤ 1nm). At the same time, in order to enhance the heat dissipation effect of the laser medium, reduce the thermal lens effect and birefringence effect under high power, and further improve the power and beam quality of the thin-disk laser, it is necessary to use a laser medium with thinner thickness (less than 0.5 mm) and higher geometric accuracy and surface quality.

[0003] The processing of ultrathin wafers often concludes with polishing to remove various damage accumulated during previous steps, such as scratches, subsurface damage, and pits. Currently, the leading technology is chemical mechanical polishing (CMP), which uses material modification to create a soft film on the workpiece surface. This film is then removed through the mechanical shearing action of the polishing pad and abrasive particles. Subsequently, to improve material removal efficiency, strong chemical oxidants and some strong free radical-type chemical oxidants have been added to assist CMP processing. However, these removal efficiencies are only around 10–40 nm / min (Mu Qing, Research on Material Removal Processes in YAG Crystal Polishing, Dalian University of Technology, 2020; Zili Z, et al, A Novel Chemical Mechanical Polishing Slurry for Yttrium Aluminum Garnet Crystal, Applied Surface Science, 2019, 496(C)). Therefore, it is imperative to explore new methods for efficiently processing ultrathin wafers and combine them with mechanical polishing to innovate and develop polishing technologies for ultrathin wafers.

[0004] Currently, semiconductor photoelectrocatalytic-assisted CMP (CMP) processing technology offers a novel approach for the fabrication of wafer-based devices. The semiconductor materials used in this process are typically composite semiconductors. In practical applications, TiO2 and other narrow-bandgap semiconductors are often used. The principle is as follows: TiO2 acts as a window for the narrow-bandgap BiVO4, enabling full response across the ultraviolet and visible light bands, improving the generation efficiency of photogenerated electrons and holes and enhancing carrier density. When the multiple components come into close contact, their respective energy band positions shift accordingly, forming an intrinsic electric field that drives the separation of photogenerated carriers and improves quantum efficiency. Simultaneously, the applied electric field effectively separates electron-hole pairs, preventing recombination, allowing the holes, already highly oxidizing, to accumulate on the semiconductor surface. Therefore, photoelectrochemical reactions in aqueous solutions eliminate the need for strong chemical oxidants; relying solely on the photoelectrocatalytic effect of the composite semiconductor material, they can rapidly modify atoms on the surface of ultrathin wafers.

[0005] However, existing research on semiconductor photoelectrocatalytic-assisted CMP processing technologies still faces several shortcomings that require improvement. The choice of semiconductor composite materials and the preparation of different heterojunction types in photoelectrocatalysis directly affect the generation, separation, and transfer of photogenerated electrons and holes in each component, thereby affecting their oxidation performance. During the actual processing process, whether the light radiation energy can directly act on the surface of the semiconductor composite material can significantly affect the photoelectrocatalytic effect. To date, most photoelectrocatalytic-assisted CMP processing technologies use non-transparent polishing components, resulting in almost zero light radiation effect. Although patents related to hollow conductive polishing pads exist (such as CN 113134784 A, CN 115625627 A, and CN115415857), light radiation is ultimately transmitted through limited cavities within the polishing pads, resulting in significant light loss. Furthermore, as ultrathin wafers are fabricated at increasingly thin thicknesses, conventional workpiece supports are susceptible to deformation and may even crack due to the cumulative effects of processing stress. Furthermore, conventional photoelectrocatalytic devices are no longer suitable for crystalline materials with poor or no conductivity.

[0006] In view of this, how to propose a method that can effectively solve the transmittance of photoelectrocatalytic systems, prevent ultra-thin chips from deforming, and have strong universality has become an urgent problem to be solved in this technical field. Summary of the Invention

[0007] In response to the technical problems raised above, the present invention, funded by the National Key R&D Program (No. 2022YFB3605902), provides an ultra-thin wafer photoelectrocatalytic-assisted CMP processing device based on translucent auxiliary materials, as well as a preparation method and a method of use. The present invention does not require the ultra-thin wafer to be directly connected to the photoelectrocatalytic system, so it has strong universality. At the same time, because the core components of the device are all made of materials with high light transmittance, they have strong light transmittance and can greatly promote the participation of light radiation. In addition, the present invention uses a partitioned groove substrate to glue the ultra-thin wafers, which does not involve extreme conditions such as high temperature, high pressure and vacuum, thereby realizing the efficient and high-quality processing of all types of thin-sheet ultra-thin wafers using photoelectrocatalytic-assisted CMP technology.

