Machining device and support base

Abstract

This machining device brings a tool into contact with a rotating workpiece to thereby machine the workpiece. The machining device includes a support base for rotatably supporting the workpiece. The support base supports the workpiece on a support surface and includes at least one sensor unit for measuring a force that is applied to the support surface. With the machining device, it is possible to solve the problem of measuring a machining load in conventional machining devices.

Description

Processing device and support table

[0001] The present disclosure relates to a processing device and a support table.

[0002] There is known a processing device that contacts a tool with a workpiece fixed to a rotating support table to process the workpiece. Examples of such processing devices include grinding devices, polishing devices, cutting devices, and molding devices. Examples of grinding devices include cylindrical grinding machines and chamfering devices (Patent Document 1) for processing the edge portions of semiconductor wafers. In such a processing device, there is a desire to measure the processing load. The processing load can be an important parameter for setting conditions for precise processing of the workpiece and for tool life management.

[0003] European Patent Application Publication No. 962282

[0004] As a method for simply measuring the processing load, a method of measuring the current value of a motor that rotates the rotation axis (spindle) of the support table is known. However, this method had two problems. One is the time lag. Measuring the current value of the motor means measuring the load of the motor. The timing of the motor load and the processing load may not exactly match. The other is that it is difficult to measure minute load fluctuations. The current value during processing may include noise or the like. Noise may interfere with the measurement of minute load fluctuations. Also, if the capacity of the motor is large, minute load fluctuations may not easily appear in the current value.

[0005] As another method for measuring the processing load, a method of directly measuring by attaching a sensor to the spindle is also known. As the sensor, a torque sensor, a strain gauge, or the like is used. According to this method, there is a possibility that the processing load can be measured with higher sensitivity compared to the method of monitoring the current value of the motor. On the other hand, it is easily affected by the vibration of the spindle, and vibration may interfere with the measurement of minute processing loads. Also, attaching expensive sensors to each spindle of a processing device that processes a workpiece using a plurality of tools separately is costly and maintenance is complicated, which is a problem.

[0006] The processing apparatus of this disclosure solves at least one of the problems related to measuring the processing load in conventional processing apparatuses, as described above.

[0007] The first processing apparatus of this disclosure is a processing apparatus that processes a workpiece by bringing a tool into contact with the rotating workpiece, and comprises a support base that rotatably supports the workpiece, the support base comprising at least one sensor unit that supports the workpiece on a support surface and measures the force applied to the support surface.

[0008] The processing apparatus of this disclosure solves at least one of the problems related to measuring processing load in conventional processing apparatuses.

[0009] This is a hardware configuration diagram of the processing apparatus of Example 1. This is a plan view of the processing apparatus of Example 1. This is a side view of the processing section. This is a perspective view of the grinding table. This is a partially exploded view of the grinding table. This is a partially exploded view of the grinding table. This is a cross-sectional view of the grinding table along line A-A. This is a perspective view of the sensor unit. This is an exploded view of the sensor unit. This is a perspective view of the sensor. This is a flow chart showing the procedure for measuring the processing load. This is a functional block diagram of the controller. This is a perspective view of a modified grinding table. This is a cross-sectional view of a modified grinding table along line B-B. This is a perspective view of a modified sensor unit. This is an exploded view of a modified sensor unit. This is a perspective view of a modified sensor unit.

[0010] Hereinafter, embodiments of the processing apparatus of this disclosure will be described with reference to the drawings. Throughout all drawings, the same reference numerals will be used for the same components. Furthermore, these embodiments are merely illustrative and do not limit this disclosure in any way. The embodiments and their modifications described below can be combined in any way, and such combinations are included within the scope of this disclosure.

[0011] Figure 1 is a hardware configuration diagram of the processing apparatus of Embodiment 1, and Figure 2 is a plan view thereof. The processing apparatus 10 is a chamfering apparatus that processes the edge portion of a wafer (semiconductor wafer). Embodiment 1 is a chamfering apparatus, but the processing apparatus of this disclosure is not limited to a chamfering apparatus. Any processing apparatus that processes a workpiece by bringing a tool into contact with a rotating workpiece and has a support base that rotatably supports the workpiece is acceptable. Examples of such apparatuses include grinding apparatuses such as cylindrical grinding machines, polishing apparatuses such as CMP (Chemical Mechanical Polishing) apparatuses and buffing apparatuses, cutting apparatuses such as lathes, and molding apparatuses such as spinning machines.

[0012] The processing apparatus 10 comprises a controller 1, a transport unit 2, a measuring unit 3, a storage unit 6, and a processing unit 7. The measuring unit 3 comprises a measuring table 4 and a measuring instrument 5. The processing unit 7 comprises a grinding table 8 and a grinding wheel 9. Each part of the processing apparatus 10 is controlled by the controller 1.

[0013] The processing apparatus 10 only needs to include at least a controller 1 and a processing unit 7, and does not need to include the other hardware mentioned above, or conversely, it may include hardware other than that mentioned above. Other hardware includes a cleaning and drying unit that cleans and dries wafers, a truing unit that truing grinding wheels 9, and a dressing unit that dresses grinding wheels 9.

[0014] Controller 1 controls each part of the processing apparatus 10. Controller 1 is a computer, including a processor and memory (not shown) as hardware. The memory stores programs (instruction sets) for controlling each part. The processor can execute the instructions included in the programs and control each part of the processing apparatus 10.

[0015] Furthermore, the controller 1 may be equipped with a touch-sensitive display or the like as an input / output interface. It may also be connected to a network via a communication interface (not shown). The controller 1 and other hardware may be integrated, or they may be separated by a certain distance but connected by, for example, a cable or short-range wireless communication to form a single set, or the controller 1 may be located in a remote location and connected via the internet or satellite communication. In addition, the controller 1 may also serve as a control device for devices other than the processing device 10. For example, multiple processing devices 10 may be controlled by a single controller 1.

[0016] The transport unit 2 includes an arm 2A that can rotate and translate. The arm 2A takes out wafers W from the wafer cassette 6A of the storage unit 6, puts wafers W into storage, transfers wafers W to the measuring table 4, and transfers wafers W to the grinding table 8.

[0017] Arm 2A may be, for example, a three-axis rotating arm. Arm 2A may also be equipped with a suction pad for securing the wafer W. The suction pad is brought into contact with the back surface of the wafer W, and the wafer W is held by the arm 2A through reduced pressure suction. While holding the wafer W, arm 2A can move forward and backward, up and down, and rotate. By combining these movements, it is possible to remove the wafer W from the wafer cassette 6A, store it, and transfer the wafer W between each table. Each part of the processing apparatus 10 (transport unit 2, measuring unit 3, storage unit 6, and processing unit 7) is controlled by the controller 1.

