Processing device

Abstract

To accurately measure a shape or a dimension of a polygonal work before holding the work on a holding surface of a chuck table.SOLUTION: A temporary placement mechanism 60 of a processing device 1 comprises: a temporary placement table 61 on which a wafer (work piece) W is temporarily placed; a temporary placement table rotation mechanism 62 which rotates the temporary placement table 61; an encoder 63 which detects a rotation angle of the temporary placement table 61; and a photosensor 64 which detects a side of the wafer W. A control unit 100 includes: a perpendicular calculation section 101 for calculating a perpendicular drawn from a center of the temporary placement table 61 to a straight line connecting two points where the side of the wafer W is detected by the photosensor 64; an internal angle calculation section 102 for calculating two internal angles which are adjacent in a circumferential direction of the perpendicular calculated by the perpendicular calculation section 101; and a side length calculation section 103 for calculating a length of the side of the wafer W from the internal angles calculated by the internal angle calculation section 102 and a distance between a center of the temporary placement table 61 and the side of the wafer W.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a processing apparatus capable of calculating the length of each side of a polygonal workpiece based on data detected by a sensor.

Background Art

[0002] For example, in the manufacturing process of semiconductor chips used in various electrical products, processing such as grinding and polishing is performed on the back surface of a wafer (the surface opposite to the surface on which devices such as ICs and LSIs are formed). However, there are non-circular rectangular or polygonal wafers. For example, Patent Documents 1 and 2 propose grinding apparatuses capable of grinding a rectangular wafer to a uniform thickness.

[0003] When holding a rectangular wafer on the holding surface of a chuck table in such a grinding apparatus, the center of the holding surface is made to coincide with the center of the wafer, and further, the dimensions and shape of the holding surface are made to coincide with the dimensions and shape of the wafer. Then, as disclosed in Patent Document 3, after positioning a rectangular wafer on a temporary placement table, the wafer is held by a transfer mechanism and transferred to the chuck table. Then, the wafer transferred to the chuck table is sucked and held on the holding surface by suction of the holding surface of the chuck table.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, when a wafer in the shape of a polygon that does not match the dimensions and shape of the holding surface of the chuck table is transported to the chuck table, for example, when the wafer is sucked and held on the chuck table, air leakage occurs between the wafer and the holding surface of the chuck table, and there is a problem that the wafer cannot be reliably held on the holding surface for processing.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a processing apparatus capable of accurately measuring the shape and dimensions of a polygonal workpiece before holding the workpiece on the holding surface of a chuck table.

Means for Solving the Problems

[0007] The invention according to claim 1 for achieving the above object is a processing apparatus including a chuck table that holds a polygonal workpiece by a holding surface having the same shape as the shape of the workpiece, a processing unit that processes the workpiece held on the chuck table, a temporary placement mechanism that temporarily places the workpiece, a transfer mechanism that transfers the workpiece from the temporary placement mechanism to the chuck table, and a control unit. The temporary placement mechanism includes a temporary placement table that temporarily places the workpiece, a temporary placement table rotation mechanism that rotates the temporary placement table, an encoder that detects the rotation angle of the temporary placement table, and a sensor that detects the sides of the workpiece. The control unit includes a perpendicular line calculation unit that obtains a perpendicular line drawn from the center of the temporary placement table to a straight line connecting two points where the sensor detects the sides of the workpiece, an interior angle calculation unit that calculates two interior angles adjacent to each other in the circumferential direction of the perpendicular line calculated by the perpendicular line calculation unit, and a side length calculation unit that calculates the length of the side of the workpiece based on the interior angle calculated by the interior angle calculation unit and the distance between the center of the temporary placement table and the side of the workpiece.

[0008] Further, in the invention according to claim 2, in the invention according to claim 1, a holding surface encoder for detecting the rotation angle of the chuck table and a holding surface sensor for detecting the sides of the holding surface of the chuck table are provided. The control unit includes a holding surface perpendicular line calculation unit for obtaining a perpendicular line drawn from the center of the chuck table to a straight line connecting two points where the holding surface sensor detects the sides of the holding surface, a holding surface inner angle calculation unit for calculating two inner angles adjacent in the circumferential direction of the perpendicular line calculated by the holding surface perpendicular line calculation unit, and a holding surface side length calculation unit for calculating the length of the side of the holding surface based on the inner angle calculated by the holding surface inner angle calculation unit and the distance between the center of the chuck table and the side of the holding surface. The inner angle of the perpendicular line of the workpiece calculated by the inner angle calculation unit is made to coincide with the inner angle of the perpendicular line of the holding surface calculated by the holding surface inner angle calculation unit, and the length of each side of the workpiece calculated by the side length calculation unit is made to coincide with the length of each side of the holding surface calculated by the holding surface side length calculation unit, and the workpiece is held on the holding surface.