[0008] The technical means adopted in the present invention are as follows:

[0009] An ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on a light-transmitting auxiliary material comprises a body, a light source and a polishing head, wherein the light source is arranged on the body.

[0010] The machine body includes a machine base, a machine frame, a rotating shaft, a polishing disc, a polishing pad and a polishing load applying device, wherein the polishing load applying device is mounted on the machine base through the machine frame, the rotating shaft is provided at the output end of the polishing load applying device, the polishing pad and the polishing disc are adhered, and the polishing disc is mounted on the machine base;

[0011] The polishing head includes a coupling sleeve, a conductive slip ring, a fixing frame, a base plate, a conductive electrode, and conductive glass. The polishing head and the rotating shaft are fixedly connected via the coupling sleeve, the coupling sleeve is connected to the fixing frame, the conductive slip ring is mounted on the fixing frame, the conductive slip ring is used to connect the power supply to the conductive electrode, the workpiece is fixed on the conductive glass, and the base plate is used to support the ultra-thin wafer. The fixing frame, base plate, and conductive glass are all made of materials with a preset light transmittance.

[0012] The polishing head is provided with a polishing liquid buffer tank and evenly distributed arc-shaped through holes. During the processing, the polishing liquid passes through the polishing liquid buffer tank, the arc-shaped through holes and the holes on the conductive glass on the polishing head, and finally forms a solution layer of a certain thickness between the conductive glass and the polishing disk. The solution layer, the conductive glass and the conductive cathode constitute an electrolytic reactor. A layer of narrow-bandgap photoelectric catalytic semiconductor composite material film is deposited on the surface of the conductive glass to continuously generate hydroxyl radicals.

[0013] Furthermore, the polishing head fixing frame is made of materials including UV-transmitting glass and traditional optical plastics.

[0014] Furthermore, the conductive electrode includes a conductive cathode and a conductive anode. The conductive cathode includes a cathode platinum sheet, which is an annular thin sheet and is attached to the edge of the end face of the polishing head; the conductive anode includes an anode copper sheet. The conductive glass that supports the anode semiconductor film is connected to the annular copper sheet away from the polishing disk surface to enhance the conductive area.

[0015] Furthermore, the conductive glass is circular, and a plurality of holes are evenly distributed at a certain distance from the center of the circle.

[0016] Furthermore, the substrate is double-sided polished fused quartz glass, and a matrix separation groove is provided on the side where the ultra-thin wafer is fixed, for dot matrix bonding of the ultra-thin wafer, and the adhesive is a two-component epoxy resin adhesive that cures at room temperature.

[0017] The present invention also provides a method for preparing an ultra-thin wafer photoelectrocatalytic assisted CMP device based on a light-transmitting auxiliary material.

[0018] The method comprises the following steps: A1, adding 2 mL of tetraisopropoxytitanium to 6 mL of isopropanol in a ratio of 1:3, stirring for ≥1 h to uniformly mix the two, thereby forming liquid A; dropping 0.5 mL of glacial acetic acid into liquid A, stirring for ≥1 h; at the same time, adding a certain amount of BiVO4 into 1.6 mL of isopropanol, dropping 0.15 mL of distilled water, and ultrasonically dissolving for ≥30 min to form liquid B; dropping liquid B into liquid A, stirring the resulting mixture at room temperature for ≥1 h to uniformly mix the two; dropping distilled water, stirring until a sol appears; placing the resulting colloid into a high-pressure reactor, and heating at 2 °C·min -1 The temperature was raised to 200 °C, kept constant for 2 h, and then cooled to room temperature. The heat-treated colloid was transferred from the reactor to a beaker, stirred for 2 h, and then spin-coated on the entire surface of the punched conductive glass and the substrate surface. Finally, it was aged for later use.

