Method for grinding a plate-shaped workpiece

Abstract

The present invention provides a grinding method of a plate-shaped workpiece, which can shorten the grinding time in the grinding process of the plate-shaped workpiece in the case where the infeed grinding is followed by the creep feed grinding. In the infeed grinding and the creep feed grinding, the same grinding tool is used. Therefore, it is not necessary to position the chuck table holding the plate-shaped workpiece with respect to two different grinding tools. Therefore, the grinding time can be shortened. In addition, in the infeed grinding, the lower surface of the grinding tool is used, while in the creep feed grinding, the side surface of the grinding tool is used. Therefore, compared with the case where the plate-shaped workpiece is ground to a prescribed thickness by only the infeed grinding or the creep feed grinding, the consumption amount of the grinding tool can be reduced.

Description

Technical Field

[0001] This invention relates to a grinding method for plate-shaped workpieces. Background Technology

[0002] Patent document 1 discloses a grinding method for a wafer that performs creep grinding after infeed grinding.

[0003] Patent Document 1: Japanese Patent Application Publication No. 63-077647

[0004] However, in the above grinding method, a grinding wheel for plunge grinding is used when performing plunge grinding, and a grinding wheel for creep grinding is used when performing creep grinding. This use of two different grinding wheels wastes the time that the chuck stage, which holds the wafer in position relative to both grinding wheels, is used for. Summary of the Invention

[0005] Therefore, the object of the present invention is to shorten the grinding time in the grinding of plate-shaped workpieces when creeping feed grinding is performed after infeed grinding.

[0006] According to the present invention, a grinding method for a plate-shaped workpiece is provided, wherein the plate-shaped workpiece held by a chuck table is ground using an annular grinding wheel. The grinding method includes a plunge grinding step and a feed grinding step. The plunge grinding step comprises the following actions: rotating the chuck table about a table rotation axis passing through the center of the holding surface holding the plate-shaped workpiece; positioning the grinding wheel above the holding surface such that its lower surface passes through the center of the holding surface; rotating the grinding wheel about a wheel rotation axis passing through the center of the grinding wheel; and... The grinding wheel and the chuck table move relative to each other in a direction perpendicular to the holding surface, thereby grinding the upper surface of the plate-shaped workpiece through the lower surface of the grinding wheel. The creep-feed grinding process includes the following actions: after the entry grinding process, positioning the lower surface of the grinding wheel used in the entry grinding at a position that is outside the outer periphery of the plate-shaped workpiece and lower than the upper surface of the plate-shaped workpiece; stopping the rotation of the chuck table; and moving the plate-shaped workpiece and the grinding wheel relative to each other in a direction parallel to the holding surface, thereby grinding the upper surface of the plate-shaped workpiece through the side surface of the rotating grinding wheel.

[0007] Preferably, the grinding method for the plate-shaped workpiece further includes a pre-feed grinding step performed before the infeed grinding step, the pre-feed grinding step comprising the following actions: positioning the lower surface of the grinding wheel used in the infeed grinding at a position that is outside the outer periphery of the plate-shaped workpiece and lower than the upper surface of the plate-shaped workpiece; and moving the plate-shaped workpiece and the grinding wheel relative to each other in a direction parallel to the holding surface, thereby grinding the upper surface of the plate-shaped workpiece by the side of the rotating grinding wheel.

[0008] The preferred grinding method for the plate-shaped workpiece further includes an inclination change step, which is performed after the entry grinding step and before the start of the feed grinding step. The inclination change step is performed such that, relative to the direction of relative movement of the plate-shaped workpiece and the grinding wheel in the feed grinding step, the axis of rotation of the grinding wheel is tilted slightly towards the direction of movement than the vertical direction.

[0009] In this grinding method, the same grinding wheel is used for both plunge grinding and creep grinding. Therefore, it is unnecessary to position the chuck table holding the plate-shaped workpiece relative to two different grinding wheels. This reduces grinding time.

[0010] Furthermore, in plunge grinding, the lower surface of the grinding wheel is used, while in creep grinding, the side surface of the grinding wheel is used. Therefore, compared to grinding a plate-shaped workpiece to a specified thickness solely by plunge grinding or creep grinding, the consumption of grinding wheels can be reduced. Attached Figure Description

[0011] Figure 1 This is a perspective view showing the structure of the grinding device.