Effect of the Invention

[0009] According to the invention described in claim 1, before holding a polygonal workpiece on the holding surface of the chuck table, while rotating the workpiece placed temporarily on the temporary placement table, each side of the workpiece is detected by a sensor, and the rotation angle of the workpiece when each side of the workpiece is detected is detected by an encoder. Based on these data, two inner angles adjacent in the circumferential direction of the perpendicular line calculated by the perpendicular line calculation unit are calculated by the inner angle calculation unit, and based on this inner angle, the side length calculation unit calculates the length of each side of the workpiece. Therefore, the shape and dimensions of the workpiece can be accurately measured, and it can be determined whether the workpiece held on the chuck table has a regular shape and dimensions.

[0010] Further, according to the invention described in claim 2, since the shape and dimensions of the holding surface of the chuck table are measured in the same manner as in the invention described in claim 1 by the holding surface perpendicular line calculation unit, the holding surface inner angle calculation unit, and the holding surface side length calculation unit, the workpiece can be held in a state where it is accurately positioned on the holding surface of the chuck table, and problems such as air leakage occurring between the holding surface and the workpiece do not occur.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

[0013] [Configuration of the Processing Apparatus] First, the overall configuration of the processing apparatus according to the present invention will be described with reference to FIG. 1. In the following description, the directions of the arrows shown in FIG. 1 are taken as the X-axis direction (front-rear direction) and the Y-axis direction (left-right direction), respectively.

[0014] The processing apparatus 1 shown in FIG. 1 is an apparatus for grinding (rough grinding and finish grinding) and polishing the back surface (the upper surface in FIG. 2) of a regular hexagonal wafer W (see FIGS. 2 and 3) which is a workpiece, and then cleaning the polished wafer W, and includes a rectangular box-shaped base 200 that is long in the Y-axis direction.

[0015] On the central part of the base 200, a disk-shaped turntable 2 is arranged which intermittently rotates by a predetermined angle (90° in this embodiment) in the direction of the illustrated arrow around a vertical central axis. On the wafer loading / unloading area R1, rough grinding area R2, finish grinding area R3, and polishing area R4 partitioned into four in the circumferential direction on the upper surface of the turntable 2, disk-shaped chuck tables 10 capable of rotating (spinning) around a vertical central axis are respectively arranged.

[0016] Note that below the turntable 2, a turntable rotation mechanism (not shown) for intermittently rotating the turntable 2 by a predetermined angle (90° in this embodiment) in the direction of the arrow in FIG. 1 around a vertical central axis is provided. Therefore, when the turntable 2 intermittently rotates by a predetermined angle (90° in this embodiment) by the turntable rotation mechanism (not shown), each chuck table 10 can sequentially move to the wafer loading / unloading area R1, rough grinding area R2, finish grinding area R3, and polishing area R4 while revolving. Here, on the upper surface of each chuck table 10, holding surfaces 10a having the same shape (regular hexagon) as the shape of the regular hexagonal wafer W are respectively formed, and each holding surface 10a is selectively connected to a suction source (not shown) such as a vacuum pump or an ejector.

[0017] Also, below each chuck table 10, a chuck table rotation mechanism 11 for rotating (spinning) these chuck tables 10 at a predetermined speed around a vertical central axis is respectively provided. Here, as shown in FIG. 1, each chuck table rotation mechanism 11 includes a drive motor (not shown) which is a drive source, a drive pulley 12 coupled to the output shaft of the drive motor, a driven pulley (not shown) coupled to a rotation shaft (not shown) of the chuck table 10, and an endless timing belt 13 wound around the drive pulley 12 and the driven pulley. Therefore, when the drive pulley 12 rotates by the drive motor, the rotation is transmitted to the driven pulley via the timing belt 13, and the driven pulley, the rotation shaft (not shown), and the chuck table 10 rotate (spin) integrally at a predetermined speed.

[0018] On the base 200 of the processing apparatus 1 shown in FIG. 1, as processing units, a rough grinding unit 20, a finish grinding unit 30, and a polishing unit 40 are provided. Here, the rough grinding unit 20 is a processing unit that roughly grinds the back surface (upper surface) of the wafer W held on the holding surface 10a of the chuck table 10 located in the rough grinding area R2, and the finish grinding unit 30 is a processing unit that finish grinds the back surface (upper surface) of the wafer W held on the holding surface 10a of the chuck table 10 located in the finish grinding area R3. Further, the polishing unit 40 is a processing unit that polishes the back surface (upper surface) of the wafer W held on the holding surface 10a of the chuck table 10 located in the polishing area R4.

[0019] Although not shown, the rough grinding unit 20 and the finish grinding unit 30 each include a servo motor that rotationally drives a vertical spindle and a disk-shaped grinding wheel attached to the lower end of the spindle. A plurality of block-shaped grinding wheels, which are cutting tools, are annularly arranged on each grinding wheel. Further, the polishing unit 40 includes a servo motor that rotationally drives a vertical spindle and a disk-shaped polishing pad attached to the lower end of the spindle. In the rough grinding area R2 and the finish grinding area R3, a thickness measuring device 21 that measures the thickness of the wafer W during rough grinding and a thickness measuring device 31 that measures the thickness of the wafer W during finish grinding are respectively arranged, and in the polishing area R4, a thickness measuring device 41 that measures the thickness of the wafer W during polishing is arranged.

