JP6598668B2 - Grinding equipment - Google Patents

Description

  The present invention relates to a grinding apparatus for grinding a wafer.

  In a grinding apparatus for grinding a wafer, the wafer is conveyed from the temporary placement table to the chuck table and sucked and held on the holding surface of the chuck table. Then, the height of the holding surface of the chuck table for holding the wafer and the height of the surface to be ground (upper surface) are measured with two height gauges, and the wafer is ground until the difference reaches a predetermined finished thickness (for example, Patent Document 1). A protective tape is affixed to the opposite surface of the wafer to be ground, and the wafer is sucked and held on the holding surface of the chuck table via the protective tape.

  When grinding with a load applied to the wafer, the base material and the adhesive layer of the protective tape adhered to the wafer are crushed by the grinding load, and the flatness of the surface to be ground of the wafer is lowered. In order to prevent this, if the wafer is a hard substrate such as a SiC substrate or a sapphire substrate and requires a grinding load, a support substrate (substrate) such as glass or ceramics is pasted on the wafer instead of a protective tape. Wear it and hold it on the chuck table.

  Unlike the above-described protective tape having a uniform thickness, the substrate may have a different thickness for each individual. Therefore, unless the thickness of the substrate is measured, the finished thickness of the wafer cannot be accurately calculated, and the wafer cannot be set to a predetermined thickness. When measuring the thickness of the substrate to which the wafer is attached, the height of the upper surface of the substrate is measured after measuring the holding surface height of the chuck table using a height gauge provided in the grinding apparatus. Then, the thickness of the substrate is calculated from the difference between the upper surface height of the substrate and the holding surface height of the chuck table, and the wafer is ground so that the thickness of the wafer becomes a predetermined thickness.

JP 2008-073785 A

  However, if the holding surface height of the chuck table is measured before the wafer-laminated substrate is transferred to the chuck table, and the upper surface height of the substrate is measured after being transferred to the chuck table, the measurement operation is performed twice. Need to repeat. For this reason, it takes time to start grinding the wafer.

  The present invention has been made in view of the above points, and can reduce the time required to start grinding a wafer attached to a substrate and can grind the thickness of the wafer to a predetermined finish thickness. The purpose is to provide.

  The grinding apparatus of the present invention includes a chuck table having a holding surface for holding a bonded work in which a wafer is bonded to a disk-shaped substrate having an outer diameter larger than that of the wafer to form a protruding portion, and the holding surface side is a chuck table. The grinding means for grinding the wafer of the bonded workpiece held by the grinding wheel with a grinding wheel, the first measuring means for measuring the height of the holding surface, and the height of the upper surface of the wafer of the bonded workpiece held by the chuck table are measured. A grinding apparatus comprising: a second measuring unit that performs; a conveying unit that conveys the bonded workpiece to the chuck table; and a temporary placing unit that temporarily places the bonded workpiece. The temporary storage table and the height of the upper surface of the temporary storage table and the height of the substrate upper surface of the protruding portion Substrate thickness measuring means for calculating the thickness of the substrate, the substrate thickness value measured by the substrate thickness measuring means, and the holding surface height value measured by the first measuring means, Wafer thickness = wafer upper surface height value− (holding surface height value + sub) using the wafer upper surface height value obtained by measuring the height of the wafer upper surface of the bonded workpiece conveyed to the chuck table by the second measuring means. Grinding is performed until the wafer thickness calculated by the calculation unit includes a calculation unit that calculates the thickness of the wafer according to the formula of (straight thickness value) and reaches the finishing thickness set in advance.