[0019] Furthermore, the annular copper sheet and the annular platinum sheet are both embedded into the corresponding groove structures of the fixing frame by gluing;

[0020] The annular copper sheet and the circular conductive glass are fixedly connected by graphite conductive adhesive (model: A528), and the exposed part of the copper sheet is insulated and sealed with glass adhesive to isolate it from contact with the polishing liquid;

[0021] The electrode pins and the copper and platinum electrode sheets are connected by punching and welding, and then connected to the inner ring wire of the conductive slip ring to form a conductive path.

[0022] Furthermore, the conductive glass has a thickness of 2-10 mm, a light transmittance of 70-92%, and a surface conductive film thickness of 100-700 nm.

[0023] The present invention also discloses a photoelectrocatalytic assisted CMP processing method for ultra-thin wafers based on a light-transmitting auxiliary material, comprising the following steps:

[0024] Connect the workpiece to be processed to the substrate through two-component epoxy resin glue. The workpiece can be evenly pasted along the circumference of the substrate. During the pasting process, attention should be paid to the uniform thickness of each matrix glue point and the order of glue dispensing.

[0025] The substrate and the conductive glass are bonded together by epoxy resin glue;

[0026] During the machining process, the main adjustment parameters include load, spindle speed, polishing disc speed, light intensity, abrasive type and particle size, polishing liquid flow rate and polishing liquid pH value;

[0027] After processing, the remaining impurities on the surface are first blown dry with nitrogen, and then the colloid is dissolved by soaking in ketone and ether solvents to achieve the removal of the workpiece.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] The polishing head holder described in this invention is made of pure polymethyl methacrylate (PMMA, acrylic sheet) with excellent light transmittance, reaching approximately 92%. This effectively reduces energy loss during light radiation, and its low illumination angle requirements make it suitable for a wide range of applications. Furthermore, the holder is provided with an arc-shaped through-hole, allowing the polishing liquid and light to fully contact the catalytic material on the conductive glass surface.

[0030] 2. The anode of this invention utilizes conductive glass with a transmittance of approximately 86%, which also enhances the propagation of light energy. Several holes are arranged around the circular glass, providing three advantages: first, they facilitate the outflow of polishing liquid, ultimately forming a thick layer of solution between the outer surface of the conductive glass and the polishing pad; second, they allow for the subsequent expansion of the total working surface area of ​​the photoelectrocatalyst film and the conductive ITO film; and third, they mitigate the physical weakening of light intensity, assisting in the irradiation process.

[0031] 3. The semiconductor material used for photoelectrocatalysis in this invention utilizes a TiO2 / X composite material (e.g., TiO2-BiVO4), and its heterojunction is a Type II. A specific advantage of a Type II heterojunction is that holes and electrons can transfer from the component with a higher potential to the component with a lower potential, effectively separating electrons and holes and thereby enhancing catalytic performance.

[0032] 4. The present invention employs copper and platinum rings as the anode and cathode, respectively, as the medium for transmitting electrical energy. The copper rings are tightly connected to the conductive glass, effectively enhancing the uniform distribution of the glass's electric field. The platinum rings are attached to the edge of the polishing head parallel to the polishing disc, ensuring sufficient and stable contact with the polishing fluid.

[0033] 5. The present invention has a reasonable design, simple structure, low cost, and strong universality. At the same time, the solution can achieve high-efficiency and high-quality polishing of ultra-thin wafers at room temperature and pressure or without the addition of chemicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative labor.

[0035] Figure 1 This is the photoelectrocatalytic assisted CMP processing system of the present invention.

[0036] Figure 2 The polishing head structure of the present invention is shown in the isodimensional diagram (a) and the top view (b).

[0037] Figure 3 The polishing head of the present invention is shown in the front view (a) and the BB cross-sectional view (b).

[0038] Figure 4 This is a structural diagram of the conductive glass of the present invention.

[0039] Figure 5 Schematic diagram of the substrate structure of the present invention.

