Grinding method of composite wafer and grinding method of chip-on wafer

Abstract

To male uniform the thickness of a member on an upper surface of a supporting wafer among a plurality of wafers.SOLUTION: A non-contact thickness measuring device 82 measures the thickness of a specified region 105 of a chip 103. Therefore, even if the thickness of a support wafer 101 differs among wafers 100, the thickness of the specified region 105 of the chip 103 can be made uniform among the plurality of wafers 100. In a finish grinding step, the chip 103 is ground until the thickness of the specified region 105, which is intended to be defined as a finish thickness, reaches a predetermined finish thickness. Therefore, the thickness of the specified region 105 can be controlled favorably.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for grinding a wafer. [Background technology]

[0002] A chip-on-wafer (CoW) has a support wafer and a chip mounted on the support wafer. As disclosed in Patent Document 1, when grinding a CoW, the height of the top surface of the CoW and the height of a holding surface that holds the CoW are measured, and the difference between the height of the top surface of the CoW and the height of the holding surface is calculated as the thickness of the CoW. The CoW is then ground until this thickness reaches a preset finishing thickness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-165339 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional grinding methods, the thickness of the support wafer varies from CoW to CoW, resulting in different chip thicknesses for each CoW.

[0005] Therefore, an object of the present invention is to make the thickness of a designated member, among members arranged on the upper surface of a support wafer, uniform among a plurality of CoWs. [Means for solving the problem]

[0006] The grinding method for a composite wafer (first grinding method) of the present invention is a method for grinding a composite wafer, which is a wafer having a plurality of chips arranged on the upper surface of a support wafer, or a wafer having a device wafer with devices formed on the upper surface of a support wafer, and includes a holding step of holding the support wafer by a chuck table, and a step of rotating the chuck table while moving a non-contact thickness measuring device and the chuck table relatively in the radial direction of the chuck table, to grind an area including a part of the chip whose thickness is to be measured by the non-contact thickness measuring device during at least the finish grinding of the composite wafer. Alternatively, the method includes a thickness data storage step of measuring the thickness of an area including a portion of the device wafer and storing the measured thickness and the XY coordinates of the horizontal plane at the thickness measurement point as thickness data; a region setting step of setting a specified region that specifies the thickness during finish grinding using the thickness data stored in the thickness data storage step; and a finish grinding step of measuring the thickness of the specified region using the XY coordinates of the specified region with the non-contact thickness gauge and grinding the top surface of the composite wafer with a grinding wheel until the measured thickness reaches a predetermined finish thickness.

[0007] In the first grinding method, the area setting step may include a two-dimensional arrangement step of two-dimensionally arranging the thickness data stored in the thickness data storage step using the XY coordinates, a characteristic area setting step in which an operator sets a characteristic area in the two-dimensionally arranged thickness data, and a first specified area recognition step of extracting the characteristic area from the thickness data by performing pattern matching on the two-dimensionally arranged thickness data using the characteristic area, and recognizing the specified area in the thickness data based on the extraction result.

[0008] In the first grinding method, the area setting step may include a second specified area recognition step of using the thickness data stored in the thickness data storage step to obtain an area having a thickness within a predetermined thickness monitoring width and recognizing this area as the specified area.

[0009] The chip-on-wafer grinding method (second grinding method) of the present invention is a chip-on-wafer grinding method in which a plurality of chips are arranged on the upper surface of a support wafer and the chips are sealed with a sealing material, and includes a holding step of holding the support wafer of the chip-on-wafer by a chuck table, a non-contact thickness measuring device and the chuck table being moved relatively in the radial direction of the chuck table while rotating the chuck table, and measuring the thickness of the sealing material arranged on the upper surface of the support wafer of the chip-on-wafer from the upper surface of the support wafer to the upper surface of the sealing material, and a thickness of the sealing material arranged on the upper surface of the chip from the upper surface of the sealing material to the upper surface of the chip. the thickness of the sealing material up to the upper surface of the chip-on-wafer is measured at least for a portion where the thickness is measured by the non-contact thickness gauge during finish grinding, and the measured thickness and the XY coordinates of the horizontal plane at the thickness measurement point are stored as thickness data; a region setting process is performed using the thickness data stored in the thickness data storage process to set a specified region that is a region that specifies the thickness during finish grinding; and a finish grinding process is performed using the XY coordinates of the specified region to measure the thickness of the specified region with the non-contact thickness gauge, and grinding the upper surface of the chip-on-wafer with a grinding wheel until the measured thickness reaches a predetermined finish thickness.

[0010] In the second grinding method, the area setting step may include a two-dimensional arrangement step of two-dimensionally arranging the thickness data stored in the thickness data storage step using the XY coordinates, a characteristic area setting step in which an operator sets a characteristic area in the two-dimensionally arranged thickness data, and a first specified area recognition step of extracting the characteristic area from the thickness data by performing pattern matching on the two-dimensionally arranged thickness data using the characteristic area, and recognizing the specified area in the thickness data based on the extraction result.

[0011] In the second grinding method, the area setting process may include a second specified area recognition process that uses the thickness data stored in the thickness data storage process to obtain an area having a thickness within a predetermined thickness monitoring width and recognizes this area as the specified area. [Effects of the Invention]

[0012] In the present invention, the thickness of the chip, device wafer, or encapsulant, which is a component on the support wafer, is measured using a non-contact thickness gauge. Therefore, even if the thickness of the support wafer varies for each chip-on-wafer, the thickness of the chip, device wafer, or encapsulant can be made uniform across multiple chip-on-wafers.

[0013] Furthermore, in the finish grinding process, the upper surface of the chip-on-wafer (the upper surface of the chip, device wafer, or encapsulant) is ground until the thickness of the specified area, which is to be specified as the finished thickness, reaches a predetermined finished thickness. Therefore, it is possible to precisely control the thickness of the specified area. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a perspective view showing the configuration of a grinding device. [Figure 2] FIG. 1 is an explanatory diagram showing the configuration of a chip-on-wafer. [Figure 3] FIG. 10 is an explanatory diagram showing a thickness data storage step. [Figure 4] FIG. 2 is a top view showing a measurement line, which is the trajectory of a non-contact thickness measuring instrument. [Figure 5] FIG. 1 is a top view showing an example of an image of the top surface of a chip-on-wafer. [Figure 6] FIG. [Figure 7] FIG. 2 is an explanatory diagram showing the configuration of a composite wafer including a device wafer. [Figure 8] FIG. 10 is an explanatory diagram showing another chip-on-wafer configuration. [Figure 9] FIG. 10 is an explanatory diagram showing a thickness data storage step. [Figure 10] 10 is a graph showing thickness data. [Figure 11] 10 is a graph showing thickness data. [Figure 12]FIG. 10 is a perspective view showing the configuration of another grinding device. DETAILED DESCRIPTION OF THE INVENTION

[0015] As shown in FIG. 1, a grinding apparatus 1 which is a processing apparatus according to this embodiment is an apparatus which grinds a wafer 100 held on a holding surface 22 of a chuck table 20 by a grinding wheel 77.

[0016] As shown in Fig. 2, wafer 100 is an example of a composite wafer, and is a circular chip-on-wafer (CoW). Wafer 100 has a support wafer 101, tape 102 attached to the underside of support wafer 101, and multiple chips 103 formed on the upper surface of support wafer 101. Chip 103 has a roughly rectangular plate shape and is fixed to support wafer 101 by, for example, a mold. In addition, a notch 110 is formed in part of the outer edge of wafer 100.