[0018] The measurement unit 3 is equipped with a measuring instrument 5. The measurement unit 3 only needs to be equipped with one or more measuring instruments 5, and it is preferable to be equipped with multiple instruments. Examples of measuring instruments 5 include laser sensors, capacitance sensors, air microsensors, image sensors, and photoelectric sensors. The measurement unit 3 can acquire information about the shape of the wafer W, such as the size, thickness, eccentricity, and position of alignment marks (notches, orientation flats), held on the measurement table 4, using the measuring instrument 5. In particular, photoelectric sensors that irradiate the wafer W with light and receive reflected light (reflective type) or irradiate the wafer W with light and measure the obstruction of the optical path by the wafer W (transmissive type) can be used, allowing for more precise acquisition of information about the shape of the wafer W.

[0019] Measurement is performed while the wafer W is held on the measurement table 4. The timing of the measurement can be selected as appropriate. The measurement may be performed before or after processing. In particular, it is preferable to perform the measurement both before and after processing.

[0020] The measurement table 4 is a disc-shaped support base with a smaller diameter than the wafer W. The measurement table 4 uses its surface as a support surface to hold the wafer W on the support surface. The method of holding is not particularly limited, but one method is to hold it by reduced pressure adsorption. The measurement table 4 rotates around a rotation axis parallel to the Z axis by a motor or the like (not shown).

[0021] Figure 3 is a side view of the processing unit 7. The processing unit 7 includes a grinding table 8 as a support base for rotatably supporting the wafer W, which is the workpiece. It also includes a grinding wheel 9 as a tool for processing the wafer W held on the grinding table 8. The grinding table 8 holds the wafer W on its support surface, with the surface of the table 8 serving as the support surface. The method of holding is not particularly limited, but one example is holding by reduced pressure adsorption.

[0022] One typical function of the processing unit 7 is to chamfer a wafer W held on the grinding table 8 using a grinding wheel 9. Since the wafer W and the support surface of the grinding table 8 are made one unit by reduced pressure adsorption, the processing load on the wafer W can be determined by measuring the load on the support surface. In other words, the force applied to the wafer W during processing can be measured as the force applied to the support surface.

[0023] Chamfering refers to the process of forming a bevel portion that extends from the flat surface of the wafer W. Typically, it is a process that forms a semicircular or trapezoidal bevel portion in which an upper bevel extending from the upper flat surface, a lower bevel extending from the lower flat surface, and the side surface connecting them are smoothly connected. The bevel portion is formed, for example, by grinding the edge by bringing the wafer W and the grinding wheel 9, which are held on the grinding table 8, into contact with each other while rotating them. During chamfering, it is not necessary for both the grinding table 8 (i.e., the wafer W) and the grinding wheel 9 to be rotating; at least the wafer W needs to be rotating.

[0024] The wafers to be chamfered are disc-shaped, and their material and size are not particularly limited and can be appropriately selected according to the application. Examples of wafer materials include silicon, gallium arsenide, silicon carbide, gallium nitride, indium phosphide, and gallium oxide. Examples of sizes include 200 mm, 300 mm, and 450 mm. The thickness is generally 700 to 1000 μm.

[0025] The number of grinding wheels provided in the processing unit 7 does not have to be one; there may be multiple. Multiple grinding wheels may be used simultaneously or sequentially. Multiple grinding wheels may be used to chamfer a single wafer. In this case, each grinding wheel may play a different role. For example, one grinding wheel may be used for rough grinding and the other for fine grinding. From the viewpoint of improving throughput, only one grinding wheel may be used to chamfer a single wafer.

[0026] The grinding table 8 is a disc-shaped object with a smaller diameter than the wafer W. The grinding table 8 holds the wafer W on its surface and rotates it. The grinding table 8 is supported by a spindle 8A, which is the axis of rotation. The spindle 8A is rotated by a motor 8B under the control of a controller 1 according to the grinding conditions. At this time, the held wafer W also rotates together with the grinding table 8. In this example, the grinding table 8 rotates in direction 8D around axis 8C. Note that the direction of rotation (direction 8D) is just an example and can be arbitrarily changed while considering its relative relationship to the direction of rotation (direction 9D) of the grinding wheel 9 around axis 9C.

[0027] The grinding wheel 9 is supported by a spindle 9B, which is the rotation axis, and is rotated by a motor (not shown). The grinding wheel 9 is also moved independently in the XY and Z directions according to the grinding conditions under the control of the controller 1 by a position adjustment mechanism (not shown). Examples of the position adjustment mechanism include those described in paragraphs 0020 to 0021 of European Patent Application Publication No. 962282 (EP0962282(A1)) and Figure 1. This specification incorporates reference to the above application specification.

[0028] The grinding wheel 9 is disc-shaped. Grinding grooves 9A are provided on the outer circumference of the grinding wheel 9. The grinding grooves 9A are brought into contact with the periphery (edge) of the wafer W to chamfer it. Multiple grinding grooves 9A may each have the same shape or different shapes. If each grinding groove 9A has a different shape, two or more grinding grooves 9A of different shapes may be used to chamfer a single wafer. Note that the shape of the grinding wheel 9 is just an example, and there may be only one grinding groove 9A per grinding wheel 9. Also, when machining by rotating only the wafer W and bringing a non-rotating tool into contact with it, the tool does not need to be disc-shaped like the grinding wheel 9. For example, the tool may be a rod-shaped cutting tool.

[0029] The type of grinding wheel 9 is not particularly limited. As an example, a metal-bonded grinding wheel can be used, in which abrasive grains made of metal and / or inorganic compounds are held by a binder mainly composed of metal. As another example, a resin-bonded grinding wheel can be used, in which abrasive grains are held by a binder mainly composed of resin.

[0030] Examples of abrasive materials include alumina, silicon carbide, boron nitride, and diamond. One type of these abrasive material may be used in the grinding wheel, or a combination of several may be used.

[0031] Next, the structure of the grinding table 8 will be described in detail. Figure 4 is a perspective view of the grinding table. Figures 5 and 6 are exploded views of the grinding table, and Figure 7 is a cross-sectional view of the grinding table along line A-A.

[0032] The grinding table 8 comprises a disc-shaped base plate 20, side walls 21 fixed to the outer circumference of the base plate 20, and a disc-shaped chuck plate 22 placed on the side walls 21. The chuck plate 22 constitutes the support surface of the grinding table 8. The wafer W is supported on the chuck plate 22.

[0033] The outer diameters of the base plate 20, sidewall 21, and chuck plate 22 are approximately the same, and the sidewall 21 is positioned along the outer circumference of the base plate 20, so that the sidewall 21 rises up like a wall from the edge of the base plate 20. The centers of the base plate 20, sidewall 21, and chuck plate 22 coincide, and this center is the axis of rotation of the grinding table 8. The sidewall 21 may be integrated with the base plate 20 or the chuck plate 22.

