Machining device for workpiece

Abstract

The present invention provides a machining device for workpieces comprising an upper rotary table support mechanism that supports an upper rotary table from above so that it can be moved vertically by a cylinder extending along a direction of a rotation axis of the upper rotary table, a horizontal plate that is attached to the cylinder such that a main surface of the latter is oriented perpendicular to a longitudinal axis of the cylinder, at least three distance sensors that measure height positions of a surface of the horizontal plate when the upper rotary table has moved downwards to a fixed position, and a control device configured to calculate a relative height position of the upper rotary table and an angle formed between the rotation axis of the upper rotary table and the longitudinal axis of the cylinder from the height positions of the surface of the horizontal plate measured by the distance sensors.Consequently, an irregularity in holding the workpiece can be accurately detected a short time before machining the workpiece in order to avoid damage to the workpiece or the machining device, and an eccentric angle of the cylinder can be detected during machining of the workpiece in order to reduce a reduction in the quality of the workpiece.

Description

TECHNICAL AREA

[0001] The present invention relates to a machining device for a workpiece, e.g. a double-sided polishing device or a double-sided lapping device, which inserts a workpiece into a holding opening of a carrier, holds the workpiece and simultaneously machines both sides of the workpiece. STATE OF THE ART

[0002] When flattening a thin sheet workpiece such as a silicon wafer, a double-sided polishing or lapping device has traditionally been used. In the double-sided polishing device, for example, a disc-shaped carrier with a planetary gear is arranged on an outer peripheral part between upper and lower rotary tables, which have polishing discs made of urethane foam or textile composites attached to them. A workpiece is held in a holding opening of this carrier; a central pinion and an inner pinion, which engage with the planetary gear, are rotated alternately, causing a rotary movement of the carrier or an orbital movement of the same around the central pinion.The rotary and orbital movements of this carrier, along with the rotation of the upper and lower turntables, cause the workpiece and the turntables to slide, simultaneously polishing both the upper and lower surfaces of the workpiece. During the polishing process, polishing compound is supplied from numerous holes in the upper turntable to ensure efficient polishing.

[0003] The upper rotary table can move up and down, and the carrier can be positioned on it in an ascending position, or the workpiece can be held in this position within the carrier. Once the workpiece is gripped, the upper rotary table moves downwards, clamping the workpiece and the carrier between the upper and lower rotary tables. Depending on the situation, the workpiece is either held manually by an operator or by an automatic handling device (see, for example, patent literature 1).

[0004] The upper turntable is moved up and down by an upper turntable support mechanism, which supports the turntable from above. This mechanism includes a cylinder with a shaft that can move up and down, and the cylinder's shaft is connected to the upper turntable via a connecting section. A universal joint or a ball bearing, for example, is used for this connecting section. This allows for a degree of freedom in the tilting of the upper turntable during the polishing process, ensuring that the load is safely transferred to the workpiece, even if the thickness of the workpiece or the substrate varies. COUNTERPOINT LIST PATENT LITERATURE

[0005] Patent literature 1: unexamined Japanese patent (Kokai) with publication number 2005-243996 REVELATION OF THE INVENTION; TASK TO BE SOLVED BY THE INVENTION

[0006] If the workpiece is polished in a condition where it is not properly held in the holder's opening—that is, in a condition where the workpiece is held irregularly—it will protrude significantly from the opening and be damaged. In this case, not only will the workpiece protruding from the holder be damaged, but other workpieces will also be damaged, or the holder itself will very likely be damaged in a chain reaction. Furthermore, the gears, polishing wheels, and rotary tables of the device may be damaged in some situations.

[0007] Consequently, yield is reduced due to damage to the workpiece, productivity is lowered due to repair work on the machining device, and costs are increased due to the replacement of damaged components of the device or the polishing wheels.

[0008] Possible causes of irregularity in workpiece holding include situations where the workpiece is not correctly inserted into the holding opening from the outset, situations where the workpiece is correctly inserted but protrudes from the holding opening due to, for example, rotation of the rotary table before the polishing process begins, and similar scenarios. It can be considered that such irregularities in holding are caused by simple operational errors when the workpiece is held manually by an operator, or by inadequate device functionality due to a failure or similar issue when the automatic operating device is used for holding, as described in patent literature 1.

