JP6618822B2 - Method for detecting wear amount of grinding wheel - Google Patents

Description

  The present invention relates to a method for detecting a consumption amount of a grinding wheel.

  Semiconductor wafers, wafers such as sapphire and SiC, and plate-like objects such as glass and ceramics are widely used in electronic devices as electronic devices. In the process of thinning wafers and plate-like objects, grinding machines that use a grinding wheel for thinning are used.

  In order to prevent the device surface of the workpiece from being damaged during grinding by the grinding machine, an adhesive tape (protective member) called a protective tape is attached to the device surface, and the workpiece is chucked through the protective member. It is known that the exposed surface side is thinned with a grinding wheel or a polishing wheel (hereinafter, the grinding wheel will be described as a representative of the grinding wheel or the polishing wheel). In the grinding apparatus, the grinding wheel is worn (consumed) by grinding. Therefore, the grinding device adjusts the height of the grinding wheel according to the wear amount (consumption amount) of the grinding wheel, aligns the grinding wheel and the workpiece, and thins the workpiece. For example, when the workpiece reaches the desired thickness (at the end of processing), the amount of grinding wheel consumption is calculated from the position where the grinding means is positioned, and the grinding wheel is consumed at the start of the next processing. If the grinding means is not present, the grinding means is positioned at a position where the grinding means is lowered in the thickness direction by the amount of consumption of the grinding wheel.

  A technique for measuring the thickness of a plate-like workpiece after grinding by contacting the workpiece is known (for example, see Patent Document 1). A technique is known in which the thickness of a plate-like workpiece after grinding is measured without contacting the workpiece (see, for example, Patent Document 2).

JP 2009-072851 A JP 2010-199227 A

  By the way, since the protection member has elasticity, if it is pushed in the thickness direction by the grinding means during the grinding process, the protective member shrinks slightly compared to before grinding. For this reason, when calculating the amount of wear of the grinding wheel, there is a possibility that the amount of shrinkage of the protective member that has been pressed and shrunk by the grinding means is calculated as the amount of wear of the grinding wheel. In this case, the calculated consumption amount of the grinding wheel is calculated to be larger than the original consumption amount of the grinding wheel. For this reason, at the start of the next processing, the grinding means is positioned at a position where the grinding means is lowered in the thickness direction more than the consumption amount of the original grinding wheel. In this case, the grinding wheel may come into contact with the workpiece held by the protective member having the original thickness. In other words, the grinding wheel may come into contact with the workpiece held by the protective member having the original thickness at the start of the next processing at a high feed rate before the air cut of the grinding device.

  The present invention has been made in view of the above, and the purpose thereof is a grinding wheel that accurately calculates the amount of wear of the grinding wheel even when a protective member having elasticity is attached to one surface. An object of the present invention is to provide a consumption amount detection method.

  In order to solve the above-described problems and achieve the object, the method for detecting the amount of wear of a grinding wheel according to the present invention includes the other surface of a plate-like workpiece having an elastic protective member attached to one surface. A method for detecting a consumption amount of a grinding wheel in a grinding apparatus for grinding with a grinding wheel, the grinding apparatus holding a workpiece on a holding surface via the protective member, and holding the workpiece on the chuck table A grinding means mounted with the grinding wheel for grinding the other surface of the workpiece, a grinding feed means for bringing the grinding means close to and away from the holding surface, and a position for detecting the position of the grinding means Detecting means; a first gauge for measuring the height of the upper surface of the workpiece relative to the holding surface; A second gauge for measuring the thickness of the workpiece, After grinding the workpiece with the grinding means until the workpiece measured with two gauges has a predetermined finished thickness, the upper surface of the workpiece before grinding and the height of the grinding wheel coincide with each other. From the height h1 of the grinding means detected by the position detection means, the height h2 of the grinding means at the end of grinding, and the grinding amount Z of the workpiece, (h1−h2) −Z = a is obtained. The upper surface height H1 of the workpiece before grinding measured by the first gauge, the upper surface height H2 of the workpiece after grinding, and the workpiece before grinding measured by the second gauge. (H1−T1) − (H2−T2) = a contraction amount a1 of the protective member is obtained from the thickness T1 of the workpiece and the finished thickness T2 of the workpiece, and the consumption amount of the grinding wheel is calculated by aa1. Ask.