[0040] In the figure: 1—polishing load applying device, 2—polishing liquid nozzle, 3—polishing head, 4—polishing disk, 5—machine base, 6—retaining frame, 7—light source, 8—stop bolt, 9—polishing liquid recovery tank, 10—locking bolt, 11—coupling sleeve, 12—fastening bolt, 13—stop plate, 14, 15—electrode pins, 16—glass glue, 17—annular platinum sheet, 18—conductive glass, 19—rotating spindle, 20—connecting bolt, 21—conductive slip ring inner ring, 22—conductive slip ring outer ring, 23—fixing frame, 24—polishing liquid buffer tank, 25—arc-shaped through hole, 26—annular copper sheet, 27—graphite conductive glue, 28—ultra-thin wafer, 29—conductive column, 30—substrate, 31—conductive glass hole, 32—substrate surface matrix separation groove. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention 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.

[0042] 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 in no way 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 making creative work are within the scope of protection of the present invention.

[0043] 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 invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0044] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​described in these embodiments 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 techniques, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0045] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying 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 outline of each component itself.

[0046] For ease of description, spatially relative terms such as "above," "above," "on the upper surface of," and "above" may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above" or "on top of" another device or structure would then be positioned as "below" or "below" the other device or structure. Thus, the exemplary term "above" may include both the orientations of "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used herein should be interpreted accordingly.

[0047] 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. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0048] like Figures 1 to 5 As shown, the embodiment of the present invention discloses an ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on a light-transmitting auxiliary material, comprising a body, a light source 7 and a polishing head 3. The light source 7 is arranged on the body. In this embodiment, the light source 7 is fixed on the polishing load applying device 1.

[0049] The machine body includes a machine base 5, a frame, a rotating spindle 19, a polishing disc 4, a polishing pad and a polishing load applying device 1. The polishing load applying device 1 is installed on the machine base 5 through the frame. Specifically, the polishing load applying device 1 is fixed to the frame by welding. The output end of the polishing load applying device 1 is provided with the rotating spindle 19. The polishing pad and the polishing disc 4 are adhered. The polishing disc 4 is installed on the machine base 5. In this embodiment, the polishing disc 4 is connected to the tray fixed to the spindle of the machine base 5 through the pin on the back side.

[0050] The polishing head 3 includes a coupling sleeve 11, a conductive slip ring, a fixed frame 23, a base plate 30, a conductive column 29, and a conductive glass 18. The polishing head 3 and the rotating spindle 19 are fixedly connected via the coupling sleeve 11. The coupling sleeve 11 is connected to the fixed frame 23. The coupling sleeve 11 is tightly connected to the fixed frame 23 via a connecting bolt 20. After adjusting the positions of the two, they are locked with a locking bolt 10, and the lower end is tightened with a fastening bolt 12. The conductive slip ring is mounted on the fixed frame 23 and is used to connect the power supply to the conductive electrode. The ultra-thin wafer 28, which is the workpiece to be processed, is fixed to the conductive glass 18. The base plate 30 is used to support the ultra-thin wafer 28. The base plate 30 plays a supporting role for the ultra-thin wafer 28, solving the problem of weak rigidity caused by the ultra-thinness of the ultra-thin wafer 28. The fixed frame 23, base plate 30, and conductive glass 18 are all made of materials with a preset light transmittance.

[0051] Specifically, the inner ring 21 of the conductive slip ring is secured to the studs of the mounting bracket 23 via fastening bolts 12, limiting the slip ring's circumferential rotation. Conductive studs 29 connect the rings to the electrode pins 14-15 on the annular copper sheet 26 and the annular platinum sheet 17, respectively, to transmit the required electric field. The annular copper sheet 26 and the annular platinum sheet 17 are adhesively bonded into the grooves of the mounting bracket 23, effectively preventing them from falling out during rotation. The protruding portion of the annular copper sheet 26 is sealed with glass glue 16 to prevent electrolysis from contact with the polishing fluid. Graphite conductive glue 27 and conductive glass 18 are then bonded to the rings to transmit electrical energy. The outer ring 22 of the conductive slip ring is secured to the mounting bracket 6 via retaining plates 13 and retaining bolts 8 to prevent rotation with the device and is connected to an external power source.