[0009] The following reasons may be considered for the workpiece, which has been correctly inserted into the holding opening, protruding from the holding opening before the polishing process begins.

[0010] The workpiece is buoyed by water or paste remaining in the holding opening of the carrier placed on the lower turntable and therefore tends to protrude. More precisely, in a general double-sided polishing or lapping device, one carrier can hold one or more workpieces, and a plurality of carriers, e.g., five carriers, are typically provided in the device at equal intervals, i.e., 72° intervals. To hold the workpiece in the carrier, a target carrier within the plurality of carriers is moved to a specific workpiece holding position by rotating the inner and central pinions. The operator manually positions the workpiece to be held by the carrier at this specific holding position, or the automatic handling device positions it so that it is held by the carrier.After the wafer holding process is completed by the carrier positioned at that specific pick-up position, when the inner and central pinions are rotated 72° in the same direction, an immediately adjacent carrier is then moved to the pick-up position for the workpiece (this process can be called carrier indexing). Repeating the workpiece holding and indexing processes five times allows all five carriers to hold workpieces. Under conditions where the workpiece experiences buoyancy and therefore tends to protrude, it is possible for the workpiece to protrude from the carrier when the carrier is moved or rotated as during indexing.

[0011] In the manufacturing process of a workpiece such as a silicon wafer, for example, a double-sided lapping step or a double-sided polishing step plays an important role in adjusting the thickness or flatness of the workpiece. In particular, the need for flatness increases significantly with the miniaturization of semiconductor equipment, and its importance grows year by year.

[0012] To ensure excellent flatness or to further improve it, a load must be applied evenly to all workpieces. To achieve this, the lower rotary table must be brought into a horizontal position, while the upper rotary table must be rotated while remaining horizontal relative to the support mounted on it or the workpiece held by the support. Therefore, in addition to machine accuracy such as component accuracy or assembly accuracy, precise adjustment must be performed to ensure that the center position of the upper rotary table or the center of the cylinder coincides with the axis of rotation of the upper rotary table.

[0013] In actual operation, however, there are factors that prevent the upper turntable from rotating while held in the horizontal position. These factors include a deviation of the cylinder's center from the upper turntable's axis of rotation, or a decrease in machine accuracy over time, as described below.

[0014] A hook is located on the upper rotary table, and this hook engages in a groove provided in a middle roller when the upper rotary table moves to the downward position where the machining operation is performed. Consequently, the middle roller rotates, allowing the upper rotary table to rotate as well. The upper rotary table moves upward from the machining position at the time of loading and unloading workpieces or carriers, or during cleaning or replacement of the polishing wheels. At this point, the hook disengages from the groove in the middle roller. As described above, the insertion of the hook into the groove is repeated during continuous operation. It is possible that the adjusted center of the cylinder may deviate due to this process and a mechanical action during polishing or similar operations.

[0015] If the workpiece or support is damaged during the polishing process, various positions within the fixture will be subjected to considerable stress, and a reduction in machine accuracy is highly likely. In actual operation, the accuracy of even a perfectly calibrated machine generally decreases over time, as described above.

[0016] In particular, in a machining device with a cylinder coupled to an upper rotary table via a universal joint or a ball bearing, the deviation of the center of the cylinder or the reduction in the machine accuracy of the device often occurs in the form of an event in which an angle formed between the axis of rotation of the upper rotary table and a longitudinal axis of the cylinder (which may hereinafter be referred to as an eccentric angle of the cylinder) increases.

[0017] However, since the aforementioned reduction in machine accuracy or the cylinder center deviation is difficult to detect unless operation is stopped, frequent readjustments are problematic in terms of productivity. Therefore, if the workpiece quality has changed due to such age-related wear, it is difficult to identify the cause at an earlier stage and take corrective action.