  According to this configuration, using the substrate thickness value measured by the substrate thickness measuring means, the holding surface height value and the wafer upper surface height value measured by the first measuring means and the second measuring means, The thickness of the wafer being ground can be calculated and the wafer can be ground to a predetermined finish thickness. Also, before transferring the bonded workpiece from the temporary placement table to the chuck table, the temporary thickness of the temporary placement table is determined by the difference between the height of the upper surface of the temporary placement table and the height of the upper surface of the substrate of the protruding portion. The thickness of the substrate can be calculated. For this reason, the thickness of the substrate of the subsequent bonded workpiece can be calculated in advance using the wafer grinding time of the preceding bonded workpiece in the temporary placement table. Therefore, the time for measuring the thickness of the substrate after the bonded workpiece is transferred from the temporary placement table to the chuck table is omitted, so that the wafer grinding time can be shortened.

  According to the present invention, it is possible to shorten the time until the wafer attached to the substrate starts to be ground and to grind the thickness of the wafer to a predetermined finish thickness.

It is a perspective view of the grinding device concerning this embodiment. It is a schematic diagram of the temporary placement means according to the present embodiment. It is a figure which shows an example of the positioning operation | movement of the temporary placement means which concerns on this Embodiment. It is a figure which shows an example of the measurement operation | movement of the thickness of the substrate which concerns on this Embodiment. It is a figure which shows an example of the measurement operation | movement of the thickness of the wafer which concerns on this Embodiment. It is a figure of the temporary placement means which concerns on a modification.

  Hereinafter, the grinding apparatus according to the present embodiment will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a grinding apparatus according to the present embodiment. Note that the grinding apparatus according to the present embodiment is not limited to the apparatus configuration dedicated to the grinding process as shown in FIG. 1. For example, the grinding apparatus and a series of processes such as a grinding process, a polishing process, and a cleaning process are performed. You may incorporate in the fully automatic type processing apparatus implemented fully automatically.

  As shown in FIG. 1, the grinding device 1 is a full-auto type processing device, and includes a series of conveyance processing, rough grinding processing, finish grinding processing, cleaning processing, and unloading processing for a wafer W that is a workpiece. This operation is configured to be fully automatic. The wafer W is formed in a substantially disk shape and is conveyed to the grinding device 1 while being accommodated in the cassette C. On the lower surface of the wafer W, a disk-shaped substrate S having an outer diameter larger than that of the wafer W is adhered with wax, an adhesive, or the like to form a bonded workpiece WS. The substrate S protruding from the wafer W forms a protruding portion 87 (see FIG. 2A). The wafer W may be a plate-like wafer to be ground, and may be a semiconductor substrate such as silicon or gallium arsenide, an inorganic material substrate such as ceramic, glass, or sapphire, or a package of semiconductor products. A substrate or the like may be used. The substrate S may be made of glass, ceramic or the like.

  A pair of cassettes C in which a plurality of bonded workpieces WS are accommodated are placed on the front side of the base 11 of the grinding apparatus 1. Behind the pair of cassettes C, a cassette robot 16 that puts and removes the bonded workpiece WS with respect to the cassettes C is provided. On both diagonally rear sides of the cassette robot 16, a temporary placement means 21 for temporarily placing the bonded workpiece WS before processing and a cleaning mechanism 14 for cleaning the processed bonded workpiece WS are provided. Between the temporary placement means 21 and the cleaning mechanism 14, a conveying means 31 that conveys the bonded workpiece WS before processing to the chuck table 41, and an unloading means 36 that carries out the processed bonded workpiece WS from the chuck table 41. Is provided.

  The cassette robot 16 is configured by providing a hand portion 18 at the tip of a robot arm 17 composed of a multi-node link. In the cassette robot 16, the bonded workpiece WS before processing is transferred from the cassette C to the temporary placement means 21, and the processed bonded workpiece WS is transferred from the cleaning mechanism 14 to the cassette C.

  The transport means 31 is configured by providing a transport pad 33 at the tip of a transport arm 32 that can turn on the base 11. In the transport unit 31, the bonded workpiece WS is lifted from the temporary placement table 22 by the transport pad 33, and the bonded work WS is transported to the chuck table 41 by turning the transport pad 33 by the transport arm 32.