[0020] Furthermore, a cleaning unit 50 for cleaning the wafer W polished by the polishing unit 40 is provided on the base 200. This cleaning unit 50 includes a disk-shaped spinner table 51 that holds the wafer W and rotates at high speed, and a cleaning water nozzle 52 that sprays cleaning water such as pure water toward the wafer W held and rotated by the spinner table 51. The cleaning water nozzle 52 is attached to the tip of an arm 53 that can horizontally swivel.

[0021] In the vicinity of the cleaning unit 50 on the base 200, a temporary placement mechanism 60 for temporarily placing the wafer W before processing is provided. As shown in FIG. 2, this temporary placement mechanism 60 includes a disc-shaped temporary placement table 61 for horizontally placing the wafer W on its holding surface, a temporary placement table rotation mechanism 62 for rotating the temporary placement table 61, an encoder 63 for detecting the rotation angle of the temporary placement table 61, and a photosensor 64 for optically detecting the edge of the wafer W.

[0022] Here, the temporary placement table 61 is horizontally attached to the upper end of a vertical rotation shaft 67 that is rotatably supported on a rectangular base 65 via a bearing 66. And as shown in FIG. 2, the holding surface (upper surface) of the temporary placement table 61 is connected to a suction source 69 such as a vacuum pump via a pipe 68, and an electromagnetic (solenoid type) on-off valve V is provided in the pipe 68. The on-off valve V is electrically connected to the control unit 100, and its opening and closing are controlled by the control unit 100.

[0023] The temporary placement table rotation mechanism 62 includes a drive motor 71 which is a drive source vertically mounted on the lower surface of the base 65 by a bracket 70, a small-diameter drive pulley 72 coupled to the upper end of an output shaft (motor shaft) 71a extending vertically upward from the drive motor 71, a large-diameter driven pulley 73 coupled to the lower end of the rotation shaft 67, and an endless timing belt 74 wound around the drive pulley 72 and the driven pulley 73. Therefore, when the drive motor 71 is started, the output shaft 71a of the drive motor 71 rotates, and the rotation of this output shaft 71a is decelerated from the drive pulley 72 through the timing belt 74 and transmitted to the driven pulley 73. Thus, the driven pulley 73, the rotation shaft 67, and the temporary placement table 61 rotate at a predetermined speed around the axis center of the rotation shaft 67. At this time, the rotation angle of the temporary placement table 61 is calculated from the rotation angle of the drive motor 71 detected by the encoder 63.

[0024] Further, the photosensor (photointerrupter) 64 includes a light emitting element 64a and a light receiving element 64b that are arranged to face each other above and below a wafer W with a part of the wafer W facing a space portion of a C-shaped holder 75 in a side view. Here, the light emitting element 64a is composed of a light emitting diode (LED) or the like, the light receiving element 64b is composed of a phototransistor or the like, and when the light emitted from the light emitting element 64a reaches the light receiving element 64b without being blocked by the wafer W and is received by the light receiving element 64b, the photosensor 64 outputs an ON signal. When the light emitted from the light emitting element 64a is blocked by the wafer W and is not received by the light receiving element 64b, an OFF signal is output, and the ON / OFF signal is transmitted to the control unit 100. Note that the photosensor 64 is movable in the X-axis direction by a sensor advancing / retreating mechanism 76.

[0025] Furthermore, as shown in FIG. 1, a holding surface sensor 77 for optically detecting the sides of the regular hexagonal holding surface 10a of the chuck table 10 is arranged near the chuck table 10 located in the wafer loading / unloading area R1. This holding surface sensor 77 performs the same function as the photosensor 64 arranged in the temporary placement mechanism 60 and is electrically connected to the control unit 100 shown in FIG. 2.

[0026] By the way, a first transfer mechanism 80 and a second transfer mechanism 90 are arranged in the processing apparatus 1 shown in FIG. 1. Here, the first transfer mechanism 80 includes an arm 82 movable along a guide rail 81 arranged along the Y-axis direction, a disk-shaped suction pad 83 attached to the tip of the arm 82 via a lifting / lowering shaft (not shown), and a moving mechanism (not shown) for moving the suction pad 83 along the guide rail 81 in the Y-axis direction. The first transfer mechanism 80 functions to hold the wafer W on the temporary placement table 61 of the temporary placement mechanism 60 and move it in the Y-axis direction along the guide rail 81, and deliver the wafer W to the chuck table 10 located in the wafer loading / unloading area R1.

