JP5481264B2 - Grinding equipment - Google Patents

Description

  The present invention relates to a grinding apparatus, and more particularly to a grinding apparatus for grinding a workpiece such as a semiconductor wafer.

  In the manufacturing process of a semiconductor device, in order to obtain a target thickness of the device, thinning is performed by back-grinding at the stage of a semiconductor wafer which is an aggregate of a large number of devices. In accordance with the remarkable thinning of devices in recent years, wafers are processed to be thinner, and higher accuracy is required in managing the thickness. Grinding and polishing of the wafer can proceed while measuring the thickness, but as a thickness detection means in such a form, a contact type that detects the displacement of the thickness while bringing the measuring probe into contact with the work surface. Thickness detection means is known (see, for example, Patent Document 1).

  However, in the contact-type thickness detecting means, the thickness of the wafer is excluded except for the problem that the surface to be processed is scratched by the probe to be contacted, and that the scratch causes a reduction in the bending strength of the wafer, and the thickness of the protective tape. There was a problem such as being unable to detect only. For this reason, the present applicant has proposed an optical non-contact type thickness detecting means capable of detecting the thickness without bringing a probe or the like into contact with the wafer (see, for example, Patent Document 2).

  In this non-contact type thickness detection means, the detection range (for example, 100 μm or less) in which the thickness of the wafer can be detected may be limited, and a wafer having a thickness exceeding the detection range of the non-contact type thickness detection means is processed. In some cases, it was necessary to use contact-type thickness measuring means in combination.

Japanese Patent Laid-Open No. 2001-9716 JP 2009-50944 A

  By the way, in the grinding of semiconductor wafers, the detection by the non-contact type thickness detection means can detect only the thickness of the wafer without damaging the surface of the wafer, so the detection means from the contact type to the non-contact type at an early stage. There is a desire to switch. On the other hand, there is a problem that the thickness of the wafer cannot be accurately detected when the contact type is switched from the contact type to the non-contact type at a stage where the non-contact type thickness detection means cannot stably detect.

  The present invention has been made in view of such a situation, and an object thereof is to provide a grinding apparatus capable of switching from contact-type thickness detection to non-contact-type thickness detection at an appropriate processing timing.

  The grinding apparatus of the present invention includes a holding means having a holding surface for holding a workpiece, a processing means for grinding the workpiece held on the holding surface, and a thickness detection for detecting the thickness of the workpiece held on the holding surface. Means for detecting the thickness of the workpiece without contacting the upper surface of the workpiece. Non-contact type detection unit and workpiece detected by the non-contact type detection unit from grinding based on the thickness of the workpiece detected by the contact type detection unit when the thickness of the workpiece approaches a predetermined thickness by grinding. A switching control unit that switches to grinding based on the thickness of the non-contact type in a state in which grinding based on the thickness of the workpiece detected by the contact type detection unit is being performed. The thickness detection of the workpiece by the protruding portion is started, and a plurality of first inclinations representing a change in the thickness with respect to the passage of time are obtained from the thickness information of the plurality of workpieces detected by the contact type detection portion with the passage of time. A first inclination is obtained by averaging one inclination, and a second inclination representing a change in thickness with respect to time from thickness information of a plurality of workpieces detected with the passage of time by the non-contact detection unit. The second average slope is obtained by averaging a plurality of second slopes, and the second average slope is within an allowable range that is a slope that approximates the first average slope. Based on this, the grinding process based on the workpiece thickness detected by the contact type detection unit is switched to the grinding process based on the workpiece thickness detected by the non-contact type detection unit.

  According to the above grinding apparatus, during the grinding process based on the detection result of the contact type detection unit, the first average inclination representing the average change in the thickness of the workpiece over time is obtained from the detection result of the contact type detection unit. At the same time, a second average inclination representing an average of changes in the thickness of the work over time is obtained from the detection result of the non-contact detection unit. The second average inclination falls within an allowable range in which a change tendency substantially the same as the first average inclination is obtained, so that the non-contact detection unit can obtain detection accuracy comparable to that of the contact detection unit. As described above, the grinding process based on the detection result of the contact detection unit is switched to the grinding process based on the detection result of the non-contact detection unit. For this reason, it is not switched to the non-contact type thickness detection when the detection accuracy of the non-contact type detection unit is low, such as when the workpiece is thick. In this way, it is possible to switch from contact type thickness detection to non-contact type thickness detection by specifying the timing at which the workpiece thickness can be accurately detected by the non-contact type detection unit.

