Semiconductor element polishing apparatus, polishing method, and polished semiconductor element
By employing a chemical mechanical polishing method that combines rotary and axial motion, the problem of ultra-precision machining of millimeter-sized hard and brittle material spheres has been solved, achieving nanoscale surface smoothness and high-precision roundness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHWEAT UNIV OF SCI & TECH
- Filing Date
- 2026-03-20
- Publication Date
- 2026-07-21
AI Technical Summary
Existing technologies struggle to achieve ultra-precision drum polishing of millimeter-scale hard and brittle material spheres, particularly in ensuring uniform grinding and high-precision machining of the spherical surface, where there are significant technological gaps and a lack of effective chemical-mechanical synergy and motion trajectory control.
By employing precise coordinated control of the rotary motion and axial composite motion of the drum, combined with the principle of chemical mechanical polishing, and through a capsule-shaped inner cavity design and modular drum structure, efficient and uniform polishing of hard and brittle materials can be achieved.
It achieves nanoscale smooth surface processing of millimeter-sized hard and brittle material spheres, significantly improving surface quality and processing consistency, ensuring roundness accuracy, and providing efficient process adaptability and stable processing performance.
Smart Images
Figure CN122425602A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ultra-precision machining technology for hard and brittle materials, and particularly to a semiconductor element polishing device, polishing method, and polishing semiconductor element based on the principle of chemical mechanical polishing. Specifically, it relates to the process and equipment technology for achieving ultra-precision surface machining of semiconductor elements through the synergistic effect of composite motion trajectory and chemical mechanical polishing. Background Technology
[0002] Microsphere ultra-precision machining technology is a core branch of precision manufacturing, with irreplaceable application value in semiconductor packaging, precision instruments, aerospace, and high-end medical devices. Hard and brittle material spheres, represented by millimeter-scale (0.8–3 mm in diameter) single-crystal silicon spheres, serve as core components of high-performance inertial navigation systems, MEMS (microelectromechanical systems), and solar spherical cells, placing near-extremely stringent requirements on their geometric accuracy (micrometer-level roundness) and surface quality (nanometer-level roughness).
[0003] Monocrystalline silicon is a typical hard and brittle material (Mohs hardness reaches 7), and its precision machining faces severe challenges: while using high-hardness abrasives (such as diamond) can improve material removal efficiency, it easily introduces micro-scratches, surface damage, and even brittle fracture, compromising the integrity of the workpiece; on the other hand, using low-hardness abrasives results in low removal rates and insufficient processing efficiency, making it difficult to achieve effective morphology control and precision correction. Chemical mechanical polishing (CMP) technology, through the synergistic effect of chemical etching and mechanical removal, provides a feasible technical path for high-quality surface processing of hard and brittle materials, but its application on millimeter spheres, especially in tumbler polishing environments, still faces many challenges.
[0004] While drum polishing has long been widely used in deburring and finishing processes in fields such as jewelry and medical devices, its material removal mechanism mainly relies on random collisions and sliding friction between the workpiece and the abrasive. This results in poor controllability of the processing trajectory, typically achieving only micrometer-level (μm) surface roughness, which is insufficient to meet the processing requirements of nanometer-level (nm) ultra-smooth surfaces. Existing commercial drum polishing equipment generally suffers from inherent problems such as limited functionality, coarse process parameter control, and poor adaptability. Its simple rotary motion mode cannot provide a uniform and controllable polishing trajectory for millimeter-sized silicon balls, leading to poor processing consistency and failing to meet the manufacturing requirements of high-precision components.
[0005] Especially for spheres made of hard and brittle materials such as silicon nitride, zirconium oxide, and single-crystal silicon, achieving ultra-precision machining requires ensuring "equal probability grinding" of the spherical surface, meaning that each point on the sphere has a nearly identical probability of being ground. However, most currently reported technologies struggle to simultaneously meet these core requirements. For example, some multi-axis grinding devices, such as the Chinese invention patent application publication CN120461246A, while providing a high-precision solution for point contact machining, have limited their application in mass production due to their complex mechanisms and high costs. Furthermore, while improved roller equipment, such as the utility model patent CN202322438329U, optimizes the post-processing flow by introducing a screening structure, it does not fundamentally change the kinematic nature of the polishing process and remains insufficient for nanoscale surface machining of millimeter-sized spheres.
[0006] In summary, there are significant technological gaps in the field of ultra-precision drum polishing of millimeter-sized hard and brittle spheres, especially silicon microspheres. On the one hand, there is a lack of specialized processes that can effectively coordinate chemical etching and mechanical removal to achieve a highly efficient dynamic balance between etching, film formation, and film removal. On the other hand, there is a lack of specialized polishing equipment capable of precisely controlling the movement trajectory of microspheres within the drum, ensuring processing uniformity, and possessing high process adaptability. These gaps represent urgent technological needs in this field, and are the core problems that this invention aims to solve. Summary of the Invention
[0007] To address the aforementioned problems, this invention provides a semiconductor element polishing apparatus, polishing method, and semiconductor element polishing based on the principle of chemical mechanical polishing. Through precise coordinated control of the rotary motion of the drum and the combined axial motion, it achieves efficient and uniform ultra-precision polishing of millimeter-level hard and brittle element surfaces. In a first aspect, the present invention provides a semiconductor element polishing apparatus, comprising: a roller for holding a semiconductor element to be polished; the roller having a capsule-shaped cavity; a rotation drive assembly for driving the roller to rotate about the axis of the roller; and a linear drive assembly for driving the roller to make linear reciprocating movements in a direction parallel to the axis.