[0027] Further, the second transfer mechanism 90 includes an arm 91 that can rotate horizontally, and a disk-shaped suction pad 93 attached to the tip of the arm 91 via a lifting shaft 92, and is movable in the Y-axis direction along a guide rail 94 disposed along the Y-axis direction. This second transfer mechanism 90 functions to transfer the wafer W (the wafer whose polishing by the polishing unit 40 has been completed) held by the chuck table 10 located in the wafer loading / unloading area R1 to the cleaning unit 50.

[0028] Also, as shown in FIG. 1, two cassettes 3 and 4 are arranged in parallel along the X-axis direction at the +Y-axis end of the base 200. Here, one cassette 3 accommodates a plurality of wafers W before processing, and the other cassette 4 accommodates a plurality of wafers W after processing is completed. A transfer robot 110 is arranged near the cassette 3 on the base 200. This transfer robot 110 includes an articulated arm 111, and a suction pad 112 for sucking and holding the wafer W is attached to the tip of this articulated arm 111. Note that this transfer robot 110 is movable along the X-axis direction along the guide rail 113, and functions to take out the wafer W before processing accommodated in one cassette 3 and transfer the taken-out wafer W to the temporary placement mechanism 60.

[0029] [Operation of the processing apparatus] Next, the processing of the wafer W by the processing apparatus 1 configured as described above will be described.

[0030] First, when processing the wafer W by the processing apparatus 1 shown in FIG. 1, one wafer W before processing is taken out from the cassette 3 by the transfer robot 110, and the taken-out wafer W is held by the transfer robot 110 and transferred to the temporary placement mechanism 60. Then, in the temporary placement mechanism 60, the length of the side of the wafer W and the like are measured, and the details thereof will be described later. Also, the length of the side of the holding surface 10a of the chuck table 10 located in the wafer loading / unloading area R1 is also measured, and the details thereof will also be described later.

[0031] As described above, in the temporary placement mechanism 60, when the length of the side of the wafer or the like is measured and the length of the side of the holding surface 10a of the chuck table 10 located in the wafer loading / unloading area R1 is measured, the wafer W is held by the suction pad 83 of the first transfer mechanism 80 and transferred to the chuck table 10 located in the wafer loading / unloading area R1. At this time, the wafer W is held on the holding surface 10a of the chuck table 10 so that the measured side length of the wafer W and the measured side length of the holding surface 10a of the chuck table 10 match.

[0032] As described above, the first transfer mechanism 80 holding the wafer W moves in the -Y axis direction along the guide rail 81, transfers the wafer W to the chuck table 10 located in the wafer loading / unloading area R1, and delivers it to the chuck table 10. Then, in the wafer loading / unloading area R1, the wafer W delivered to the chuck table 10 is sucked and held on the holding surface 10a by the holding surface 10a being evacuated by a suction source (not shown).

[0033] As described above, when the wafer W is held on the holding surface 10a of the chuck table 10 located in the wafer loading / unloading area R1, the turntable 2 rotates 90° in the direction of the arrow in FIG. 1 (counterclockwise) around its vertical axis center, and the chuck table 10 moves to the rough grinding area R2 together with the wafer W. In this rough grinding area R2, the back surface (upper surface) of the wafer W held on the holding surface 10a of the chuck table 10 is rough ground by the rough grinding unit 20. In rough grinding the wafer W, grinding water (for example, pure water) is supplied from a grinding water supply source (not shown) to the processed portion of the wafer W, and the thickness of the wafer W is measured by the thickness measuring device 21.

[0034] And when the upper surface (back surface) of the wafer W is roughly ground to a predetermined thickness by the rough grinding unit 20, the turntable 2 rotates by 90° around its vertical axis center, and the chuck table 10 moves to the finish grinding area R3 together with the wafer W. In this finish grinding area R3, the back surface (upper surface) of the wafer W held on the holding surface 10a of the chuck table 10 is finish ground by the finish grinding unit 30. In addition, even in the finish grinding of the wafer W, grinding water is supplied from a grinding water supply source (not shown) to the workpiece portion of the wafer W, and the thickness of the wafer W is measured by the thickness measuring device 31.

[0035] As described above, in the finish grinding area R3, when the wafer W is finish ground by the finish grinding unit 30, the turntable 2 rotates by 90° around its vertical axis center, and the chuck table 10 moves to the polishing area R4 together with the wafer W. In this polishing area R4, the upper surface (back surface) of the wafer W is polished by the polishing pad of the polishing unit 40 while receiving the supply of slurry which is an abrasive, the work hardened layer formed on the upper surface of the wafer W by the grinding process is removed, and the flexural strength of the wafer W is increased.