[0034] An opening 23, which is the outlet for the decompression path 40, is provided at the center of the chuck plate 22. A first groove 24A extends radially from the opening 23 to the surface of the chuck plate 22. Furthermore, multiple second grooves 24B of different diameters intersect the first groove 24A in a concentric pattern around the opening 23. The first groove 24A and the second grooves 24B form a spiderweb-like groove on the surface of the chuck plate 22, centered on the opening 23. With this structure, when a wafer W is placed on the surface of the chuck plate 22, the opening 23, the first groove 24A, and the second grooves 24B are decompressed, and the wafer W is attracted to the chuck plate 22. At this time, it is preferable that the positions of the wafer W and the rotation axis of the chuck plate 22 are adjusted so that they coincide.

[0035] As shown in Figure 5, the chuck plate 22 has three through holes 26 that penetrate in the thickness direction. Each of the through holes 26 is a counterbore. There are three through holes 26 in the chuck plate 22, and they are spaced at equal intervals of 120°. The through holes 26 are also equidistant from the center of the chuck plate 22 and are located outside the halfway point when viewed radially.

[0036] A flat-head bolt 25 is inserted into the through-hole 26. The flat-head bolt 25 is a partially threaded bolt with threads cut into its tip. The sensor unit body 30A, fixed to the base plate 20, is positioned directly below the through-hole 26. The sensor unit body 30A is positioned so as to contact the chuck plate 22 from the back side of the chuck plate 22. The flat-head bolt 25 passes through the sensor unit body 30A and is fastened to a nut 60D located on the underside of the sensor unit body 30A. In this way, the chuck plate 22 is fixed to the base plate 20 via the sensor unit body 30A. Details of this structure will be described later.

[0037] Furthermore, since the through-hole 26 is a counterbore, when the chuck plate 22 is (indirectly) fixed to the base plate 20 by the flat-head bolts 25, the heads of the flat-head bolts 25 do not protrude from the surface of the chuck plate 22. In order to adsorb the wafer W onto the chuck plate 22 under reduced pressure, it is preferable that the height of the heads of the flat-head bolts 25 be the same as or lower than the height of the chuck plate 22 when viewed from the side. By making the through-hole 26 a counterbore, the height of the flat-head bolts 25 can be easily adjusted.

[0038] Figure 6 shows the internal structure of the grinding table 8 with the chuck plate 22 removed. Three sensor unit bodies 30A are fixed on the base plate 20. Each sensor unit body 30A is composed of three torus-shaped sensors (force sensors) for load measurement, two sensor mounts, etc. Details of the structure of the sensor unit body 30A will be described later.

[0039] The sensor unit bodies 30A are arranged at equal intervals of 120° in the circumferential direction of the base plate 20. Each sensor unit body 30A is positioned directly below the through hole 26, in a location where a flat-head bolt 25 can be inserted into the central opening of the torus-shaped sensor, which will be described later. In other words, the sensor unit bodies 30A are positioned directly below the through hole 26, such that the central opening of the torus-shaped sensor communicates with the through hole 26.

[0040] A transmission board 31 for transmitting sensor data to the controller 1 and a power supply unit 32 for supplying the necessary power to each part are arranged on the base plate 20. The power supply unit 32 includes a coil for receiving power wirelessly from the main body of the processing unit 7. The method of receiving power wirelessly from the main body is not particularly limited, and known methods such as electromagnetic induction, magnetic field resonance, and rotary transformer can be used. In this example, the power supply unit 32 uses either electromagnetic induction or magnetic field resonance and is formed in a ring shape with a common center with the center of the base plate 20. The shape and arrangement of the power supply unit are not limited to the above and can be appropriately changed depending on the method of power transmission and reception. The power supply unit may also include a battery, or if an electric field coupling method is adopted, it may include electrodes.

[0041] Furthermore, the base plate 20 is provided with a cylindrical support portion 33 fixed to and integrated with the base plate 20 at its center, and a rubber V-shaped ring 34 fixed along the peripheral wall of the upper part of the support portion 33. The V-shaped ring 34 swingably supports the chuck plate 22 and also has the function of airtightly separating the decompression path 40 from the atmospheric environment. A spindle 8A (not shown) is coupled to the back surface of the base plate 20, and the rotational force of the motor 8B is transmitted to the grinding table 8 via the base plate 20, which is integrated with the support portion 33.

[0042] Figure 7 is a cross-sectional view of the grinding table 8 along line A-A. A pressure reduction path 40 is formed within the support portion 33. The pressure reduction path 40 is connected to a pressure reduction mechanism such as a pump (not shown) via a lower port 40B. A V-shaped ring 34 is fixed to the upper end of the support portion 33. The lip portion of the V-shaped ring 34 is in contact with the back surface of the chuck plate 22. When the chuck plate 22 is tightened to the base plate 20 with flat-head bolts 25, the V-shaped ring 34 deforms and comes into close contact with the chuck plate 22, creating an airtight connection between the opening 23 of the chuck plate 22 and the pressure reduction path 40. As a result, the opening 23 functions as the outlet of the pressure reduction path 40. Furthermore, since the V-shaped ring 34 is an elastic body and only pivots to fix the chuck plate 22, it does not interfere with measurements by the sensor unit including the flat-head bolts 25, making it possible to measure even smaller load fluctuations.

[0043] Incidentally, in this embodiment, the chuck plate 22 that is the support surface of the workpiece is swingably supported (by the base plate 20) at the end of the decompression path 40 via a V-shaped ring 34 that is an elastic body. This V-shaped ring 34 is an example of an elastic body, and its shape is not limited to the above. For example, O-rings, tubes, blocks made of rubber or silicone, and coil springs made of metal or resin can also be used. At this time, from the viewpoint of partitioning the decompression path 40 airtightly from the atmospheric pressure environment, it is preferable to use, as the elastic body, rubber having airtightness, and tubes, packings, rings, gaskets, seals, bushings, etc. made of elastomers such as silicone. On the other hand, when using, as the elastic body, a coil spring made of metal or the like that does not have airtightness, it is preferable to separately ensure airtightness by passing a tube made of an elastomer or the like inside or outside thereof and connecting the decompression path 40 and the opening 23 airtightly.

[0044] Next, the structure of the sensor unit 30 and the details of the fixing method to the base plate 20 will be described using FIGS. 7 to 10. FIG. 8 is a perspective view of the sensor unit 30 composed of the sensor unit main body 30A and the flat head bolt 25. FIG. 9 is an exploded view of the sensor unit 30. FIG. 10 is a perspective view of the sensor 50 included in the sensor unit 30.