[0018] In view of the problem described above, the object of the present invention is to provide a low-cost machining device that can accurately detect irregularities in the holding of a workpiece within a short time before machining, in order to prevent damage to the workpiece or the machining device, and that can detect irregularities in the device, such as a deviation of the center of a cylinder, during machining of the workpiece, in order to reduce a reduction in the quality of the workpiece. MEANS OF SOLVING THE TASK

[0019] To solve the problem according to the invention, a machining device for a workpiece is provided which inserts a workpiece into a holding opening of a carrier which is arranged on a lower rotary table, holds the workpiece, moves an upper rotary table downwards into a fixed position in order to clamp the carrier holding the workpiece between the upper rotary table and the lower rotary table, and simultaneously machines both sides of the workpiece while moving the upper rotary table or the lower rotary table.The device rotates the lower turntable about a rotational axis, comprising: an upper turntable support mechanism that supports the upper turntable from above so that it can be moved vertically by a cylinder extending along one direction of a rotational axis of the upper turntable; a horizontal plate attached to the cylinder such that a principal surface of the plate is oriented perpendicular to a longitudinal axis of the cylinder; at least three distance sensors that measure height positions of a surface of the horizontal plate when the upper turntable has moved downwards to the fixed position; and a control device configured to calculate a relative height position of the upper turntable and an angle formed between the rotational axis of the upper turntable and the longitudinal axis of the cylinder from the height positions of the surface of the horizontal plate measured by the distance sensors.

[0020] With such a machining device, irregularities in the workpiece's holding position can be accurately detected shortly before machining, based on a calculated relative height of the upper rotary table and an eccentric angle of the cylinder. Furthermore, irregularities in the device itself, such as the cylinder's eccentric angle (i.e., a deviation from the cylinder's center), can be detected during machining, thus reducing workpiece quality. Moreover, this can be achieved at low cost simply by adding a basic function to an existing device.

[0021] The processing device for a workpiece can be a double-sided polishing device or a double-sided lapping device.

[0022] Such a device can preferably be adapted to a manufacturing process of a workpiece such as a silicon wafer, which in particular requires a high degree of flatness.

[0023] It is preferred that the control device includes a recording medium in which the relative height position of the upper rotary table and the angle formed between the axis of rotation of the upper rotary table and the longitudinal axis of the cylinder, when the upper rotary table has moved downwards to the fixed position in a state in which the workpiece is normally held in the holding opening of the carrier, are recorded as reference values.

[0024] With such an arrangement, the irregularity in holding the workpiece or the deviation of the center of the cylinder can be easily and accurately determined using the recorded reference value.

[0025] Furthermore, it is preferred that the control device calculates at least either the relative height position of the upper rotary table and / or the angle formed between the axis of rotation of the upper rotary table and the longitudinal axis of the cylinder when the upper rotary table has moved downwards to the fixed position, and detects an irregularity in holding the workpiece if a difference between the calculated value and the reference value exceeds a threshold value.

[0026] With such an arrangement, irregularities in the holding of the workpiece can be detected automatically in a shorter time.

[0027] Furthermore, it is preferred that the control device calculates at least either the relative height position of the upper rotary table and / or the angle formed between the axis of rotation of the upper rotary table and the longitudinal axis of the cylinder during machining of the workpiece, and detects an irregularity in the device if a difference between the calculated value and the reference value exceeds a threshold value.

[0028] With such an arrangement, the eccentric angle of the cylinder can always be automatically detected during the machining of the workpiece. IMPACT OF THE INVENTION

[0029] The machining device for a workpiece according to the present invention can calculate the relative height position of the upper rotary table and the angle formed between the axis of rotation of the upper rotary table and the longitudinal axis of the cylinder from the height positions of the surface of the horizontal plate measured by the distance sensors. Therefore, any irregularity in holding the workpiece can be accurately detected quickly and cost-effectively before machining, thus preventing damage to the workpiece or the machining device. Furthermore, irregularities in the device, such as a deviation of the cylinder's center, can be continuously detected during machining, thereby reducing the reduction in workpiece quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Fig. Figure 1 is a schematic view showing a double-sided polishing device as an example of a machining device according to the present invention;

[0031] Fig. Figure 2 is a schematic view when an upper rotary plate of the double-sided polishing device according to the present invention has moved downwards to a fixed position;