[0012] Figure 2 (a)~ Figure 2 (c) is a cross-sectional view showing the grinding method.

[0013] Figure 3 This is a partial cross-sectional side view showing the infeed grinding process.

[0014] Figure 4 This is a partial cross-sectional side view showing the creep-feed grinding process.

[0015] Figure 5 It is a top view showing the positional relationship between the grinding wheel and the plate-shaped workpiece during infeed grinding.

[0016] Figure 6 This is a schematic diagram showing the cutting marks from the grinding process.

[0017] Figure 7 This is a schematic diagram showing the grinding marks from the slow feed.

[0018] Figure 8 (a)~ Figure 8 (d) is a cross-sectional view showing other grinding methods.

[0019] Figure 9 This is a cross-sectional view showing the tilting process that tilts the axis of rotation of the grinding wheel.

[0020] Label Explanation

[0021] 1: Grinding device; 7: Control unit; 10: Base; 11: Column; 12: Folding cover; 13: Opening; 30: Workpiece holding mechanism; 31: Chuck table; 32: Holding surface; 33: Support component; 34: Chuck table motor; 35: Support column; 39: Cover plate; 40: Y-axis moving mechanism; 41: Holding table; 42: Y-axis guide rail; 43: Y-axis ball screw; 44: Y-axis motor; 45: Y-axis moving table; 46: Y-axis encoder; 50: Grinding feed mechanism; 51: Z-axis guide rail; 52: Z-axis ball screw; 53: Z-axis moving table 54: Moving stage; 55: Z-axis motor; 56: Z-axis encoder; 60: Support; 61: Thickness measuring mechanism; 62: First contact; 63: Second contact; 70: Grinding mechanism; 71: Spindle housing; 72: Spindle; 73: Spindle motor; 74: Grinding wheel mounting base; 75: Grinding wheel; 76: Grinding wheel base; 77: Grinding tool; 100: Plate-shaped workpiece; 101: Front side; 102: Back side; 110: Substrate; 111: Si chip; 112: Electrode; 113: Molded resin layer; 120: Cutting grinding mark; 121: Soft feed grinding mark. Detailed Implementation

[0022] like Figure 1 As shown, the grinding apparatus 1 of this embodiment is an apparatus for grinding a plate-shaped workpiece 100. The plate-shaped workpiece 100 is, for example, a quadrilateral plate-shaped workpiece, including a front side 101 and a back side 102.

[0023] like Figure 2 As shown in (a), the plate-shaped workpiece 100 is, for example, a composite structure comprising a quadrilateral PCB (polychlorinated biphenyl) substrate 110, a plurality of Si chips 111, a plurality of electrodes 112 containing Cu (copper), and a molding resin layer 113. The Si chips 111 and electrodes 112 are arranged on the substrate 110, for example, in a lattice pattern. The molding resin layer 113 is formed on the substrate 110 in a manner that seals the Si chips 111 and electrodes 112. The side of the plate-shaped workpiece 100 on which the Si chips 111, electrodes 112, and molding resin layer 113 are formed is the front side 101.

[0024] like Figure 1As shown, the grinding apparatus 1 has: a cuboid base 10; an upwardly extending column 11; and a control unit 7 for controlling the various components of the grinding apparatus 1.

[0025] An opening 13 is provided on the upper surface of the base 10. A workpiece holding mechanism 30 is disposed within the opening 13. The workpiece holding mechanism 30 includes: a chuck table 31 having a holding surface 32 for holding the plate-shaped workpiece 100; a support member 33 supporting the chuck table 31; a chuck table motor 34 serving as a table rotation member, which rotates the chuck table 31 and the support member 33; and a support column 35 capable of adjusting the tilt of the chuck table 31.

[0026] The chuck stage 31 is formed in a quadrilateral shape, and has a quadrilateral holding surface 32 on its upper surface. The chuck stage 31 holds the plate-shaped workpiece 100 through this holding surface 32. The holding surface 32 is formed of a porous material and holds the plate-shaped workpiece 100 by means of attraction through communication with an attraction source (not shown).