  The temporary placement means 21 is configured by arranging a pair of positioning pins 23 a and 23 b, a substrate thickness measurement means 24 for calculating the thickness of the substrate S, and a measurement table 25 around the temporary placement table 22. In the temporary placement means 21, the bonded workpiece WS is lifted by the temporary placement table 22, and the positioning pins 23a and 23b are brought into contact with the outer peripheral edge of the substrate S, so that the center O2 of the substrate S of the bonded workpiece WS is set. It is positioned at the center O1 (see FIG. 3) of the temporary placement table 22. The details of the substrate thickness measuring means 24 and the measurement table 25 will be described later.

  The carry-out means 36 is configured by providing a carry-out pad 38 at the tip of a carry-out arm 37 that can turn on the base 11. In the unloading means 36, the bonded workpiece WS is lifted from the chuck table 41 by the unloading pad 38, and the unloaded pad 38 is turned by the unloading arm 37, whereby the bonded workpiece WS is unloaded from the chuck table 41.

  The cleaning mechanism 14 is configured by providing various nozzles (not shown) that spray cleaning water and dry air toward the spinner table 15. In the cleaning mechanism 14, the spinner table 15 holding the bonded workpiece WS is lowered into the base 11, the cleaning water is sprayed in the base 11, the wafer W of the bonded workpiece WS is spinner cleaned, and then dried. Air is blown to dry the wafer W of the bonded workpiece WS.

  A turntable 40 provided with three chuck tables 41 at equal intervals in the circumferential direction is provided behind the conveying means 31 and the unloading means 36. A rotating means (not shown) for rotating the chuck table 41 is provided below the chuck table 41. A holding surface 42 that holds the lower surface of the bonded workpiece WS is formed on the upper surface of each chuck table 41.

  When the turntable 40 is rotated, a transfer carry-out position where the bonded workpiece WS held on the chuck table 41 is transferred and carried out, a rough grinding position corresponding to the rough grinding means 46, and a finish grinding corresponding to the finish grinding means 51. Positioned sequentially.

  In addition, columns 12 and 13 are erected around the turntable 40. The column 12 is provided with a moving mechanism 61 that moves the rough grinding means 46 up and down. The moving mechanism 61 includes a pair of guide rails 62 arranged in front of the column 12 and parallel to the Z-axis direction, and a motor-driven Z-axis table 63 slidably installed on the pair of guide rails 62. Yes.

  A rough grinding means 46 is supported on the front surface of the Z-axis table 63 via a housing 64. A ball screw 65 is screwed to the back side of the Z-axis table 63, and a drive motor 66 is connected to one end of the ball screw 65. The ball screw 65 is rotationally driven by the drive motor 66, and the rough grinding means 46 is moved along the guide rail 62 in the Z-axis direction.

  Similarly, the column 13 is provided with a moving mechanism 71 that moves the finish grinding means 51 up and down. The moving mechanism 71 includes a pair of guide rails 72 arranged in front of the column 13 and parallel to the Z-axis direction, and a motor-driven Z-axis table 73 slidably installed on the pair of guide rails 72. Yes.

  A finish grinding means 51 is supported on the front surface of the Z-axis table 73 via a housing 74. A ball screw 75 is screwed to the back side of the Z-axis table 73, and a drive motor 76 is connected to one end of the ball screw 75. The ball screw 75 is rotationally driven by the drive motor 76, and the finish grinding means 51 is moved along the guide rail 72 in the Z-axis direction.

  The rough grinding means 46 and the finish grinding means 51 are configured by providing mounts 47 and 52 at the lower end of a cylindrical spindle. In the rough grinding means 46, the wafer W of the bonded workpiece WS held on the chuck table 41 is roughly ground. On the lower surface of the mount 47 of the rough grinding means 46, a grinding wheel 49 in which a plurality of rough grinding wheels 48 are annularly arranged is rotatably mounted. The rough grinding wheel 48 is composed of, for example, a diamond grinding stone in which diamond abrasive grains are hardened with a binder such as resin bond or vitrified bond.

