Semiconductor wafer polishing equipment and polishing method

Abstract

The present invention discloses a semiconductor wafer polishing device and a polishing method, comprising: a placement mechanism for placing a plurality of wafers; an upward throwing mechanism and a downward throwing mechanism for polishing both sides of the wafer and rotating independently of each other; and a measuring mechanism for measuring the distance between different positions of the lower end surface of the upward throwing mechanism and the corresponding positions of the upper end surface of the downward throwing mechanism; wherein the placement mechanism is built into the upper end surface of the downward throwing mechanism and is driven to rotate by the downward throwing mechanism; the upward throwing mechanism and the downward throwing mechanism can adjust the distance between each other to adjust the deformation amount of the lower end surface of the upward throwing mechanism and the deformation amount of the upper end surface of the downward throwing mechanism. The present invention can not only accurately guarantee the geometric parameters of the wafer, but also save polishing time. The polishing time for adjusting the deformation amount of a single wafer is increased by about 96%, with high polishing efficiency and high control accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor silicon wafer polishing, and in particular relates to a semiconductor wafer polishing device and a polishing method. Background Art

[0002] As the cost requirements of semiconductor wafer manufacturing are increasing, and large-area silicon wafers have advantages in terms of the number of chips produced per unit and unit cost, the size of semiconductor silicon substrates has also tended to be larger in diameter, from the earliest 2 inches and 3 inches to today's 8 inches, 12 inches and 18 inches under development. The area of ​​silicon wafers is increasing, and the geometric parameter requirements of 12-inch wafers on silicon polishing wafers are also increasing. During the wafer polishing process, how to ensure the flatness of the wafer surface, monitor the change of wafer thickness in real time, and make timely adjustments through effective and controllable polishing equipment. Summary of the invention

[0003] The present invention provides a semiconductor wafer polishing device and a polishing method, which are particularly suitable for double-sided polishing of large-size wafers. The device can not only accurately ensure the geometric parameters of the wafers, but also save polishing time. The polishing time for adjusting the deformation of a single wafer is increased by about 96%.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A semiconductor wafer polishing device, comprising:

[0006] A placement mechanism for placing a plurality of wafers;

[0007] An upward and downward polishing mechanism and a downward polishing mechanism for polishing both sides of the wafer and rotating independently of each other;

[0008] and a measuring mechanism for measuring the distances between different positions of the lower end surface of the upward throwing mechanism and corresponding positions of the lower end surface of the downward throwing mechanism;

[0009] Wherein, the placing mechanism is built into the upper end surface of the lower throwing mechanism and is driven to rotate by the lower throwing mechanism;

[0010] The distance between the upward throwing mechanism and the downward throwing mechanism can be adjusted to adjust the deformation amount of the lower end surface of the upward throwing mechanism and the deformation amount of the upper end surface of the downward throwing mechanism.

[0011] Furthermore, the placement mechanism includes an outer ring disk provided with an inner gear and a plurality of inner ring disks provided with outer gears;

[0012] The inner ring disc is placed inside the outer ring disc and meshes with the outer ring disc;

[0013] The inner ring disks are arranged to mesh with each other;

[0014] Preferably, the inner ring discs are all meshed with an axle center wheel arranged at the center of the upper end surface of the lower casting mechanism.

[0015] Furthermore, the upper throwing mechanism includes an upper throwing plate, an upper pressure plate and an upper hydraulic system placed directly above the upper throwing plate, wherein:

[0016] The upper hydraulic system increases pressure or releases pressure to control the upper pressure plate to drive the upper throwing plate to deform away from the lower throwing mechanism or to deform close to the lower throwing mechanism, so as to adjust the distance between the upper throwing plate and the upper end surface of the lower throwing mechanism.

[0017] Furthermore, the lower throwing mechanism includes a lower throwing plate, a lower pressure plate and a lower hydraulic system placed directly below the lower throwing plate, wherein:

[0018] The lower hydraulic system increases pressure or releases pressure to control the lower pressure plate to drive the lower throwing plate to deform away from the upper throwing plate or to deform closer to the upper throwing plate, so as to adjust the distance between the lower throwing plate and the lower end surface of the upper throwing mechanism.

[0019] Furthermore, the measuring mechanism comprises:

[0020] A measuring piece No. 1 for measuring the distance from one side of the inner diameter circle of the upper throwing plate to the lower throwing plate;

[0021] A second measuring piece for measuring the distance from the middle position between the inner diameter circle and the outer diameter circle of the upper throwing plate to the lower throwing plate;

[0022] and a third measurement for measuring the distance from one side of the outer diameter circle of the upper throwing plate to the lower throwing plate;

[0023] The first measuring piece, the second measuring piece and the third measuring piece are all arranged on the same side.

[0024] Furthermore, the No. 1 measuring piece is arranged on the side of the upper casting plate close to the inner diameter;

[0025] The third measuring piece is arranged on the side of the upper casting plate close to the outer diameter;

[0026] The second measuring piece is arranged between the first measuring piece and the third measuring piece and is close to one side of the third measuring piece.