  According to the present invention, by comparing the change tendency of the detection result by the contact type detection unit and the detection result by the non-contact type detection unit, from the contact type thickness detection to the non-contact type thickness detection at an appropriate processing timing. Can be switched.

1 is an external perspective view of a grinding apparatus according to an embodiment of the present invention. It is a figure for demonstrating the relationship between the grinding wheel at the time of the grinding process of the grinding device which concerns on the said embodiment, and a semiconductor wafer. It is a figure for demonstrating an example of the detection characteristic of the contact-type detection part at the time of the grinding process of the grinding device which concerns on the said embodiment, and a non-contact-type detection part. It is a figure for demonstrating the relationship between the thickness detection system of the grinding device which concerns on the said embodiment, and the thickness of a semiconductor wafer. It is a flowchart of the switching control by the switching control part of the grinding device concerning the above-mentioned embodiment. It is a figure which shows the detection result of the non-contact-type detection part in the parallel detection area | region of the grinding device which concerns on the said embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. A grinding apparatus according to an embodiment of the present invention includes a contact type detection unit and a non-contact type detection unit that detect the thickness of a workpiece (workpiece), and detects the thickness from the former to the latter at an appropriate machining timing. The part is switched.

  FIG. 1 is an external perspective view of a grinding apparatus 1 according to an embodiment of the present invention. FIG. 2 is a view for explaining the relationship between the grinding wheel 61 and the semiconductor wafer W during the grinding process of the grinding apparatus 1 according to the present embodiment. In the following, for the sake of convenience of explanation, the lower left side shown in FIG. 1 is called the front side of the grinding apparatus 1, and the upper right side shown in FIG. 1 is called the rear side of the grinding apparatus 1. In the following, for convenience of explanation, the vertical direction shown in FIG. 1 is referred to as the vertical direction of the grinding apparatus 1.

  As shown in FIG. 1, the grinding apparatus 1 has a base 2 having a generally rectangular parallelepiped shape. On the front side of the upper surface of the base 2, an operation panel 3 that receives instructions for the grinding device 1 is provided. A table support 4 for supporting the chuck table 41 is provided on the rear side of the operation panel 3. A column portion 5 is provided on the rear side of the table support 4. A grinding unit 6 is supported on the front surface of the support column 5 so as to be movable in the vertical direction. A thickness detection unit 7 that detects the thickness of the semiconductor wafer W held on the chuck table 41 is provided in the vicinity of the grinding unit 6.

  The grinding apparatus 1 according to the present embodiment having such a configuration is configured to process the semiconductor wafer W by relatively rotating the grinding unit 6 and the chuck table 41 holding the semiconductor wafer W. ing. In the grinding process, the thickness detection unit 7 detects the thickness of the semiconductor wafer W, and the grinding process for the semiconductor wafer W is continued or stopped based on the detection result. More specifically, as shown in FIG. 2, a part of a grinding wheel 61 of a grinding unit 6 to be described later is disposed so as to face the semiconductor wafer W held on the chuck table 41 and comes into contact with the semiconductor wafer W. Move to position. Then, the semiconductor wafer W is ground by rotating the chuck table 41 in the direction of arrow B and rotating the grinding wheel 61 in the direction of arrow C. Then, the thickness detection unit 7 detects the thickness of the semiconductor wafer W in a region that is not disposed facing the grinding wheel 61 to control the continuation or stop of the grinding process on the semiconductor wafer W. The contact detection unit 71 and the non-contact detection unit 75 constituting the thickness detection unit 7 will be described later.

  In the grinding apparatus 1 according to the present embodiment, a semiconductor wafer W such as a silicon wafer or GaAs is described as an example of a workpiece (workpiece), but the present invention is not limited to this configuration. Glass, sapphire-based inorganic material substrates, plate-like metal or resin ductile materials, and various processed materials requiring flatness on the order of micron to submicron order may be used as the workpiece.