[0032] Fig. Figure 3 is a schematic view when the upper rotary table of the double-sided polishing device according to the present invention has moved upwards;

[0033] Fig. Figure 4 is a schematic view showing a double-sided lapping device as an example of the machining device according to the present invention;

[0034] Fig. Figure 5 is a view illustrating an eccentric angle of a cylinder in the double-sided polishing device according to the present invention;

[0035] Fig. Figure 6 is a schematic view to illustrate a state in which a workpiece protrudes from a holding opening of a carrier in the double-sided polishing device according to the present invention;

[0036] Fig. Figure 7 is a diagram showing a change in the height position of the upper turntable when, in one example, an irregularity in wafer holding was detected; and

[0037] Fig. Figure 8 is a view to explain an eccentric amount and a misalignment amount, which are defined in the example. BEST MODE OR BEST MODES FOR EXECUTING THE INVENTION

[0038] Although one embodiment of the present invention is described below, the present invention is not limited to this embodiment.

[0039] To solve the problem described above, namely to detect both irregularities in the holding of a workpiece before machining and deviations in the center of a cylinder during machining at low cost, the present inventors have conducted investigations. As a result, they discovered that the height position of an upper rotary table and / or the eccentric angle of the cylinder could be monitored to detect irregularities in the workpiece holding. Furthermore, they found that providing three or more distance sensors that measure the height positions of a surface on a horizontal plate fixed to the cylinder allows both the relative height position of the upper rotary table and the eccentric angle of the cylinder to be obtained in real time at low cost during workpiece machining, thus completing the present invention.

[0040] The machining device for a workpiece according to the present invention will now be described in detail. The machining device according to the present invention is configured to insert a thin sheet workpiece, such as a silicon wafer, into a holding opening of a carrier arranged on a lower rotary table, to hold it, to move an upper rotary table downwards to a fixed position such that the carrier holding the workpiece is clamped between the upper and lower rotary tables, and to simultaneously machine both sides of the workpiece while the upper and lower rotary tables are rotated about their axes of rotation. For example, there is a double-sided polishing device or a double-sided lapping device. Here, the double-sided polishing device is taken as an example and described in relation to Fig. 1 described.

[0041] As in Fig. Shown in 1, it contains the double-sided polishing device 1 according to the present invention an upper turntable 2 and a lower turntable 3 , which are designed to be vertically opposite each other, and polishing discs 4 are on the turntables 2 or 3 attached. A central sprocket. 6 is on a central part between the upper turntable 2 and the lower turntable 3 provided and an inner pinion 7 is provided on a circumferential part. A retaining opening. 8 , in which a workpiece W is held, is in each carrier 5 formed. At the time of the double-sided polishing process, the carrier holds 5 the workpiece W in the holding opening 8 and is between the upper turntable 2 and the lower turntable 3 arranged in this state.

[0042] Although the workpiece W is manually placed in the carrier by an operator 5 To hold the workpiece W, a robot arm can be provided which moves the workpiece W to the holding opening. 8 of the carrier 5 transported and placed in the holding opening 8 uses.

[0043] Outer peripheral teeth of each carrier 5 engage with the respective tooth sections of the central pinion 6 and the inner pinion 7 one and the carrier 5 revolves around the central pinion 6 , while it rotates around its own axis, when the upper turntable 2 and the lower turntable 3 be rotated by a drive source not illustrated. At this point, both sides of the part in the holding opening are rotated. 8 of the carrier 5 The workpiece W is simultaneously polished by the upper and lower polishing wheels. 4polished. At the time of polishing the workpiece, polishing paste is fed from a nozzle (not illustrated) onto the polishing surfaces of the workpiece via a multitude of through-holes located in the upper rotary table. 2 are planned.

[0044] The upper turntable 2 is supported by an upper turntable support mechanism 9 Supported from above to allow vertical movement. The upper turntable support mechanism 9 has a cylinder 10 on, which extends along the direction of a rotation axis of the upper turntable 2 extends. A wave 11 , which extend downwards along the direction of the axis of rotation of the upper turntable 2 extends to a lower end of the cylinder 10 coupled and a lower end of the wave 11 is connected to a section 12 coupled. The upper turntable support mechanism 9 supports the upper turntable2 from above through this connecting section 12 . A height setting of the upper turntable 2 can be caused by upward and downward movements of the wave 11 of the cylinder 10 can be precisely controlled.