[0045] The sensor unit main body 30A is mainly a combination of a sensor mount and a sensor. The sensor unit main body 30A includes, as a sensor mount, two types of L-shaped sensor mounts arranged adjacent to each other radially from the center of the base plate 20 (chuck plate 22). The first L-shaped sensor mount 60 on the center side of the base plate 20 includes a base portion 60A that is a flat pedestal for arranging the sensor, and a flat wall portion 60B that rises along the Z-axis direction from the radially outer end of the base portion 60A and holds the sensor on the side surface.

[0046] On the flat wall portion 60B side of the first L-shaped sensor mount 60, a second L-shaped sensor mount 61 is arranged. The second L-shaped sensor mount 61 includes a flange portion 61A for fixing the second L-shaped sensor mount 61 itself to the base plate 20, and a flat wall portion 61B that rises along the Z-axis direction from the end portion on the center side of the chuck plate 22 of the flange portion 61A and holds a sensor on the side surface. The second L-shaped sensor mount 61 is fixed to the base plate 20 such that the flat wall portion 61B faces the flat wall portion 60B. The second L-shaped sensor mount 61 is fixed to the base plate 20 with bolts inserted into the flange portion 61A from the back surface of the base plate 20.

[0047] The sensor unit main body 30A includes a sensor 50 for measuring load in the X-axis direction, a sensor 51 for measuring load in the Y-axis direction, and a sensor 52 for measuring load in the Z-axis direction. Each sensor is fixed to the sensor mount such that the direction of the force to be measured is different, but the sensors are the same as sensors. It is not necessary to use the same sensor, but even if the functions are different, if the shapes of the sensors are the same, maintenance and assembly are easier, and the sensor unit can be made more space-saving.

[0048] As shown in FIG. 10, the sensor 50 is a force sensor having a toroidal (sometimes called washer-shaped or doughnut-shaped) structure with a circular opening 50A in the center. Such sensors are known, and those capable of measuring compressive / tensile load or shear load with respect to the measurement surface 50B are known. The sensors used in this embodiment are all crystal piezoelectric sensors capable of measuring shear load with respect to the measurement surface. As already described, the sensors 50, 51, and 52 in this example are sensors having the same structure for detecting shear load with respect to the measurement surface, only the measurement directions of the forces at the respective measurement surfaces 50B, 51B, and 52B are different.

[0049] Sensor 50 is for measuring the load in the X-axis direction, and sensor 51 is for measuring the load in the Y-axis direction. The X-axis and Y-axis directions are directions along the surface of the chuck plate 22, which is the support surface. Therefore, sensors 50 and 51 are sensors that measure the component of the force applied to the chuck plate 22 (support surface) during machining, in the direction along the support surface. The sensor unit 30 may be equipped with multiple sensors for measuring in the X-axis direction and the Y-axis direction, or it may be further equipped with sensors for measuring loads in directions other than those mentioned above in the XY plane.

[0050] Sensors 50 and 51 are placed on the base portion 60A of the first L-shaped sensor mount 60. At this time, the through hole 60C provided to penetrate the base portion 60A in the thickness direction, the openings 50A and 51A, and the through hole 26 of the chuck plate 22 are arranged to communicate to form a communication hole. The flat-head bolt 25 is inserted through this communication hole and fixed from the back surface of the first L-shaped sensor mount 60 with a nut 60D. Note that the arrangement of sensors 50 and 51 may be sensor 51, then sensor 50 from the chuck plate 22 side.

[0051] By inserting a flat-head bolt 25 through the communication hole formed by the interconnection of the through-hole 26, openings 50A and 51A, and through-hole 60C, and tightening it with a nut 60D from the bottom of the first L-shaped sensor mount 60, the lower surface of the chuck plate 22 and the measuring surface 50B of the sensor 50 come into close contact. Similarly, the lower surface of the sensor 50 and the measuring surface 51B of the sensor 51 come into close contact. The length of the flat-head bolt 25 is adjusted to ensure that the chuck plate 22, sensor 50, sensor 51, and the first L-shaped sensor mount 60 come into close contact when tightened with the nut 60D, taking into account the respective thicknesses of these components. In this case, the first L-shaped sensor mount 60 itself is directly fixed to the chuck plate 22, but not directly fixed to the base plate 20.

[0052] On the other hand, sensor 52 is for measuring load in the Z-axis direction. The Z-axis direction is the direction in which the chuck plate 22, which is the support surface, faces. Therefore, sensor 52 is a sensor that measures the component of the force applied to the chuck plate 22 (support surface) during processing in the direction in which the support surface faces. In particular, in wafer chamfering, when processing the upper bevel surface of the bevel portion, the grinding wheel 9 contacts the wafer W from above, so a downward processing load along the Z axis tends to be generated. Conversely, when processing the lower bevel surface, an upward processing load along the Z axis tends to be generated. The Z-axis sensor 52 can measure both of these.

[0053] The sensor 52 is held between the flat wall portion 60B of the first L-shaped sensor mount 60 and the flat wall portion 61B of the second L-shaped sensor mount 61. The flat wall portions 60B and 61B are planar in order to hold the sensor between them, and are both parallel to the Z-axis direction, and furthermore, the planes (flat wall portions) are also parallel to each other.

[0054] The sensor 52 is positioned between the flat wall portion 60B and the flat wall portion 61B with its measuring surface 52B facing the flat wall portion 60B. At this time, the through hole 61C provided in the flat wall portion 61B, the opening 52A of the sensor 52, and a screw receiving portion (not shown) provided in the flat wall portion 60B are adjusted to communicate and form a communication hole. A bolt 61D is inserted through the communication hole from the through hole 61C side and screwed into the screw receiving portion, fixing the first L-shaped sensor mount 60, the sensor 52, and the second L-shaped sensor mount 61 in that order from the center side of the base plate 20. The measuring surface 52B of the sensor 52 is fixed in close contact with the outer plane of the flat wall portion 60B of the first L-shaped sensor mount 60. With this configuration, the first L-shaped sensor mount 60 is fixed to the second L-shaped sensor mount 61 with the sensor 52 for detecting load in the Z-axis direction sandwiched in between. As a result, the first L-shaped sensor mount 60 is indirectly fixed to the base plate 20 via the second L-shaped sensor mount 61.

[0055] Since sensors 50, 51, and 52 can measure the shear load on the measurement surfaces 50B, 51B, and 52B, respectively, the sensor unit 30 configured as described above can be used to measure the X-axis, Y-axis, and Z-axis components of the load applied to the chuck plate 22, which is fixed via flat-head bolts 25. As already explained, since the wafer W is held by the chuck plate 22, the processing load on the wafer W can be determined by measuring the load fluctuations on the chuck plate 22.