[0036] As described above, when the upper surface of the wafer W is polished by the polishing unit 40, the turntable 2 rotates by 90° around its vertical axis center, and the chuck table 10 moves to the wafer loading / unloading area R1 together with the wafer W. In this wafer loading / unloading area R1, the wafer W is sucked and held by the suction pad 93 of the second transfer mechanism 90 and transferred to the cleaning unit 50. In the cleaning unit 50, the wafer W is held on the spinner table 51, the wafer W is rotationally driven at a predetermined speed around the vertical central axis together with the spinner table 51, and cleaning water (for example, pure water) is jetted from the cleaning water nozzle 52 onto the upper surface of the wafer W, whereby the upper surface of the wafer W is cleaned. Then, the wafer W with the upper surface cleaned is removed from the spinner table 51 by the transfer robot 110 and transferred to the cassette 4 and stored in the cassette 4, and a series of processes for one wafer W is completed.

[0037] Here, the method for obtaining the length of the side of the wafer W in the temporary placement mechanism 60 will be described below with reference to FIG. 3.

[0038] When the wafer W is placed on the temporary placement table 61, the on-off valve V shown in FIG. 2 is opened. Then, since the holding surface of the temporary placement table 61 is evacuated by the suction source 69, a negative pressure is generated on the holding surface, and the wafer W is sucked and held on the holding surface of the temporary placement table 61 by this negative pressure. At this time, it is assumed that the center of the wafer W coincides with the center O(0,0) of the temporary placement table 61. Here, as shown in FIG. 3, consider a rectangular xy coordinate system with the center O(0,0) of the temporary placement table 61 as the origin. Also, in the perpendicular lines of each side of the wafer W, let the distance between the center O(0,0) of the temporary placement table 61 and each side of the wafer W be a known constant value r.

[0039] As described above, when the wafer W is sucked and held on the holding surface of the temporary placement table 61, the temporary placement table 61 and the wafer W held thereon are rotated around the center O(0,0) of the temporary placement table 61 by the temporary placement table rotation mechanism 62 shown in FIG. 2. In FIG. 3, for the sake of convenience, the wafer W is assumed to be stationary, and the photosensor 64 is considered to rotate around the center O(0,0) of the temporary placement table 61 with respect to this wafer W, and its rotation locus is shown by a broken-line circle C.

[0040] Then, the rotation locus C of the photosensor 64 and the sides of the regular hexagonal wafer W intersect at points a to f shown in FIG. 3, and the output signal (ON / OFF signal) of the photosensor 64 is switched at these intersection points a to f. Therefore, the control unit 100 can obtain the rotation angle of the wafer W at the intersection points a to f based on the signal transmitted from the encoder 63. Accordingly, the rotation angle α1 of the wafer W from point a to point b, the rotation angle α2 of the wafer W from point b to point c, the rotation angle α3 of the wafer W from point c to point d, the rotation angle α4 of the wafer W from point e to point f, and the rotation angle α5 of the wafer W from point f to point a can be obtained respectively.

[0041] Incidentally, as shown in FIG. 2, the control unit 100 includes a perpendicular line calculation unit 101 that obtains a perpendicular line drawn from the center O of the temporary placement table 61 to a straight line connecting two intersections where the photosensor 64 has detected the sides of the wafer W, an interior angle calculation unit 102 that calculates two interior angles adjacent to each other in the circumferential direction of the perpendicular line calculated by the perpendicular line calculation unit 101, and a side length calculation unit 103 that calculates the length of the side of the wafer W based on the interior angle calculated by the interior angle calculation unit 102 and the distance between the center O of the temporary placement table 61 and the side of the wafer W.

[0042] Then, the perpendicular line calculation unit 101 obtains a perpendicular line N1 drawn from the center O of the temporary placement table 61 to a straight line connecting the intersection point a and the intersection point b shown in FIG. 3, and a perpendicular line N2 drawn from the center O of the temporary placement table 61 to a straight line connecting the intersection point c and the intersection point d. Then, the interior angle calculation unit 102 calculates the interior angle θ1 formed by the two perpendicular lines N1 and N2 by the following formula: θ1 = α1 / 2 + α2 + α3 / 2 …(1) and obtains it.

[0043] Also, the perpendicular line calculation unit 101 obtains a perpendicular line N3 drawn from the center O of the temporary placement table 61 to a straight line connecting the intersection point e and the intersection point f shown in FIG. 3. Then, the interior angle calculation unit 102 calculates the interior angle θ2 formed by the perpendicular line N3 drawn from the center O of the temporary placement table 61 to a straight line connecting the intersection point e and the intersection point f and the perpendicular line N1 drawn from the center O of the temporary placement table 61 to a straight line connecting the intersection point a and the intersection point b by the following formula: θ2 = α1 / 2 + α5 + α4 / 2 …(2) and obtains it.

[0044] As described above, when the interior angles θ1 and θ2 are respectively obtained by the interior angle calculation unit 102, the length of the side of the wafer W is obtained by the side length calculation unit 103 as follows.

[0045] That is, as shown in FIG. 3, a straight line L1 passing through one side of the wafer W is given by the following formula: y = A·x + b …(3) Here, A is the slope and b is the intercept is set.