[0027] A method for polishing a semiconductor wafer, using the polishing device as described in any one of the above, the steps comprising:

[0028] Collect the inner distance, middle distance and outer distance between the lower end surface of the upper throwing mechanism and the upper end surface of the lower throwing mechanism;

[0029] The inner distance, the middle distance and the outer distance are processed according to a set formula to obtain the deformation amount of the lower end surface of the upper throwing mechanism and the deformation amount of the upper end surface of the lower throwing mechanism;

[0030] The deformation amount of the lower end surface of the upward throwing mechanism and the deformation amount of the upper end surface of the downward throwing mechanism are adjusted by controlling the upward throwing mechanism and the downward throwing mechanism to be compressed or retracted.

[0031] Furthermore, the deformation amount of the lower end surface of the throwing mechanism is the difference between the inner distance and the outer distance.

[0032] Furthermore, the deformation amount of the upper end surface of the lower throwing mechanism is the difference between the middle distance and the inner and outer correction distances;

[0033] The inner and outer correction distances are the sum of the product of the outer distance and the first correction coefficient and the product of the inner distance and the second correction coefficient.

[0034] Furthermore, the sum of the first correction coefficient and the second correction coefficient is 1;

[0035] Preferably, the first correction coefficient is 0.60-0.90.

[0036] The present invention is used to design a semiconductor wafer polishing device and a polishing method, which are particularly suitable for double-sided polishing of large-size wafers. By adjusting the distance between an upper polishing mechanism and a lower polishing mechanism, the deformation amount of the lower end surface of the upper polishing mechanism and the deformation amount of the upper end surface of the lower polishing mechanism are adjusted, thereby accurately ensuring the geometric parameters of the wafer, and at the same time, the polishing time can be saved, and the polishing time for adjusting the deformation amount of a single wafer is increased by about 96%. The polishing efficiency is high, the control accuracy is high, the polishing quality of the wafer is guaranteed, the quality of the wafer is improved, and the production cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of a semiconductor wafer polishing device according to an embodiment of the present invention;

[0038] Figure 2 is a top view of a placement mechanism according to an embodiment of the present invention;

[0039] Figure 3 It is a schematic diagram of the position of the measuring mechanism on the upper throwing plate according to an embodiment of the present invention.

[0040] In the figure:

[0041] 100, placement mechanism 110, outer ring disk 120, inner ring disk

[0042] 200, upper polishing mechanism 210, upper polishing plate 220, upper polishing pad

[0043] 230, upper pressure plate 240, upper hydraulic system 241, upper connecting rod 1

[0044] 242, upper connecting rod 2 243, upper adjusting rod 1 244, upper adjusting rod 2

[0045] 245, upper hydraulic cylinder 246, upper air intake pipe 247, upper exhaust pipe

[0046] 250, polishing liquid tube group 251, polishing liquid tube 1 252, polishing liquid tube 2

[0047] 253, polishing liquid pipe 3 300, lower throwing mechanism 310, lower throwing plate

[0048] 320, lower polishing pad 330, lower pressure plate 340, lower hydraulic system

[0049] 341, lower connecting rod one 342, lower connecting rod two 343, lower adjusting rod one

[0050] 344, lower adjustment rod 2 345, lower hydraulic cylinder 346, lower air intake pipe

[0051] 347, lower exhaust pipe 350, axle wheel 400, measuring mechanism

[0052] 410, first measuring piece 420, second measuring piece 430, third measuring piece DETAILED DESCRIPTION

[0053] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] This embodiment provides a semiconductor wafer polishing device, such as Figure 1As shown, it includes: a placement mechanism 100 for placing a plurality of wafers, an upper throwing mechanism 200 and a lower throwing mechanism 300 for polishing both sides of the wafers and rotating independently of each other, a measuring mechanism 400 for measuring the distance between different positions of the lower end surface of the upper throwing mechanism 200 and the corresponding positions of the upper end surface of the lower throwing mechanism 300, and a controller for collecting and processing the measurement data of the measuring mechanism 400 and obtaining the deformation amount of the lower end surface of the upper throwing mechanism 200 and the deformation amount of the upper end surface of the lower throwing mechanism 300. Among them, the controller is a commonly used PLC controller, such as Siemens S7-200SMARTPLC, and the drawings are omitted; the controller is connected to the measuring mechanism 400, the upper throwing mechanism 200 and the lower throwing mechanism 300 respectively. The placing mechanism 100 is built into the upper end surface of the lower throwing mechanism 300 and is driven to rotate by the lower throwing mechanism 300; the upper throwing mechanism 200 and the lower throwing mechanism 300 rotate in opposite directions and at different speeds, and the upper throwing mechanism 200 and the lower throwing mechanism 300 can independently adjust the distance between the lower end surface of the upper throwing mechanism 200 and the upper end surface of the lower throwing mechanism 300 to adjust the deformation amount of the lower end surface of the upper throwing mechanism 200 and the deformation amount of the upper end surface of the lower throwing mechanism 300.