[0056] The sensor unit 30 in this embodiment uses a torus-shaped sensor that measures loads in the X-axis, Y-axis, and Z-axis directions as shear force. Therefore, it is necessary to position the sensor 52 for measuring the load in the Z-axis direction vertically (positioning the opening 52A in the direction along the Z-axis). By using a combination of two types of L-shaped sensor mounts, fixing the sensor 52 becomes easier.

[0057] The sensor unit 30 is equipped with one sensor each for detecting load in the X, Y, and Z axes, but it may also be equipped with two or more sensors for any one of the directions, or for all directions. Furthermore, the sensor mount does not need to be L-shaped. In the case of using a torus-shaped sensor that detects load as shear force, as in this embodiment, it is preferable that the sensor mount consists of at least two sensor mounts.

[0058] Furthermore, it is preferable that each sensor mount has a plane parallel to the Z-axis (the direction in which the support surface faces). In addition, it is preferable that each sensor mount has a section for fixing the sensor mount itself to either the base plate 20 or the chuck plate 22. In this embodiment, the section for fixing the sensor mount itself refers to the through hole 60C and nut 60D of the first L-shaped sensor mount 60, the flange portion 61A of the second L-shaped sensor mount 61, and the bolt for fastening the flange portion 61A to the base plate 20.

[0059] Furthermore, it is preferable that one or more of the sensor mounts have a surface parallel to the XY plane (the direction along the support surface). In this embodiment, this corresponds to the base portion 60A. Furthermore, it is preferable that these sensor mounts are fixed to each other with their surfaces parallel to the Z axis facing each other, and a torus-shaped sensor for measuring load in the Z-axis direction sandwiched between them. Furthermore, it is preferable that one of these sensor mounts is fixed to the base plate 20 but not directly fixed to the chuck plate 22, and the other sensor mount is fixed to the chuck plate 22 but not directly fixed to the base plate 20. Furthermore, it is preferable that at least one of the sensor mounts has a surface parallel to the XY plane, and that a torus-shaped sensor for measuring load in the X-axis direction and the Y-axis direction is placed and fixed thereon.

[0060] In general terms, a preferred example is a sensor unit comprising a combination of multiple sensors and multiple sensor mounts, wherein the multiple sensors include sensors for measuring load in a direction along the support surface and sensors for measuring load in a direction facing the support surface, one of the sensor mounts is fixed to a base plate and the other of the sensor mounts is fixed to a chuck plate, at least one of the sensor mounts has a planar base portion along the support surface, the base portion holds the sensor for measuring load in a direction along the support surface in close contact with either the base plate or the chuck plate, and the multiple sensor mounts preferably have planar flat wall portions parallel to the direction facing the support surface, and the opposing flat wall portions preferably fix each other in close contact, sandwiching the sensor for measuring load in the direction facing the support surface.

[0061] In the following explanation, a sensor mount having a planar base portion that conforms to the support surface, that is, a sensor mount on which sensors in the X-axis direction and / or Y-axis direction are mounted, is referred to as a main mount. Sensor mounts that do not have this feature are referred to as sub-mounts. A sensor unit includes multiple sensor mounts, and at least one of them only needs to be a main mount. The other may be a sub-mount or a main mount.

[0062] In particular, in terms of being able to arrange the necessary sensors in a more space-saving manner, it is preferable that the sensor mount consists of one main mount and one or more sub-mounts. The main mount (in this embodiment, the first L-shaped sensor mount 60) preferably has a plane parallel to the XY plane for arranging torus-shaped sensors for load detection in the X and Y axes, and a plane parallel to the Z axis, and is preferably directly fixed to either the chuck plate 22 or the base plate 20, but not directly fixed to the other.

[0063] The submount (the second L-shaped sensor mount 61 in this embodiment) has a plane parallel to the Z-axis direction and includes a section (flange portion 61A and fastening bolts in this embodiment) for fixing the submount itself to the base plate 20 or the top plate, and is preferably directly fixed to either the chuck plate 22 or the base plate 20, but not directly fixed to the other.

[0064] Furthermore, it is preferable that a sensor for detecting load components in the Z-axis direction is sandwiched and held between the main mount and the submount, and that the main mount, sensor, and submount are fixed to each other. In other words, it is preferable that the main mount and submount are each directly fixed to either the base plate 20 or the chuck plate 22, but not directly fixed to the other, and that the main mount and submount hold a sensor for measuring load in the Z-axis direction sandwiched between them in close contact with a plane parallel to the Z-axis, and that they are fixed to each other.

[0065] In this embodiment, the first L-shaped sensor mount 60 (main mount) and the second L-shaped sensor mount 61 are each made of metal and integrally molded, but they may be composed of two or more parts. For example, the base portion 60A and the flat wall portion 60B may be separate parts.

[0066] In this embodiment, the main mount fastens the sensor 50 in the X-axis direction, the sensor 51 in the Y-axis direction, and the chuck plate 22, while the sub-mount fastens the main mount, the sensor 52 in the Z-axis direction, and the base plate 20. However, the configuration of the sensor unit is not limited to the above, and the main mount may be fastened to the base plate 20 instead of the chuck plate 22, and the sub-mount may be fastened to the chuck plate 22 instead of the base plate. This configuration will be described later as a modified example.

[0067] Furthermore, the number of main mounts and submounts included in the sensor unit is not limited to the above. It can be appropriately changed depending on the number of sensors included in the sensor unit. For example, if there are four sensors for measuring load in the XY plane (typically sensors for measuring in the X-axis direction and the Y-axis direction), there may be two main mounts, and the sensor for measuring load in the Z-axis direction can be held between these two main mounts. In this way, the sensor mount may be composed of multiple main mounts. Each main mount may hold both the sensor for measuring load in the X-axis direction and the sensor for measuring load in the Y-axis direction, or one main mount may hold the sensor for measuring load in the X-axis direction and the other main mount may hold both the sensor for measuring load in the Y-axis direction, or one main mount may hold the sensor for measuring load in the X-axis direction and the sensor for measuring load in the Y-axis direction, and the other main mount may not hold these sensors. In other words, even if the shape is that of a main mount, it may be used as a sensor mount to achieve the same function as a submount.

[0068] Furthermore, the method of fixing the main mount and sub-mount to the base plate and chuck plate is not limited to the form specifically shown in this embodiment. In this example, the first L-shaped sensor mount 60 is fixed to the chuck plate 22 by flat-head bolts 25, but for example, the first L-shaped sensor mount 60 can also be fixed using a chuck plate 22 that has one or more pillar members extending downward along the Z-axis from the back surface, such that the chuck plate 22 and the flat-head bolts 25 are integrated into one part. If threads are cut into the lower part of these pillar members in the same way as the flat-head bolts 25, it can be directly combined with the sensor unit body 30A in this embodiment. In this case, the chuck plate with pillar members functions as both a support surface and part of the sensor unit.