[0046] Here, the perpendicular line N2 is y = tanθ1·x …(4) Since it is represented by this, the slope A of the straight line L1 orthogonal to this perpendicular line N2 is -1 / tanθ1 = -cotθ1. And since this straight line L1 passes through the point P1(r·cosθ1, r·sinθ1), the following equation holds from equation (3). r·sinθ1 = -cotθ1·r·cosθ1 + b …(5) Therefore, the y-intercept b of the straight line L1 from equation (5) is represented by the following equation. b = r(sinθ1 + cotθ1·cosθ1) Therefore, the straight line L1 represented by equation (3) is expressed as follows. y = -cotθ1·x + r(sinθ1 + cotθ1·cosθ1) …(6) So, if we substitute the value r of the x-coordinate of the point P1 for x in equation (6), the value y1 of the y-coordinate of the point P1 is obtained by the following equation. y1 = r(sinθ1 + cotθ1·cosθ1 - cotθ1) …(7) Also, for the straight line L5 passing through one side of the wafer W, the following equation: y = B·x + c …(8) Here, B is the slope and c is the y-intercept is assumed.

[0047] Here, the perpendicular line N3 is y = -tanθ2·x …(9) Since it is represented by this, the slope B of the straight line L5 orthogonal to this perpendicular line N3 is 1 / tanθ2 = cotθ2. And since this straight line L5 passes through the point Q1(r·cosθ2, -r·sinθ2), the following equation holds from equation (9). -r·sinθ2 = cotθ2·r·cosθ2 + c …(10) Therefore, the y-intercept c of the straight line L5 from equation (9) is represented by the following equation. c = -r(sinθ2 + cotθ2·cosθ2) Therefore, the straight line L5 represented by equation (3) is expressed as follows. y = cotθ2·x - r(sinθ2 + cotθ2·cosθ2) …(11) Therefore, if the value r of the x - coordinate of point Q2 is substituted for x in equation (11), the value y2 of the y - coordinate of point Q2 can be obtained by the following equation. y2 = r(cotθ2 - sinθ2 - cotθ2·cosθ2) …(12) As a result of the above, the length of one side of the regular - hexagon - shaped wafer W is obtained as the difference between y1 shown in equation (7) and y2 shown in equation (12) as follows. y1 - y2 = r(sinθ1 + cotθ1·cosθ1 - cotθ1) - r(cotθ2 - sinθ2 - cotθ2·cosθ2) …(13) By the way, in this embodiment, since the wafer W is a regular hexagon, when the interior angles θ1 = θ2 = θ(= 60°), equation (13) becomes as follows. y1 - y2 = r(sinθ + cotθ·cosθ - cotθ) …(13’) Here, since sin60° = √3 / 2, cot60° = 1 / √3, and cos60° = 1 / 2, substituting these values into equation (13’) gives the length of one side of the wafer W as expressed by the following equation. y1 - y2 = r(√3 / 2 + 1 / √3·1 / 2 - 1 / √3) = 2r / √3 …(13”) Note that the lengths of the other sides of the wafer W can be obtained in the same manner as above.

[0048] As described above, in the present embodiment, before holding the wafer W on the holding surface 10a of the chuck table 10 located in the wafer transfer-in / out region R1, while rotating the wafer W temporarily placed on the temporary placement table 61 of the temporary placement mechanism 60, each side of the wafer W is detected by the photosensor 64, and the rotation angle of the wafer W when each side of the wafer W is detected is detected by the encoder 63. Based on these data, the inner angles θ1 and θ2 between two adjacent sides N1 and N2, N1 and N3 in the circumferential direction of the perpendicular line calculated by the perpendicular line calculation unit 101 are calculated by the inner angle calculation unit 102, and based on these inner angles θ1 and θ2, the side length calculation unit 103 calculates the length of each side of the wafer W. Therefore, the shape and dimensions of the wafer W can be accurately measured, and it is possible to determine whether the wafer W held on the holding surface 10a of the chuck table 10 has a regular shape and dimensions.

[0049] Also, the length of each side of the regular hexagonal holding surface 10a of the chuck table 10 located in the wafer transfer-in / out region R1 and the inner angle of adjacent perpendicular lines in the circumferential direction are also determined based on the detection of the sides of the holding surface 10a by the holding surface sensor 77 and the like in the same manner as the method for obtaining the side length of the wafer W and the inner angle of two adjacent perpendicular lines described above.

[0050] That is, the control unit 100 shown in FIG. 2 is provided with a holding surface perpendicular line calculation unit 104 for obtaining a perpendicular line drawn from the center of the chuck table 10 with respect to a straight line connecting two points where the holding surface sensor 77 detects the sides of the holding surface 10a, a holding surface inner angle calculation unit 105 for calculating two inner angles adjacent to each other in the circumferential direction of the perpendicular line calculated by the holding surface perpendicular line calculation unit 104, and a holding surface side length calculation unit 106 for calculating the length of the side of the holding surface 10a based on the inner angle calculated by the holding surface inner angle calculation unit 105 and the distance between the center of the chuck table 10 and the side of the holding surface 10a.