  According to the method for detecting the consumption amount of the grinding wheel of the present invention, the height of the upper surface of the workpiece including the protection member is measured with the first gauge, and the actual thickness of the workpiece is measured with the second gauge. As a result, even if the protective member attached to the workpiece shrinks during grinding, the consumption of the grinding wheel can be reduced by subtracting the actual thickness of the workpiece from the height of the upper surface of the workpiece. It can be calculated accurately. Thus, even when a protective member having elasticity is attached to one surface, the amount of wear of the grinding wheel can be accurately calculated.

FIG. 1 is a perspective view of a grinding apparatus according to an embodiment. FIG. 2 is a side view for explaining the grinding means, the workpiece, and the chuck table of the grinding apparatus according to the embodiment. FIG. 3 is an enlarged side view illustrating the grinding means, the workpiece, and the chuck table of the grinding apparatus according to the embodiment. FIG. 4 is an enlarged side view showing the grinding means and the chuck table of the grinding apparatus according to the embodiment in an enlarged manner. FIG. 5 is an enlarged side view showing the grinding means, the workpiece, and the chuck table of the grinding apparatus according to the embodiment in an enlarged manner.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. In addition, various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

  FIG. 1 is a perspective view of a grinding apparatus according to an embodiment. FIG. 2 is a side view for explaining the grinding means, the workpiece, and the chuck table of the grinding apparatus according to the embodiment. FIG. 3 is an enlarged side view illustrating the grinding means, the workpiece, and the chuck table of the grinding apparatus according to the embodiment. FIG. 4 is an enlarged side view showing the grinding means and the chuck table of the grinding apparatus according to the embodiment in an enlarged manner. FIG. 5 is an enlarged side view showing the grinding means, the workpiece, and the chuck table of the grinding apparatus according to the embodiment in an enlarged manner.

  The grinding device 1 according to the present embodiment grinds the other surface of the plate-like workpiece W with the protective tape T having elasticity attached to one surface. As shown in FIG. 1, the grinding apparatus 1 includes an unprocessed wafer cassette 11, a transport unit 12, a temporary placement unit 13, a carry-in / carry-out unit 14, a turntable 15, a plurality of chuck tables 16, A grinding unit (grinding means) 17, a cleaning unit 18, a processed wafer cassette 19, a position detection means 20, a first gauge 30, a second gauge 40, and a control means 50 are provided.

  Here, the workpiece W is an object to be processed by the grinding device 1. In the present embodiment, the workpiece W is a disk-shaped semiconductor wafer or optical device wafer whose base material is silicon, sapphire, gallium or the like. The workpiece W has a protective tape (protective member) T attached to the surface (one surface), the protective tape T is held by the chuck table 16, and the back surface (the other surface, the top surface) Wa on the back side of the surface. Is subjected to grinding and polishing, and thinned to a predetermined thickness. The protective tape T is made of an elastic material and contracts in the thickness direction. More specifically, when the protective tape T is pushed in the thickness direction by the grinding wheel 173 of the grinding unit 17 during the grinding process, the protective tape T contracts slightly in the thickness direction as compared to before grinding. As an example, the protective tape T has a thickness of 100 to 300 μm, and may shrink by about 5 to 20 μm in the thickness direction during grinding.

  The unprocessed wafer cassette 11 is disposed in the apparatus main body of the grinding apparatus 1. The unprocessed wafer cassette 11 accommodates a plurality of workpieces W before processing.