[0017] As shown in FIG. 1, the grinding apparatus 1 includes a rectangular parallelepiped base 10, a column 11 extending upward, a control unit 7 that controls each member of the grinding apparatus 1, and a storage unit 8.

[0018] An opening 13 is provided on the upper surface side of the base 10. In the opening 13, a wafer holding mechanism 30 is disposed.

[0019] The wafer holding mechanism 30 includes a chuck table 20 having a holding surface 22 that holds the wafer 100, a chuck table base 29 that supports the chuck table 20, a rotation mechanism 26 connected to the base end side of the chuck table base 29 via an endless belt 25, a support member 28 that supports the chuck table base 29, and a plurality of support pillars 27 that support the support member 28.

[0020] The chuck table 20 includes a porous member 21 and a frame 23 that houses the porous member 21 so that the upper surface of the porous member 21 is exposed. The upper surface of the porous member 21 is a holding surface 22 that holds the wafer 100 by suction. The holding surface 22 is connected to a suction source (not shown) to hold the tape 102 side of the wafer 100 by suction.

[0021] The rotation mechanism 26 includes a motor and a drive pulley, and rotates the endless belt 25 to rotate the chuck table base 29. As a result, the chuck table 20 supported by the chuck table base 29 rotates around a table rotation axis that passes through the center of the holding surface 22.

[0022] A cover plate 39 that moves along the Y-axis direction together with the chuck table 20 is provided around the periphery of the chuck table 20. A bellows cover 12 that expands and contracts in the Y-axis direction is connected to the cover plate 39. A Y-axis direction moving mechanism 40 is disposed below the wafer holding mechanism 30.

[0023] The Y-axis direction moving mechanism 40 moves the chuck table 20 and the grinding wheel 77 of the grinding mechanism 70 relatively in the Y-axis direction, which is a direction parallel to the holding surface 22. In this embodiment, the Y-axis direction moving mechanism 40 is configured to move the wafer holding mechanism 30 including the chuck table 20 in the Y-axis direction relative to the grinding mechanism 70.

[0024] The Y-axis direction movement mechanism 40 includes a pair of Y-axis guide rails 42 parallel to the Y-axis direction, a Y-axis movement table 45 that slides on these Y-axis guide rails 42, a Y-axis ball screw 43 parallel to the Y-axis guide rails 42, a Y-axis motor 44 connected to the Y-axis ball screw 43, and a holder 41 that holds these.

[0025] The Y-axis moving table 45 is slidably installed on the Y-axis guide rail 42. A nut portion (not shown) is fixed to the Y-axis moving table 45. A Y-axis ball screw 43 is threadedly engaged with this nut portion. The Y-axis motor 44 is connected to one end of the Y-axis ball screw 43.

[0026] In the Y-axis direction moving mechanism 40, the Y-axis motor 44 rotates the Y-axis ball screw 43, thereby moving the Y-axis moving table 45 in the Y-axis direction along the Y-axis guide rails 42. The wafer holding mechanism 30 is placed on the Y-axis moving table 45. Therefore, as the Y-axis moving table 45 moves in the Y-axis direction, the wafer holding mechanism 30 including the chuck table 20 moves in the Y-axis direction.

[0027] In this embodiment, the chuck table 20 of the wafer holding mechanism 30 is moved along the Y-axis direction by the Y-axis moving mechanism 40 between a holding position 301 on the -Y direction side for holding the wafer 100 by the holding surface 22 and a processing position 302 on the +Y direction side where the wafer 100 is ground by the grinding mechanism 70.

[0028] Furthermore, a column 11 is erected at the rear (+Y direction side) of the base 10. In front of the column 11, a grinding mechanism 70 for grinding the wafer 100 and a vertical movement mechanism 50 are provided.

[0029] The vertical movement mechanism 50 moves the chuck table 20 and the grinding wheel 77 of the grinding mechanism 70 relatively in the Z-axis direction (grinding feed direction) perpendicular to the holding surface 22. In this embodiment, the vertical movement mechanism 50 is configured to move the grinding mechanism 70 including the grinding wheel 77 in the Z-axis direction relative to the chuck table 20.

[0030] The vertical movement mechanism 50 includes a pair of Z-axis guide rails 51 parallel to the Z-axis direction, a Z-axis movement table 53 that slides on the Z-axis guide rails 51, a Z-axis ball screw 52 parallel to the Z-axis guide rails 51, a Z-axis motor 54 connected to the Z-axis ball screw 52, ​​and a holder 56 attached to the Z-axis movement table 53. The holder 56 supports a grinding mechanism 70.

[0031] Z-axis moving table 53 is slidably installed on Z-axis guide rail 51. A nut portion (not shown) is fixed to Z-axis moving table 53. Z-axis ball screw 52 is threadedly engaged with this nut portion. Z-axis motor 54 is connected to one end of Z-axis ball screw 52.

[0032] In the vertical movement mechanism 50, the Z-axis motor 54 rotates the Z-axis ball screw 52, ​​causing the Z-axis movement table 53 to move in the Z-axis direction along the Z-axis guide rail 51. As a result, the holder 56 attached to the Z-axis movement table 53 and the grinding mechanism 70 supported by the holder 56 also move in the Z-axis direction together with the Z-axis movement table 53.

[0033] The grinding mechanism 70 grinds the wafer 100 held by suction on the holding surface 22. The grinding mechanism 70 includes a spindle housing 71 fixed to the holder 56, a spindle 72 rotatably held in the spindle housing 71, a spindle motor 73 that rotates the spindle 72, a wheel mount 74 attached to the lower end of the spindle 72, and a grinding wheel 75 supported by the wheel mount 74.

[0034] The spindle housing 71 is held by the holder 56 so as to extend in the Z-axis direction. The spindle 72 extends in the Z-axis direction so as to be perpendicular to the holding surface 22 of the chuck table 20, and is rotatably supported by the spindle housing 71.

[0035] The spindle motor 73 is connected to the upper end side of the spindle 72. The spindle motor 73 rotates the spindle 72 around an axis extending in the Z-axis direction.

[0036] The wheel mount 74 is formed in a disk shape and is fixed to the lower end (tip) of the spindle 72. The wheel mount 74 supports the grinding wheel 75.

[0037] The grinding wheel 75 is formed to have an outer diameter that is approximately the same as the outer diameter of the wheel mount 74. The grinding wheel 75 includes an annular wheel base 76 made of a metal material.

[0038] A plurality of grinding wheels 77 are fixed to the underside of the wheel base 76 and arranged in an annular shape around the entire circumference. The grinding wheels 77 are rotated together with the spindle 72 by the spindle motor 73, and grind the upper surface of the wafer 100 held on the chuck table 20, on which the chips 103 are formed.

[0039] The grinding apparatus 1 also includes a touch panel 9. The touch panel 9 displays various types of information related to the grinding apparatus 1. The touch panel 9 is also used to set various types of information. In this way, the touch panel 9 functions as an input member for inputting information, and also as a display member for displaying information.

[0040] A thickness measuring mechanism 80 for measuring the thickness of the wafer 100 in a non-contact manner is disposed on the side of the opening 13 in the base 10 .