[0069] Alternatively, the second L-shaped sensor mount 61 may be fixed to the chuck plate 22, and the base plate 20 may be fitted with the pillar member described above. The desired effect can be obtained by inserting the pillar member through the opening of the torus-shaped sensor and bringing the measuring surface of the sensor into direct or indirect contact with the back surface of the chuck plate 22.

[0070] In addition, torus-shaped sensors other than quartz piezoelectric sensors can be used. For example, strain gauge type, piezoelectric type using piezoelectric materials other than quartz, and capacitive type sensors can be used. Among these, piezoelectric sensors have excellent characteristics such as fast response speed, the ability to measure minute loads, and high durability. Furthermore, quartz piezoelectric sensors have several excellent characteristics when applied to processing equipment, derived from the properties of quartz as a piezoelectric material. One is that the fluctuation of piezoelectric properties due to temperature changes is small. The grinding table 8 is equipped with a power supply unit 32 that receives wireless power from the main body. The coil of the power supply unit 32 may generate heat during use. If this heat is transferred to the sensor, it usually affects the measurement value in some way. However, due to the properties of quartz as a piezoelectric material, the quartz piezoelectric sensor is less affected by temperature changes in the measurement result. While it is convenient to use the power supply unit 32 to supply power to the rotating grinding table 8, it is necessary to consider the effect of heat generation, but quartz piezoelectric sensors are superior as a countermeasure against thermal drift of the sensor. Furthermore, because quartz is hard and highly durable, and its piezoelectric properties remain stable over the long term, it is suitable for processing equipment that requires stable operation over long periods in environments with heavy processing loads and high temperatures.

[0071] In this embodiment, the sensor unit 30 is configured such that a sensor 50 for the X-axis direction and a sensor 51 for the Y-axis direction are fixed to a first L-shaped sensor mount 60, and a sensor 52 for the Z-axis direction is fixed between the first L-shaped sensor mount 60 and the second L-shaped sensor mount 61, and all of them measure the load components in each direction as shear force. However, torus-shaped sensors that can measure compression and / or tensile force are also known, and by combining these, it is possible to form a sensor unit that measures three-axis loads in a smaller space. For example, if a sensor that measures compression / tensile load is used to detect the component in the Z-axis direction, a sensor unit that measures three-axis loads can be realized by stacking three sensors on the first L-shaped sensor mount 60 (main mount). In other words, sensors measuring the X-axis component as shear force, sensors measuring the Y-axis component as shear force, and sensors measuring the Z-axis component as compression / tensile force can be stacked on the back surface of the chuck plate 22 in any order, and fastened together with flat-head bolts 25, as in this embodiment. In this case, the main mount may also be directly fixed to the base plate 20. This configuration allows for the measurement of the X, Y, and Z components of the machining load in a simpler structure and in a smaller space.

[0072] On the other hand, one advantage of using a sensor that measures the load as shear force for measurement in the Z-axis direction, as in this embodiment, is that it reduces the influence of temperature changes on the measured value and allows for the measurement of smaller loads. The inventors have experimentally found that sensors that measure the load as compressive / tensile force (sensors using an X-cut quartz element in the case of a quartz piezoelectric type) have the characteristic that the thermal expansion and contraction of the sensor housing itself due to temperature changes is output as a small electric charge. On the other hand, the inventors have also experimentally found that sensors that measure the load as shear force (sensors using a Y-cut quartz element in the case of a quartz piezoelectric type) have the characteristic that they do not emit an electric charge even if the sensor housing expands / contracts thermally in a direction parallel to the measurement surface. Therefore, by using a sensor that measures the load as shear force for measuring the load in the Z direction, even small loads can be measured more accurately without being obscured by thermal drift.

[0073] Another advantage of using a torus-shaped sensor is that it is easier to fix the sensor in place. In this embodiment, the sensor unit is assembled in a simple way that saves space and uses fewer parts: the sensors 50 and 51 are sandwiched between the sensor unit body 30A on the base plate 20 and the chuck plate 22, and these are fastened together with flat-head bolts 25.

[0074] As shown in Figure 6, in this embodiment, three sensor units 30 are arranged at equal intervals of 120° along the circumferential direction of the base plate 20 (the rotation direction of the grinding table 8). Each of the sensor units 30 includes a sensor 50 for measuring the X-axis component of the load fluctuation on the chuck plate 22, a sensor 51 for measuring the Y-axis component, and a sensor 52 for measuring the Z-axis component. Therefore, one of the sensor units 30 can measure the load in three directions: the X-axis, Y-axis, and Z-axis. Thus, even if there is only one sensor unit 30, it can function for load measurement.

[0075] One advantage of having multiple sensor units 30 as in this embodiment is that it can cancel out the effects of temperature changes on the measured values ​​and calculate more accurate final results. The grinding table 8 is equipped with a non-contact power supply unit 32 near the center of rotation. The inventors have experimentally discovered that the power supply unit 32 generates heat when it receives power from the main body of the processing unit 7, causing thermal expansion (or thermal contraction) of each component constituting the grinding table 8. At this time, the inventors have also found that concentric thermal expansion occurs in the chuck plate 22, and this is measured as a load in the X-axis direction, the Y-axis direction (direction along the support surface), and the Z-axis direction (direction facing the support surface). This load can be reduced by using materials with low thermal expansion (such as Invar material or cordierite ceramics) for the chuck plate 22, base plate 20, etc. However, in this embodiment, by combining the measured values ​​in the corresponding directions of multiple sensors arranged at equal intervals in the rotation direction, the effects of thermal expansion are canceled out, making it possible to measure even smaller loads.

[0076] When combining sensor measurements, it is preferable to use two or more sensors, and their arrangement should be at equal intervals in the rotational direction of the chuck plate 22, relative to the center of the chuck plate 22. Thermal expansion / contraction may cause stress in the circumferential, radial, and thickness directions of the chuck plate 22, but combining the measurements of multiple sensors can minimize the impact on the measurement values. Such combination methods are well known and can be appropriately selected depending on the number and arrangement of sensors. In particular, if multiple sensor units are arranged at equal intervals in the rotational direction relative to the rotation axis (center of rotation) of the chuck plate 22, the combination becomes easier and the resulting measurement results become more accurate.