[0055] Specifically, Figure 2As shown, the placement mechanism 100 includes an outer ring disk 110 with an inner gear and a plurality of inner ring disks 120 with outer gears. The outer diameter of the outer ring disk 110 is smaller than the outer diameter of the lower throwing disk 310 in the lower throwing mechanism 300 and is placed in the upper end surface of the lower throwing disk 310. The inner ring disks 120 are a plurality of circular disks with the same structure. The inner ring disks 120 are placed inside the outer ring disk 110 and are evenly placed along the circumference of the outer ring disk 110. While the gears of the inner ring disk 120 and the outer ring disk 110 are meshed, the adjacent inner ring disks 120 are meshed with each other; and all the inner ring disks 120 are meshed with the outer gears of the shaft wheel 350 set at the center of the upper end surface of the lower throwing mechanism 300, and the shaft wheel 350 is set through the axis of the lower throwing disk 310 in the lower throwing mechanism 300. Since the outer ring disk 110 is placed on the lower throwing disk 310 and has the same rotation speed and direction as the lower throwing disk 310; the diameter of the upper throwing disk 210 in the upper throwing mechanism 200 is slightly smaller than the diameter of the lower throwing disk 310, that is, the diameter of the outer ring disk 110, and the rotation direction of the upper throwing disk 210 is opposite to that of the lower throwing disk 310 and the rotation speed of the upper throwing disk 210 is greater than the rotation speed of the lower throwing disk 310, that is, the rotation direction of the upper throwing disk 210 is opposite to that of the outer ring disk 110; the shaft wheel 350 has the same rotation direction as the lower throwing disk 310 but different rotation speeds, since the outer ring disk 110 of the shaft wheel 350 The diameter is small. In order to ensure the consistency of the operation of the central wheel 350 and the lower throwing plate 310, the rotation speed of the central wheel 350 is faster and the rotation speed of the lower throwing plate 310 is slower. It can be further known that since there is a certain speed ratio difference between the inner ring disk 120 and the outer ring disk 110 carrying the wafer, the inner ring disk 120 carrying the wafer can make planetary motion around the central wheel 350, and the upper throwing plate 210 rotates in the opposite direction relative to the lower throwing plate 310. Therefore, the wafer is rotated with the lower throwing plate 310 and is also affected by the reverse rotation of the upper throwing plate 210. At the same time, an upper polishing pad 220 is adhered to the lower end surface of the upper polishing disk 210, and a lower polishing pad 320 is adhered to the upper end surface of the lower polishing disk 310, so that the wafer is double-sided contact ground by the upper polishing pad 220 and the lower polishing pad 320 rotating in opposite directions up and down, and the double-sided surface of the wafer is chemically mechanically polished by real-time spraying of alkaline polishing liquid and SiO2 particles, thereby achieving double-sided polishing of the wafer and removing the damaged layers on both sides.

[0056] In this embodiment, the selected polishing liquid is a mixture of NaOH alkali solution and SiO2 particles. During the polishing process, NaOH plays a chemical corrosion role, converting the silicon atoms on the surface of the wafer into Na2SiO3. At the same time, the SiO2 particles have a mechanical grinding effect on the surface of the wafer. The products of these two effects continuously enter the polishing liquid, thereby achieving the polishing effect on the surface damage layer. The chemical reaction formula of polishing is:

[0057] Si+2NaOH+H2O—>Na2SiO3+2H2

[0058] like Figure 1As shown, the upper throwing mechanism 200 includes an upper throwing plate 210, an upper polishing pad 220 placed below the upper throwing plate 210, an upper pressure plate 230 placed just above the upper throwing plate 210, and an upper hydraulic system 240, wherein the upper polishing pad 220 is bonded to the lower end surface of the upper throwing plate 210, and its outer diameter is adapted to the outer diameter of the upper throwing plate 210; the upper pressure plate 230 is adjustably connected to the upper throwing plate 210. In order to ensure that the upper polishing pad 220 is completely free on the outer ring plate 110 in the placement mechanism 100 and fully and maximally covers all wafers, the outer diameter of the upper polishing pad 220 is slightly smaller than the inner diameter of the outer ring plate 110, with a single-side diameter difference of 5-10 mm. The upper pressure plate 230 is an inverted cone-shaped structure and is buckled onto the upper end surface of the upper throwing plate 210. The upper hydraulic system 240 increases or decreases pressure to control the upper pressure plate 230 to drive the outer edge of the upper throwing plate 210 to deform toward the side away from the lower throwing mechanism 300 or toward the side close to the lower throwing mechanism 300, so as to adjust the distance between the upper throwing plate 210 and the upper end surface of the lower throwing mechanism 300.