[0041] The thickness measurement mechanism 80 has a non-contact thickness gauge 82 that measures the thickness of the wafer 100 in a non-contact manner, an arm 83 that supports the non-contact thickness gauge 82 at its tip, and a support member 84 that can support and rotate the arm 83. The support member 84 allows the non-contact thickness gauge 82 to rotate and move along the radial direction of the chuck table 20 (holding surface 22) so as to pass through the center of the holding surface 22.

[0042] The non-contact thickness measuring device 82 measures the thickness of the wafer 100 held on the chuck table 20. In particular, in this embodiment, the non-contact thickness measuring device 82 is configured to be able to measure the thickness of the chips 103 on the wafer 100. That is, the non-contact thickness measuring device 82 irradiates the wafer 100 with measurement light having a wavelength that is transparent to the chips 103 of the wafer 100 from above, receives upper-surface reflected light reflected from the upper surface of the chip 103, and lower-surface reflected light reflected from the lower surface of the chip 103 through the chip 103, and measures the thickness T1 (see FIG. 3 ) of the chip 103 by spectral interference.

[0043] The control unit 7 also includes a CPU that performs arithmetic processing according to a control program, and a storage medium such as a memory. The control unit 7 controls the above-mentioned members of the grinding apparatus 1 to comprehensively control the components of the grinding apparatus 1. For example, the control unit 7 controls the above-mentioned members of the grinding apparatus 1 to grind the wafer 100. The storage unit 8 is used to store information necessary for the control of the control unit 7.

[0044] The following describes a method for grinding the wafer 100 controlled by the control unit 7. The method for grinding the wafer 100 according to this embodiment is a method for grinding the wafer 100, which is a chip-on-wafer in which a plurality of chips 103 are arranged on the upper surface of a support wafer 101.

[0045] [Holding process] In the method for grinding the wafer 100 according to this embodiment, a holding step is first performed. In this step, the support wafer 101 of the wafer 100 is held by the chuck table 20. Specifically, the control unit 7 first controls the Y-axis direction moving mechanism 40 to place the wafer holding mechanism 30 including the chuck table 20 at a holding position 301 on the -Y direction side where the chuck table 20 holds the wafer 100. Next, an operator or a conveying device (not shown) places the support wafer 101 side (tape 102 side) of the wafer 100 on the holding surface 22 of the chuck table 20 so that the upper surface on which the chips 103 of the wafer 100 are formed faces upward. Thereafter, the control unit 7 connects the holding surface 22 to a suction source, whereby the wafer 100 is suction-held by the holding surface 22.

[0046] [Thickness data storage process] After the holding step, a thickness data storage step is performed. In this step, the non-contact thickness gauge 82 and the chuck table 20 are moved relative to each other in the radial direction of the chuck table 20 while the chuck table 20 is rotated to measure the thickness of a predetermined area of ​​the wafer 100, and the measured thickness and the horizontal XY coordinates of each thickness measurement point are stored as thickness data. This predetermined area is an area that includes at least a portion of the chip 103 whose thickness will be measured by the non-contact thickness gauge 82 during the subsequent finish grinding process. In this embodiment, the predetermined area is approximately the entire surface of the wafer 100, thickness measurement points are set on approximately the entire surface of the wafer 100, and the thickness of approximately the entire surface of the wafer 100 (the thickness of all the chips 103) is measured.

[0047] Specifically, the control unit 7 first controls the Y-axis direction moving mechanism 40 to position the wafer holding mechanism 30 including the chuck table 20 at the processing position 302 on the +Y direction side where the thickness of the wafer 100 can be measured by the thickness measurement mechanism 80.

[0048] 3, the control unit 7 causes the rotation mechanism 26 to rotate the chuck table 20 about the rotation axis 401 passing through the center of the holding surface 22 (arrow 501). Furthermore, the control unit 7 causes the arm unit 83 and the non-contact thickness gauge 82 to turn using the support member 84, thereby moving the non-contact thickness gauge 82 in the radial direction of the chuck table 20 (wafer 100) (arrow 502). In this way, the control unit 7 sequentially positions the non-contact thickness gauge 82 at each thickness measurement point of the wafer 100 held on the chuck table 20, and measures the thickness of the entire surface including all of the chips 103.

[0049] 4, measurement lines 801, which are the locus of the non-contact thickness gauge 82, are shown by dashed lines. The thickness measurement points of the wafer 100 are positions along these measurement lines 801. As described above, in this embodiment, the control unit 7 rotates the non-contact thickness gauge 82 in the radial direction of the chuck table 20, for example, from the outside to the inside, while rotating the chuck table 20, so that a plurality of concentric measurement lines 801 are formed on the upper surface of the wafer 100. This allows the thickness of the entire surface of the wafer 100 to be measured.

[0050] At this time, the control unit 7 determines two-dimensional coordinates (XY coordinates based on the notch 110) of the horizontal plane at the thickness measurement points of the wafer 100 along the measurement line 801, using the notch 110 of the wafer 100 as a reference. Then, the control unit 7 stores the relationship (combination) between the XY coordinates of each thickness measurement point of the wafer 100 and the thickness of each thickness measurement point in the memory unit 8 as thickness data.

[0051] [Area setting process] After the thickness data storage step, a region setting step is performed. In this step, the thickness data stored in the thickness data storage step is used to set a specified region, which is a region that specifies the thickness during finish grinding. This specified region is the region where the thickness of the tip 103 is to be specified, i.e., the region that is to be specified as the finish thickness in the subsequent finish grinding step. Specifically, in the region setting step of this embodiment, the following two-dimensional arrangement step, feature region setting step, and first defined region recognition step are performed.

[0052] [Two-dimensional array process] In this step, the thickness data stored in the thickness data storage step is two-dimensionally arranged in X and Y coordinates. In this embodiment, the thickness data acquired in the thickness data storage step is converted into an image (an image based on image components such as brightness, color tone, or color difference) to form an image of the top surface of the wafer 100 (an image of the chip 103) as thickness data two-dimensionally arranged in X and Y coordinates (image formation step).

[0053] 5 shows an example of an image of the upper surface of the wafer 100 formed in this process. In the example shown in this figure, each chip 103 is displayed with an image component (such as a color tone) according to its thickness.

[0054] It should be noted that a device is formed on each chip 103, and depending on the device, there may be an area where the thickness of the chip 103 is measured to be thinner than the actual thickness. For example, in the example shown in Fig. 3, a device including a film 104 is formed on each chip 103, and the thickness of the area of ​​the chip 103 including the film 104 of the device is measured to be thinner than the actual thickness.

[0055] Therefore, in this embodiment, as shown in Figure 3, the worker sets the area on the chip 103 other than the area including the device film 104 (the area measured as having a thickness thinner than the actual thickness) as the area where the thickness on the chip 103 is desired to be specified, i.e., the specified area 105, which is the area where the worker wants to specify the finishing thickness in the subsequent finishing grinding process. In addition, in the region where the thickness is measured to be thinner than the actual thickness, for example, a nitride film is formed as the film 104. Since the non-contact thickness measuring device 82 receives the reflected light refracted by the nitride film, it may measure the thickness of the chip 103 as being thinner. In other words, the thickness measured by the non-contact thickness measuring device 82 may be a value different from the actual thickness. In addition to nitride films, film 104 may also be oxide films or wiring layers made of copper or aluminum. Adhesive materials may also affect the measurement results of non-contact thickness gauge 82. Adhesive materials (materials used for bonding) are underfill materials such as epoxy resin and acrylic resin. Bumps placed on the bonding surface may also affect the measurement results of non-contact thickness gauge 82. As described above, since components that affect the measurement results of the non-contact thickness gauge 82 are often formed on the entire surface of the wafer 100, the specified area 105 may contain components that affect the measurement results as described above. Therefore, the grinding device 1 may be provided with a correction setting unit that, once the specified area 105 is defined, sets (performs) a correction of the measurement value to correct the measured thickness of the specified area 105 to the actual thickness.