[0045] Moving the upper turntable 2 through the upper turntable support mechanism 9 downwards and a jamming of the supports 5 , each holding the workpiece W, between the upper turntable 2 and the lower turntable 3 Can a polishing load be applied to the supports? 5 and apply workpiece W. If a height setting of the upper rotary table 2 The process is controlled, and at this point the workpieces W and the carriers can be targeted. 5 The applied polishing load can be adjusted. The height position of the upper rotary table. 2, which enables the obtaining of a desired polishing load, is determined as a fixed position and the upper rotary table 2 It is moved downwards to the same fixed position each time it is polished.

[0046] As a connecting section 12 For example, a universal joint or a ball bearing can be used. Even if the thicknesses of the workpieces W or the supports vary, a degree of freedom can consequently be transferred to an inclination of the upper rotary table during the polishing process in order to safely transfer the load to the workpieces W. Fig. 2 and Fig. Figure 3 shows an example where a universal joint is used for the connecting section. 12 is used.

[0047] As in Fig. 2 shown, a turntable is located on the upper turntable 2 arranged hook 17 into a groove 19 inserted and fitted, which is in a medium roller 18is intended to be the case when the upper turntable 2 has moved downwards to the fixed position. In this state, rotational drive forces of the middle roller can be applied. 18 to the upper turntable 2 be transferred to the upper turntable 2 to turn. On the other hand, as in Fig. 3 shown, the hook 17 out of the groove 19 removed when the upper turntable 2 moved upwards from its fixed position.

[0048] As in Fig. Shown in 1, is on the cylinder 10 a horizontal plate 13 fixed and a main surface of the horizontal plate 13 is perpendicular to a longitudinal axis of the cylinder 10 At least three distance sensors 14 are above the horizontal plate 13 provided and these distance sensors 14 enable measurement of the height positions of the surface of the horizontal plate 13, when the upper turntable 2 has moved downwards to the fixed position, i.e., when the workpieces W are in the carriers 5 be held and then the carriers 5 between the upper turntable 2 and the lower turntable 3 They can get trapped, and also during the processing of the workpieces.

[0049] Although the distance sensors 14 are not particularly limited, as in Fig. 2 and Fig. As shown in Figure 3, they can be arranged so that they are at the ends of arms. 29 are held, which extend from an underside of the connecting section. 12 extend upwards. Consequently, it is possible to influence the measurement accuracy of the distance sensors. 14 through an eccentric angle of the cylinder 10 to suppress. In this case, the lengths of the arms are 29 so that distances between the distance sensors 14and the surface of the horizontal plate 13 desired values ​​can be displayed when the upper turntable is 2 has moved downwards to the fixed position, as the distance sensors 14 also with the up and down movements of the upper turntable 2 move up and down.

[0050] In the Fig. 2 and Fig. In the 3 examples shown, a main body of the cylinder moves as described above. 10 and the horizontal plate 13 not up and down, but the wave 11 of the cylinder 10 moves up and down to rotate the upper turntable 2 to move vertically. In this case, the distance sensors can 14 The sensors must be of the contact type. In particular, they are configured such that the lower ends of the distance sensors 14 in contact with the surface of the horizontal plate 13come when the upper turntable 2 has moved downwards to the fixed position. At this point, a relative height position of the upper turntable can be determined. 2 based on the measured height positions of the surface of the horizontal plate 13 and a distance by which the wave 11 The actual downward movement can be calculated. Alternatively, the measured height positions of the surface of the horizontal plate can be used. 13 than the relative height position of the upper turntable 2 be used.

[0051] If the horizontal plate 13 is configured to move together with the wave 11 of the cylinder 10 The distance sensors can move up and down. 14 They should be non-contact sensors.