  The table support 4 is provided in a square shape and rotatably supports the chuck table 41. The table support 4 is connected to a drive mechanism (not shown), and is slid in the front-rear direction in the opening 2 a formed on the upper surface of the base 2 by a drive force supplied from the drive mechanism. Thereby, the chuck table 41 is separated from the grinding position where the semiconductor wafer W is opposed to the grinding unit 6 and the front side from the grinding position, and the unprocessed semiconductor wafer W is supplied. Is slid to and from the repositioning position at which it is collected.

  Before and after the table support 4, a dustproof cover 21 is provided to prevent the grinding wheel 61 generated during grinding of the semiconductor wafer W from entering the base 2, such as scraps. The dustproof cover 21 is attached to the front and rear surfaces of the table support base 4, and is provided so as to be extendable / contractable according to the movement position thereof, and is configured to cover the opening 2 a of the base 2.

  The chuck table 41 constitutes a holding unit, and is formed in a disk shape, and a holding surface 41 a on which the semiconductor wafer W is held is formed. An adsorption surface is formed of a porous ceramic material at the central portion of the holding surface 41a. The chuck table 41 is connected to a suction source (not shown) disposed in the base 2 and holds the semiconductor wafer W by suction on the suction surface of the holding surface 41a. The chuck table 41 is connected to a rotation driving mechanism (not shown), and is rotated while the semiconductor wafer W is held on the holding surface 41a by the rotation driving mechanism. Note that a protective tape 81 for device protection is attached to one side of the semiconductor wafer W on which the device is formed (see FIG. 4), and the protective tape 81 side is directed downward as indicated by an arrow A. Is mounted on the holding surface 41 a of the chuck table 41.

  The support column 5 is provided in a rectangular parallelepiped shape, and a grinding unit moving mechanism 51 for moving the grinding unit 6 above the chuck table 41 is provided on the front surface thereof. The grinding unit moving mechanism 51 has a Z-axis table 52 that moves up and down with respect to the support column 5 by a ball screw type moving mechanism. The grinding unit 6 is supported on the Z-axis table 52 via a support portion 53 attached to the front side thereof.

  The grinding unit 6 constitutes a processing means, and has a grinding wheel 61 that is detachably attached to the lower end of a spindle (not shown). The grinding wheel 61 is composed of, for example, a diamond grinding stone in which diamond abrasive grains are hardened with a binder such as metal bond or resin bond.

  The thickness detection unit 7 constitutes a thickness detection means, and a contact type detection unit 71 that detects the thickness by contacting the semiconductor wafer W and a non-contact type detection unit that detects the thickness without contacting the semiconductor wafer W. 75. The contact detection unit 71 and the non-contact detection unit 75 are arranged to face each other with the opening 2a of the base 2 interposed therebetween, and are configured to be able to detect the thickness of the semiconductor wafer W on the chuck table 41. In the grinding apparatus 1 according to the present embodiment, the thickness is detected by the contact detection unit 71 until the middle of the grinding process, and then the thickness detection is switched to the non-contact detection unit 75 and the grinding process is continued.

  The contact-type detection unit 71 includes a support unit 72 standing on the base 2 and two measurement probes 73 and 74 provided on the support unit 72. The contact-type detection unit 71 contacts one probe 73 with the upper surface of the semiconductor wafer W, and contacts the other probe 74 with the upper surface of the chuck table 41 to measure the height positions of the probes 73 and 74. Then, the contact type detection unit 71 detects the thickness of the semiconductor wafer W by taking the difference in the height positions of the probes 73 and 74 in a processor (not shown).

  The non-contact type detection unit 75 includes an inverted L-shaped arm unit 76 standing on the base 2 and a laser head unit 77 provided at the tip of the arm unit 76. The laser head unit 77 is disposed at a position close to the upper surface of the semiconductor wafer W held on the chuck table 41 and irradiates the laser beam perpendicularly to the upper surface of the semiconductor wafer W. In addition to the laser light source, the laser head 77 is connected to a photodiode that receives reflected light from the semiconductor wafer W and a detection circuit that analyzes the waveform of the interference wave received by the photodiode. Yes. In the non-contact type detection unit 75, the waveform of the interference wave received by the photodiode is analyzed by a detection circuit, and the thickness of the semiconductor wafer W is detected according to the waveform.