[0056] [Feature area setting process] After the two-dimensional arrangement step, a characteristic region setting step is performed. In this step, an operator sets characteristic regions (key pattern regions) in the two-dimensionally arranged thickness data. In this embodiment, the operator sets the characteristic regions using an image of the top surface of the wafer 100 (see FIG. 5) as the two-dimensionally arranged thickness data.

[0057] Specifically, the control unit 7 displays an image of the top surface of the wafer 100 shown in FIG. 5 on the touch panel 9. Then, the operator sets a characteristic region in the image displayed on the touch panel 9 using an input device such as a mouse. A characteristic region is, for example, a region that has a distinctive pattern (a collection of shapes or multiple thickness values) compared to other regions, and is suitable for pattern matching. In this embodiment, the operator sets a cross-shaped portion of the chip 103 as the characteristic region 106. In response to the setting of the characteristic region 106 by the operator, the control unit 7 acquires the pattern of the characteristic region 106 set by the operator. Note that the characteristic region may be the same as the specified region in the chip 103 where the thickness is to be specified.

[0058] Also, in this step, the operator sets the specified region 105 (the position of the specified region 105). That is, the operator sets the positional relationship between the feature region 106 in the chip (device) 103 and the specified region 105 whose thickness is to be specified, for example, using the touch panel 9. That is, the relationship between the center coordinates of the feature region 106 and the center coordinates of the specified region 105 whose thickness is to be specified is set. In response to this, the control unit 7 stores the distances in the X direction and the Y direction between the center of the feature region 106 and the center of the specified region 105 whose thickness is to be specified in the memory unit 8 as the positional relationship between the feature region 106 and the specified region 105.

[0059] [First defined area recognition step] After the characteristic region setting step, a first specified region recognition step is performed. In this step, the characteristic region 106 is used to perform pattern matching on the two-dimensionally arranged thickness data to extract the characteristic region 106 from the thickness data, and based on the extraction result, the position of the specified region 105 (the region whose thickness is measured by the non-contact thickness gauge 82 during finish grinding) in the thickness data is recognized using the pre-stored distances in the X and Y directions between the characteristic region 106 and the specified region 105.

[0060] In this embodiment, the control unit 7 performs pattern matching on the top surface image of the wafer 100 as two-dimensionally arranged thickness data, based on the pattern (shape and collection of multiple thickness values) of the feature region 106 set by the operator. In this case, the control unit 7 extracts the pattern of the feature region 106 from the top surface image of the wafer 100 to determine the XY coordinates of the multiple feature regions 106 (the feature region 106 of each chip 103) in the top surface image. Then, based on, for example, the positional relationship between the feature region 106 and the specified region 105 (the distance in the X direction and the distance in the Y direction between the feature region 106 and the specified region 105) that has been acquired in advance, the control unit 7 recognizes the XY coordinates of the multiple specified regions 105 (the specified region 105 of each chip 103), which are regions whose thicknesses are to be measured by the non-contact thickness gauge 82 during finish grinding, from the extracted feature region 106.

[0061] [Finishing grinding process] After the area setting step (first predetermined area recognition step), a finish grinding step is carried out. In this step, the thickness of each predetermined area 105 is measured by a non-contact thickness measuring device 82 using the XY coordinates of the multiple predetermined areas 105 set in the area setting step, and the upper surface of the wafer 100 is ground with a grinding wheel 77 until the measured thickness reaches a preset finish thickness.

[0062] Specifically, the control unit 7 rotates the grinding wheel 77 of the grinding mechanism 70 and the chuck table 20, while lowering the grinding mechanism 70 using the vertical movement mechanism 50, and grinds the upper surface of the wafer 100 (the upper surface of the chip 103) held on the chuck table 20 with the grinding wheel 77. At this time, the control unit 7 uses the thickness measurement mechanism 80 to measure the thickness of the specified region 105 of the chip 103 being ground, and continues grinding until the thickness of the specified region 105 reaches a predetermined finish thickness.

[0063] That is, during finish grinding, the control unit 7 rotates the arm unit 83 and the non-contact thickness gauge 82 (see FIG. 3) using the support member 84 to measure the thickness at thickness measurement points along the measurement line 801 on the upper surface of the wafer 100 as shown in FIG. 6 (only one of the multiple measurement lines 801 is shown in FIG. 6), and obtains the relationship between the XY coordinates and the thickness of each thickness measurement point. Then, using the XY coordinates of the specified area 105 obtained in the measurement point recognition step, the control unit 7 extracts only the thickness of the specified area 105 from the thicknesses of each thickness measurement point measured along the measurement line 801, and continues grinding until this thickness reaches the predetermined finish thickness.

[0064] As described above, in this embodiment, the thickness of the specified region 105 of the chip 103 is measured by the non-contact thickness measuring device 82. Therefore, even if the thickness of the support wafer 101 differs for each wafer 100, the thickness of the specified region 105 of the chip 103 can be made uniform among a plurality of wafers 100.

[0065] In this embodiment, the tip 103 is ground until the thickness of the specified region 105, which is to be specified as the finishing thickness in the finish grinding process, reaches a predetermined finishing thickness. Therefore, it is possible to properly control the thickness of the specified region 105 in the tip 103.

[0066] Furthermore, in this embodiment, in the region setting step, a region of the chip 103 other than the region including the film 104 is set as the specified region 105. As described above, it is difficult for the non-contact thickness gauge 82 to accurately measure the thickness of the region including the film 104 of the chip 103. Therefore, in this embodiment, a region where the thickness of the chip 103 can be accurately measured by the non-contact thickness gauge 82 (a region not including the film 104) is set as the specified region 105, and while monitoring the thickness of this specified region 105, finish grinding is performed so that the thickness of this specified region 105 becomes the finish thickness. Therefore, it is possible to control the thickness of the specified region 105 even better.

[0067] In this embodiment, the description has been given of grinding the chips 103 attached to the support wafer 101 to a predetermined finishing thickness, but the member on the support wafer 101 that is ground to the predetermined finishing thickness may be a member other than the chips 103. For example, the grinding method of this embodiment may be used when grinding a device wafer of a wafer (wafer-on-wafer, stacked wafer) in which a device wafer is attached to the support wafer 101 to a predetermined finishing thickness.

[0068] Specifically, the composite wafer ground in this embodiment is not limited to a chip-on-wafer such as wafer 100, but may be a wafer-on-wafer wafer 200 having a configuration as shown in Fig. 7. This wafer 200 has a device wafer 120 stacked on the top surface of support wafer 101 instead of chip 103 in the configuration of wafer 200 shown in Figs.

[0069] This device wafer 120 is stacked on the support wafer 101 so that its device formation surface 121 faces the upper surface of the support wafer 101. A plurality of devices 122 are formed on the device formation surface 121 of the device wafer 120. Furthermore, streets 123 are formed between the devices 122. The streets 123 include, for example, metal wiring, an interlayer insulating film, and / or a TEG. Furthermore, a film 124 made of a nitride film or the like is formed on the devices 122.