[0008] As a preferred embodiment of the present invention, the hardness of the semiconductor element to be polished is ≥7.
[0009] As a preferred embodiment of the present invention, the material of the semiconductor element to be polished is selected from at least one of silicon nitride, zirconium oxide, silicon, and ceramics.
[0010] In this invention, the roller moves simultaneously in two dimensions: rotational motion around the axis and linear motion along the direction parallel to the axis. This causes the movement of the semiconductor element within the roller to be mainly due to sliding friction, and it exhibits a spiral motion trajectory.
[0011] In a preferred embodiment, the movement trajectory of the semiconductor element to be polished within the drum is a variable-diameter spiral. A variable-diameter spiral means that the spiral radius located in the middle of the drum is larger than the spiral radii at both ends of the drum.
[0012] The inner cavity of the roller described in this invention is designed as a unique capsule shape, with the inner wall profile of the roller having a continuous and smooth curve transition. The geometry of the capsule-shaped inner cavity adopts specific parameters, and the cylinder body and at least one end cap are connected by a curved surface. The ratio of the radius of curvature of the transition curve of the curved surface to the diameter of the ball to be polished is ≥10:1, preferably 10:1. This ensures that the contact between the semiconductor element (e.g., a spherical semiconductor element) and the inner wall of the roller is a flexible contact during the frictional movement, avoiding rigid collisions between the semiconductor element and the inner wall of the roller with a right-angled or acute-angled structure, thereby effectively preventing damage to the obtained roundness accuracy.
[0013] As a preferred embodiment of the present invention, the roller has end caps I and II located at both ends of the cylinder body respectively; the cylinder body is connected to end caps I and end caps II respectively, preferably in a detachable manner, and is sealed; end caps I and end caps II are arc-shaped bodies protruding outward from the cylinder body; the cylinder body is connected to end caps I and end caps II respectively via curved surfaces.
[0014] In a preferred embodiment, the roller consists of a cylindrical body (with a bottom, the bottom being an outwardly convex arcuate surface, i.e., the interior of the bottom is not flat but concave) and an end cap; or the roller consists of a cylindrical body (without top or bottom) and two end caps (end cap I and end cap II) located at opposite ends of the cylindrical body; the cylindrical body is connected to the two end caps respectively. End cap I and end cap II are arcuate surfaces convex outward from the cylindrical body (i.e., the interiors of the two end caps are concave).
[0015] The roller is an independent sealing unit, which is sealed to at least one end cover through sealing components (such as sealing rings), and then connected to the concentric chuck of the spindle system to form a completely sealed polishing chamber, ensuring that there is no leakage of slurry during the polishing process.
[0016] The semiconductor element polishing apparatus further includes a first self-centering chuck and a second self-centering chuck; the rotary drive assembly is connected to end cap I via the first self-centering chuck, and the rotary drive assembly is connected to end cap II via the second self-centering chuck.
[0017] In a preferred embodiment, the first and second self-centering chucks have the same structure; the self-centering chuck consists of a rotating plate, a positioning plate, and positioning blocks; the rotating plate has at least 4 guide rails (the guide rails extend from the center of the rotating plate to the distal end), preferably 6 guide rails, each guide rail having the same curvature and direction of curvature, and all guide rails are arranged in a centrally symmetrical manner; the positioning plate has at least 4 through slots (the through slots extend from the center of the positioning plate to the distal end), preferably 6 through slots, each through slot having the same curvature and direction of curvature, and all through slots are arranged in a centrally symmetrical manner; the direction of curvature of the guide rails is opposite to the direction of curvature of the through slots, each guide rail corresponds to one through slot, and the guide rail and the corresponding through slot intersect at a point, forming an X shape; the number of positioning blocks is the same as the number of guide rails and through slots; the positioning blocks pass through the through slots and slide along the guide rails.
[0018] Preferably, the working surface of the positioning block is pretreated (by applying a polyurethane (PU) coating to the nitrile rubber (NBR) substrate) to adjust the coefficient of friction to the range of 0.35 to 0.55, thus avoiding damage to the roller surface and the positioning block surface. It can be adapted to the replacement needs of rollers with different diameters and lengths through a precision adjustment mechanism.
[0019] Preferably, the semiconductor element polishing apparatus further includes: a support assembly for supporting the rotary drive assembly and the roller; the rotary drive assembly includes rotary drive device I and rotary drive device II; the rotary drive device I and rotary drive device II are symmetrically arranged at both ends of the roller with the roller as the center; and / or, the linear drive assembly includes a linear drive device, which drives the support assembly and correspondingly drives the rotary drive assembly and the roller to perform linear motion.
[0020] Preferably, the drive motor is mounted on the upper platform via an L-shaped fixing plate to ensure that the motor output shaft is strictly coaxial with the main shaft. The L-shaped fixing plate ensures that the flatness of the mounting surface is less than 0.01 mm and the perpendicularity is less than 0.02 mm.