  In addition, the thickness detection unit 7 includes a storage unit 78 that stores detection results by the contact type detection unit 71, detection results by the non-contact type detection unit 75, and the like, and thickness detection methods for the semiconductor wafer W are contact type and non-contact type. And a switching control unit 79 that performs switching control between and. The storage unit 78 stores detected values (thickness information) of the thickness of the semiconductor wafer W detected by the contact detection unit 71 and the non-contact detection unit 75 at predetermined time intervals. The storage unit 78 includes one or a plurality of storage media such as a hard disk drive (HDD) and a random access memory (RAM).

  The switching control unit 79 measures an appropriate timing for switching the thickness detection method based on the detection values of the contact type detection unit 71 and the non-contact type detection unit 75 stored in the storage unit 78, and changes from the contact type to the non-contact type. Switch to control. Details of the switching control by the switching control unit 79 will be described later. The switching control unit 79 includes a processor that executes various processes, a memory, and the like. The memory in the switching control unit 79 is composed of one or a plurality of storage media such as a ROM (Read Only Memory) and a RAM depending on the application. The memory stores a control program for switching control of the thickness detection method.

  Here, an example of detection characteristics of the contact detection unit 71 and the non-contact detection unit 75 during grinding will be described with reference to FIG. In FIG. 3, it is assumed that the grinding unit 6 is ground while being controlled at a constant processing speed, the vertical axis is the detection value, the horizontal axis is the processing time, and the solid line P1 is the detection characteristic of the contact detection unit. A broken line P2 indicates an example of detection characteristics of the non-contact type detection unit.

  As shown in FIG. 3, the detection characteristic P1 of the contact-type detection unit 71 changes linearly with the lapse of the grinding time. Thus, the contact detection unit 71 is configured to be able to detect the thickness of the semiconductor wafer W with high accuracy according to the processing time of the grinding process. On the other hand, the detection characteristic P2 of the non-contact detection unit 75 varies in detection value until a predetermined time elapses from the start of the grinding process, and changes linearly with a slope substantially similar to the detection characteristic P1 after the predetermined time elapses. doing. This is because the non-contact detection unit 75 cannot accurately detect the semiconductor wafer W until the predetermined time has elapsed since the start of the grinding process.

  Thus, until the semiconductor wafer W is sufficiently thinned (for example, 100 μm or less), the thickness of the semiconductor wafer W is erroneously detected by the non-contact detection unit 75. Further, when the semiconductor wafer W is thinned, the contact detection unit 71 may damage the semiconductor wafer W to reduce the refractive strength. For this reason, in the switching control unit 79, the detection method is switched from the contact type to the non-contact type at a processing timing at which the inclinations of the detection characteristics P1 and P2 are substantially the same. Thus, the thickness is detected by the contact-type detection unit 71 while the non-contact-type detection unit 75 is erroneously detected, and thereafter the thickness is detected by the non-contact type detection unit 75.

In this case, the switching control unit 79 starts the switching control from the contact type to the non-contact type when the detection value near a predetermined thickness t ₀ (described later) of the semiconductor wafer W is detected by the contact type detection unit 71. Hereinafter, the relationship between the thickness detection method and the thickness of the semiconductor wafer W will be described with reference to FIG.

As shown in FIG. 4, the semiconductor wafer W has a predetermined thickness t ₀ that serves as a guide when starting the switching control described above. Further, the semiconductor wafer W, about the predetermined thickness t _0, parallel detection area A1 in which the thickness in parallel with the contact-type detector 71 and the non-contact type detecting section 75 is detected is provided. Above the parallel detection area A1 is a contact detection area A2 whose thickness is detected by the contact detection section 71, and below the parallel detection area A1 is a noncontact detection area where the thickness is detected by the noncontact detection section 75. A3.