[0052] The polishing head 3 is equipped with a polishing liquid buffer tank 24 and evenly distributed arc-shaped through-holes 25. During processing, the polishing liquid passes through the polishing liquid buffer tank 24, the arc-shaped through-holes 25, and the holes in the conductive glass 18 on the polishing head 3. Finally, a solution layer of a certain thickness is formed between the conductive glass 18 and the polishing plate 4. The solution layer, the conductive glass, and the conductive cathode constitute an electrolytic reactor. A narrow-bandgap photoelectrocatalytic semiconductor composite film is deposited on the surface of the conductive glass 18 to continuously generate hydroxyl radicals. During processing, the load application device is responsible for controlling the workpiece's rotational speed and the amount of applied pressure; the polishing liquid nozzle 2 and the light source 7 respectively provide the required polishing liquid and light radiation energy to the device.

[0053] The polishing head's electric field is supplied by a conductive glass 18 coated with a Type II heterojunction TiO2-BiVO4 semiconductor composite thin film as the anode and a platinum ring 17 as the cathode. The polishing liquid, conductive glass 18, and platinum ring 17 form an electrolytic reactor. The laser wafer is clamped using a molten glass substrate 30 with matrix-shaped dividing grooves 32 on its surface, secured with a room-temperature-curing two-component epoxy resin adhesive. This effectively reduces deformation during the loading and gluing of the ultra-thin wafer. This invention boasts high photoelectrocatalytic efficiency, excellent light energy absorption, wide applicability, simple structure, and low cost, enabling high-quality and efficient processing.

[0054] During the process, the polishing liquid ejected from the polishing liquid nozzle 2 passes through the polishing liquid buffer tank 24, the arc-shaped through-hole 25, and the conductive glass holes 31 on the conductive glass surface, ultimately forming a solution layer of a certain thickness between the conductive glass 18 and the polishing plate 4. The solution layer, the conductive glass 18 (anode), and the annular platinum sheet 17 (cathode) form an electrolytic reactor. A polishing liquid recovery tank 9 is provided on the machine base to facilitate the recovery of the polishing liquid.

[0055] The polishing head fixing frame is made of pure polymethyl methacrylate (PMMA, acrylic plate) to reduce energy loss during light propagation.

[0056] The conductive electrode includes a conductive cathode and a conductive anode. The conductive cathode comprises an annular platinum sheet 17, a thin ring-shaped sheet attached to the edge of the end face of the polishing head 3. The conductive anode comprises an annular copper sheet 26. The conductive glass 18, which supports the anode semiconductor film, faces away from the polishing disk and is connected to the annular copper sheet to increase the conductive area. The present invention uses conductive ITO glass as the working electrode in the photoelectrocatalytic process, and together with the cathode platinum sheet (Pt) and polishing liquid, forms an electrolytic reactor. A narrow-bandgap photoelectrocatalytic semiconductor composite material thin film is deposited and covered on the surface of the conductive glass, which continuously and efficiently produces hydroxyl radicals (•OH) and promotes chemical reactions at the workpiece interface. The cathode platinum sheet (Pt) is a thin ring-shaped sheet attached to the edge of the polishing head to facilitate sufficient and stable contact with the polishing liquid. The conductive glass, which supports the anode semiconductor film (facing away from the polishing disk), is connected to the annular copper sheet to facilitate current conduction.

[0057] The conductive glass 18 is circular, and has a number of holes evenly distributed at a certain distance from the center of the circle, which are used to expand the working area of ​​the subsequent photoelectric catalyst and the conductive film ITO; the photoelectric catalyst film adopts a type II heterojunction TiO2-BiVO4 composite material, which can adapt to the response of the entire ultraviolet and visible light band.

[0058] To prevent significant deformation of the ultra-thin laser crystal due to cumulative stress during processing, a slotted substrate is used. A matrix-type bonding method is used between the substrate and the ultra-thin wafer using a two-component epoxy adhesive that cures at room temperature. Furthermore, to prevent deformation during wafer placement and ensure uniform adhesive thickness across the substrate surface, the substrate material is double-sided polished fused quartz glass, which has similar physical and chemical properties.