  The transport unit 12 includes a pick unit 121 that holds the workpiece W. The pick part 121 is arranged to be movable in the X-axis direction, the Y-axis direction, and the Z-axis direction. In the pick unit 121, the transport unit 12 takes out the workpiece W before processing from the unprocessed wafer cassette 11 and transports it onto the temporary placement unit 13. In the pick unit 121, the transport unit 12 transports the processed workpiece W from the cleaning unit 18 to the processed wafer cassette 19 and accommodates it.

  In the temporary placement unit 13, the workpiece W before grinding is placed by the transport unit 12.

  The carry-in / carry-out unit 14 is arranged to be movable in the X-axis direction, the Y-axis direction, and the Z-axis direction. The carry-in / carry-out unit 14 conveys the workpiece W before processing from the temporary placement unit 13 to the chuck table 16. The carry-in / carry-out unit 14 carries the processed workpiece W from the chuck table 16 to the cleaning unit 18.

  The turntable 15 is a disk-shaped table provided on the upper surface of the apparatus main body of the grinding apparatus 1. The turntable 15 is disposed so as to be rotatable around the Z axis. A chuck table 16 is disposed on the turntable 15.

  The chuck table 16 holds the workpiece W. The chuck table 16 is disposed on the turntable 15. In the present embodiment, a pair of chuck tables 16 are arranged at positions separated from the center of the turntable 15. The chuck table 16 has a disk shape in which a portion constituting the holding surface 16a is formed of porous ceramic or the like. The chuck table 16 is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). As shown in FIG. 2, the chuck table 16 has the surface of the workpiece W placed on the holding surface 16 a via the protective tape T. The chuck table 16 sucks and holds the workpiece W placed on the holding surface 16a through the protective tape T. The chuck table 16 rotates the workpiece W held by suction around the Z axis. The chuck table 16 is provided so as to be movable in the XY plane when the turntable 15 rotates around the Z axis. Accordingly, the chuck table 16 positions the workpiece W placed on the holding surface 16a at the carry-in / out position and the grinding position.

  The grinding unit 17 performs grinding on the upper surface Wa of the workpiece W held on the chuck table 16 positioned at the grinding position, thereby thinning the workpiece W. The grinding unit 17 includes a grinding feed means 171 for processing and feeding the grinding unit 17 and a grinding wheel 172 that rotates at high speed around the Z axis. The grinding feeding means 171 moves the grinding unit 17 close to the workpiece W held on the chuck table 16 along the Z-axis direction and feeds the grinding unit 17. The grinding feed means 171 moves the grinding unit 17 away from the workpiece W held by the chuck table 16 along the Z-axis direction and separates the grinding unit 17 from the workpiece W. The grinding wheel 172 includes a plurality of grinding wheels 173 that are pressed against the upper surface Wa of the workpiece W held on the chuck table 16 and grind the upper surface Wa of the workpiece W. In such a grinding unit 17, the grinding wheel 172 is rotated in the same direction as the chuck table 16 around the Z axis, and is fed by the grinding feed means 171, and the grinding wheel 173 is held on the chuck table 16. By pressing against the upper surface Wa of the workpiece W, the upper surface Wa of the workpiece W is ground.

  More specifically, as shown in FIG. 3, in the grinding unit 17, the grinding wheel 173 rotates from the upper standby position PS while the grinding wheel 172 rotates around the Z axis. It descends at a high speed to the air cut start point PA just before reaching the upper surface Wa. The air cut start point PA is a position of a distance D between the lower surface of the grinding wheel 173 and the upper surface Wa of the workpiece W before grinding. The grinding unit 17 performs an air cut in which the grinding wheel 173 descends at a low speed while the grinding wheel 173 is idling to a slight distance D from the air cut starting point PA to the point reaching the upper surface Wa of the workpiece W before grinding. Do. When the grinding wheel 173 reaches the upper surface Wa of the workpiece W before grinding, the grinding unit 17 further performs grinding feed with the grinding feed means 171 to grind the workpiece W.