[0077] It is preferable that the radial position of each sensor from the center of rotation is the same. In particular, when the power supply unit 32 is ring-shaped including a coil and is located near the center of rotation, it is preferable that the position of the flat-head bolt 25 (sensor unit 30) be as far away as possible from it, specifically on the outer circumference of the chuck plate 22. Specifically, it is preferable that it be outside half (0.5) of the radius of the chuck plate 22. There are further advantages to arranging the sensor unit 30 on the outer circumference of the chuck plate 22, which are particularly noticeable in chamfering devices. This is that the sensor can be installed closer to the machining point (point of application). In a chamfering device, the machining point of the workpiece is near its outer circumference. In other words, the point of application is near the outer circumference of the support surface. In this case, if the sensor unit 30 is located further away from the point of application, near the center of the chuck plate 22, the load may act as a moment when transmitted to the measurement point. In contrast, if a sensor unit is located on the outer circumference, closer to the machining point, it is easier to measure the machining load more directly. On the other hand, as shown in the modified example described later, there are also advantages to arranging the sensor unit 30 near the center. Therefore, the position and number of sensor units 30 can be appropriately determined depending on the application and purpose.

[0078] The number of sensor units on the grinding table 8 is not particularly limited, but 1 to 10 is preferred, 2 to 5 is more preferred, and 3 is even more preferred. In particular, in this example, where three sensors are evenly spaced at 120°, the synthesis of the corresponding components (XY axis direction, Z axis direction) of each sensor is easier, and more accurate measurement results can be obtained.

[0079] Next, a method for measuring the processing load during wafer processing by the processing apparatus 10 will be described. Figure 11 is a flowchart showing the procedure for measuring the processing load. First, in step S101, the wafer W is placed on the chuck plate 22 of the grinding table 8. Under the control of the controller 1, the wafer W is transported from the storage unit 6 or the measurement table 4 of the measurement unit 3 by the arm 2A of the transport unit 2 and placed on the chuck plate 22. When the wafer W is placed on the chuck plate 22, the inside of the depressurization path 40 is depressurized, and the wafer W is held in place by suction on the chuck plate 22.

[0080] Next, the output values ​​of sensors 50, 51, and 52 are reset to zero. Figure 12 is a functional block diagram of the controller 1. The controller 1 has a control unit 11, a sensor reset unit 12, and a signal processing unit 13, which are functions realized by a processor executing a program stored in memory. The control unit 11 controls each part of the processing apparatus 10. When the sensor reset unit 12 detects that a wafer W has been placed on the chuck plate 22 and is being adsorbed under reduced pressure, it resets sensors 50, 51, and 52 to zero. This is done to correct the offset that may occur in the measured values ​​of sensors 50, 51, and 52 when the wafer W is placed on the chuck plate 22, and to obtain a more accurate measurement. In other words, the controller 1 is equipped with a sensor reset unit 12 that detects that the workpiece (wafer W) is supported on the support base (grinding table 8) and zero-calibrates the sensor output. With a processing apparatus 10 equipped with a sensor reset unit 12, the offset when the workpiece is fixed to the support base can be corrected, and a more accurate measurement result of the processing load can be obtained. The timing and number of zero resets can be set arbitrarily. For example, a zero reset may be performed after the wafer W has been adsorbed and the rotation of the grinding table 8 has stabilized, but before the tool makes contact.

[0081] Next, in step S103, the wafer W is processed using the grinding wheel 9, which is a tool. The control unit 11 processes the wafer W by controlling the rotational speed of the wafer W, the movement trajectory of the grinding wheel 9, the rotational speed, and the depth of cut according to the processing conditions. At this time, each of the sensors 50, 51, and 52 included in the sensor unit 30 measures load fluctuations in a predetermined direction.

[0082] Next, in step S104, the output values ​​of the corresponding sensors in the multiple sensor units 30 are combined to generate the final measurement result. The corresponding sensor output values ​​refer to the output values ​​of the sensors in the multiple sensor units that measure the components in the X-axis direction and the Y-axis direction (direction along the support surface), and the output values ​​of the sensors that measure the component in the Z-axis direction (direction facing the support surface).

[0083] The synthesis of sensor output values ​​is performed in the signal processing unit 13. The signal processing unit 13 synthesizes the output values ​​of multiple sensors measuring the X-axis component of the load and the output values ​​of multiple sensors measuring the Y-axis component according to a predetermined program to generate a final measurement result for the component in the direction along the support surface. The signal processing unit 13 also synthesizes (e.g., averages) the signals of sensors measuring the Z-axis component of the load to generate a final measurement result for the direction the support surface faces. In other words, the controller 1 includes a signal processing unit 13 that synthesizes the sensor measurements taken during the processing of the workpiece (wafer W) in a predetermined manner to generate a final measurement result. The processing apparatus 10 equipped with the signal processing unit 13 can offset the influence of temperature changes on the measurement values ​​and reduce the influence of temperature changes on the final measurement result. Although steps 103 and 104 are shown to be performed sequentially in the flowchart of Figure 12, these steps may be performed simultaneously.

[0084] Next, a modified example of the grinding table will be described based on the drawings. Figure 13 is a perspective view of the modified grinding table 81. Figure 14 is a cross-sectional view of the grinding table 81 along line B-B.

[0085] The grinding table 81 is equipped with a flat-head bolt 251 at the center of rotation, and the sensor unit body is positioned directly below it, similar to Embodiment 1. The structure of the sensor unit used is different from that of Embodiment 1. Figure 15 is a perspective view of the sensor unit 301, and Figure 16 is an exploded view of the sensor unit 301.

[0086] The sensor unit 301 consists of two sensor mounts, three sensors, and flat-head bolts 251, etc. The sensors used are the same as in Embodiment 1, consisting of a sensor 50 for measuring load in the X-axis direction, a sensor 51 for measuring load in the Y-axis direction, and a sensor 52 for measuring load in the Z-axis direction. All of these sensors are torus-shaped force sensors that measure load in a predetermined direction along the measurement surface as shear force.

[0087] The sensor mount consists of a main mount 601 and a sub-mount 611. A sensor 50 for measuring load in the X-axis direction and a sensor 51 for measuring load in the Y-axis direction are attached to the main mount 601. A sensor 52 for measuring load in the Z-axis direction is held in place by being sandwiched between the main mount 601 and the sub-mount 611.

[0088] The main mount 601 is formed by fastening two parts together. The two parts are a flat-edge U-shaped sensor mount 601A, which has a U-shaped recess formed in the short direction at an intermediate position in a strip-shaped member, and a terrace block 601B which has a step at an intermediate position. The flat-edge U-shaped sensor mount 601A includes a base portion 601C for attaching sensors 50 and 51. The base portion 601C extends flat from the end portion of the central U-shaped groove, parallel to the XY plane.