[0059] The upper hydraulic system 240 includes a plurality of upper connecting rods 241 and 242 connecting the upper pressure plate 230 and the upper throwing plate 210. An upper adjusting rod 243 and an upper adjusting rod 244 connected to their lower end faces are provided on one side close to the upper connecting rod 241 and the upper connecting rod 242. The upper adjusting rod 243 and the upper adjusting rod 244 are connected to the upper hydraulic cylinder 245. The upper hydraulic cylinder 245 is connected to an external air pump via an upper air inlet pipe 246. At the same time, the exhaust port of the upper hydraulic cylinder 245 is connected to an upper exhaust pipe 247.

[0060] Specifically, the lower end surfaces of the upper connecting rod 241 and the upper connecting rod 242 are both connected by pneumatic bolts, that is, pneumatic threads are provided on the lower end surfaces of the upper connecting rod 241 and the upper connecting rod 242, the upper connecting rod 241 is arranged close to the middle of the upper pressure plate 230, and the upper connecting rod 242 is arranged close to the outer edge of the upper pressure plate 230, the upper connecting rod 241 and the upper connecting rod 242 are respectively evenly arranged along the circumference of their positions, and the number is at least three, the purpose is to ensure the uniformity of the force in the connection between the upper pressure plate 230 and the upper throwing plate 210, and the specific number can be determined according to actual conditions.

[0061] During pressure control, the lower end surfaces of the upper adjusting rod 1 243 and the upper adjusting rod 244 are pressurized to tighten the pneumatic thread, that is, the thread moves upward and is screwed together with the upper connecting rod 1 241 and the upper connecting rod 242, so that the connection between the upper throwing plate 210 and the upper pressure plate 230 is tightened, and the upper throwing plate 210 is pulled upward, thereby increasing the distance between the outer edge and the middle area of ​​the upper throwing plate 210 and the lower throwing plate 310, thereby weakening the polishing effect of the upper polishing pad 220 and the lower polishing pad 320 on the wafer. Correspondingly, when the pressure is released and the retracted control is performed, the lower end faces of the upper adjusting rod 1 243 and the upper adjusting rod 244 are pulled to loosen the pneumatic thread, causing the thread to move downward and loosen the connection with the upper connecting rod 1 241 and the upper connecting rod 242, so that the connection between the upper throwing plate 210 and the upper pressure plate 230 is no longer tight, and the upper throwing plate 210 is rotated downward, thereby reducing the distance between the outer edge and the middle area of ​​the upper throwing plate 210 and the lower throwing plate 310, thereby enhancing the polishing effect of the upper polishing pad 220 and the lower polishing pad 320 on the wafer.

[0062] It can be further known that by adjusting the air pressure connected to the upper adjustment rod 1 243 and the upper adjustment rod 2 244, the tightness of the connection between the upper connecting rod 1 241 and the upper connecting rod 2 242 can be adjusted, and then the tightness of the connection between the upper throwing plate 210 and the upper pressure plate 230 can be adjusted, and then the distance between the upper throwing plate 210 and the lower throwing plate 310 can be adjusted, so as to adjust the polishing intensity of the upper polishing pad 220 and the lower polishing pad 320 on the wafer. According to the special way of connecting the upper throwing plate 210 and the upper pressure plate 230, a hydraulically controlled adjustment system is used for adjustment. Only the connecting rods at one side of the outer circle of the upper throwing plate 210 and the middle position of the upper throwing plate 210 need to be controlled to adjust the deformation bending direction of the upper throwing plate 210, and the adjustment can be made reciprocatingly for multiple times, with high precision and good controllability.

[0063] Furthermore, the upper throwing mechanism 200 is also provided with a plurality of pipe groups vertically penetrating the upper throwing plate 210 and the upper pressure plate 230 for the circulation of the polishing liquid and for placing the polishing liquid pipe group 250, including an inner pipe arranged near the inner circle of the center of the upper throwing plate 210, an outer pipe arranged near the outer circle of the upper throwing plate 210, and a middle pipe arranged between the inner pipe and the outer pipe and near the outer pipe. The inner pipe, the middle pipe and the outer pipe are respectively adapted to the polishing liquid pipe 1 251, the polishing liquid pipe 2 252 and the polishing liquid pipe 3 253 in the polishing liquid pipe group 250. The polishing liquid flows into the upper polishing pad 220 through the polishing liquid pipe 1 251, the polishing liquid pipe 2 252 and the polishing liquid pipe 3 253, and flows into the lower polishing pad 320 along the gap holes on the inner ring plate 120, and then completely flows into the upper and lower surfaces of the wafer, thereby achieving polishing of the damaged layers on the upper and lower surfaces of the wafer.

[0064] The polishing liquid pipe group 250 that passes through the upper polishing plate 210 and the upper pressure plate 230 is distributed according to the monitoring position of the surface geometric parameters of the wafers. This not only ensures that all wafers can be evenly soaked with polishing liquid during the polishing process, but also ensures that all polishing liquid pipes in the polishing liquid pipe group 250 are unobstructed and have good stability, thereby ensuring the consistency of the circulation of the polishing liquid; it also reduces the waste of polishing liquid and maximizes the utilization rate of the polishing liquid.