[0021] Secondly, the present invention provides a method for polishing spherical materials using any of the above-mentioned semiconductor element polishing apparatuses.
[0022] Preferably, the rotational speed of the roller is 70 rpm to 300 rpm.
[0023] Preferably, the linear reciprocating speed of the roller is 1 mm / s to 10 mm / s.
[0024] Preferably, the linear reciprocating stroke of the roller is 80% to 90% of the roller length.
[0025] The polishing method further includes adding polishing slurry into the drum; the polishing slurry contains SiO2 particles.
[0026] The method employs mechanical removal through drum polishing while simultaneously utilizing the chemical corrosion of alkaline SiO2 polishing slurry. The synergistic effect of these two methods enables ultra-precision polishing of the sphere surface.
[0027] Typically, SiO2 particles are mixed with pure water, preferably in polishing slurry, and the concentration of the SiO2 particles is 10wt% to 15wt%.
[0028] Preferably, the particle size of the SiO2 particles is 80 nm to 120 nm.
[0029] Preferably, the polishing slurry also includes a pH adjuster, preferably an alkaline pH adjuster, such as ethylenediamine, to adjust the polishing slurry to pH 9-11.
[0030] Preferably, the polishing slurry further includes an oxidant, wherein the oxidant is hydrogen peroxide (H2O2), and the content of hydrogen peroxide is 1 wt% based on the total weight of the polishing slurry.
[0031] This invention enables high-precision polishing of spheres of different sizes by replacing sealing rollers of different sizes, adjusting the clamping diameter of the self-centering chuck, and coordinating with corresponding motion control and slurry formulations (e.g., 200mm roller diameter, 300rpm rotation speed, pH=11, 15wt% 120nm silica sol solution; 175mm roller diameter, 240rpm rotation speed, pH=10, 10wt% 80nm silica sol solution; 150mm roller diameter, 175rpm rotation speed, pH=9.5, 10wt% 80nm silica sol solution).
[0032] Thirdly, the present invention provides a polished semiconductor element obtained by polishing using any of the above polishing methods, wherein the polished semiconductor element is a microsphere, the microsphere has a nanoscale smooth surface, the diameter of the microsphere is 0.8 mm to 3 mm, the roughness of the polished semiconductor element is Ra: 1.6 nm to 2.4 nm, and the roundness is 0.6 μm to 0.7 μm.
[0033] The beneficial effects of this invention are: Through an innovative capsule-shaped internal cavity design, combined with a modular roller structure and a concentric chuck adjustment mechanism, not only is rapid replacement of rollers of different sizes achieved, but more importantly, the geometric accuracy of the spheres is effectively protected during the polishing process, preventing damage to their roundness. This design, combining mechanical motion and chemical action, can meet the high-precision, high-efficiency polishing requirements of microspheres of various sizes, significantly improving surface quality and ensuring roundness accuracy, providing a reliable technical guarantee for solving surface quality problems in the processing of microspheres made of hard and brittle materials. Through innovative roller polishing devices and chemical mechanical polishing processes, high-precision processing of millimeter-sized spheres is achieved. This technology employs a composite motion trajectory and modular design, possessing both excellent process adaptability and stable processing performance, providing an efficient solution for the manufacture of microspheres made of hard and brittle materials. Attached Figure Description
[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0035] Figure 1 This is a three-dimensional structural diagram of the polishing device of the present invention; Figure 2 This is a schematic diagram of a concentric chuck structure; Figure 3 A schematic diagram showing the connection between a six-jaw concentric chuck and the end flange of a stepped shaft. Figure 4 This is a schematic diagram of a ball screw reciprocating transmission system. Figure 5 This is a schematic diagram of a drum circumferential transmission system; Figure 6 This is a schematic diagram of the internal shape of the drum; Figure 7 This is a schematic diagram showing the position of the sphere when the drum is stationary; Figure 8 This is a schematic diagram of the trajectory of the ball during the movement of the roller; Figure 9 This is a magnified optical microscope view of the surface of the microspheres obtained by different processing methods in Example 4 and Comparative Example 1, magnified 500 times. in, Figure 9-1 a, b, c, d, e, and f in the diagram are schematic diagrams of the surface results of microspheres processed by a traditional drum polishing machine; Figure 9-2 In the diagram, g, h, i, j, k, and l represent the surface results of the microspheres processed by the device of the present invention. Figure 10 In Figure 10-1, Figure 10-2 , Figure 10-3 , Figure 10-4 , Figure 10-5 , Figure 10-6 This is a schematic diagram showing the roughness results of the microspheres obtained by white light interferometer scanning of the spherical surface using different processing methods in Example 4 and Comparative Example 1. Among them, the upper part Figure 10-1 , Figure 10-2 , Figure 10-3 The images show the results of processing with a traditional drum polisher, specifically the lower part. Figure 10-4 , Figure 10-5 , Figure 10-6 The result is obtained by the novel drum polishing machine of the present invention (Example 4); Figure 11 This is a schematic diagram showing the change in roughness of the microspheres processed in Example 4 as a function of processing time. Figure 12 This is a schematic diagram showing the change in roughness of microspheres processed by a conventional drum polishing machine as a function of processing time, as shown in Comparative Example 1. In the diagram: 1-Lower optical plate, 2-Support column, 202-Support column, 3-Upper optical platform, 4-Polishing roller, 401-End cap I, 402-Roller seal ring, 403-Polishing pad, 404-Positioning screw, 5-First self-centering chuck, 501-Chuck clamping jaw, 502-Clamping jaw fixing bolt, 6-Stepped shaft flange, 601-Positioning screw, 7-Seat bearing, 8-Stepped shaft spindle, 9-Plum blossom coupling, 10-L-shaped plate, 11-DC brushless motor, 12-Ball screw guide rail, 13-Semiconductor component to be processed, 14-Rotating plate, 15-Positioning plate, 16-Guide rail, 17-Through groove, 18-Second self-centering chuck. Detailed Implementation
[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and technical features described in this application can be combined with each other. It should also be pointed out that, unless otherwise indicated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms "comprising" or "including" and similar words used in this invention refer to elements or objects preceding the word that encompass the elements or objects listed following the word and their equivalents, without excluding other elements or objects.