[0059] The present invention also provides a method for preparing an ultra-thin wafer photoelectrocatalytic assisted CMP device based on a light-transmitting auxiliary material.

[0060] 2 mL of tetraisopropoxytitanium was added to 6 mL of isopropanol in a ratio of 1:3, and stirred for ≥1 h to mix the two evenly to form liquid A; 0.5 mL of glacial acetic acid (1:4 ratio to tetraisopropoxytitanium) was added dropwise to liquid A and stirred for ≥1 h; at the same time, a certain amount of BiVO4 was added to 1.6 mL of isopropanol (4:5 ratio to tetraisopropoxytitanium), and 0.15 mL of distilled water (3:40 ratio to tetraisopropoxytitanium) was added dropwise, and ultrasonically dissolved for ≥30 min to form liquid B; liquid B was added dropwise to liquid A, and the resulting mixture was stirred at room temperature for ≥1 h to mix the two evenly; distilled water was added dropwise and stirred until a sol appeared; the resulting colloid was placed in a high-pressure reactor and heated at 2 ℃• min -1 The temperature was raised to 200 °C, kept constant for 2 h, and then cooled to room temperature. The heat-treated colloid was transferred from the reactor to a beaker, stirred for 2 h, and then spin-coated on the entire surface of the punched conductive glass and the substrate surface. Finally, it was aged for later use.

[0061] The annular copper sheet and the circular conductive glass are fixedly connected by graphite conductive adhesive 27 (model: A528), and the exposed portion of the copper sheet is insulated and sealed with glass adhesive to isolate it from contact with the polishing liquid and avoid electrolysis.

[0062] The electrode pins 14 and 15 are connected to the copper and platinum electrode sheets by punching and welding, and then connected to the inner ring wire of the conductive slip ring to form a conductive path.

[0063] The conductive glass has a thickness of 2-10 mm, a light transmittance of 70-92%, and a surface conductive film thickness of 100-700 nm. In this embodiment, the conductive glass has a thickness of 2 mm, a light transmittance of 86%, and a surface conductive film thickness of 700 nm.

[0064] Also disclosed is a photoelectrocatalytic assisted CMP processing method for ultra-thin wafers based on a light-transmitting auxiliary material, comprising the following steps:

[0065] Connect the workpiece to be processed to the substrate through two-component epoxy resin glue. The workpiece can be evenly pasted along the circumference of the substrate. During the pasting process, attention should be paid to the uniform thickness of each matrix glue point and the order of glue dispensing.

[0066] The substrate and the conductive glass are bonded together by epoxy resin glue;

[0067] During the machining process, the main adjustment parameters include load, spindle speed, polishing disc speed, light intensity, abrasive type and particle size, polishing liquid flow rate and polishing liquid pH value;

[0068] After processing, the remaining impurities on the surface are first blown dry with nitrogen, and then the colloid is dissolved by soaking in ketone and ether solvents to achieve the removal of the workpiece.

[0069] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with 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. An ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on a light-transmitting auxiliary material, characterized in that: It includes a body, a light source and a polishing head, wherein the light source is arranged on the body. The machine body includes a machine base, a machine frame, a rotating shaft, a polishing disc, a polishing pad and a polishing load applying device, wherein the polishing load applying device is mounted on the machine base through the machine frame, the rotating shaft is provided at the output end of the polishing load applying device, the polishing pad and the polishing disc are adhered, and the polishing disc is mounted on the machine base; The polishing head includes a coupling sleeve, a conductive slip ring, a fixing frame, a base plate, a conductive electrode, and conductive glass. The polishing head and the rotating shaft are fixedly connected via the coupling sleeve, the coupling sleeve is connected to the fixing frame, the conductive slip ring is mounted on the fixing frame, the conductive slip ring is used to connect the power supply to the conductive electrode, the workpiece is fixed on the conductive glass, and the base plate is used to support the ultra-thin wafer. The fixing frame, base plate, and conductive glass are all made of materials with a preset light transmittance. The polishing head is provided with a polishing liquid buffer tank and evenly distributed arc-shaped through holes. During the processing, the polishing liquid passes through the polishing liquid buffer tank, the arc-shaped through holes and the holes on the conductive glass on the polishing head, and finally forms a solution layer of a certain thickness between the conductive glass and the polishing disk. The solution layer, the conductive glass and the conductive cathode constitute an electrolytic reactor. A layer of narrow-bandgap photoelectric catalytic semiconductor composite material film is deposited on the surface of the conductive glass to continuously generate hydroxyl radicals.