[0065] In this embodiment, polishing liquid tube 1 251, polishing liquid tube 2 252 and polishing liquid tube 3 253 are evenly arranged along the circumference of the upper polishing plate 210. Polishing liquid tube 1 251 is provided with at least three groups. Since the diameter of the circle where polishing liquid tube 2 252 and polishing liquid tube 3 253 are located is relatively large, in order to ensure the uniformity of polishing liquid distribution and circulation, the number of polishing liquid tube 2 252 and polishing liquid tube 3 253 is greater than the number of polishing liquid tube 1 251; as for the number of polishing liquid tube 1 251, polishing liquid tube 2 252 and polishing liquid tube 3 253, it can be determined according to actual conditions and is not specifically limited here.

[0066] Furthermore, the lower throwing mechanism 300 includes a lower throwing disc 310, a lower polishing pad 320 arranged on the upper end surface of the lower throwing disc 310, a lower pressure plate 330 and a lower hydraulic system 340 placed directly below the lower throwing disc 310, and an axis theory 350 that sequentially penetrates the lower pressure plate 330 and the lower throwing disc 310 and protrudes from the upper end surface of the lower throwing disc 310. Among them, the lower pressure plate 330 is adjustably connected with the lower throwing plate 310; the outer diameter of the lower polishing pad 320 is adapted to the inner diameter of the lower throwing plate 310; the lower throwing plate 310 and the axis axis 350 move in the same direction but at different speeds, and the rotation speed of the axis axis 350 is greater than the rotation speed of the lower throwing plate 310, and the axis axis 350 meshes and rotates with the inner ring plate 120 on which the wafer is placed. Since the axis axis 350 and the lower throwing plate 340 have a certain rotation speed ratio, the inner ring plate 120 carrying the wafer can rotate on the lower throwing plate 310; the lower pressure plate 330 has the same outer structure as the upper pressure plate 230, both of which are inverted cone structures. The lower hydraulic system 340 increases or releases pressure to control the lower pressure plate 330 to drive the lower throwing plate 310 to deform to the side away from the upper throwing plate 210 or to deform to the side close to the upper throwing plate 210, so as to adjust the distance between the lower throwing plate 310 and the lower end surface of the upper throwing plate 210.

[0067] Furthermore, the lower hydraulic system 400 includes a plurality of lower connecting rods 1 341 and 342 connecting the upper pressure plate 230 and the upper throwing plate 210, and a lower adjusting rod 1 343 and a lower adjusting rod 2 344 connected to their lower end surfaces are provided on one side close to the lower connecting rod 1 341 and the lower connecting rod 2 342, and the lower adjusting rod 1 343 and the lower adjusting rod 2 344 are both connected to the lower hydraulic cylinder 345; the lower hydraulic cylinder 345 is then connected to the external air pump through the lower air inlet pipe 346, and the exhaust port of the lower hydraulic cylinder 345 is connected to the lower exhaust pipe 347.

[0068] Specifically, the connection control method between the lower pressure plate 330 and the lower throwing plate 310 is the same as that between the upper throwing plate 210 and the upper pressure plate 230, that is, the upper end surfaces of the lower connecting rod 1 341 and the lower connecting rod 2 342 placed in the lower throwing plate 310 are also connected by pneumatic bolts, and the lower connecting rod 1 341 is arranged close to the middle of the lower pressure plate 330, and the lower connecting rod 2 342 is arranged close to the outer edge of the lower pressure plate 330.

[0069] During pressure control, the upper end surfaces of the lower adjusting rod 1 343 and the lower adjusting rod 2 344 are pressurized to tighten the pneumatic thread, that is, the thread moves downward and is screwed together with the lower connecting rod 1 341 and the lower connecting rod 2 342, so that the lower throwing plate 310 and the lower pressure plate 330 are tightened, and the lower throwing plate 310 is pulled downward, thereby increasing the distance between the outer edge and the middle area of ​​the lower throwing plate 310 and the upper throwing plate 210, thereby weakening the polishing effect of the upper polishing pad 220 and the lower polishing pad 320 on the wafer. Correspondingly, when the pressure is released and the retracted control is performed, the upper end surfaces of the lower adjusting rod 1 343 and the lower adjusting rod 2 344 expand to loosen the pneumatic thread, causing the thread to move upward and loosen the connection with the lower connecting rod 1 341 and the lower connecting rod 2 342, so that the connection between the lower throwing plate 310 and the lower pressure plate 330 is no longer tight, and the lower throwing plate 210 is expanded upward, thereby reducing the distance between the outer edge and the middle area of ​​the lower throwing plate 310 and the upper throwing plate 210, thereby enhancing the polishing effect of the upper polishing pad 220 and the lower polishing pad 320 on the wafer.