[0037] A polishing apparatus and method based on the principle of chemical mechanical polishing (CMP) is disclosed. The apparatus includes a base motion platform, a spindle support system symmetrically arranged on the left and right sides of the platform, and a polishing drum driven and supported by the spindle system. The sphere to be processed and the polishing medium are placed inside the polishing drum. The spindle support system includes a drive motor, a coupling, a stepped shaft supported by a pedestal bearing, and a chuck for clamping the drum. The end of the stepped shaft is provided with a flange structure. The base motion platform includes a ball screw slide rail and an optical plate, used to drive the entire spindle support system and the drum to reciprocate along the drum axis. This invention, through the combination of the drum's rotational motion and the base's axial motion, causes the sphere to form a spiral motion trajectory within the drum, primarily characterized by sliding. Simultaneously, it innovatively uses an alkaline SiO2 slurry as the polishing medium, generating a soft passivation film on the sphere surface through chemical corrosion, which is then removed mechanically, achieving a "soft-to-hard" chemical mechanical polishing (CMP) mechanism. This invention, through the synergistic combination of the aforementioned mechanical motion and chemical action, can effectively eliminate micro-scratches and pits generated during grinding and processing. While maintaining the high roundness of millimeter-sized spheres, it further reduces their surface roughness, ultimately achieving high-precision, high-efficiency, and ultra-precision polishing of millimeter-sized silicon microspheres.
[0038] In the following embodiments, the ball screw guide rail (GF40) adopts a high-precision guide rail and is equipped with a servo drive system to achieve precise reciprocating motion along the roller axis, with motion accuracy reaching the micron level.
[0039] The pedestal bearing (UCP204) is a high-precision angular contact bearing with a preload adjustment function, which can effectively control the radial runout of the spindle and ensure rotational accuracy.
[0040] The flange structure end face is equipped with a precision positioning stop, and adopts a quick connection structure with the concentric chuck. It achieves quick positioning and reliable connection through high-precision conical surface mating.
[0041] The electrical control system (DC brushless geared motor dedicated driver-XWDC-6016A) integrates a power switch, speed control device and motion control module. The speed control device adopts frequency conversion control technology, which can realize stepless adjustment of the drive motor speed. The motion control module uses a PLC controller (Dopcon TC8642 stepper motor drive) to programmably control the movement speed, stroke and reciprocating frequency of the ball screw slide rail, and store the processing parameters of different roller specifications.
[0042] A special polishing pad (metallographic polishing cloth with adhesive flocking W1.0~W1.5) is pasted on the inner surface of the polishing roller. It has a uniformly distributed micro-protrusion structure, which can enhance the driving effect on the polishing medium and improve the polishing efficiency.
[0043] Example 1: Microsphere Polishing Device The microsphere polishing device includes a roller, a rotary drive assembly, and a linear drive assembly; The roller has a capsule-shaped cavity in which the spherical material to be processed and the polishing medium are housed. A rotary drive assembly drives the roller to rotate around its axis, and a linear drive assembly drives the roller to move linearly in a direction parallel to the axis. Through these two combined drives, the movement of the spherical material to be processed within the roller is mainly due to sliding friction and presents a spiral motion trajectory.
[0044] Example 2 Polishing Method The polishing method for polishing the spherical material to be processed using the polishing apparatus of Example 1 is carried out according to the following steps: (1) Loading and sealing: A certain number of millimeter-sized spherical materials to be processed and polishing slurry are placed into the drum, and then the drum is sealed and its two ends are fixed and clamped.
[0045] (2) Parameter setting: Based on the size of the sphere to be processed and the target surface roughness, set the process parameters in the electrical control unit. The main parameters include: roller rotation speed (0-300 rpm), base axial reciprocating speed (1-10 mm / s), and reciprocating stroke (slightly less than the roller length).
[0046] (3) Start-up: Start the rotary drive assembly and the linear drive assembly at the same time. The rotary drive assembly drives the drum to rotate at a constant speed, so that the spherical material to be processed and the slurry inside the drum will move relative to each other under the action of centrifugal force and friction. The linear drive assembly drives the entire rotary drive assembly and the drum to reciprocate along the axial direction.