  In the finish grinding means 51, the wafer W of the bonded workpiece WS held on the chuck table 41 is finish ground. On the lower surface of the mount 52 of the finish grinding means 51, a grinding wheel 54 is mounted as a finish grinding processing tool in which a plurality of finish grinding wheels 53 are annularly arranged. The finish grinding wheel 53 is formed of abrasive grains having a smaller particle diameter than the coarse grinding wheel 48. In the rough grinding process and the finish grinding process, the wafer W of the bonded workpiece WS is ground to a predetermined thickness by the grinding wheels 48 and 53 and thinned.

  Further, in the vicinity of the rough grinding position and the finish grinding position, the first measuring means 91 and 93 for measuring the height of the holding surface of the chuck table 41 and the wafer W of the bonded workpiece WS held by the chuck table 41 are provided. Second measuring means 92 and 94 for measuring the height of the surface to be ground (upper surface) are provided. The first measuring means 91 and 93 and the second measuring means 92 and 94 are constituted by contact type gauges. The respective values (measured values) obtained by the first measuring means 91 and 93 and the second measuring means 92 and 94 are output to the control unit 85 that performs overall control of each part of the apparatus.

  The control unit 85 is provided with a calculation unit 86. In the calculation unit 86, the thickness of the wafer W is calculated from the values measured by the gauges 24a (see FIG. 2) in each measuring means 91-94 and the substrate thickness measuring means 24 described later. The control unit 85 includes a processor that executes various processes, a memory, and the like. The memory is composed of one or a plurality of storage media such as a ROM (Read Only Memory) and a RAM (Random Access Memory) depending on the application. The control unit 85 controls the amount of movement of the rough grinding unit 46 and the finish grinding unit 51 in the Z-axis direction according to the output result from the calculation unit 86. A method for calculating the thickness of the wafer W will be described later.

  In such a grinding apparatus 1, the bonded workpiece WS is conveyed from the cassette C to the temporary placement means 21, and the bonded workpiece WS is positioned by the temporary placement means 21. Next, the bonded workpiece WS is conveyed onto the chuck table 41, and the bonded workpiece WS held on the chuck table 41 is positioned in the order of the rough grinding position and the finish grinding position by the rotation of the turntable 40. The wafer W of the bonded workpiece WS is roughly ground at the rough grinding position, and the wafer W of the bonded workpiece WS is finish ground at the finish grinding position. Then, the wafer W of the bonded workpiece WS is cleaned by the cleaning mechanism 14, and the bonded workpiece WS is carried out from the cleaning mechanism 14 to the cassette C.

  By the way, in the grinding of a general grinding apparatus, the thickness of the bonded workpiece WS including the thickness of the substrate S is obtained from the difference between the upper surface height of the wafer W and the holding surface height of the chuck table. Has been adjusted. However, if the thickness of the substrate S varies, the thickness of the wafer W cannot be calculated accurately, and the wafer W cannot be accurately ground.

  For this reason, normally, the height of the holding surface of the chuck table is measured using the first measuring means before the bonded workpiece WS is placed on the chuck table, and the workpiece workpiece WS is transferred after the bonded workpiece WS is transferred to the chuck table. The upper surface height of the straight S is measured. However, in this method, after the holding surface height is measured by the first measuring means, the upper surface height of the substrate S is measured again by the first measuring means, so that the measuring operation is repeated twice. Become. For this reason, it takes time to start grinding the wafer W.

  Therefore, in the present embodiment, by using the waiting time while the wafer W of the preceding bonded workpiece WS is being ground, the temporary placing means 21 determines the thickness of the substrate S of the subsequent bonded workpiece WS in advance. The calculation is done in advance. Thereby, after the bonded workpiece WS is transferred from the temporary placement table 21 to the chuck table 41, the time for measuring the thickness of the substrate S by the chuck table 41 can be omitted. Throughput can be improved.