[0070] It can be further known that by adjusting the air pressure connected to the lower adjusting rod 1 343 and the lower adjusting rod 2 344, the tightness of the connection between the lower connecting rod 1 341 and the lower connecting rod 2 342 can be adjusted, thereby adjusting the tightness of the connection between the lower casting plate 310 and the lower pressure plate 330, and then adjusting the distance between the lower casting plate 310 and the upper casting plate 210, thereby adjusting the polishing intensity of the lower polishing pad 320 and the upper polishing pad 220 on the wafer.

[0071] like Figure 2 As shown, the measuring mechanism 400 includes: a No. 1 measuring piece 410 for measuring the distance from one side of the inner diameter circle of the upper throwing plate 210 to the lower throwing plate 310, a No. 2 measuring piece 420 for measuring the distance from the middle position between the inner diameter circle of the upper throwing plate 210 and the outer diameter circle to the lower throwing plate 310, and a No. 3 measuring piece 430 for measuring the distance from one side of the outer diameter circle of the upper throwing plate 210 to the lower throwing plate 310, wherein the No. 1 measuring piece 410, the No. 2 measuring piece 420 and the No. 3 measuring piece 430 are all arranged on the same side on the lower end surface of the upper throwing plate 210, and are all position sensors.

[0072] Furthermore, the No. 1 measuring piece 410 is arranged on the side of the upper casting plate 210 close to the inner diameter circle, the No. 3 measuring piece 430 is arranged on the side of the upper casting plate 210 close to the outer diameter circle, and the No. 2 measuring piece 420 is located between the No. 1 measuring piece 410 and the No. 3 measuring piece 430, that is, it is arranged between the inner diameter circle and the outer diameter circle of the upper casting plate 210 and close to the side of the No. 3 measuring piece 430; at the same time, in order to ensure that the No. 1 measuring piece 410, the No. 2 measuring piece 420 and the No. 3 measuring piece 430 are located for easy installation and maintenance, they are respectively placed on the lower end surfaces of the inner pipe, the middle pipe and the outer pipe where the polishing liquid tube 1 251, the polishing liquid tube 252 and the polishing liquid tube 3 253 are located, and their top view distribution is as shown in the figure Figure 3 shown.

[0073] A position sensor for monitoring the deformation of the upper throwing disc is arranged on the lower end surface of the polishing liquid pipe, which is not only convenient for installation and maintenance, but also optimizes the use space of the lower throwing disc and maximizes the structural space utilization of the upper throwing mechanism.

[0074] During the polishing process, the first measuring piece 410, the second measuring piece 420 and the third measuring piece 430 detect the distance between the upper throwing plate 210 and the lower throwing plate 310 in real time, namely, the inner distance, the middle distance and the outer distance respectively, and transmit the measured data to the controller, and the controller calculates the deformation amount of the lower end surface of the upper throwing mechanism 200, namely, the deformation amount of the upper throwing plate 210 and the deformation amount of the upper end surface of the lower throwing mechanism 300, namely, the deformation amount of the lower throwing plate 310 according to the following formula. The controller judges the deformation amount of the upper throwing plate 210 and the deformation amount of the lower throwing plate 310, and adjusts the outer edge of the upper throwing plate 210 to be pressed downward or pulled upward by controlling the upper throwing hydraulic system 240, and adjusts the outer edge of the lower throwing plate 310 to be pressed upward or pulled downward by controlling the lower throwing hydraulic system 340, thereby adjusting the distance between the upper throwing plate 210 and the lower throwing plate 310, and then adjusting the deformation amount of the upper throwing plate 210 and the deformation amount of the lower throwing plate 310.

[0075] The polishing equipment proposed by the present invention has a reasonable structural design and is fully capable of controlling the deformation of the upper polishing plate 210 and the deformation of the lower polishing plate 310, thereby controlling the geometric parameters of both sides of the wafer, especially the total thickness change GBIR, local flatness SFQR Max and edge local flatness ESFQR of the wafer are all within the qualified range, and after adjustment, multiple groups of wafers can be placed in each batch, and each batch can complete double-sided polishing within 2-3 minutes; the time used for adjusting the deformation of a single-piece single-sided polished wafer in the prior art is increased by nearly 96%; not only the polishing quality is good, the polishing efficiency is high, but also it is particularly suitable for the mass production of large-size wafers, with a high degree of automation and low production cost.

[0076] A method for polishing a semiconductor wafer, using the polishing device as described above, comprises the following steps:

[0077] Firstly, the measuring mechanism 400 measures the inner distance, the middle distance and the outer distance between the lower end surface of the upper throwing mechanism 200 and the upper end surface of the lower throwing mechanism 300.

[0078] Specifically, the first measuring piece 410, the second measuring piece 420 and the third measuring piece 430 are used in turn to measure the inner distance, the middle distance and the outer distance between the upper throwing plate 210 and the lower throwing plate 310, and the test data is transmitted to the controller of the peripheral device for collection in real time.