[0070] 1 is configured to be able to measure the thickness of the device wafer 120 in the wafer 200 when grinding the wafer 200. That is, the non-contact thickness measuring device 82 irradiates the device wafer 120 including the devices 122 with measurement light having a wavelength that is transparent to the device wafer 120 from above the wafer 200, receives upper-surface reflected light reflected from the upper surface of the device wafer 120, and lower-surface reflected light reflected from the lower surface of the device wafer 120 through the device wafer 120, and measures the thickness T4 (see FIG. 7) of the device wafer 120 by spectral interference.

[0071] Furthermore, in this wafer 200, the film 124 in the device 122 of the device wafer 120 makes it difficult for the non-contact thickness gauge 82 to accurately measure the thickness of the device wafer 120. Therefore, in grinding the wafer 200, an area in the device 122 where the thickness of the device wafer 120 can be accurately measured using the non-contact thickness gauge 82 is set as the specified area 105, and while the thickness of this specified area 105 is monitored, the specified area 105 is ground to the finished thickness.

[0072] A method for grinding a wafer 200 including the device wafer 120 shown in Fig. 7 will be described below. This grinding method is a wafer-on-wafer grinding method in which the device wafer 120, on the upper surface of which devices 122 are formed, is placed on the support wafer 101. [Holding process] First, the above-described holding step is carried out to hold the wafer 200 by the chuck table 20 .

[0073] [Thickness data storage process] After the holding step, the above-mentioned thickness data storage step is performed. In this step, the non-contact thickness gauge 82 and the chuck table 20 are moved relative to each other in the radial direction of the chuck table 20 while the chuck table 20 is rotated, the thickness of a predetermined area of ​​the device wafer 120 is measured, and the measured thickness and the horizontal XY coordinates of the thickness measurement points are stored as thickness data. The predetermined area of ​​the device wafer 120 is an area that includes at least a portion of the device wafer 120 whose thickness is measured by the non-contact thickness gauge 82 during the subsequent finish grinding process. The predetermined area is, for example, approximately the entire surface of the device wafer 120. In this case, thickness measurement points are set on approximately the entire surface of the device wafer 120, and the thickness of the entire surface of the device wafer 120 is measured.

[0074] 7, the control unit 7 causes the rotation mechanism 26 to rotate the chuck table 20 about the rotation axis 401 passing through the center of the holding surface 22 (arrow 501). Furthermore, the control unit 7 causes the arm unit 83 and the non-contact thickness gauge 82 to turn using the support member 84, thereby moving the non-contact thickness gauge 82 in the radial direction of the chuck table 20 (wafer 200) (arrow 502). In this way, the control unit 7 sequentially positions the non-contact thickness gauge 82 at each thickness measurement point of the device wafer 120 of the wafer 200 held on the chuck table 20, and measures the thickness of the entire surface of the device wafer 120.

[0075] At this time, the control unit 7 determines the two-dimensional coordinates (XY coordinates based on the notch 110) of the horizontal plane at each thickness measurement point, using the notch 110 of the wafer 200 as a reference. Then, the control unit 7 stores the relationship (combination) between the XY coordinates of each thickness measurement point and the thickness at each thickness measurement point as thickness data in the memory unit 8.

[0076] [Area setting process] After the thickness data storage step, the above-mentioned area setting step is performed. In this step, the thickness data stored in the thickness data storage step is used to set a specified area that defines the thickness during finish grinding. As shown in Figure 7, the operator sets an area on the device wafer 120 other than the area including the device film 104 (an area measured as having a thickness thinner than the actual thickness) as a specified area 105, which is an area on the device wafer 120 where the operator wants to specify the thickness. In the region setting step, for example, as described above, a two-dimensional arrangement step, a feature region setting step, and a first defined region recognition step are performed.

[0077] [Two-dimensional array process] In this step, the thickness data stored in the thickness data storage step is two-dimensionally arranged in X and Y coordinates. For example, as described above, by converting the thickness data acquired in the thickness data storage step into an image, an image of the top surface of the wafer 200 (an image of the top surface of the device wafer 120) is formed as thickness data two-dimensionally arranged in X and Y coordinates.

[0078] [Feature area setting process] After the two-dimensional arrangement step, the characteristic region setting step described above is carried out, in which an operator sets characteristic regions in the two-dimensionally arranged thickness data.

[0079] Specifically, an operator sets a characteristic region 106 on an image of the top surface of the wafer 200 displayed on the touch panel 9 (see FIG. 1) using a mouse or the like. This characteristic region 106 is an area on the device wafer 120 that has a pattern that is more distinctive than other areas, and is an area suitable for pattern matching. The control unit 7 acquires the pattern of the characteristic region 106 set by the operator.

[0080] In this step, the operator sets the specified region 105 (the position of the specified region 105). That is, the operator sets the positional relationship between the feature region 106 and the specified region 105 on the device wafer 120 (the distance in the X direction and the distance in the Y direction between the center of the feature region 106 and the center of the specified region 105) using, for example, the touch panel 9. Then, the control unit 7 stores this positional relationship in the memory unit 8.

[0081] [First defined area recognition step] After the characteristic region setting step, the above-mentioned first defined region recognition step is carried out. In this step, the control unit 7 extracts the characteristic region 106 from the thickness data by performing pattern matching on the two-dimensionally arranged thickness data using the characteristic region 106, and recognizes the position of the defined region 105 in the thickness data based on the extraction result and the positional relationship between the characteristic region 106 and the defined region 105 stored in advance.

[0082] [Finishing grinding process] After the region setting step (first predetermined region recognition step), the above-mentioned finish grinding step is carried out. In this step, the thickness of each of the predetermined regions 105 is measured by the non-contact thickness measuring device 82 using the XY coordinates of the plurality of predetermined regions 105 set in the region setting step, and the upper surface of the wafer 200 (the upper surface of the device wafer 120) is ground with the grinding wheel 77 until the measured thickness reaches a preset finish thickness.

[0083] Specifically, the control unit 7 rotates the grinding wheel 77 of the grinding mechanism 70 and the chuck table 20, while lowering the grinding mechanism 70 using the vertical movement mechanism 50, and grinds the upper surface of the device wafer 120 held on the chuck table 20 with the grinding wheel 77. At this time, the control unit 7 uses the thickness measurement mechanism 80 to measure the thickness of the specified region 105 of the device wafer 120 being ground, and continues grinding until the thickness of the specified region 105 reaches a predetermined finish thickness.

[0084] As described above, in this embodiment, the thickness of the specified region 105 of the device wafer 120 is measured by the non-contact thickness measuring device 82. Therefore, even if the thickness of the support wafer 101 differs for each wafer 200, the thickness of the specified region 105 of the device wafer 120 can be made uniform among a plurality of wafers 200.

[0085] Furthermore, in the finish grinding process, grinding of the device wafer 120 is carried out until the thickness of the specified region 105, which is to be specified as the finishing thickness, reaches a predetermined finishing thickness. Therefore, the thickness of the specified region 105 on the device wafer 120 can be controlled well.

[0086] Furthermore, in the region setting step, a region of the device wafer 120 other than the region including the film 124 is set as the specified region 105. As described above, it is difficult for the non-contact thickness gauge 82 to accurately measure the thickness of the region including the film 124 of the device wafer 120. Therefore, in this embodiment, a region where the thickness of the device wafer 120 can be accurately measured by the non-contact thickness gauge 82 (a region not including the film 124) is set as the specified region 105, and while monitoring the thickness of this specified region 105, finish grinding is performed so that the thickness of this specified region 105 becomes the finished thickness. Therefore, the thickness of the specified region 105 can be controlled more effectively.