[0089] Sensors 50 and 51 are sandwiched between the back surface of the U-shaped sensor mount 601A with a flat edge and the surface of the base plate 201. At this time, the opening 50A (51A), the through hole 601E provided in the base portion 601C, and the receiving hole provided in the base plate 201 are arranged to communicate and form a communication hole. The bolt 601F is inserted through the communication hole from the through hole 601E side and screwed into the receiving hole. The measuring surfaces 50B and 51B face the back surface of the U-shaped sensor mount 601A with a flat edge. When fixed in this manner, the measuring surfaces 50B and 51B are in close contact with the back surface of the base portion 601C.

[0090] The terrace block 601B is a component formed by cutting off the upper part of a rectangular parallelepiped extending in the Z-axis direction from the center of the U-shaped groove portion of the flat-edge U-shaped sensor mount 601A, thereby creating a terrace shape. The terrace block 601B is fixed to the back surface of the flat-edge U-shaped sensor mount 601A with bolts 601G. The side portion of the terrace of the terrace block 601B is a flat wall portion 601D, which is a plane parallel to the Z-axis and is configured to be in close contact with the measuring surface 52B of the sensor 52. The sensor 52 is held between the terrace block 601B and the flat wall portion 611B of a submount 611, which has the same shape and can be reversed and fitted together. In this case, the through hole 611C provided in the flat wall portion 611B of the submount 611, the opening 52A of the sensor 52, and the receiving hole provided in the terrace block 601B are arranged to communicate and form a communication hole. The bolt 611D is inserted through the through hole 611C and screwed into the receiving hole. The measuring surface 51B faces the flat wall portion 611B and makes tight contact with the flat wall portions 601D and 611B. The submount 611 is fixed to the chuck plate 22 by screwing the flat-head bolt 251 into the receiving hole 611E.

[0091] In this modified example, the main mount 601 is fixed to the base plate 201 by a pillar member bolt 601F, and the sub-mount 611 is fixed to the chuck plate 221 by a flat-head bolt 25, which is also a pillar member. A sensor 52 for detecting load in the Z-axis direction is fixed in close contact between these two sensor mounts. In addition, a sensor 50 for detecting load in the X-axis direction and a sensor 51 for detecting load in the Y-axis direction are fixed in close contact between the back surface of the main mount 601 and the front surface of the base plate 20. With the sensor unit 301 formed in this way, the X-axis, Y-axis, and Z-axis components of the machining load can be measured.

[0092] In this modified example, the submount 611 is fixed by one flat-head bolt 25, but there may be two or more flat-head bolts 25. In this configuration, the sensor unit is fixed more stably. Figure 17 shows a modified example of a sensor unit in which the submount 611 is fixed by two flat-head bolts 25, that is, the submount 611 has two receiving holes 611E. Also, as in Embodiment 1, there may be multiple sensors for measuring in the X-axis, Y-axis, and Z-axis directions.

[0093] In this configuration, the grinding table 81 has one sensor unit positioned at the rotation center of the chuck plate 221. Therefore, even with only one sensor unit, it is less susceptible to temperature changes and may yield more accurate measurements.

[0094] In this modified example, the flat-head bolt 251 and sensor unit 301 are positioned at the rotation center of the chuck plate 221, making it impossible to position the opening 231, which connects to the depressurization path 401 for wafer W adsorption, at the rotation center. Therefore, the six openings 231 are provided at intermediate positions in the first groove 241A. In Embodiment 1, the first groove was provided radially from the rotation center, but in this modified example, since the flat-head bolt 251 is positioned at the rotation center, the first groove 241A starts at an intermediate position radially from the center. Similarly, the second groove 241B is not provided at the rotation center.

[0095] The depressurization path 401 combines six paths extending from six openings 231 into one, and is connected to a depressurization mechanism (not shown) via a manifold 410 provided on the lower surface of the base plate 20, through a depressurization port 402. At this time, the base plate 201 and the opening 231 of the chuck plate 221 are connected by rubber bellows with connectors 420, and the depressurization path 401 is hermetically partitioned. The elastic bellows with connectors 420 pivotably fix the chuck plate 221 to the base plate 201, so as not to interfere with measurements by the sensor unit 301.

[0096] According to this modified version, since the sensor unit 301 is positioned at the rotational center of the chuck plate 221, it is less susceptible to temperature changes from the power supply unit 32, etc., and since fewer sensors are needed, the cost can be reduced.

[0097] 1 Controller, 7 Machining section, 8 Grinding table, 9 Grinding wheel, 10 Machining device, 12 Sensor reset section, 13 Signal processing section, 20 Base plate, 22 Chuck plate, 25 Flat head bolt, 26 Through hole, 30 Sensor unit, 30A Sensor unit body, 32 Power supply section, 34 V-shaped ring, 40 Pressure reduction path, 50-52 Sensor, 60 First L-shaped sensor mount, 61 Second L-shaped sensor mount

Claims

1. A machining apparatus for machining a workpiece by bringing a tool into contact with the rotating workpiece, comprising a support base that rotatably supports the workpiece, the support base comprising at least one sensor unit that supports the workpiece on a support surface and measures the force applied to the support surface.

2. The processing apparatus according to claim 1, wherein the sensor unit measures the components of the force in the direction along the support surface and in the direction toward the support surface.

3. The processing apparatus according to claim 2, wherein the at least one sensor unit is a plurality of sensor units, and the plurality of sensor units are arranged at equal intervals in the rotational direction with respect to the rotation center of the support surface.

4. The processing apparatus according to claim 3, comprising a controller, wherein the controller synthesizes components from the output values ​​of two or more equally spaced sensor units in at least one direction selected from the group consisting of the direction along the support surface and the direction the support surface faces, to generate a measurement result in that direction.

5. The processing apparatus according to claim 2, wherein the sensor unit measures the component of the force in the direction facing the support surface as a compressive or tensile force.

6. The processing apparatus according to claim 2, wherein the sensor unit measures the component of the force in the direction of the support surface as a shear force.

7. The processing apparatus according to claim 5 or 6, wherein the sensor unit measures the component of the force in the direction along the support surface as a shear force.

8. The processing apparatus according to claim 7, wherein the sensor unit includes a quartz piezoelectric sensor.

9. The processing apparatus according to claim 1, wherein the support base is provided with a depressurization path for adsorbing and holding the workpiece on the support surface, and the support surface is pivotably supported at the end of the depressurization path via an elastic body.

10. The processing apparatus according to claim 1, wherein the workpiece is a wafer, the tool is a grinding wheel, and the device is a chamfering device.

11. A support base for a workpiece in a machining apparatus that processes a workpiece by bringing a tool into contact with the rotating workpiece, the support base comprising at least one sensor unit for measuring the force applied to the support surface of the workpiece.

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