  The contact detection area A2 is an area that is ground based on the thickness detection of the semiconductor wafer W by the contact detection unit 71, and includes the upper surface of the semiconductor wafer W and the upper limit of the parallel detection area A1 where switching control is started. It is prescribed. The parallel detection area A <b> 1 is an area in which grinding based on the thickness detection of the semiconductor wafer W by the contact detection unit 71 is performed and the thickness of the semiconductor wafer W is detected by the non-contact detection unit 75. In the parallel detection area A1, the switching control process is performed by the switching control unit 79, and the detection method is switched from the contact type to the non-contact type. In addition, the size of the parallel detection area A1 is defined by the processing time from the start to the completion of the switching control of the switching control unit 79.

The non-contact detection area A3 is an area that is ground based on the detection of the thickness of the semiconductor wafer W by the non-contact detection unit 75. The lower limit of the parallel detection area A1 that completes the switching control and the lower surface of the semiconductor wafer W It is prescribed by. The upper limit of the parallel detection area A1 in the vicinity of a predetermined thickness t ₀ is set to the grinding apparatus 1 as a threshold for specifying the start timing of the switching control.

Here, the switching control by the switching control unit 79 will be briefly described. At the start of the grinding process, the grinding process is controlled based on the detection result of the contact type detection unit 71. When the contact type detection unit 71 detects the vicinity of the predetermined thickness t ₀ , that is, the upper limit of the parallel detection area A1, the grinding process based on the detection result of the contact type detection unit 71 is continued and the non-contact type The detection unit 75 starts thickness detection. The thickness detection values detected by the contact detection unit 71 and the non-contact detection unit 75 are stored in the storage unit 78 at predetermined time intervals.

  At this time, the switching control unit 79 takes out two detection values with a sufficient time interval from the storage unit 78, and the change amount of the detection value with respect to each of the contact detection unit 71 and the non-contact detection unit 75. Is calculated. The amount of change in the detected value represents a change in the thickness of the semiconductor wafer W over time, and a plurality of detected values are obtained for each of the contact detection unit 71 and the non-contact detection unit 75. Then, the plurality of change amounts obtained for each of the contact type detection unit 71 and the non-contact type detection unit 75 are averaged, and the average change amount of the detection value of the contact type detection unit 71 and the non-contact type detection unit The average change amount of the 75 detection values is compared.

  The average change amount indicates a change tendency (detection characteristic) of the detection value. Therefore, the contact detection unit 71 and the non-contact detection unit 75 have substantially the same detection characteristics when the average amount of change in both detection values approaches. In this case, the non-contact detection is performed when the average change amount of the detection value of the non-contact detection unit 75 is within an allowable range (for example, within ± 15%) of the average change amount of the detection value of the contact detection unit 71. Assuming that the detection accuracy equivalent to that of the contact detection unit 71 is obtained by the unit 75, the thickness detection method is switched from the contact method to the non-contact method.

  Next, a specific example of switching control by the switching control unit 79 will be described with reference to FIGS. 5 and 6. FIG. 5 is a flowchart of switching control by the switching control unit 79. FIG. 6 is a diagram illustrating a detection result of the non-contact detection unit 75 in the parallel detection region A1. The switching control described below is merely an example and is not limited to this configuration. Further, in the following description, a case will be described in which the detection method is switched and controlled using the gradient of two detection values as the change amount of the detection value.

When the vicinity of the predetermined thickness t ₀ is detected by the contact detection unit 71 in a state where the grinding process is controlled based on the detection result of the contact detection unit 71, the switching control unit 79 starts switching control. . As shown in FIG. 5, when the switching control is started, the thickness detection by the contact type detection unit 71 is continued and the thickness detection is started by the non-contact type detection unit 75 (step (hereinafter referred to as “ST”). 101). At this time, the grinding process is controlled based on the detection result of the contact detection unit 71. The detection values detected by the contact detection unit 71 and the non-contact detection unit 75 are input to the storage unit 78 at predetermined time intervals.