[0087] The chip-on-wafer ground in this embodiment may be a wafer 300 as shown in Fig. 8. This wafer 300 has the same configuration as the wafer 100 shown in Fig. 2, but has a sealant (a layer made of sealant, a mold layer) 108 covering the chips 103 on the upper surface of the support wafer 101. The sealant 108 is made of, for example, resin or glass.

[0088] 1 is configured to be able to measure the thickness of the encapsulant 108 on the wafer 300. That is, the non-contact thickness gauge 82 irradiates the wafer 300 with measurement light having a wavelength that is transparent to the encapsulant 108 from above the wafer 300, receives upper-surface reflected light reflected from the upper surface of the encapsulant 108, and lower-surface reflected light reflected from the lower surface of the encapsulant 108 through the encapsulant 108, and measures the thickness of the encapsulant 108 by spectral interference.

[0089] As shown in Figure 9, the thickness of the sealing material 108 includes a thickness T2 of the sealing material 108 from the upper surface of the support wafer 101 to the upper surface of the sealing material 108, which is the thickness of the sealing material 108 arranged on the upper surface of the support wafer 101, and a thickness T3 of the sealing material 108 from the upper surface of the chip 103 to the upper surface of the sealing material 108, which is the thickness of the sealing material 108 arranged on the upper surface of the chip 103.

[0090] The following describes a grinding method for the wafer 300 controlled by the control unit 7. This grinding method is a chip-on-wafer grinding method in which a plurality of chips 103 are arranged on the upper surface of a support wafer 101 and the chips 103 are sealed with a sealing material 108.

[0091] [Holding process] In this grinding method for wafer 300, a holding step similar to that of the grinding method for wafer 300 shown in Fig. 2 described above is performed. That is, in this step, support wafer 101 of wafer 300 is held by chuck table 20 shown in Fig. 1. Specifically, control unit 7 causes Y-axis direction moving mechanism 40 to position wafer holding mechanism 30 including chuck table 20 at holding position 301 on the -Y direction side for holding wafer 300 by holding surface 22.

[0092] Next, an operator or a conveying device (not shown) places the support wafer 101 side (tape 102 side) of the wafer 300 on the holding surface 22 of the chuck table 20 so that the upper surface of the wafer 300 on which the chips 103 and the sealing material 108 are formed faces upward. Thereafter, the control unit 7 connects the holding surface 22 to a suction source, whereby the wafer 300 is held by the holding surface 22 under suction.

[0093] [Upper surface grinding process] After the holding step, an upper surface grinding step is performed. In this step, the upper surface of the sealing material 108 of the wafer 300 is ground. Specifically, the control unit 7 first controls the Y-axis direction moving mechanism 40 to position the wafer holding mechanism 30 including the chuck table 20 at the processing position 302 on the +Y direction side.

[0094] Next, the control unit 7 rotates the grinding wheel 77 of the grinding mechanism 70 and the chuck table 20, while causing the vertical movement mechanism 50 to lower the grinding mechanism 70, and grinds the upper surface of the sealing material 108 of the wafer 300 held on the holding surface 22 of the chuck table 20 with the grinding wheel 77. At this time, the control unit 7 uses the thickness measurement mechanism 80 to measure the thickness of the sealing material 108 being ground (for example, the thickness T2 of the sealing material 108 from the upper surface of the support wafer 101 to the upper surface of the sealing material 108), and continues upper surface grinding until this distance reaches a predetermined value.

[0095] If the upper surface of the sealing material 108 is flat enough to allow the thickness of the sealing material 108 to be measured before the upper surface grinding step is performed, this upper surface grinding step may be omitted.

[0096] [Thickness data storage process] After the top surface grinding process, a thickness data storage process is performed. In this process, the non-contact thickness gauge 82 and the chuck table 20 are moved relative to each other in the radial direction of the chuck table 20 while the chuck table 20 is rotated, and the thickness of the encapsulant 108 is measured in a predetermined area of ​​the wafer 300. The measured thickness and the horizontal XY coordinates of the thickness measurement points are stored as thickness data. In this embodiment, this predetermined area includes at least the portion of the encapsulant 108 whose thickness will be measured by the non-contact thickness gauge 82 during the subsequent finish grinding process.

[0097] In this embodiment, the predetermined area is approximately the entire surface of the wafer 300, thickness measurement points are set on approximately the entire surface of the wafer 300, and the thickness of approximately the entire surface of the wafer 300 (the thickness of the entire surface of the encapsulant 108) is measured. As described above, the thickness of the encapsulant 108 includes the thickness of the encapsulant 108 from the upper surface of the support wafer 101 to the upper surface of the encapsulant 108 (thickness T2 in FIG. 9) and the thickness of the encapsulant 108 from the upper surface of the chip 103 to the upper surface of the encapsulant 108 (thickness T3 in FIG. 9).

[0098] 9, the control unit 7 causes the rotation mechanism 26 to rotate the chuck table 20 about the rotation axis 401 passing through the center of the holding surface 22 (arrow 501). Furthermore, the control unit 7 causes the arm unit 83 and the non-contact thickness gauge 82 to turn using the support member 84, thereby moving the non-contact thickness gauge 82 in the radial direction of the chuck table 20 (wafer 300) (arrow 502). In this way, the control unit 7 sequentially positions the non-contact thickness gauge 82 at each thickness measurement point of the wafer 300 held on the chuck table 20 to measure the thickness of the entire surface of the sealing material 108.

[0099] At this time, the control unit 7 determines two-dimensional coordinates (XY coordinates) of the horizontal plane at the thickness measurement points of the wafer 300 along the measurement line 801 (see FIG. 4) using the notch 110 of the wafer 300 as a reference. Then, the control unit 7 stores the relationship (combination) between the XY coordinates of each thickness measurement point of the wafer 300 and the thickness of the sealing material 108 at each thickness measurement point as thickness data in the memory unit 8.

[0100] [Area setting process] After the thickness data storage step, a region setting step is performed. In this step, the thickness data stored in the thickness data storage step is used to set a specified region, which is a region for specifying the thickness during the finish grinding process. This specified region is a region where the thickness of the encapsulant 108 is desired to be specified, i.e., a region where the finished thickness is desired to be specified in the subsequent finish grinding step. Specifically, in the region setting step of this embodiment, the following two-dimensional arrangement step, feature region setting step, and first defined region recognition step are performed.

[0101] [Two-dimensional array process] In this step, the thickness data stored in the thickness data storage step is arranged two-dimensionally in XY coordinates. In this embodiment, the thickness data acquired in the thickness data storage step is converted into an image (an image based on image components such as brightness, color tone, or color difference) to form an image of the upper surface of the wafer 300 (an image of the encapsulant 108) as thickness data arranged two-dimensionally in XY coordinates (image formation step). In this image, the encapsulant 108 is displayed using image components (such as color tone) according to its thickness.

[0102] [Feature area setting process] After the two-dimensional arrangement step, a characteristic region setting step is performed. In this step, an operator sets a characteristic region (key pattern region) in the two-dimensionally arranged thickness data. In this embodiment, the operator sets the characteristic region using an image of the top surface of the wafer 300 (an image of the encapsulant 108) as the two-dimensionally arranged thickness data.