2. The ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on a light-transmitting auxiliary material according to claim 1, characterized in that: The polishing head fixing frame is made of materials including ultraviolet-transmitting glass and traditional optical plastics.

3. The ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on a light-transmitting auxiliary material according to claim 1, characterized in that: The conductive electrode includes a conductive cathode and a conductive anode. The conductive cathode includes a cathode platinum sheet, which is an annular thin sheet and is attached to the edge of the end face of the polishing head; the conductive anode includes an anode copper sheet. The conductive glass that supports the anode semiconductor film is connected to the annular copper sheet away from the polishing disk surface to enhance the conductive area.

4. The ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on a light-transmitting auxiliary material according to claim 1, characterized in that: The conductive glass is circular, and a plurality of holes are evenly distributed at a certain distance from the center of the circle.

5. The ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on a light-transmitting auxiliary material according to claim 1, characterized in that: The substrate is double-sided polished fused quartz glass. A matrix separation groove is set on the side where the ultra-thin chip is fixed, which is used for dot matrix bonding of the ultra-thin chip. The adhesive is a two-component epoxy resin glue that cures at room temperature.

6. A method for preparing an ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on a light-transmitting auxiliary material according to any one of claims 1 to 5, characterized in that: The invention comprises the preparation of a narrow-bandgap photoelectrocatalytic semiconductor composite material film, comprising the following steps: A1, adding a certain amount of tetraisopropoxytitanium to isopropanol, stirring for ≥1 hour to uniformly mix the two, to form liquid A; dropping a certain amount of glacial acetic acid into liquid A, stirring for ≥1 hour; at the same time, adding a certain amount of BiVO4 to isopropanol, dropping a certain amount of distilled water, and ultrasonically dissolving for ≥30 minutes to form liquid B; adding liquid B dropwise into liquid A, and stirring the resulting mixed liquid at room temperature for ≥1 hour to uniformly mix the two; dropping distilled water, and stirring until a sol appears; charging the resulting colloid into a high-pressure reactor, heating to a certain temperature, and then cooling to room temperature; transferring the heat-treated colloid from the reactor into a beaker, stirring for a certain period of time, and then spin-coating the colloid onto the entire surface of the punched conductive glass and the surface of the substrate, and finally aging it for use.

7. The method according to claim 6, characterized in that The annular copper sheet and the annular platinum sheet used as the conductive electrodes are both embedded into the corresponding groove structures of the fixing frame by gluing; The annular copper sheet and the circular conductive glass are fixedly connected by graphite conductive glue, and the exposed part of the copper sheet is insulated and sealed with glass glue to isolate it from contact with the polishing liquid; The electrode pins and the copper and platinum electrode sheets are connected by punching and welding, and then connected to the inner ring wire of the conductive slip ring to form a conductive path.

8. The method according to claim 6, characterized in that The conductive glass has a thickness of 2-10 mm, a light transmittance of 70-92%, and a surface conductive film with a thickness of 100-700 nm.

9. A method for processing an ultra-thin wafer photoelectrocatalytic assisted CMP processing device based on a light-transmitting auxiliary material according to any one of claims 1 to 5, characterized in that: The steps include: Connect the workpiece to be processed to the substrate through two-component epoxy resin glue. The workpiece can be evenly pasted along the circumference of the substrate. During the pasting process, attention should be paid to the uniform thickness of each matrix glue point and the order of glue dispensing; The substrate and the conductive glass are bonded together by epoxy resin glue; During the machining process, the main adjustment parameters include load, spindle speed, polishing disc speed, light intensity, abrasive type and particle size, polishing liquid flow rate and polishing liquid pH value; After processing, the remaining impurities on the surface are first blown dry with nitrogen, and then the colloid is dissolved by soaking in ketone and ether solvents to achieve the removal of the workpiece.

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