[0052] Furthermore, an angle between the axis of rotation of the upper rotary table can be used. 2 and the longitudinal axis of the cylinder10 is formed (the eccentric angle of the cylinder) 10 ), from three or more height positions of the surface of the horizontal plate 13 calculated from the three or more distance sensors 14 be measured.

[0053] The machining device according to the present invention measures the height position of the upper rotary table. 2 or the eccentric angle of the cylinder 10 Not directly, but it can adjust the relative height of the upper turntable. 2 as well as the eccentric angle of the cylinder 10 from the height positions of the surface as well as the horizontal plate 13 calculate the values ​​from the three or more distance sensors 14These measurements are taken, allowing for verification during the machining of the workpieces W. Furthermore, such a machining device offers a simple configuration at a lower cost, thanks to the distance sensors. 14 are neither limited to the contact type nor the contactless type, and there is a high degree of design freedom.

[0054] The relative height position of the upper rotary table 2 and the eccentric angle of the cylinder 10 can be controlled by a control device 15 be calculated. As in Fig. As shown in 1, the control device 15 with each of the distance sensors 14 connected, receives measured height positions of the surface of the horizontal plate 13 from the distance sensors 14 , can the relative height position of the upper turntable 2 and the eccentric angle of the cylinder 10calculate and can provide this information to an operator.

[0055] If the number of distance sensors 14 With three sensors, the effect of the present invention can be sufficiently exerted, but with four or more, e.g. six distance sensors 14 They may be provided to further improve measurement accuracy.

[0056] The control device 15 indicates a recording medium 16 on, which determines the relative height position of the upper turntable 2 and the eccentric angle of the cylinder 10 , when the upper turntable 2 was moved downwards into the fixed position in a state in which the workpieces W are normally in the holding openings. 8 the carrier 5 These values ​​are recorded beforehand as the respective reference values. Here, the preferred reference value is the eccentric angle of the cylinder. 10 to record after the center of the cylinder10 is sufficiently adjusted so that the axis of rotation of the upper turntable 2 actually with the longitudinal axis of the cylinder 10 agrees.

[0057] A comparison of these recorded reference values ​​with actual measured values ​​allows for the determination of the presence or absence of an irregularity in the workpiece holding or an irregularity in the device. For example, in Fig. As shown in 6, the upper turntable can 2 in the double-sided polishing device, if the workpiece W is not properly seated in the holding opening 8 of the carrier 5 is detected when the upper turntable 2 Before the polishing process begins, the workpiece W is moved downwards to a fixed position, only to a position downwards that is higher than in a case where the workpiece W is correctly in the holding opening. 8 of the carrier 5is recorded. Furthermore, if only some of the numerous workpieces W are correctly positioned in the holding openings of the carriers. 5 Being detected causes a tilting of the upper turntable. 2 an increase in the eccentric angle of the cylinder 10 Therefore, confirmation of the relative height position of the upper turntable is possible. 2 is higher than the reference value, or whether the eccentric angle of the cylinder 10 If the value is greater than the reference value, it is a determination of the presence / absence of an irregularity when holding the workpiece.

[0058] More precisely, when the upper turntable 2 Once moved downwards to the fixed position, at least either the relative height of the upper turntable will be changed. 2 and / or the eccentric angle of the cylinder 10 , i.e., an angle θ is calculated, which is between an axis of rotation A of the upper turntable 2and a longitudinal axis B of the cylinder 10 is formed, as in Fig. Figure 5 shows that irregularity in workpiece holding is determined when a difference between the calculated value and the reference value exceeds a threshold. Furthermore, at least either the relative height position of the upper rotary table is determined. 2 and / or the eccentric angle θ of the cylinder 10 The control device calculates the value during workpiece machining and detects irregularities in the device when the difference between the calculated value and the reference value exceeds a threshold. 15 It can perform these calculations and investigations automatically.

[0059] The threshold values ​​used to determine the irregularities can, for example, be based on differences between the relative height position of the upper turntable. 2and the eccentric angle of the cylinder 10 , which are actually measured when an irregularity occurs, and are determined against the reference values. By incorporating a program into the control device that automatically triggers an alarm when the threshold values ​​are exceeded. 15 An automatic self-diagnostic function can be implemented.