[0047] The combination of these two motions causes the spherical material to be processed to form a spiral motion trajectory within the drum, primarily based on sliding friction. This trajectory significantly increases the probability of relative sliding and uniform contact between the spherical surface and the slurry.
[0048] Throughout the polishing process, the polishing slurry gently chemically corrodes the surface of the sphere, generating a soft silicate passivation film that is easy to remove. The mechanical sliding action between the sphere and the slurry, as well as between the sphere and the inner wall of the roller, continuously removes this soft film, achieving a "corrosion-film formation-film removal" cycle mechanism.
[0049] (4) End and post-processing: The device will stop automatically after the preset polishing time is reached. The polished spherical material is taken out for cleaning and drying, and an ultra-precision sphere with significantly reduced surface roughness and maintained roundness can be obtained.
[0050] Comparative Example 1: Traditional Polishing Device CN 119458122 A A grinding and polishing device and a roller polishing mechanism in Embodiment 2 of a polishing process for jewelry making. For example... Figure 12 As shown in CN 119458122 A, traditional jewelry polishing machines have structural limitations, including the rollers not being clamped tightly enough during operation, which can cause them to move upwards. This leads to unstable movement trajectories of millimeter-sized silicon balls during processing, making them prone to rigid collisions and surface damage, thus adversely affecting the surface roughness of the millimeter-sized silicon balls. Specifically, although the surface roughness curve changes over time with an overall decreasing trend, local areas may show a rebound.
[0051] Example 3: Millimeter-scale semiconductor device polishing apparatus like Figure 1 As shown, the device mainly includes a polishing roller 4, a rotary drive assembly, a linear drive assembly, and a support assembly, the support assembly including a base motion platform.
[0052] like Figure 4 As shown, the base motion platform consists of a lower optical plate 1, a ball screw slide rail 12, a support column 2, and a support column 202. The lower optical plate 1 serves as the rigid foundation of the entire device, supporting the upper optical platform 3 via the support column (designed with a diameter of 120mm) 2 and the support column 202 (designed with a diameter of 250mm). The ball screw slide rail 12 is mounted on the lower optical plate 1 and, in conjunction with the servo drive system, enables precise reciprocating motion along the roller axis.
[0053] like Figure 5 As shown, a symmetrical spindle support system is symmetrically arranged on both sides of the upper optical platform 3. Each side includes a stepped spindle 8 supported by a pedestal bearing 7 and a first self-centering chuck 5 for clamping the roller. The DC brushless drive motor 11 on the right side is fixed to the upper optical platform 3 by an L-shaped plate 10. The motor output shaft is coaxial with the stepped spindle 8, enabling the roller to move in a circular motion around the axis. One end of the stepped spindle 8 is connected to the DC brushless motor 11 through a swivel coupling 9, and the other end is provided with a stepped spindle flange 6. The first self-centering chuck 5 clamps both ends of the polishing roller 4 with its chuck clamping claws 501, forming a fixed support that can transmit torque.
[0054] like Figure 6 and Figure 7As shown, the polishing roller 4 consists of a cylindrical body and end caps I 401 and II located at both ends of the cylindrical body, respectively; the cylindrical body is sealed to end caps I 401 and II. End caps I 401 and II are arc-shaped bodies protruding outward from the cylindrical body. The polishing roller 4 is an independent sealing unit with a modular design. The cylindrical body and end caps I 401 adopt a precision fit structure, with a roller sealing ring 402 at the fit point, and then fixed with positioning screws 404 to ensure no leakage of slurry during polishing. The rotary drive assembly clamps and fixes the cylindrical body and end caps I 401 via a first self-centering chuck 5 (using a six-jaw concentric chuck), and the rotary drive assembly clamps and fixes the cylindrical body and end caps II via a second self-centering chuck 18. The polishing roller 4 has a capsule-shaped cavity, and the semiconductor element 13 to be processed and the polishing medium are housed inside the polishing roller 4. The ratio of the radius of curvature of the transition curve of the inner wall of the capsule-shaped cavity to the diameter of the sphere to be polished is 10:1. The two ends of the roller are fixed by the chuck clamping jaws 501 of the first self-centering chuck 5, forming a completely sealed polishing chamber.
[0055] The rotary drive assembly includes a drive motor and a symmetrical spindle system. The drive motor drives the polishing drum 4 to rotate, causing the silicon balls inside the drum to move in a circular motion relative to the drum. The linear drive assembly drives the entire spindle system and the drum to reciprocate linearly along the axial direction via a base motion platform. Through the combination of these two motions, the semiconductor element 13 to be processed forms a helical motion trajectory within the drum, primarily based on sliding friction. Figure 7 As shown, when the drum is stationary, the spheres 13 are arranged in a straight line on the inner wall of the drum. Figure 8 As shown, during the drum's movement, the ball 13 moves along the inner wall of the drum in a variable-diameter spiral trajectory. Figure 1 , Figure 2 , Figure 3 As shown, the first self-centering chuck 5 and the second self-centering chuck 18 have the same structure; each first self-centering chuck 5 includes a rotating plate 14, a positioning plate 15, and 6 sets of positioning blocks. Each set of positioning blocks consists of chuck clamping claws 501 and clamping claw fixing bolts 502. The rotating plate 14 has 6 guide rails 16, which extend from the center of the rotating plate to the distal end. Each guide rail 16 has the same curvature and direction of curvature and is arranged in a centrally symmetrical manner. The positioning plate has 6 through slots 17, which extend from the center of the positioning plate to the distal end. Each through slot 17 has the same curvature and direction of curvature and is arranged in a centrally symmetrical manner. The curvature of the guide rails is opposite to that of the through slots 17. One guide rail 16 and one through slot 17 intersect at a point, forming an X shape. Each chuck clamping claw 501 passes through the through slot 17 and slides synchronously radially along the guide rail 16 to ensure that the clamping center is always aligned with the axis of the roller. The stepped shaft flange 6 is connected to the first self-centering chuck 5 via positioning screws 601 to ensure coaxiality.