[0051] Then, when the lengths of the sides of the holding surface 10a of the chuck table 10 and the internal angles of the perpendiculars adjacent in the circumferential direction are obtained, the control unit 100 makes the internal angle of the perpendicular of the wafer W calculated by the internal angle calculation unit 102 coincide with the internal angle of the perpendicular of the holding surface 10a of the chuck table 10 calculated by the holding surface internal angle calculation unit 105, and makes the lengths of the sides of the wafer W calculated by the side length calculation unit 103 coincide with the lengths of the sides of the holding surface 10a of the chuck table 10 calculated by the holding surface side length calculation unit 106, thereby holding the wafer W on the holding surface 10a of the chuck table 10.

[0052] Therefore, according to the present embodiment, the wafer W can be accurately held in a positioned state on the holding surface 10a of the chuck table 10, and problems such as air leakage occurring between the holding surface 10a and the wafer W do not occur.

[0053] Next, a method for obtaining the lengths of the sides of the trapezoidal wafer W will be described below with reference to FIG. 4.

[0054] In the trapezoidal wafer W shown in FIG. 4, the magnitudes (absolute values) of the vectors P1, P2, P3, P4 that are perpendicular to the sides L1, L2, L3, L4 from the origin (rotation center) O are p1, p2, p3, p4 respectively, the angle formed by the vectors P1 and P2 is θ2, and the intersection of the sides L1 and L2 is T 12 , the intersection of the sides L2 and L3 is T 12 , the intersection of the sides L3 and L4 is T 34 , the intersection of the sides T4 and T1 is T 41 Let it be. Also, when the intersection of the straight line M passing through the vector P2 and the side L2 is N, the xy coordinates of this intersection N are (p2cosθ2, p2sinθ2).

[0055] Here, since the slope m of the straight line M is m = tanθ2, the slope a2 of the side L2 perpendicular to the straight line M is a2 = -1 / tanθ2 = -cotθ2. Therefore, the equation on the xy coordinates indicating the side L2 is y = a2x + b …(14) Here, b is the y-intercept Since the side L2 represented by the above equation (14) passes through the intersection point N2(x2, y2), equation (14) is represented by the following equation. y2 = a2x2 + b …(14’) Therefore, the y-intercept b of the straight line L2 is, from equation (14’), b = y2 - a2x2 which is obtained.

[0056] As a result, the side L2 represented by equation (14) is represented by the following equation. L2: y = a2x + (y2 - a2x2) = -x / tanθ2 + p2sinθ2 + p2cosθ2 / tanθ2…(14”) And the coordinates (x, y) of the intersection point T 12 between the side L1 and the side L2 are obtained by the following equation. x = p1 y = a2p1 + (y2 - a2x2) = -p1 / tanθ2 + p2sinθ2 + p2cosθ2 / tanθ2 Also, the coordinates (x, y) of the intersection point T 23 between the side L2 and the side L3 are obtained by the following equation. x = -p3 y = a2x + (y2 - a2x2) = -a2p3 + (y2 - a2x2) = p3 / tanθ2 + p2sinθ2 + p2cosθ2 / tanθ2 Furthermore, the xy coordinates (x, y) of the intersection point T 34 between the side L3 and the side L4 are obtained by the following equation. x = -p3 y = -p4 And the xy coordinates (x, y) of the intersection point T 41 between the side L4 and the side L1 are obtained by the following equation. x = p1 y = -p4 Here, let the intersection point of the straight line K parallel to the x-axis (the straight line shown by the dashed line in Fig. 4) passing through the intersection point T 12 and the side L3 be Q, and let the intersection points of the sides L1, L3 and the x-axis be R, S respectively. Then, the xy coordinates (x, y) of the intersection point Q are obtained by the following equation. x = -p3 y = -p1 / tanθ2 + p2sinθ2 + p2cosθ2 / tanθ2 Thus, the equations of the sides L1, L2, L3, and L4 on the xy coordinates are represented by the following equations. L1: x = p1 L2: y = a2x + (y2 - a2x2) = x / tanθ2 + p2sinθ2 + p2cosθ2 / tanθ2…(14”) L3: x = -p3 L4: y = -p4 As a result of the above, the lengths of the sides L1, L2, L3, and L4 of the trapezoidal wafer W are obtained by the following equations, respectively. L1 = line segment T 12 R + line segment RT 41 = -p1 / tanθ2 + p2sinθ2 + p2cosθ2 / tanθ2 + p4…(15) L2 = √(line segment T 12 Q) 2 +(T 23 Q) 2 = ((p1 + p3) 2 +(p3 / tanθ2 + p2sinθ2 + p2cosθ2 / tanθ2) 2 ) 1 / 2 = (p1 + p3) / cos(90° - θ2) = (p1 + p3) / sinθ2…(16) L3 = line segment T 23 S + line segment ST 34 = p3 / tanθ2 + p2sinθ2 + p2cosθ2 / tanθ2 + p4…(17) L4 = p1 + p3…(18)

[0057] Note that the above has described the form in which the present invention is applied to a processing apparatus for processing a regular hexagon and a trapezoidal wafer as workpieces. However, the present invention can be similarly applied to a processing apparatus for processing a wafer of an arbitrary polygon other than a regular hexagon, a regular polygon, or a trapezoid, or any workpiece other than a wafer.