[0079] Secondly: the controller processes the inner distance, the middle distance and the outer distance according to the set formula and obtains the deformation of the lower end surface of the upper throwing mechanism 200 and the deformation of the upper end surface of the lower throwing mechanism 300, that is, the deformation of the upper throwing plate 210 and the deformation of the lower throwing plate 310.

[0080] Furthermore, the deformation amount of the lower end surface of the throwing mechanism 200 is the difference between the inner distance and the outer distance, that is:

[0081] The upward throwing plate shape variable Gap = inner distance - outer distance.

[0082] The deformation amount of the upper end surface of the lower throwing mechanism 300 is the difference between the middle distance and the inner and outer correction distances; wherein the inner and outer correction distances are the sum of the product of the outer distance and the first correction coefficient and the product of the inner distance and the second correction coefficient, that is:

[0083] The variable of the lower throwing plate shape SK = middle distance - (outer distance × first correction coefficient + inner distance × second correction coefficient).

[0084] The sum of the first correction coefficient and the second correction coefficient is 1, and the first correction coefficient is 0.60-0.90.

[0085] During the polishing process, the upper hydraulic system 240 in the upper throwing mechanism 200 and the lower hydraulic system 340 in the lower throwing mechanism are controlled to be compressed or retracted to adjust the deformation of the lower end surface of the upper throwing mechanism 200 and the deformation of the upper end surface of the lower throwing mechanism 300.

[0086] Specifically, when the controller monitors that the deformation variable Gap of the upper throwing plate 210 or the deformation variable SK of the lower throwing plate 310 are both smaller than the standard value, the controller controls the pressure of the upper hydraulic cylinder 245 to decrease and the pressure of the lower hydraulic cylinder 345 to increase, and the connection between the upper adjusting rod 1 243 and the upper adjusting rod 244 is loose, thereby loosening the connection between the upper throwing plate 210 and the upper pressure plate 230, and the upper throwing plate 210 is deformed downward; at the same time, the connection between the lower adjusting rod 1 343 and the lower adjusting rod 2 344 is strengthened, and both are in a tightened state, thereby strengthening the connection between the lower throwing plate 310 and the lower pressure plate 330, and the lower throwing plate 210 is deformed downward, thereby increasing the distance between the upper throwing plate 210 and the lower throwing plate 310, and thereby adjusting the deformation variable Gap of the upper throwing plate 210 or the deformation variable SK of the lower throwing plate 310 to be within the standard range, thereby ensuring that the flatness of the wafer surface is within the qualified range.

[0087] When the controller monitors that the deformation variable Gap of the upper throwing plate 210 or the deformation variable SK of the lower throwing plate 310 are both greater than the standard value, the controller controls the pressure of the upper hydraulic cylinder 245 to decrease and the pressure of the lower hydraulic cylinder 345 to reduce, and the connection between the upper adjusting rod 1 243 and the upper adjusting rod 244 is tightened, thereby strengthening the connection between the upper throwing plate 210 and the upper pressure plate 230, and the upper throwing plate 210 is deformed upward; at the same time, the connection between the lower adjusting rod 1 343 and the lower adjusting rod 2 344 is weakened, and both are in a loose state, thereby loosening the connection between the lower throwing plate 310 and the lower pressure plate 330, and the lower throwing plate 210 is deformed upward, thereby reducing the distance between the upper throwing plate 210 and the lower throwing plate 310, and thereby adjusting the deformation variable Gap of the upper throwing plate 210 or the deformation variable SK of the lower throwing plate 310 to within the standard range, to ensure that the flatness of the wafer surface is within the qualified range.

[0088] By the above method, the geometric parameters of the 12-inch wafer are detected and compared with the geometric parameters obtained by the prior art, as shown in Table 1 below:

[0089] Table 1 Lifespan data of silicon wafers at various locations in a 300mm diameter single crystal silicon rod

[0090]

[0091] As can be seen from the above, the geometric parameters of the wafer obtained by the polishing method of this embodiment are better than the polishing quality of the prior art, and the state adjustment time of the shape deformation is reduced from 60 minutes for a single wafer with two sides to 2 minutes, which is improved by about 96%. It can be seen that the change of the shape of the wafer by the different shape states of the upper throwing plate 210 and the lower throwing plate 310 is mainly based on the change of the internal and external friction strength in the diameter direction of the wafer, and then in the manufacturing process of the wafer, by adjusting the upper throwing plate deformation variable Gap value and the lower throwing plate deformation variable SK value, the optimal shape of the wafer can be obtained to achieve the purpose of high-precision processing.

[0092] The semiconductor wafer polishing device and polishing method of the present invention are particularly suitable for double-sided polishing of large-size wafers. By adjusting the distance between the upper polishing mechanism and the lower polishing mechanism, the deformation amount of the lower end surface of the upper polishing mechanism and the deformation amount of the upper end surface of the lower polishing mechanism are adjusted, thereby accurately ensuring the geometric parameters of the wafer, and saving polishing time at the same time. The polishing time for adjusting the deformation amount of a single wafer is increased by about 96%, the polishing efficiency is high, the control accuracy is high, the polishing quality of the wafer is guaranteed, the quality of the wafer is improved, and the production cost is reduced.