[0056] like Figure 6 and Figure 7As shown, the inner surface of the polishing roller 4 is covered with a polishing pad 403 (metallographic polishing cloth with adhesive flocking W1.0~W1.5), which has a uniformly distributed micro-protrusion structure, which can enhance the driving effect on the polishing medium and improve the polishing efficiency.
[0057] The device's electrical control system integrates a power switch, a speed control device, and a motion control module.
[0058] The speed regulating device adopts frequency conversion control technology, which can realize stepless adjustment of the speed of the drive motor; The motion control module uses a PLC controller, which can programmably control the movement speed, stroke and reciprocating frequency of the ball screw slide rail, and store the processing parameters of different roller specifications.
[0059] Example 4: Polishing Method for Millimeter-Scale Semiconductor Devices Based on the apparatus of Example 3, the millimeter semiconductor element polishing method is implemented according to the following steps: (1) Loading and sealing: A certain number of millimeter-sized silicon balls (0.9 mm in diameter; hardness = 7) and the prepared alkaline SiO2 polishing slurry (HEEDA; N-(2-hydroxyethyl)ethylenediamine adjusted to 80 nm, 15 wt% SiO2 solution (a mixture of pure water and SiO2) pH adjusted to 11, and 0.1 wt% polyethylene glycol 600 added as a lubricant) are placed into the polishing roller 4. Then the roller is sealed and its two ends are fixed and clamped by the first self-centering chuck 5 and the second self-centering chuck 18.
[0060] (2) Parameter settings: Based on the size of the silicon ball to be processed and the target surface roughness, set the process parameters in the electrical control unit. The main parameters include: roller rotation speed 300 rpm, base axial reciprocating speed (8 mm / s), and reciprocating stroke 100 mm (slightly less than the roller length 130 mm).
[0061] (3) Start-up: Start-up device. The DC brushless motor 11 drives the polishing drum 4 to rotate at a constant speed through the spindle system, so that the silicon balls and slurry in the drum generate relative motion under the action of centrifugal force and friction. At the same time, the ball screw slide rail 12 drives the entire spindle system and the polishing drum 4 to reciprocate along the axial direction.
[0062] (4) Composite motion polishing: The above two motions are combined to make the silicon ball form a spiral motion trajectory with sliding friction as the main component in the drum. This trajectory greatly increases the probability of relative sliding and uniform contact between the silicon ball surface and the slurry.
[0063] (5) Chemomechanical synergy: Throughout the polishing process, the alkaline SiO2 slurry gently etches the surface of the silicon balls, generating a soft silicate passivation film that is easy to remove. The mechanical sliding action between the silicon balls and the slurry, as well as between the silicon balls and the inner wall of the roller, continuously removes this soft film, realizing a cycle mechanism of "etching-film formation-film removal".
[0064] (6) End and post-processing: After the preset polishing time is reached, the device will stop automatically. Remove the silicon balls for cleaning and drying to obtain ultra-precision silicon balls with significantly reduced surface roughness and maintained roundness.
[0065] like Figure 11 As shown, when the millimeter-level semiconductor element polishing apparatus and method of the present invention are used, the surface roughness of the millimeter-level silicon ball 13 of the workpiece changes with polishing time in a completely decreasing trend. After 168 hours of polishing, the surface roughness of 24.3 nm is reduced to 1.7 nm, and finally an ultra-smooth ultra-precision silicon ball is obtained.
[0066] Multiple millimeter-sized silicon microspheres were processed using a traditional jewelry polishing machine (comparative example 1, i.e., the device used has a fixed and non-replaceable roller, a single and low rotation speed, and a simple support structure that easily leads to roller movement) and the millimeter-sized semiconductor element polishing device of embodiment 3 and the polishing method of embodiment 4 of the present invention, respectively. The quality of the microspheres was evaluated by comparing the roundness and surface roughness of the microspheres obtained by the two methods.
[0067] The traditional jewelry polishing machine in Comparative Example 1 has structural limitations, such as the upward movement of the rollers, fixed and low rotation speed (94 rpm, 128 rpm, 170 rpm), and the inability to use and replace the rollers. This results in unstable movement of the silicon balls during the processing, which easily leads to rigid collisions and surface defects.