[0103] Specifically, the control unit 7 displays an image of the top surface of the wafer 300 on the touch panel 9. Then, an operator uses an input device such as a mouse to set a feature region in the image displayed on the touch panel 9. The feature region is, for example, a region suitable for pattern matching. In response to the setting of the characteristic region by the operator, the control unit 7 acquires the pattern (shape and a collection of multiple thickness values) of the characteristic region set by the operator. The characteristic region may be the same as the specified region where the thickness of the sealing material 108 is to be specified.

[0104] In this step, the worker sets the specified region (the position of the specified region). That is, the worker sets the positional relationship between the characteristic region in the sealing material 108 and the specified region whose thickness is to be specified, for example, using the touch panel 9. That is, the relationship between the center coordinates of the characteristic region and the center coordinates of the specified region whose thickness is to be specified is set. In response to this, the control unit 7 stores the distances in the X direction and the Y direction between the center of the characteristic region and the center of the specified region whose thickness is to be specified in the storage unit 8 as the positional relationship between the characteristic region and the specific part.

[0105] [First defined area recognition step] After the feature region setting step, a first specified region recognition step is performed. In this step, the feature region is used to perform pattern matching on the two-dimensionally arranged thickness data to extract the feature region from the thickness data, and based on the extraction result, the position of the specified region (the region whose thickness is to be measured by the non-contact thickness gauge 82 during finish grinding) in the thickness data is recognized using the pre-stored distances in the X and Y directions between the feature region and the specified region.

[0106] In this embodiment, the control unit 7 performs pattern matching on the top surface image of the wafer 300 as two-dimensionally arranged thickness data, based on the pattern of the feature region (a collection of shapes and multiple thickness values) set by the operator. In this case, the control unit 7 obtains the XY coordinates of multiple feature regions in the top surface image by extracting the pattern of the feature region from the top surface image of the wafer 300. Then, based on, for example, the positional relationship between the feature region and the specified region (the distance in the X direction and the distance in the Y direction between the feature region and the specified region) that has been acquired in advance, the control unit 7 recognizes the XY coordinates of the specified region, which is the region where the thickness is to be measured by the non-contact thickness measuring device 82 during finish grinding, from the extracted feature region.

[0107] [Finishing grinding process] After the area setting step (first predetermined area recognition step), a finish grinding step is carried out. In this step, the thickness of each predetermined area is measured by a non-contact thickness measuring device 82 using the XY coordinates of the multiple predetermined areas set in the area setting step, and the upper surface of the wafer 300 is ground with a grinding wheel 77 until the measured thickness reaches a preset finish thickness.

[0108] Specifically, the control unit 7 rotates the grinding wheel 77 of the grinding mechanism 70 and the chuck table 20, while lowering the grinding mechanism 70 using the vertical movement mechanism 50, and grinds the upper surface of the wafer 300 (the upper surface of the encapsulant 108) held on the chuck table 20 with the grinding wheel 77. At this time, the control unit 7 uses the thickness measurement mechanism 80 to measure the thickness of a specified region of the encapsulant 108 being ground, and continues grinding until the thickness of the specified region reaches a predetermined finish thickness.

[0109] That is, during finish grinding, the control unit 7 acquires the relationship between the thickness and the XY coordinates of a plurality of thickness measurement points on the upper surface of the wafer 300 by rotating the arm unit 83 and the non-contact thickness gauge 82 (see FIG. 9) using the support member 84. Then, the control unit 7 uses the XY coordinates of the specified area obtained in the first specified area recognition step to extract only the thickness of the specified area from the thicknesses measured at each thickness measurement point, and carries out grinding until this thickness reaches the specified finish thickness.

[0110] As described above, in this embodiment, the thickness of the specified region of the encapsulant 108 is measured by the non-contact thickness measuring device 82. Therefore, even if the thickness of the support wafer 101 differs for each wafer 300, the thickness of the specified region of the encapsulant 108 can be made uniform among the multiple wafers 300.

[0111] Furthermore, in the finish grinding process, grinding of the sealing material 108 is carried out until the thickness of the specified region that is to be defined as the finishing thickness reaches a predetermined finishing thickness. Therefore, it is possible to precisely control the thickness of the specified region of the sealing material 108.

[0112] The predetermined area of ​​the wafer 100, 200, 300 where the thickness measurement is performed in the thickness data storage step does not have to be the entire surface of the wafer 100, 200, 300, but may include at least the specified region (for example, specified region 105, which is part of the chip 103) where the thickness is measured by the non-contact thickness gauge 82 during the finish grinding process. Also, it is not necessary to measure the thickness of all the specified regions on the wafer 100, 200, 300. In the thickness data storage step, it is sufficient to measure the thickness of the specified region where the thickness is measured by the non-contact thickness gauge 82 during the finish grinding process.

[0113] In addition, in the finish grinding process, the thickness of all specified areas on wafers 100, 200, and 300 may be measured, and grinding may be carried out until the thickness of all specified areas reaches the specified finish thickness, or the thickness of some specified areas designated in advance by the operator may be measured, and grinding may be carried out until the thickness of these specified areas reaches the specified finish thickness.

[0114] 4, the control unit 7 rotates the non-contact thickness gauge 82 in the radial direction of the chuck table 20 while rotating the chuck table 20 so that a plurality of concentric measurement lines 801 are formed on the upper surface of the wafer 100, 200, 300. In this regard, the control unit 7 may rotate the non-contact thickness gauge 82 in the radial direction of the chuck table 20 while rotating the chuck table 20 so that one or more spiral measurement lines 801 are formed on the upper surface of the wafer 100, 200, 300.

[0115] In the two-dimensional arrangement step, the thickness data acquired in the thickness data storage step is converted into an image, and an image of the top surface of the wafer 100, 200, 300 (an image of the chip 103 or the encapsulant 108) is formed as two-dimensionally arranged thickness data. Then, in the characteristic region setting step, an operator sets a characteristic region using the image. Furthermore, in the first defined region recognition step, the control unit 7 performs pattern matching on the image to extract the characteristic region set by the operator.

[0116] In this regard, in the two-dimensional arrangement step, the thickness data does not need to be converted into an image, and the thickness values ​​may be arranged two-dimensionally. In this case, in the characteristic region setting step, the operator sets, for example, a portion to be set as a characteristic region (for example, a group of adjacent thickness values ​​to be set as the characteristic region 106 of the chip 103). Then, in the first defined region recognition step, the control unit 7 extracts the characteristic region by, for example, performing pattern matching on the two-dimensionally arranged thickness data using the thickness of the characteristic region as a pattern.

[0117] In the region setting step, a predetermined region that defines the thickness during finish grinding is set using the thickness data stored in the thickness data storage step. In the region setting step of the above-described embodiment, a two-dimensional arrangement step, a characteristic region setting step, and a first predetermined region recognition step are performed. In this regard, the region setting step may also include a second predetermined region recognition step, as described below. In this step, the control unit 7 uses the thickness data stored in the thickness data storage step to acquire a region having a thickness within a predetermined thickness monitoring width and recognizes this region as a predetermined region.

[0118] For example, when a portion of the chip 103 is set as the specified region, it is assumed that thickness data such as that shown in FIG. 10 is acquired in the thickness data storage step. This figure shows the thickness (μm) and the angle (deg) at which the thickness was obtained. This angle corresponds to the position of each thickness measurement point arranged along a single circular measurement line 801, and is 0 degrees at the position of the notch 110, for example. The angle of each thickness measurement point corresponds to the XY coordinates on the top surface of the wafer 100. For example, the control unit 7 recognizes an area having a thickness within the thickness monitoring width W1 (a portion from just under 25 μm to over 33 μm) shown in FIG. 10 as the specified region, and acquires its position (XY coordinates).