  Next, the switching control unit 79 determines whether or not N or more detection values are detected in each of the contact detection unit 71 and the non-contact detection unit 75 (ST102). When the detection values of the contact detection unit 71 and the non-contact detection unit 75 are less than N, the process of ST101 is repeated until N or more. On the other hand, when the detection values of the contact type detection unit 71 and the non-contact type detection unit 75 are N or more, the Nth and subsequent detection values, and the Nth and previous detection values that are separated from the detection value by a predetermined interval, Is used to calculate the slope indicating the amount of change in the detected value over time (ST103). In the following description, the inclination based on the detection by the contact detection unit 71 is described as a first inclination, and the inclination based on the detection by the non-contact detection unit 75 is described as a second inclination.

  For example, when the Nth detection value is detected by the non-contact detection unit 75, as shown in FIG. 6, the second slope of the detection value with respect to time is calculated from the Nth and N−31th detection values. Is done. When the non-contact detection unit 75 detects the (N + 1) th detection value, the second inclination is calculated from the (N + 1) th and N-30th detection values. As described above, in the example of FIG. 6, the inclination of the detection value with respect to the passage of time is calculated using two detection values separated by 31 pieces. Further, the first inclination is also calculated for the detection value of the contact detection unit 71 by the same method. It should be noted that the interval between the two detection values used for the calculation of the inclination only needs to be separated so as not to pick up an error caused by uneven sticking of the protective tape 81 attached to the semiconductor wafer W.

  Next, the switching control unit 79 determines whether or not M or more first and second inclinations have been calculated (ST104). If the first and second slopes are less than M, the processes from ST101 to ST103 are repeated until the number of slopes is M or more. On the other hand, when the first and second inclinations are M or more, the switching controller 79 averages the M first inclinations to calculate the first average inclination, and the M second inclinations. The slopes are averaged to calculate a second average slope (ST105).

  For example, after the second inclination is obtained from the Nth and N−31th detection values of the non-contact detection unit 75, the processing from ST101 to ST103 is repeated 15 times, and a total of 16 second inclinations are obtained. Calculated. As shown in FIG. 6, after calculating the 16th second slope from the N−16th and N + 15th detection values, the second average slope is averaged by a total of 16 second slopes. Is calculated. Similarly, the first average inclination is calculated for the detection value of the contact detection unit 71. Note that the number of inclinations is not limited to 16, but may be any number as long as the first and second average inclinations are stable values.

  Next, the switching control unit 79 compares the first average slope with the second average slope, and the second average slope is within an allowable range of the first average slope (for example, the slope of the first average slope). On the other hand, it is determined whether or not the inclination is within ± 15% (ST106). The allowable range is set to a range in which the non-contact detection unit 75 can obtain substantially the same detection accuracy as the contact detection unit 71. If it is determined that the second average inclination is outside the allowable range of the first average inclination, the processes of ST101 to ST105 are repeated until the second average inclination is within the allowable range of the first average inclination. On the other hand, when the second average inclination is determined to be within the allowable range of the first average inclination, the grinding control based on the detection result of the non-contact detection unit 75 is changed from the grinding control based on the detection result of the contact detection unit 71. It is switched (ST107). Then, grinding is continued based on the detection result of the non-contact detection unit 75, and the semiconductor wafer W is thinned.

  Note that here, a case has been described in which a slope is calculated from two detected values and represents switching based on this slope as representing a change in the detected value with time, but the present invention is not limited to this. Instead, it can be changed as appropriate. The switching of the detection method may be controlled based on a change amount that represents a change in the detection value with time, and may be controlled based on, for example, a difference between two detection values. That is, the detection method is switched by comparing the average difference based on the detection value of the contact detection unit 71 and the average difference based on the detection value of the non-contact detection unit 75.