  The grinding wheel 173 of the grinding unit 17 is worn (consumed) by grinding. As shown in FIG. 4, the Z-axis position of the grinding unit 17 detected by the position detecting means 20 in the state in which the height of the lower surface of the grinding wheel 173 and the holding surface 16 a of the chuck table 16 coincide with each other is used as the reference position P. And When the grinding wheel 173 is consumed and the length in the Z-axis direction is small by the consumption amount S, the height of the grinding unit 17 is lowered from the reference position P by the consumption amount S of the grinding wheel 173, so that the bottom surface of the grinding wheel 173 is reduced. The height and the holding surface 16a of the chuck table 16 coincide. Thus, the height of the grinding unit 17 is adjusted according to the consumption amount S of the grinding wheel 173.

  Returning to FIG. 1, the cleaning unit 18 cleans the upper surface Wa of the workpiece W after being processed by the grinding unit 17. The cleaning unit 18 includes a spinner table 181 on which the processed workpiece W is placed, sucked and held, and rotates around the Z axis, and a cleaning liquid supply (not shown) that drops the cleaning liquid onto the workpiece W on the spinner table 181. Means. The cleaning unit 18 supplies the cleaning liquid from the cleaning liquid supply means to the work W on the spinner table 181 while rotating the spinner table 181 holding the work W by suction around the Z axis. The upper surface Wa is cleaned.

  The processed wafer cassette 19 is disposed in the apparatus main body of the grinding apparatus 1. The processed wafer cassette 19 accommodates a plurality of processed workpieces W after processing.

  The position detector 20 detects the Z-axis position of the grinding unit 17. For example, the position detection means 20 includes a Z-axis position detection scale (not shown) and a Z-axis position detection sensor (not shown). The Z-axis position detection scale is a scale arranged along the Z-axis direction. The Z-axis position detection scale is disposed on the fixed portion of the grinding unit 17 or the apparatus main body of the grinding apparatus 1. In this embodiment, the Z-axis position detection scale is arranged on the guide rail of the grinding feed means 171. The Z-axis position detection sensor detects the scale of the Z-axis position detection scale. The Z-axis position detection sensor is disposed on the movable part of the grinding unit 17. In the present embodiment, the Z-axis position detection sensor is disposed at the center of the grinding wheel 172 in the Z-axis direction. The position detection means 20 outputs the Z-axis position of the grinding unit 17 that is the detected scale value to the control means 50 as a position signal. The position detection means 20 is not limited to the above configuration, and for example, the Z-axis position may be detected using a servo motor of the grinding feed means 171.

  Returning to FIG. 2, the first gauge 30 detects the height of the upper surface Wa of the workpiece W with respect to the holding surface 16 a of the chuck table 16. In other words, the first gauge 30 detects the height of the upper surface Wa of the workpiece W including the protective tape T. The first gauge 30 is a contact type. The first gauge 30 outputs the detected height of the upper surface Wa of the workpiece W to the control means 50. The first gauge 30 includes a base portion (not shown) standing on the upper surface of the main body of the grinding device 1, a reference height gauge 31 and a movable height gauge 32 extending from the upper end of the base portion toward the upper side of the chuck table 16. Have. The reference height gauge 31 and the movable height gauge 32 are arranged so as to be swingable up and down with respect to the base portion.

  The reference height gauge 31 detects the height of the holding surface 16 a of the chuck table 16. The reference height gauge 31 includes a probe 31a at the free end. The probe 31a is disposed so as to contact the holding surface 16a. The movable height gauge 32 detects the height of the upper surface Wa of the workpiece W with respect to the holding surface 16a. The movable height gauge 32 includes a probe 32a at the free end. The probe 32a is disposed so as to contact the outer peripheral side of the upper surface Wa of the workpiece W.