  Hereinafter, the temporary placement means will be described in detail with reference to FIG. FIG. 2 is a schematic diagram of temporary placement means according to the present embodiment. 2A is a top view showing the temporary placement means according to the present embodiment, and FIG. 2B is a side view of the temporary placement means according to the present embodiment as viewed from the direction of arrow A in FIG. 2A.

  As shown in FIGS. 2A and 2B, the temporary placement means 21 positions the bonded workpiece WS with the box base 26 on the base 11 and measures the thickness of the substrate S. A temporary placement table 22 is provided at the center of the upper surface of the box base 26 of the temporary placement means 21. A pair of positioning pins 23 a and 23 b are placed around the temporary placement table 22. A measurement table 25 is disposed between the pair of positioning pins 23a and 23b so as to extend radially outward from the temporary placement table 22. Above the measurement table 25, a substrate thickness measuring means 24 for calculating the thickness of the substrate is provided. The upper surface of the box base 26 is inclined by an angle θ. For this reason, the upper surfaces of the temporary placement table 22 and the measurement table 25 are also inclined following the upper surface of the box base 26.

  The pair of positioning pins 23a and 23b are formed in a cylindrical shape, and are arranged so as to be equidistant from the center O1 of the temporary placement table 22, respectively. A pair of positioning pins 23 a and 23 b are abutted against the outer peripheral edge of the wafer W placed on the temporary placement table 22, whereby the center O <b> 2 of the bonded workpiece WS is positioned at the center O <b> 1 of the temporary placement table 22.

  A motor 27a (a motor corresponding to the positioning pin 23b is not shown) is provided inside the box base 26 just below the positioning pins 23a and 23b. The positioning pins 23a and 23b are attached to the output shaft of the motor 27a so as to be rotatable around the vertical axis. When the bonded workpiece WS is lifted and the outer periphery contacts the positioning pins 23a and 23b, the center is measured from the outer periphery of the wafer W by an optical system (not shown) by rotating the positioning pins 23a and 23b. Thus, the sticking deviation of the wafer W with respect to the substrate S can be detected.

  The upper surface of the measurement table 25 and the upper surface of the temporary placement table 22 are flush with each other, and the air flow paths 28 in the tables 25 and 22 communicate with each other. On the upper surface of the measurement table 25, a plurality of blowing ports 25a for blowing air are formed in two rows in the radial direction. A central port 22a is formed at the center O1 of the temporary placement table 22 and communicates with the air flow path 28 in the table. A supply nozzle 96 is attached to the lower surface of the box base 26, and the supply nozzle 96 is connected to an air supply source 98 via a valve 97. By opening the valve 97, air is supplied to the supply nozzle 96, sent from the supply nozzle 96 to the air flow path 28 through the blowout path 26 a provided in the box base 26, and blown out from the center port 22 a and the blowout port 25 a. Is done.

  Here, with reference to FIG.3 and FIG.4, the positioning operation | movement of the bonding workpiece | work WS and the measurement operation | movement of the thickness of the substrate S are demonstrated in detail. FIG. 3 is a diagram showing an example of the positioning operation of the temporary placing means according to the present embodiment. FIG. 4 is a diagram illustrating an example of the measurement operation of the thickness of the substrate according to the present embodiment. In the following description, the description of the center detection of the wafer W is omitted assuming that there is no wafer W sticking deviation with respect to the substrate S.

  As shown in FIG. 3A, in the temporary placement means 21, the bonded workpiece WS is conveyed to the temporary placement table 22 and placed on the temporary placement table 22 that is inclined with the inclination of the box base 26. In the illustrated example, the center O2 of the bonded workpiece WS does not match the center O1 of the temporary placement table 22, and the bonded workpiece WS is placed on the temporary placement table 22 in a state where a deviation has occurred. At this time, the valve 97 is closed and air is not supplied from the air supply source 98.