[0058] In addition, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the technical idea described in the claims, the specification, and the drawings, of course.

Explanation of Reference Numerals

[0059] 1: Processing apparatus, 2: Turntable, 3, 4: Cassette, 10: Chuck table, 10a: Holding surface of chuck table, 11: Chuck table rotation mechanism committee, 12: Driving five pulley, 13: Timing belt, 20: Rough grinding unit (processing unit) 21: Thickness measuring instrument, 30: Finishing grinding unit (processing unit), 31: Thickness measuring instrument, 40: Polishing unit (processing unit), 41: Thickness measuring instrument, 50: Cleaning unit, 51: Spinner table, 52: Cleaning water nozzle, 53: Arm, 60: Temporary placement mechanism, 61: Temporary placement table, 62: Temporary placement table rotation mechanism, 63: Encoder, 64: Photo sensor (sensor), 64a: Light emitting element, 64b: Light receiving element, 65: Base, 66: Bearing, 67: Rotation shaft, 68: Pipe, 69: Suction source, 70: Bracket, 71: Driving motor, 71a: Output shaft, 72: Driving pulley, 73: Driven pulley, 74: Timing belt, 75: Holder, 76: Sensor advancing and retracting mechanism, 77: Holding surface sensor, 80: First transfer mechanism (transfer mechanism), 81: Guide rail, 82: Arm, 83: Suction pad, 90: Second transfer mechanism, 91: Arm, 92: Lifting shaft, 93: Suction pad, 94: Guide rail, 100: Control unit, 101: Vertical line calculation unit, 102: Inner angle calculation unit, 103: Side length calculation unit, 104: Holding surface vertical line calculation unit, 105: Holding surface inner angle calculation unit, 106: Holding surface side length calculation unit, 200: Base, C: Rotation locus of sensor, L1, L5, L6: Straight lines passing through sides of wafer (sides of trapezoid), N1, N2, N3: perpendicular lines, R1: wafer loading / unloading area, R2: rough grinding area, R3: finish grinding area, R4: polishing area, V: on-off valve, W: wafer (workpiece), θ1, θ2: interior angles

Claims

1. A machining apparatus comprising: a chuck table for holding a polygonal workpiece by a holding surface having the same shape as the shape of the workpiece; a machining unit for machining the workpiece held by the chuck table; a temporary placement mechanism for temporarily placing the workpiece; a transfer mechanism for transferring the workpiece from the temporary placement mechanism to the chuck table; and a control unit, wherein the temporary placement mechanism includes: a temporary placement table for temporarily placing the workpiece; a temporary placement table rotation mechanism for rotating the temporary placement table; an encoder for detecting the rotation angle of the temporary placement table; a sensor for detecting the sides of the workpiece; and, the control unit includes: a perpendicular line calculation unit for obtaining a perpendicular line drawn from the center of the temporary placement table to a straight line connecting two points where the sensor detects the sides of the workpiece; an interior angle calculation unit for calculating two interior angles adjacent to each other in the circumferential direction of the perpendicular line calculated by the perpendicular line calculation unit; a side length calculation unit for calculating the length of the side of the workpiece based on the interior angle calculated by the interior angle calculation unit and the distance between the center of the temporary placement table and the side of the workpiece; and is characterized by the above.

2. a holding surface encoder for detecting the rotation angle of the chuck table; and a holding surface sensor for detecting the sides of the holding surface of the chuck table, wherein the control unit includes: a holding surface perpendicular line calculation unit for obtaining a perpendicular line drawn from the center of the chuck table to a straight line connecting two points where the holding surface sensor detects the sides of the holding surface; a holding surface interior angle calculation unit for calculating two interior angles adjacent to each other in the circumferential direction of the perpendicular line calculated by the holding surface perpendicular line calculation unit; a holding surface side length calculation unit for calculating the length of the side of the holding surface based on the interior angle calculated by the holding surface interior angle calculation unit and the distance between the center of the chuck table and the side of the holding surface; and, the machining apparatus according to Claim 1, characterized in that the interior angle of the perpendicular line of the workpiece calculated by the interior angle calculation unit is made to coincide with the interior angle of the perpendicular line of the holding surface calculated by the holding surface interior angle calculation unit, and the length of each side of the workpiece calculated by the side length calculation unit is made to coincide with the length of each side of the holding surface calculated by the holding surface side length calculation unit, thereby holding the workpiece on the holding surface.

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