  The second gauge 40 irradiates the workpiece W with measurement light and detects the thickness of the workpiece W from the reflected light from the upper surface Wa of the workpiece W and the reflected light from the upper surface of the protective tape T. In other words, the second gauge 40 detects the actual thickness of the workpiece W. The second gauge 40 is a non-contact type. The second gauge 40 outputs the detected thickness of the workpiece W to the control means 50. The second gauge 40 is erected on the upper surface of the apparatus main body of the grinding apparatus 1, and a base part (not shown) whose tip extends above the chuck table 16 and a cylindrical head part 41 provided at the tip of the base part. And. Inside the head unit 41, an irradiation unit that emits measurement light, and a light reception unit that receives the reflected light from the upper surface Wa of the workpiece W and the reflected light from the upper surface Ta of the protective tape T irradiated from the irradiation unit. Are arranged. The second gauge 40 is processed based on the time difference between the reflected light received by the light receiving unit and reflected from the upper surface Wa of the workpiece W and reflected from the upper surface Ta of the protective tape T. The thickness of the object W is detected.

  The control means 50 controls each of the above-described components constituting the grinding apparatus 1 to cause the grinding apparatus 1 to perform a machining operation on the workpiece W. The control means 50 is mainly composed of an arithmetic processing unit constituted by, for example, a CPU, and a microprocessor (not shown) provided with a ROM, a RAM and the like. The control means 50 is connected to a display means (not shown) for displaying the state of the machining operation, an operation means (not shown) used when the operator registers machining content information, and the like.

  The control means 50 controls the position detection means 20, the first gauge 30, and the second gauge 40 during the grinding of the workpiece W to detect the detection values shown in FIG. More specifically, the control means 50 uses the position detection means 20 to determine the height h1 of the grinding unit 17 in a state where the upper surface Wa of the workpiece W before grinding and the lower surface of the grinding wheel 173 coincide with each other, and the end of grinding The height h2 of the grinding unit 17 at the time is detected. The control means 50 causes the first gauge 30 to detect the upper surface height H1 of the workpiece W before grinding and the upper surface height H2 of the workpiece W after grinding. The control means 50 causes the second gauge 40 to detect the thickness T1 of the workpiece W before grinding and the thickness T2 of the workpiece W after grinding.

  Control of the grinding unit 17 by the control means 50 will be described in detail. The control means 50 controls the grinding feed means 171 of the grinding unit 17 so that the workpiece W is ground to the finished thickness T2. The control means 50 calculates the wear amount S of the grinding wheel 173 based on the detection values output from the position detection means 20, the first gauge 30 and the second gauge 40, and the grinding feed means 171 of the grinding unit 17. To control.

  More specifically, the control means 50 determines (h1−) based on the height h1 of the grinding unit 17 before grinding, the height h2 of the grinding unit 17 at the end of grinding, and the grinding amount Z of the workpiece W. h2) -Z = a is calculated. a is the amount of wear of the grinding wheel 173 based on the position of the grinding unit 17. The grinding amount Z of the workpiece W is calculated as the difference between the thickness T1 and the finish thickness T2 of the workpiece W before processing. The control means 50 includes an upper surface height H1 of the workpiece W before grinding, an upper surface height H2 of the workpiece W after grinding, a thickness T1 of the workpiece W before grinding, and the workpiece W. Based on the finished thickness T2, the shrinkage amount a1 of the protective tape T is calculated by (H1-T1)-(H2-T2). And the control means 50 calculates the consumption amount S of the grinding wheel 173 by a-a1. Then, the control means 50 controls the grinding feed means 171 of the grinding unit 17 based on the calculated consumption amount S of the grinding wheel 173.

  Next, a method for detecting the amount of wear of the grinding wheel using the grinding apparatus 1 according to the present embodiment will be described with reference to the drawings. The method for detecting the amount of wear of the grinding wheel detects the amount of wear S of the grinding wheel 173 in the grinding apparatus 1 that grinds the upper surface Wa of the plate-like workpiece W to which the protective tape T is adhered with the grinding wheel 173.

  First, the operator places the unprocessed wafer cassette 11 containing the workpiece W and the processed wafer cassette 19 at predetermined positions on the apparatus main body of the grinding apparatus 1. At this time, the grinding unit 17 is separated from the chuck table 16 by the grinding feed means 171. Then, the operator registers the processing content information in the control means 50. The machining content information includes the finished thickness T2 of the workpiece W and the first air cut start point PA.