  Next, as shown in FIG. 3B, the valve 97 is opened, air is supplied from the air supply source 98 through the supply nozzle 96 to the air flow path 28, and the center port 22a communicating with the air flow path 28 is blown up. Air is blown up from the mouth 25a. At this time, air is blown up toward the lower surface of the bonded workpiece WS, and the bonded workpiece WS placed on the temporary placement table 22 and the measurement table 25 floats horizontally. An air layer is generated between the floating bonded workpiece WS and the temporary placement table 22 and the measurement table 25, and the friction between the bonded workpiece WS and the tables 22 and 25 is reduced. Thereby, the bonded workpiece WS slides along the inclination of the temporary placement table 22, and the outer peripheral edge of the bonded workpiece WS comes into contact with the positioning pins 23a and 23b in a state where the bonded workpiece WS is lifted.

  Next, as shown in FIG. 3C, the valve 97 is closed, the supply of air from the air supply source 98 is stopped, and the blowing of air from the center port 22a and the blowing port 25a is stopped. Accordingly, the bonded workpiece WS is lowered to the temporary placement table 22 from the state where the outer peripheral edge is in contact with the positioning pins 23a and 23b and is floating. The center O2 of the bonded workpiece WS placed on the temporary placement table 22 again matches the center O1 of the temporary placement table 22, and the positioning of the bonded workpiece WS is completed.

  As shown in FIG. 4, the substrate thickness measuring means 24 includes a pin-like contact gauge 24 a at the tip of the arm 24 b and is supported by a support portion 24 c disposed in the vicinity of the measurement table 25. ing. The gauge 24 a is provided so as to be perpendicular to the upper surface of the measurement table 25. The gauge 24a is supported above the protruding portion 87 of the bonded workpiece WS.

  When the bonded workpiece WS is placed on the temporary placement table 22 in a state where the center O2 of the bonded workpiece WS and the center O1 of the temporary placement table 22 are aligned, the substrate thickness measuring means 24 will move the preceding bonded workpiece. While the WS wafer W is being ground, the thickness ΔH1 of the substrate S is calculated. The substrate thickness measuring unit 24 measures the height H2 of the upper surface 82 of the substrate S by bringing the gauge 24a into contact with the protruding portion 87 of the subsequent bonded workpiece WS. The measurement result is output to the calculation unit 86 (see FIG. 1), the value of H2 measured by the gauge 24a, and the temporary placement table 22 (measurement table 25) previously measured by the gauge 24a and recorded in the memory of the calculation unit 86. The substrate thickness value of the bonded workpiece WS is calculated from the difference ΔH1 from the value of the height H1 of the upper surface 22b. As described above, the substrate thickness value ΔH1 is calculated during the grinding of the preceding wafer W, whereby the bonded workpiece WS is transferred from the temporary placement table 22 to the chuck table 41 and then the height of the upper surface 82 of the substrate S is increased. Since there is no need to measure the height H2, the time until the wafer W starts to be ground can be shortened.

  The height H2 of the upper surface 82 of the substrate S may be measured at a plurality of locations on the substrate S to calculate the average height. In this case, after the height H2 of the upper surface 82 of the substrate S is measured by the substrate thickness measuring means 24, air is blown up again from the center port 22a and the blowing port 25a to float the bonded workpiece WS, and the bonded workpiece WS is brought into contact with the positioning pins 23a and 23b. The bonding work WS is rotated by rotating the positioning pins 23a and 23b. Then, the blowing of air from the center port 22a and the blowing port 25a is stopped, the bonded workpiece WS is lowered, and the height H2 of another portion of the substrate S is measured.

  Next, with reference to FIG. 5, the measurement operation of the thickness of the wafer W will be described in detail. FIG. 5 is a diagram illustrating an example of a wafer thickness measurement operation according to the present embodiment.