[0068] In Embodiments 3 and 4 of the present invention, the combination of the rotary motion of the drum and the axial motion of the base causes the silicon ball to form a spiral motion trajectory mainly characterized by sliding within the drum. At the same time, the use of alkaline SiO2 slurry achieves a synergistic effect of chemical mechanical polishing, effectively improving processing accuracy and efficiency.
[0069] In this embodiment, the obtained microspheres were photographed three times at 100X magnification using an optical microscope to obtain the original images. The central light spot was then removed using Photoshop software, and finally, the roundness value of each microsphere image was calculated using a MATLAB program. Within a predetermined range, a smaller roundness value indicates better / rounder roundness. White light interferometry scans the microsphere surface through fringe interference, obtaining precise spherical data and roughness values, allowing for more intuitive comparison and analysis. For each microsphere, roundness and roughness data from three randomly selected surfaces were collected, and the average value was taken to reduce experimental error.
[0070] Table 1. Roughness and roundness results of microspheres obtained by two polishing machines.
[0071] In this embodiment, to systematically verify the advantages of the millimeter-level drum polishing device of the present invention compared with traditional methods, multiple sets of comparative experiments were conducted for evaluation. The experimental data are shown in Table 1, illustrating the differences in surface roughness and roundness of the microspheres between the two processing methods. The microspheres obtained using the drum polishing method of Comparative Example 1 had an average roughness of 10.767 nm and a roundness of 0.757 μm, while the microspheres processed by the device of the present invention had an average roughness reduced to 1.649 nm and a roundness optimized to 0.671 μm. This result fully demonstrates that the present invention not only achieves a breakthrough in surface roughness treatment (roughness reduction of 92.8%), but also performs excellently in maintaining geometric accuracy (roundness improvement rate of 10.1%), effectively solving the batch consistency problem caused by uneven processing force in traditional drum polishing.
[0072] In this embodiment, the surface roughness of the microspheres was analyzed using data obtained from optical microscopy and white light interferometry. For surface morphology analysis, a detailed observation of the microspheres was performed using an optical microscope (500X magnification) and a white light interferometer. Direct observation with an optical microscope can identify macroscopic defects such as pits and scratches; the white light interferometer provides precise three-dimensional surface data through fringe interference scanning.
[0073] Figure 9-1 In the diagram, a represents the surface morphology defects detected in three tests of the first randomly selected sample under a 500x optical microscope after processing with a conventional drum polisher; b represents the surface morphology defects detected in three tests of the second randomly selected sample under a 500x optical microscope after processing with a conventional drum polisher; c represents the surface morphology defects detected in three tests of the third randomly selected sample under a 500x optical microscope after processing with a conventional drum polisher; d represents the surface morphology defects detected in three tests of the fourth randomly selected sample under a 500x optical microscope after processing with a conventional drum polisher; e represents the surface morphology defects detected in three tests of the fifth randomly selected sample under a 500x optical microscope after processing with a conventional drum polisher; and f represents the surface morphology defects detected in three tests of the sixth randomly selected sample under a 500x optical microscope after processing with a conventional drum polisher. Figure 9-2In the diagram, g represents the surface morphology of one face of the first sample randomly selected under a 500x optical microscope after processing by the millimeter-level drum polishing device of the present invention; h represents the surface morphology of one face of the second sample randomly selected under a 500x optical microscope after processing by the millimeter-level drum polishing device of the present invention; i represents the surface morphology of one face of the third sample randomly selected under a 500x optical microscope after processing by the millimeter-level drum polishing device of the present invention; j represents the surface morphology of one face of the fourth sample randomly selected under a 500x optical microscope after processing by the millimeter-level drum polishing device of the present invention; k represents the surface morphology of one face of the fifth sample randomly selected under a 500x optical microscope after processing by the millimeter-level drum polishing device of the present invention; and l represents the surface morphology of one face of the sixth sample randomly selected under a 500x optical microscope after processing by the millimeter-level drum polishing device of the present invention.
[0074] from Figure 9 In Figure 9-1 and Figure 9-2 As can be seen from the comparison, microspheres processed by traditional methods exhibit obvious fragmentation and detachment on their surface. These defects can cause stress concentration and affect the mechanical properties of the microspheres. In contrast, the microspheres processed by the device of this invention only show uniformly distributed tiny pits, and the defect size is controlled within an acceptable range.
[0075] Figure 10 In Figure 10-1 This is the surface morphology and roughness measured on one surface of the first sample randomly selected by white light interferometer after processing by a traditional drum polishing machine; Figure 10-2 This is the surface morphology and roughness measured on one surface of the second sample randomly selected by white light interferometer after processing by a traditional drum polishing machine; Figure 10-3 This is the surface morphology and roughness measured on one surface of the third sample randomly selected by a white light interferometer after processing by a traditional drum polishing machine; Figure 10-4 This is the surface morphology and roughness measured on one surface of the first sample randomly selected by a white light interferometer after millimeter-level drum polishing machine processing according to the present invention. Figure 10-5 This is the surface morphology and roughness measured on one surface of the second sample randomly selected by white light interferometer after millimeter-level drum polishing machine processing according to the present invention. Figure 10-6 This is the surface morphology and roughness measured on one surface of the third sample randomly selected by a white light interferometer after millimeter-level drum polishing machine processing according to the present invention.