[0119] Furthermore, when a portion of the sealing material 108 is set as the specified region, it is assumed that thickness data such as that shown in Fig. 11 is acquired in the thickness data storage step. This figure also shows the thickness (µm) and the angle (deg) at which the thickness was obtained. The control unit 7 recognizes, for example, a region having a thickness within the thickness monitoring width W2 (a portion from approximately 15 µm to 17 µm) shown in Fig. 11 as the specified region, and acquires its position (XY coordinates).

[0120] In this second predetermined area recognition step, the predetermined area, which is the area that determines the thickness during the finish grinding process, can be recognized in a short time, thereby shortening the time required to grind the wafer 100.

[0121] In addition, in this embodiment, as shown in Figure 1, the thickness measurement mechanism 80 has a support member 84, and this support member 84 rotates an arm portion 83 having a non-contact thickness gauge 82 at its tip, thereby rotating and moving the non-contact thickness gauge 82 along the radial direction of the chuck table 20 so as to pass through the center of the holding surface 22.

[0122] 12, the thickness measurement mechanism 80 may have a linear movement unit 85 instead of the support member 84. This linear movement unit 85 moves an arm unit 83 extending in the X-axis direction horizontally in a linear manner along the Y-axis direction, thereby linearly moving a non-contact thickness gauge 82 attached to the tip of the arm unit 83 along the radial direction of the chuck table 20 so as to pass through the center of the holding surface 22. Even with the thickness measurement mechanism 80 configured in this way, it is possible to appropriately measure the thicknesses of the wafers 100, 200, 300 held on the chuck table 20 (the thicknesses of the chip 103, the device wafer 120, and the encapsulant 108). [Explanation of symbols]

[0123] 1: Grinding device, 7: Control unit, 8: Memory unit, 9: Touch panel, 10: base, 11: column, 12: bellows cover, 13: opening, 20: chuck table, 21: porous member, 22: holding surface, 23: frame body, 25: endless belt, 26: rotation mechanism, 27: support column, 28: support member, 29: chuck table base, 30: wafer holding mechanism, 39: Cover plate, 40: Y-axis direction movement mechanism, 41: Support base, 42: Y-axis guide rail, 43: Y-axis ball screw, 44: Y-axis motor, 45: Y-axis moving table, 50: vertical movement mechanism, 51: Z-axis guide rail, 52: Z-axis ball screw, 53: Z-axis moving table, 54: Z-axis motor, 56: holder, 70: grinding mechanism, 71: spindle housing, 72: spindle, 73: spindle motor, 74: Wheel mount, 75: Grinding wheel, 76: Wheel base, 77: Grinding stone, 80: Thickness measurement mechanism, 82: Non-contact thickness measurement device, 83: Arm portion, 84: Support member, 85: Linear moving part, 100-300: Wafer, 101: supporting wafer, 102: tape, 103: chip, 104: membrane, 105: defined area, 106: feature area, 108: encapsulant, 110: notch, 120: device wafer, 121: device formation surface, 122: device, 123: Street, 124: Membrane, 301: Holding position, 302: Processing position, 401: Rotation axis, 801: Measurement line, T1: Chip thickness, T2: Encapsulation thickness, T3: Encapsulation thickness, T4: device wafer thickness, W1: Thickness monitoring width for chip, W2: Thickness monitoring width for encapsulant

Claims

1. A method for grinding a composite wafer, which is a wafer having a plurality of chips arranged on an upper surface of a support wafer, or a wafer having a device wafer having devices formed on an upper surface of a support wafer, comprising: a holding step of holding the support wafer by a chuck table; a thickness data storage step of rotating the chuck table while moving the non-contact thickness gauge and the chuck table relative to each other in the radial direction of the chuck table, measuring the thickness of an area including a part of the chip whose thickness is to be measured by the non-contact thickness gauge during at least the finish grinding of the composite wafer, or an area including a part of the device wafer, and storing the measured thickness and the XY coordinates of the horizontal plane at the thickness measurement point as thickness data; a region setting step of setting a predetermined region that is a region that defines a thickness during finish grinding using the thickness data stored in the thickness data storage step; a finish grinding step of measuring the thickness of the specified area with the non-contact thickness measuring device using the XY coordinates of the specified area, and grinding the upper surface of the composite wafer with a grinding wheel until the measured thickness reaches a predetermined finish thickness. A method for grinding composite wafers.

2. The region setting step includes: a two-dimensional arrangement step of two-dimensionally arranging the thickness data stored in the thickness data storage step using the XY coordinates; a characteristic region setting step in which an operator sets a characteristic region in the two-dimensionally arranged thickness data; a first defined area recognition step of extracting the feature area from the thickness data by performing pattern matching on the two-dimensionally arranged thickness data using the feature area, and recognizing the defined area in the thickness data based on the extraction result; 2. The method for grinding a composite wafer according to claim 1.

3. The region setting step includes: a second predetermined area recognition step of acquiring an area having a thickness within a preset thickness monitoring width using the thickness data stored in the thickness data storage step, and recognizing this area as the predetermined area; 2. The method for grinding a composite wafer according to claim 1.

4. A method for grinding a chip-on-wafer in which a plurality of chips are arranged on an upper surface of a support wafer and the chips are sealed with a sealing material, comprising the steps of: a holding step of holding the support wafer of the chip-on-wafer by a chuck table; a thickness data storage step of rotating the chuck table while moving the non-contact thickness gauge and the chuck table relatively in the radial direction of the chuck table, measuring the thickness of the encapsulant disposed on the upper surface of the support wafer of the chip-on-wafer, i.e., from the upper surface of the support wafer to the upper surface of the encapsulant, and the thickness of the encapsulant disposed on the upper surface of the chip, i.e., from the upper surface of the chip to the upper surface of the encapsulant, for at least a portion whose thickness is measured by the non-contact thickness gauge during finish grinding, and storing the measured thickness and the XY coordinates of the horizontal plane at the thickness measurement point as thickness data; a region setting step of setting a predetermined region that is a region that defines a thickness during finish grinding using the thickness data stored in the thickness data storage step; a finish grinding step of measuring the thickness of the specified area with the non-contact thickness measuring device using the XY coordinates of the specified area, and grinding the upper surface of the chip-on-wafer with a grinding wheel until the measured thickness reaches a predetermined finish thickness. Chip-on-wafer grinding method.

5. The region setting step includes: a two-dimensional arrangement step of two-dimensionally arranging the thickness data stored in the thickness data storage step using the XY coordinates; a characteristic region setting step in which an operator sets a characteristic region in the two-dimensionally arranged thickness data; a first defined area recognition step of extracting the feature area from the thickness data by performing pattern matching on the two-dimensionally arranged thickness data using the feature area, and recognizing the defined area in the thickness data based on the extraction result; 5. The chip-on-wafer grinding method according to claim 4.

6. The region setting step includes: a second predetermined area recognition step of acquiring an area having a thickness within a preset thickness monitoring width using the thickness data stored in the thickness data storage step, and recognizing this area as the predetermined area; 5. The chip-on-wafer grinding method according to claim 4.

Images