  When the turntable 40 rotates, the chuck table 41 is revolved, and when the bonding workpiece WS held on the holding surface 42 of the chuck table 41 is positioned at the rough grinding position of the rough grinding means 46, the outer periphery of the grinding wheel 49 is bonded. The workpiece WS is positioned at a position passing through the center of the wafer W. At this time, the first measuring means 91 comes into contact with the holding surface 42 outside the bonded workpiece WS, and the height H3 of the holding surface 42 is measured. Further, the second measuring means 92 comes into contact with the upper surface 81 of the wafer W of the bonded workpiece WS, and the height H4 of the upper surface 81 of the wafer W is measured. The measurement result is output to the calculation unit 86.

  Next, the grinding wheel 49 is rotated while the chuck table 41 is rotated, the grinding wheel 49 is brought close to the upper surface 81 of the wafer W, the grinding wheel 49 is brought into contact with the upper surface 81 of the wafer W, and the upper surface 81 of the wafer W is moved. Rough grinding is performed by a grinding wheel 49. The change in the height H4 of the upper surface 81 of the wafer W is measured in real time by the second measuring means 92.

At this time, the calculation unit 86 (see FIG. 1) calculates the thickness of the bonded workpiece WS (the thickness of the substrate S and the wafer) from the difference ΔH2 between the height H4 of the upper surface 81 of the wafer W and the height H3 of the holding surface 42. The total value with the thickness of W) is calculated. Then, from this ΔH2, the substrate thickness value ΔH1 calculated in advance by the substrate thickness measuring means 24 of the temporary placing means 21 is subtracted to obtain a thickness ΔH3 of the wafer W. That is, the calculation unit 86 calculates the thickness of the wafer W using the following formula (1).
Wafer thickness (ΔH3) = Wafer upper surface height value (H4) − (Holding surface height value (H3) + Substrate thickness value (ΔH1)) (1)

  The movement amount of the rough grinding means 46 is controlled by the control unit 85 (see FIG. 1) based on the calculated thickness ΔH3 of the wafer W. By this control, the rough grinding of the wafer W is continued until the thickness ΔH3 of the wafer W reaches a predetermined thickness, and when the predetermined thickness is reached, the rough grinding means 46 is lifted, and the grinding wheel 49 is separated from the wafer W to remove the wafer W. The rough grinding is completed. Further, the finish grinding by the finish grinding means 51 is ground in the same manner as the rough grinding by the coarse grinding means 46.

  As described above, in the grinding apparatus 1 according to the present embodiment, the substrate thickness value ΔH1 measured by the substrate thickness measuring means 24, the first measuring means 91, 93, and the second measuring means 92, 94 are used. Using the measured holding surface height value H3 and wafer upper surface height value H4, the thickness ΔH3 of the wafer W being ground can be calculated, and the wafer W can be ground to a predetermined finish thickness. Further, before the bonded workpiece WS is transported from the temporary placement table 22 to the chuck table 41, the height H1 of the upper surface 22b of the temporary placement table 22 and the protruding portion 87 are measured by the substrate thickness measuring unit 24 in the temporary placement table 22. The thickness ΔH1 of the substrate S can be calculated from the difference from the height H2 of the upper surface 82 of the substrate. For this reason, it is possible to calculate the thickness ΔH1 of the substrate S of the subsequent bonded workpiece WS in advance using the grinding time of the wafer W of the preceding bonded workpiece WS in the temporary placement table 22. Therefore, since the time for measuring the thickness ΔH1 of the substrate S after the bonded workpiece WS is transferred from the temporary placement table 22 to the chuck table 41, the grinding time of the wafer W can be shortened.