[0060] It should be noted that the in Fig. The angle θ shown in Figure 5 is highlighted to clarify the explanation, but the angle θ is actually small and its change cannot be visually perceived.

[0061] Although the double-sided polishing device has been described above as an example of the machining device according to the present invention, the machining device can also be adapted to a double-sided lapping device, and the same effects as described above can be achieved.

[0062] Fig. 4 is a double-sided lapping device according to the present invention. As in Fig. As shown in section 4, the double-sided lapping device features 21 an upper and a lower turntable 22 and 23 (Läpp turntables) which are designed to be positioned opposite each other in a vertical direction. The lower turntable 23 features a central pinion 25 on an upper surface at its middle section and features an inner sprocket ring 26 on, which is provided on its circumferential part. Furthermore, a pinion part that fits into the central pinion. 25 and the inner pinion 26 intervenes on an outer peripheral surface of each carrier 24 formed, which holds workpieces W, thereby providing an overall gear structure.

[0063] A multitude of holding openings 27 is in every carrier 24The workpieces W to be lapped are positioned in the holding openings. 27 used or held in it. Each carrier 24 is between the upper and lower turntables 22 and 23 clamped and performs a planetary gear movement, i.e., a rotation and a revolution, when the lower turntable 23 rotates. At this point, a nozzle is extruded through through-holes. 28 , which are in the upper turntable 22 provided by a nozzle, paste between the workpieces W and the upper and lower rotary table 22 and 23 The material is fed in and both sides of the workpieces W are lapped.

[0064] As with the description of the double-sided polishing device, the double-sided lapping device also features 21 a horizontal plate 30 , which are attached to a cylinder 32 is fixed to an upper turntable support mechanism that secures the upper turntable22 supported from above so that it can be moved vertically, three or more distance sensors 31 , the height positions of a surface of the horizontal plate 30 measure, and a control device 15 on, which with each of the distance sensors 31 is connected. Although in Fig. 4 not shown, is the cylinder 32 with the upper turntable 22 connected via a connecting section. A relative height position of the upper turntable. 22 and an eccentric angle of the cylinder 32 can be controlled by the control device 15 from height positions of a surface of the horizontal plate 30 calculated from the distance sensors 31 be measured.

[0065] The machining device for a workpiece described above, according to the present invention, can continuously monitor the height position of the upper rotary table and the tilt of the cylinder, prevent damage to the workpieces or the machining device due to irregularities in workpiece holding, or detect irregularities in the device by monitoring the static accuracy of the upper rotary table, thereby reducing the reduction in workpiece quality. Consequently, costs for replacing materials / components due to damage to workpieces, polishing wheels, and carriers can be reduced, and downtime of the machining device can be minimized. As a result, manufacturing costs and productivity can be significantly improved. EXAMPLES

[0066] Although the present invention is now specifically described below with reference to an example and a comparative example of the present invention, the present invention is not limited thereto. (Example)

[0067] Double-sided polishing of a 300 mm diameter silicon wafer was repeatedly performed using a workpiece machining device (a double-sided polishing device) according to the procedure described in [reference to relevant document]. Fig. The present invention is shown in Figure 1. The double-sided polishing device has a total of five supports, each with a holding opening. At this time, the detection of irregularities in holding a wafer before the start of the polishing process and the accuracy of the device during the polishing process were verified.

[0068] In the double-sided polishing device, three contact-type distance sensors (manufactured by Keyence Corporation: GT-H10) were positioned above a horizontal platform in such a way that they maintained uniform distances. As in Fig. As shown in Figure 2, the height positions of the distance sensors were adjusted in such a way that they do not come into contact with a surface of the horizontal plate in a state in which an upper turntable has moved upwards, but that they do come into contact with the surface of the horizontal plate in a state in which the upper turntable has moved downwards to a fixed position. (Detection of irregularity during stopping)