  Then, when there is a machining operation start instruction from the operator, the control unit 50 causes the grinding device 1 to start the machining operation. The control means 50 causes the transport unit 12 to take out one workpiece W before processing from the unprocessed wafer cassette 11 and place it on the temporary placement unit 13. The control means 50 causes the conveyance unit 12 to place the workpiece W on the temporary placement unit 13 on the chuck table 16 at the loading / unloading position, and causes the workpiece W to be sucked and held on the chuck table 16. The control means 50 rotates the turntable 15 around the Z axis, and moves the chuck table 16 holding the workpiece W by suction to the grinding position. These processes are sequentially performed on the workpiece W before processing in the unprocessed wafer cassette 11.

  The control means 50 causes the grinding feed means 171 to lower the grinding unit 17 and cause the grinding unit 17 to perform grinding while supplying grinding water to the workpiece W held on the chuck table 16.

  More specifically, first, the control unit 50 causes the grinding apparatus 1 to perform a machining operation on the first workpiece W. The control means 50 lowers the grinding unit 17 at a high speed from the upper standby position PS to the first air cut start point PA in a state where the grinding wheel 172 is rotated around the Z axis. Then, the control means 50 causes the grinding unit 17 to grind the upper surface Wa of the workpiece W, and the thickness T2 of the workpiece W after grinding measured by the second gauge 40 is the finished thickness T2. The workpiece W is thinned until it reaches

  When the thickness T2 of the workpiece W after grinding reaches the finished thickness T2, the control means 50 ends the grinding process by the grinding unit 17. The control means 50 causes the grinding feed means 171 to raise the grinding unit 17 to the upper standby position PS and to separate it from the workpiece W on the chuck table 16.

  The control means 50 drives the turntable 15 to rotate about the Z axis. The control means 50 moves the chuck table 16 that sucks and holds the processed workpiece W to the loading / unloading position.

  The control means 50 causes the transport unit 12 to transport the workpiece W positioned at the carry-in / out position to the cleaning unit 18. The control means 50 causes the cleaning unit 18 to clean the workpiece W. The control means 50 stores the workpiece W after cleaning in the processed wafer cassette 19 in the transport unit 12.

  The control means 50 ends the position detecting means 20, the first gauge 30, and the second gauge until the processing operation for the first workpiece W is completed and the processing operation for the second workpiece W is started. Based on the detected values detected at 40, the wear amount S of the grinding wheel 173 is calculated.

  More specifically, the control means 50 determines the grinding wheel 173 based on the height h1 of the grinding unit 17 before grinding, the height h2 of the grinding unit 17 at the end of grinding, and the grinding amount Z of the workpiece W. Is calculated by (h1-h2) -Z.

  The control means 50 includes an upper surface height H1 of the workpiece W before grinding, an upper surface height H2 of the workpiece W after grinding, a thickness T1 of the workpiece W before grinding, and the workpiece W. Based on the finished thickness T2, the shrinkage amount a1 of the protective tape T is calculated by (H1-T1)-(H2-T2). Specifically, for example, the upper surface height H1 of the workpiece W before grinding is 880 μm, the upper surface height H2 of the workpiece W after grinding is 360 μm, the thickness T1 of the workpiece W before grinding is 700 μm, When the thickness T2 of the workpiece W after grinding is 200 μm, the shrinkage amount a1 of the protective tape T is calculated as 20 μm by (H1−T1) − (H2−T2).

  And the control means 50 calculates the consumption amount S of the actual grinding wheel 173 by a-a1. In other words, the actual consumption amount S of the grinding wheel 173 is a value obtained by subtracting 20 μm of the contraction amount a1 of the protective tape T from the consumption amount a of the grinding wheel 173 based on the position of the grinding unit 17.