[0093] The above embodiments of the present invention are described in detail, and the contents are only preferred embodiments of the present invention, and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A semiconductor wafer polishing device, characterized in that: include: A placement mechanism for placing a plurality of wafers; An upward and downward polishing mechanism and a downward polishing mechanism for polishing both sides of the wafer and rotating independently of each other; and a measuring mechanism for measuring the distances between different positions of the lower end surface of the upward throwing mechanism and corresponding positions of the lower end surface of the downward throwing mechanism; Wherein, the placing mechanism is built into the upper end surface of the lower throwing mechanism and is driven to rotate by the lower throwing mechanism; The distance between the upward throwing mechanism and the downward throwing mechanism can be adjusted to adjust the deformation amount of the lower end surface of the upward throwing mechanism and the deformation amount of the upper end surface of the downward throwing mechanism; The upper throwing mechanism comprises an upper throwing plate, an upper pressure plate and an upper hydraulic system placed directly above the upper throwing plate; The lower throwing mechanism comprises a lower throwing plate, a lower pressure plate and a lower hydraulic system placed directly below the lower throwing plate; The measuring mechanism comprises: A No. 1 measuring piece for measuring the distance from one side of the inner diameter circle of the upper throwing plate to the lower throwing plate; A second measuring piece for measuring the distance from the middle position between the inner diameter circle and the outer diameter circle of the upper throwing plate to the lower throwing plate; and a No. 3 measuring piece for measuring the distance from one side of the outer diameter circle of the upper throwing plate to the lower throwing plate; Use measuring pieces No. 1, No. 2 and No. 3 to measure the inner distance, middle distance and outer distance between the upper throwing plate and the lower throwing plate.

2. A semiconductor wafer polishing device according to claim 1, characterized in that: The placement mechanism comprises an outer ring disk provided with an inner gear and a plurality of inner ring disks provided with outer gears; The inner ring disc is placed inside the outer ring disc and meshes with the outer ring disc; The inner ring disks are meshed with each other.

3. A semiconductor wafer polishing device according to claim 2, characterized in that: The inner ring discs are all meshed with the shaft center wheel arranged at the center of the upper end surface of the lower casting mechanism.

4. A semiconductor wafer polishing device according to claim 1, characterized in that: The upper hydraulic system increases pressure or releases pressure to control the upper pressure plate to drive the upper throwing plate to deform away from the lower throwing mechanism or to deform close to the lower throwing mechanism, so as to adjust the distance between the upper throwing plate and the upper end surface of the lower throwing mechanism.

5. A semiconductor wafer polishing device according to claim 1, characterized in that: The lower hydraulic system increases pressure or releases pressure to control the lower pressure plate to drive the lower throwing plate to deform away from the upper throwing plate or to deform closer to the upper throwing plate, so as to adjust the distance between the lower throwing plate and the lower end surface of the upper throwing mechanism.

6. A semiconductor wafer polishing device according to claim 1, characterized in that: The first measuring piece, the second measuring piece and the third measuring piece are all arranged on the same side.

7. A semiconductor wafer polishing device according to claim 1, characterized in that: The No. 1 measuring piece is arranged on the side of the upper casting plate close to the inner diameter; The third measuring piece is arranged on the side of the upper casting plate close to the outer diameter; The second measuring piece is arranged between the first measuring piece and the third measuring piece and is close to one side of the third measuring piece.

8. A method for polishing a semiconductor wafer, characterized in that: Using the polishing device according to any one of claims 1 to 7, the steps include: Collect the inner distance, middle distance and outer distance between the lower end surface of the upper throwing mechanism and the upper end surface of the lower throwing mechanism; The inner distance, the middle distance and the outer distance are processed according to a set formula to obtain the deformation amount of the lower end surface of the upper throwing mechanism and the deformation amount of the upper end surface of the lower throwing mechanism; The deformation amount of the lower end surface of the upward throwing mechanism and the deformation amount of the upper end surface of the downward throwing mechanism are adjusted to be within a standard range by controlling the upward throwing mechanism and the downward throwing mechanism to be compressed or retracted.

9. A semiconductor wafer polishing method according to claim 8, characterized in that: The deformation amount of the lower end surface of the upward throwing mechanism is the difference between the inner distance and the outer distance.

10. A semiconductor wafer polishing method according to claim 8, characterized in that: The deformation amount of the upper end surface of the lower throwing mechanism is the difference between the middle distance and the inner and outer correction distances; The inner and outer correction distances are the sum of the product of the outer distance and the first correction coefficient and the product of the inner distance and the second correction coefficient.

11. A semiconductor wafer polishing method according to claim 10, characterized in that: The sum of the first correction coefficient and the second correction coefficient is 1.

12. A semiconductor wafer polishing method according to claim 11, characterized in that: The first correction coefficient is 0.60-0.90.

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