  As described above, according to the grinding apparatus 1 according to the present embodiment, during the grinding process based on the detection result of the contact detection unit 71, the change in the thickness of the semiconductor wafer W over time from the detection by the contact detection unit 71 is changed. A first average slope that represents the average is obtained, and a second average slope that represents the average of changes in the thickness of the semiconductor wafer W over time from the detection by the non-contact detection unit 75 is obtained. The second average inclination falls within an allowable range in which a change tendency similar to that of the first average inclination is obtained, so that the non-contact detection unit 75 has a detection accuracy equivalent to that of the contact detection unit 71. As obtained, the grinding process based on the detection result of the contact detection unit 71 is switched to the grinding process based on the detection result of the non-contact detection unit 75. For this reason, when the semiconductor wafer W is thick, it is not switched to the non-contact type thickness detection when the detection accuracy of the non-contact type detection unit 75 is low. As described above, it is possible to specify the timing at which the thickness of the semiconductor wafer W can be accurately detected by the non-contact type detection unit 75 and switch from the contact type thickness detection to the non-contact type thickness detection.

  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, 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, a case will be described in which the inclination representing the change in the thickness of the semiconductor wafer W is calculated from the two detection values detected by the contact detection unit 71 or the non-contact detection unit 75. However, the present invention is not limited to this and can be changed as appropriate. For example, the inclination may be calculated from three or more detection values.

  Moreover, in the said embodiment, the 1st average inclination with respect to the contact-type detection part 71 and the 2nd average inclination with respect to the non-contact-type detection part 75 are calculated | required during grinding, and the case where it compares is demonstrated. However, it is not limited to this and can be changed as appropriate. For example, for the first average inclination with respect to the contact detection unit 71, a value obtained before grinding may be used, or a preset threshold value may be used.

  Moreover, although the case where the thickness of the semiconductor wafer W is optically detected by the non-contact type detection unit 75 has been described in the above embodiment, the present invention is not limited to this and can be changed as appropriate. The non-contact type detection unit 75 only needs to be able to detect the thickness of the semiconductor wafer W in a non-contact manner. For example, the thickness may be detected by ultrasonic waves or the like.

  Further, the switching control unit 79 may be constituted by a part of a control unit that performs overall control of the entire grinding apparatus 1. Further, the switching control unit 79 may include the storage unit 78.

  As described above, the present invention compares the change tendency between the detection result by the contact type detection unit and the detection result by the non-contact type detection unit, so that the contact type thickness detection can be performed at a suitable processing timing. It is useful for a grinding apparatus that performs grinding based on the detection of the thickness of a semiconductor wafer.

DESCRIPTION OF SYMBOLS 1 Grinding device 2 Base 3 Operation panel 4 Table support stand 5 Support | pillar part 6 Grinding unit (processing means)
7 Thickness detection unit (thickness detection means)
21 Dust cover 41 Chuck table (holding means)
71 Contact type detection unit 72 Support unit 73, 74 Probe 75 Non-contact type detection unit 76 Arm unit 77 Laser head unit 78 Storage unit 79 Switching control unit W Semiconductor wafer (work)

Claims (1)

Holding means having a holding surface for holding the workpiece;
Processing means for grinding the workpiece held on the holding surface;
A thickness detecting means for detecting the thickness of the work held on the holding surface, and a grinding apparatus comprising:
The thickness detecting means includes
A contact type detection unit that detects the thickness of the workpiece by contacting the upper surface of the workpiece;
A non-contact detection unit that detects the thickness of the workpiece without contacting the upper surface of the workpiece;
From grinding based on the thickness of the workpiece detected by the contact type detection unit to grinding based on the thickness of the workpiece detected by the non-contact type detection unit when the thickness of the workpiece approaches a predetermined thickness by grinding. A switching control unit for switching,
The switching control unit
In the state where grinding based on the thickness of the workpiece detected by the contact detection unit is being performed, the thickness detection of the workpiece by the non-contact detection unit is started,
The contact type detection unit obtains a plurality of first inclinations representing thickness changes with time from the thickness information of the plurality of workpieces detected with the passage of time, and averages the plurality of first inclinations. Find the average slope of
The non-contact type detection unit obtains a plurality of second inclinations representing a change in thickness with respect to the passage of time from the thickness information of the plurality of workpieces detected with the passage of time, and averages the plurality of second inclinations. Find the average slope of the two,
The non-contact type detection unit from the grinding based on the thickness of the workpiece detected by the contact type detection unit based on the fact that the second average inclination is within an allowable range that is an inclination approximate to the first average inclination. A grinding apparatus characterized by switching to grinding based on the thickness of the workpiece detected in step (b).

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