[0076] Quantitative analysis using a white light interferometer yielded the results. Figure 10As shown, Sa refers to surface roughness. The smaller the value, the smoother the microsphere surface and the better the quality. The surface roughness curve of the microspheres processed by this invention is more gradual, and the overall Sa value is significantly lower than that of microspheres processed by traditional drum polishing machines. This advantage stems from the unique kinematic design of this invention: by optimizing the drum speed (up to 300 rpm) and introducing axial compound motion, the centrifugal force is enhanced, making the contact between the polishing medium and the microsphere surface more uniform. This avoids the problem of incomplete material removal caused by the low-speed rotation (about 175 rpm) of traditional drum polishing machines and the surface defects caused by uneven force on the microspheres.
[0077] Processing time has a particularly critical impact on microsphere quality. Too short a time will not adequately remove surface material, while too long a time will lead to over-processing. In this embodiment, experiments were conducted on different tumbler polishers and their processing times, and the results are as follows: Figure 9 and Figure 10 As shown in the figure. Experiments have verified that traditional drum polishing machines require 216 hours to reduce the roughness to approximately 10 nm, and further extending the time results in saturation; while the device of this invention can achieve an ultra-precise roughness below 1.6 nm in only 168 hours. This demonstrates that the present invention can significantly save processing time and achieve higher processing accuracy.
[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A semiconductor device polishing apparatus, characterized in that, The semiconductor element polishing apparatus includes: A roller for holding semiconductor components to be polished; the roller has a capsule-shaped cavity; A rotary drive assembly for driving the roller to rotate about the roller's axis; A linear drive assembly is used to drive the roller to make linear reciprocating movements in a direction parallel to the axis.
2. The semiconductor device polishing apparatus according to claim 1, characterized in that, The hardness of the semiconductor element to be polished is ≥7; The material of the semiconductor element to be polished is selected from at least one of silicon nitride, zirconium oxide, silicon, and ceramics; The movement trajectory of the semiconductor element to be polished in the drum is a variable diameter spiral.
3. The semiconductor device polishing apparatus according to claim 1, characterized in that, The roller has end caps I and II located at both ends of the cylinder body; The cylindrical body is connected to end cap I and end cap II respectively; End cap I and end cap II are arc-shaped bodies that bulge outward from the cylinder. The cylindrical body is connected to end cap I and end cap II via curved surfaces, respectively; The semiconductor element to be polished is a sphere, and the ratio of the radius of curvature of the transition curve of the curved surface to the diameter of the sphere to be polished is ≥10:
1.
4. The semiconductor element polishing apparatus according to claim 3, characterized in that, The semiconductor element polishing apparatus further includes a first self-centering chuck and a second self-centering chuck; The rotary drive assembly is connected to the end cover I via a first self-centering chuck; The rotary drive assembly is connected to end cap II via a second self-centering chuck; The first self-centering chuck and the second self-centering chuck have the same structure, both consisting of a rotating plate, a positioning plate, and a positioning block; The rotating plate has at least four guide rails, each with the same curvature and direction of curvature; The positioning plate has at least four through slots, each with the same curvature and direction of curvature; The curvature of the guide rail is opposite to that of the through groove. Each guide rail corresponds to one through groove, and the guide rail and the corresponding through groove intersect at one point, forming an X shape. The number of positioning blocks is the same as the number of guide rails and through slots; the positioning blocks pass through the through slots and slide along the guide rails.
5. The semiconductor device polishing apparatus according to claim 1, characterized in that, The semiconductor element polishing apparatus further includes: a support assembly for supporting the rotary drive assembly and the roller; The rotary drive assembly includes rotary drive device I and rotary drive device II; The rotary drive device I and rotary drive device II are symmetrically arranged at both ends of the drum with the drum as the center. And / or, the linear drive assembly includes a linear drive device, which drives the support assembly and correspondingly drives the rotary drive assembly and the roller to perform linear motion.
6. A polishing method, characterized in that, A method for polishing a semiconductor element to be polished using the semiconductor element polishing apparatus according to any one of claims 1-5.
7. The polishing method according to claim 6, characterized in that, The rotational speed of the roller is 70 rpm to 300 rpm; The linear reciprocating speed of the roller is 1 mm / s to 10 mm / s; The linear reciprocating movement of the roller has a stroke of 80% to 90% of the roller length.
8. The polishing method according to claim 7, characterized in that, The polishing method further includes adding polishing slurry into the drum; The polishing slurry contains SiO2 particles.
9. The polishing method according to claim 8, characterized in that, The particle size of the SiO2 particles is 80 nm to 120 nm; The concentration of SiO2 particles in the polishing slurry is 10wt% to 15wt%. The polishing slurry also includes a pH adjuster, wherein the pH of the polishing slurry is 9 to 11; The polishing slurry also includes an oxidant, which is hydrogen peroxide.
10. A polished semiconductor device obtained by any one of the polishing methods according to claims 6-9, characterized in that, The polished semiconductor element is a microsphere with a diameter of 0.8 mm to 3 mm; the roughness of the polished semiconductor element is Ra: 1.6 nm to 2.4 nm, and the roundness is 0.6 μm to 0.7 μm.