[0069] A program that automatically calculates the relative height of the upper turntable and the eccentric angle of a cylinder when the upper turntable has moved downwards to the fixed position, detects an irregularity in the holding if these calculated values ​​exceed respective thresholds, and requests that a wafer be reheld, was integrated into a control device. The relative height of the upper turntable was determined as the average of three calculated values. The thresholds were determined based on the relative height of the upper turntable when the upper turntable was to be moved downwards to the fixed position in a state where the wafer was intentionally protruding from the holder's holding opening.Although the workpieces or carriers were damaged due to irregularities in wafer holding, which occurred several times a month in conventional examples, all holding irregularities were detected by the present invention. Fig. Figure 7 shows calculated values ​​of the height positions of the upper turntable when an irregularity occurred in holding the wafer. (Verification of the accuracy of the device)

[0070] An eccentric angle of the cylinder was calculated during polishing, and a position on a polishing surface, indicated by the longitudinal axis of the cylinder, was calculated from the calculated eccentric angle of the cylinder. As in Fig. As shown in Figure 8, a maximum width W of a locus of the cylinder's axis on the polishing surface was defined as an eccentricity value, and a distance d from a rotation axis of the upper turntable to the center of the locus was defined as a misalignment value. The in Fig. The 8 shown characters x and y represent the in Fig.Figure 5 shows the x and y directions. Monitoring the eccentricity and misalignment values ​​during polishing allowed for a quantitative assessment of the upper rotary table's behavior and centering accuracy. Consequently, it was possible to quickly determine whether the fixture's accuracy was the cause of wafer quality variations. Control values ​​were applied to the eccentricity and misalignment values, and a program was implemented in a control device to trigger an alarm indicating a decrease in fixture accuracy when these values ​​were exceeded. The fixture's accuracy was adjusted when this alarm was triggered. As a result, the wafer's flatness (SFRQmax) was improved by 3%.

[0071] It should be noted that the present invention is not limited to the foregoing embodiment. The foregoing embodiment is only an illustrative example, and all examples having essentially the same configuration and performing the same functions and effects as the technical concept described in the claims of the present invention are included within the technical scope of the present invention.

Claims

[1] Machining device for a workpiece, which inserts a workpiece into a holding opening of a carrier arranged on a lower turntable, holds the workpiece, moves an upper turntable downwards into a fixed position to clamp the carrier holding the workpiece between the upper turntable and the lower turntable, and simultaneously machines both sides of the workpiece while rotating the upper turntable and the lower turntable about a rotary axis, the device comprising: an upper turntable support mechanism that supports the upper turntable from above so that it can be moved vertically by a cylinder extending along one direction of a rotation axis of the upper turntable; a horizontal plate that is attached to the cylinder in such a way that a main surface of the cylinder is aligned perpendicularly to a longitudinal axis of the cylinder; at least three distance sensors that measure the height positions of a surface of the horizontal plate when the upper turntable has moved downwards to the fixed position; and a control device configured to calculate a relative height position of the upper turntable and an angle formed between the axis of rotation of the upper turntable and the longitudinal axis of the cylinder from the height positions of the surface of the horizontal plate measured by the distance sensors. [2] Machining device for a workpiece according to claim 1, wherein the machining device for a workpiece is a double-sided polishing device or a double-sided lapping device. [3] Machining device for a workpiece according to claim 1 or 2, wherein the control device comprises a recording medium in which the relative height position of the upper rotary table and the angle formed between the axis of rotation of the upper rotary table and the longitudinal axis of the cylinder, when the upper rotary table has moved downwards to the fixed position in a state in which the workpiece is normally held in the holding opening of the carrier, are recorded as reference values. [4] Machining device for a workpiece according to claim 3, wherein the control device calculates at least either the relative height position of the upper rotary table and / or the angle formed between the axis of rotation of the upper rotary table and the longitudinal axis of the cylinder when the upper rotary table has moved downwards to the fixed position, and detects an irregularity in holding the workpiece if a difference between the calculated value and the reference value exceeds a threshold value. [5] Machining device for a workpiece according to claim 3 or 4, wherein the control device calculates at least either the relative height position of the upper rotary table and / or the angle formed between the axis of rotation of the upper rotary table and the longitudinal axis of the cylinder during machining of the workpiece, and detects an irregularity on the device if a difference between the calculated value and the reference value exceeds a threshold value.