  Next, the control means 50 causes the grinding apparatus 1 to perform a machining operation on the second workpiece W. First, the control means 50 takes out one workpiece W before the next machining from the unprocessed wafer cassette 11 and positions it at the grinding position in the same manner as the first workpiece W. The control means 50 lowers the grinding unit 17 at a high speed to the height at which the grinding feed means 171 lowers the air cut starting point PA by the consumption amount S of the grinding wheel 173. The control means 50 grinds the workpiece W with the grinding unit 17.

  The control means 50 repeats such processing for the third and subsequent workpieces W to thin the workpiece W.

  As described above, the grinding apparatus 1 according to the present embodiment measures the height of the upper surface Wa of the workpiece W including the protective tape T with the first gauge 30 and uses the second gauge 40 to measure the workpiece W. Measure actual thickness. Thereby, even if the protective tape T contracts during grinding, the consumption amount S of the grinding wheel 173 is excessively reduced by subtracting the actual thickness of the workpiece W from the height of the upper surface Wa of the workpiece W. Accurate calculation is possible without detection. Thus, even when the protective tape T having elasticity is attached to one surface, the wear amount S of the grinding stone 173 can be accurately calculated in consideration of the shrinkage amount of the protective tape T. .

  Since the grinding device 1 can accurately calculate the wear amount S of the grinding wheel 173, the grinding unit 17 can be adjusted to an appropriate height when the next workpiece W starts to be ground. Thus, the grinding apparatus 1 can suppress the grinding wheel 173 from contacting the workpiece W held by the protective tape T having the original thickness at a high feed rate before the air cut.

  On the other hand, in the conventional grinding apparatus, in order to avoid the grinding wheel coming into contact with the workpiece W, the height of the grinding wheel has to be measured or set up. . Since the grinding device 1 according to the present embodiment does not need to actually measure the height of the grinding wheel or perform setup, it is possible to improve the production efficiency.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention.

  The second gauge 40 of the present embodiment is a non-contact type using ultrasonic waves, but a non-contact type can be arbitrarily selected, and for example, a measuring instrument using ultrasonic waves may be used.

  In the present embodiment, the type of the grindstone has been described as being the grinding grindstone 173, but a grinding grindstone may be used.

DESCRIPTION OF SYMBOLS 1 Grinding machine 11 Unprocessed wafer cassette 12 Transport unit 13 Temporary placement unit 15 Turntable 16 Chuck table 16a Holding surface 17 Grinding unit (grinding means)
171 grinding feed means 173 grinding wheel 18 cleaning unit 19 cassette for processed wafer 20 position detection means 30 first gauge 40 second gauge 50 control means T protective tape (protective member)
W Workpiece

Claims (1)

A grinding wheel wear amount detection method in a grinding device for grinding the other surface of a plate-like workpiece with a protective member having elasticity on one surface with a grinding wheel,
The grinding apparatus
A chuck table for holding the workpiece on a holding surface via the protective member; a grinding means on which the grinding wheel for grinding the other surface of the workpiece held on the chuck table is mounted; A grinding feed means for bringing the grinding means close to and away from the holding surface, a position detecting means for detecting the position of the grinding means, a first gauge for measuring the height of the upper surface of the workpiece relative to the holding surface, A second gauge that irradiates the workpiece with measurement light and measures the thickness of the workpiece with reflected light from the upper surface of the workpiece and the upper surface of the protective member;
After grinding the workpiece with the grinding means until the workpiece measured with the second gauge has a predetermined finished thickness,
The height h1 of the grinding means detected by the position detecting means where the upper surface of the workpiece before grinding matches the height of the grinding wheel, the height h2 of the grinding means at the end of grinding, and the work (H1−h2) −Z = a is obtained from the grinding amount Z of the object,
The upper surface height H1 of the workpiece before grinding measured by the first gauge, the upper surface height H2 of the workpiece after grinding, and the workpiece before grinding measured by the second gauge. From the thickness T1 and the finished thickness T2 of the workpiece, (H1−T1) − (H2−T2) = a contraction amount a1 of the protective member is obtained,
A method for detecting the amount of wear of the grinding wheel, wherein the amount of wear of the grinding wheel is determined at a-a1.

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