  In the above-described embodiment, the contact-type gauge 24a is used as the substrate thickness measuring unit 24. However, the present invention is not limited to this configuration. As shown in FIG. 6, the substrate thickness measuring means 24 may use an optical thickness measuring device 29. FIG. 6 is a diagram of temporary placement means according to a modification. 6A is a plan view showing a temporary placement means according to a modification, and FIG. 6B is a side view of the temporary placement means according to the modification as seen from the direction of arrow A in FIG. 6A. The optical thickness measuring device 29 is, for example, a reflection type optical displacement sensor, which irradiates the measuring light toward the substrate S of the bonded workpiece WS and reflects the reflected light reflected from the upper surface of the substrate S and the substrate S. The thickness [Delta] H1 of the substrate S is measured based on the optical path difference between the reflected light reflected from the upper surface and the reflected light reflected from the lower surface. When the optical thickness measuring device 29 is used, the thickness ΔH1 of the substrate S can be measured in a state where air is supplied from the center port 22a and the bonded workpiece WS is floated.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, direction, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above-described embodiment, the bonded workpiece WS is floated, the bonded workpiece WS is brought into contact with the positioning pins 23a and 23b, and the bonded workpiece WS is rotated by rotating the positioning pins 23a and 23b. However, the present invention is not limited to this configuration. It is good also as a structure which rotates the bonding workpiece | work WS by rotating the temporary placement table 22 in which the bonding workpiece | work WS is mounted.

  Moreover, although it was set as the structure which positions the bonding workpiece | work WS by the positioning pins 23a and 23b, it is not limited to this structure. When the substrate thickness measuring means 24 has only one measurement position of the substrate S, the bonded workpiece WS may be positioned by a plate-shaped positioning block.

  As described above, the present invention has an effect that it is possible to shorten the time until the wafer of the subsequent bonded workpiece starts to be ground using the grinding time of the wafer of the preceding bonded workpiece, Particularly, it is useful for a grinding apparatus for grinding a hard substrate such as sapphire.

DESCRIPTION OF SYMBOLS 1 Grinding device 21 Temporary placement means 22 Temporary placement table 22a Center port 23a, 23b Positioning pin 24 Substrate thickness measurement means 24a Gauge 24b Arm 24c Support part 25 Measurement table 25a Blow-up port 29 Optical thickness measuring device 31 Conveyance means 41 Chuck table 42 Holding surface of chuck table 46 Coarse grinding means 48, 53 Grinding wheel 51 Finish grinding means
81 Wafer upper surface 82 Substrate upper surface 86 Calculation unit 87 Projection unit 91, 93 First measurement unit 92, 94 Second measurement unit O1 Center of temporary placement table O2 Center of bonded workpiece H1 Height of upper surface of temporary placement table Height H2 Height of substrate upper surface H3 Height of chuck table holding surface H4 Height of wafer upper surface of bonded workpiece ΔH1 Substrate thickness value ΔH3 Wafer thickness S Substrate W Wafer WS Bonded workpiece

Claims (1)

A chuck table having a holding surface for holding a bonded work in which a wafer is bonded to a disk-shaped substrate having an outer diameter larger than that of a wafer to form a protruding portion, and a bonding method in which the chuck table holds the holding surface side A grinding means for grinding the wafer of the workpiece with a grinding wheel, a first measuring means for measuring the height of the holding surface, and a second for measuring the height of the wafer upper surface of the bonded workpiece held on the chuck table. A grinding device comprising: a measuring means; a conveying means for conveying a bonded work to the chuck table; and a temporary placing means for temporarily placing the bonded work,
The temporary placement means includes a temporary placement table for temporarily placing a bonded workpiece, and a substrate thickness measurement for calculating a thickness of the substrate based on a difference between a height of the upper surface of the temporary placement table and a height of the upper surface of the substrate of the protruding portion. Means,
A substrate thickness value measured by the substrate thickness measuring means;
A holding surface height value obtained by measuring the height of the holding surface with the first measuring means;
Using the wafer upper surface height value obtained by measuring the height of the wafer upper surface of the bonded workpiece conveyed to the chuck table by the second measuring means,
Wafer thickness = wafer top surface height value-(holding surface height value + substrate thickness value)
Including a calculation unit for calculating the thickness of the wafer,
A grinding apparatus that performs grinding until the wafer thickness calculated by the calculation unit reaches a preset finish thickness.

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