[0027] The chuck table motor 34 causes the chuck table 31 to rotate about the center of the holding surface 32. That is, the chuck table 31, via the chuck table motor 34 located below, can rotate about the center of the holding surface 32 about an axis of rotation (table rotation axis 301; see reference 301) while holding the plate-shaped workpiece 100 through the holding surface 32. Figure 3 It rotates together with the support component 33 around the center.

[0028] A cover plate 39 is provided around the chuck table 31, which moves along the Y-axis direction together with the chuck table 31. Additionally, a pleated cover 12 that extends and retracts in the Y-axis direction is connected to the cover plate 39. Furthermore, a Y-axis moving mechanism 40 is provided below the workpiece holding mechanism 30.

[0029] The Y-axis moving mechanism 40 moves the workpiece holding mechanism 30 and the grinding mechanism 70 relative to each other in the Y-axis direction, which is parallel to the holding surface 32. In this embodiment, the Y-axis moving mechanism 40 is configured to move the workpiece holding mechanism 30, which includes the chuck table 31, relative to the grinding mechanism 70 in the Y-axis direction.

[0030] The Y-axis moving mechanism 40 includes: a pair of Y-axis guide rails 42 parallel to the Y-axis direction; a Y-axis moving stage 45 sliding on the 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; a Y-axis encoder 46 for detecting the rotation angle of the Y-axis motor 44; and a holding stage 41 for holding them.

[0031] The Y-axis moving stage 45 is configured to be able to move with the aid of the sliding member 451 (see reference). Figure 3 It slides on the Y-axis guide rail 42. A nut part 401 is fixed on the lower surface of the Y-axis moving stage 45 (see reference). Figure 3 A Y-axis ball screw 43 is screwed into the nut portion 401. A Y-axis motor 44 is connected to one end of the Y-axis ball screw 43.

[0032] In the Y-axis moving mechanism 40, the Y-axis motor 44 rotates the Y-axis ball screw 43, thereby moving the Y-axis moving stage 45 along the Y-axis guide rail 42 in the Y-axis direction. The support member 33 of the workpiece holding mechanism 30 is mounted on the Y-axis moving stage 45 by means of a support column 35. Therefore, as the Y-axis moving stage 45 moves in the Y-axis direction, the workpiece holding mechanism 30, including the chuck table 31, moves in the Y-axis direction.

[0033] In this embodiment, generally speaking, the workpiece holding mechanism 30 moves along the Y-axis direction between the workpiece placing area in front of (-Y direction side) where the plate-shaped workpiece 100 is placed on the holding surface 32 and the grinding area behind (+Y direction side) where the plate-shaped workpiece 100 is ground, via the Y-axis direction moving mechanism 40.

[0034] In addition, such as Figure 1 As shown, a column 11 is erected at the rear (+Y direction side) of the base 10. A grinding mechanism 70 and a grinding feed mechanism 50 for grinding the plate-shaped workpiece 100 are provided on the front surface of the column 11.

[0035] The grinding feed mechanism 50 moves the workpiece holding mechanism 30, which includes the chuck table 31, and the grinding mechanism 70 relative to each other in the Z-axis direction (grinding feed direction), which is perpendicular to the holding surface 32. In this embodiment, the grinding feed mechanism 50 is configured to move the grinding mechanism 70 relative to the chuck table 31 in the Z-axis direction.

[0036] The grinding feed mechanism 50 includes: a pair of Z-axis guideways 51 parallel to the Z-axis direction; a Z-axis moving stage 53 sliding on the Z-axis guideways 51; a Z-axis ball screw 52 parallel to the Z-axis guideways 51; a Z-axis motor 54; a Z-axis encoder 55 for detecting the rotation angle of the Z-axis motor 54; and a support 56 mounted on the front surface (front) of the Z-axis moving stage 53. The support 56 holds the grinding mechanism 70 in place.

[0037] Z-axis moving stage 53 is configured to be able to move by means of sliding component 531 (see reference). Figure 3 The Z-axis moving stage 53 slides on the Z-axis guide rail 51. A nut portion 501 is fixed to the rear surface (back side) of the Z-axis moving stage 53 (see reference). Figure 3A Z-axis ball screw 52 is screwed into the nut portion 501. A Z-axis motor 54 is connected to one end of the Z-axis ball screw 52.

[0038] In the grinding feed mechanism 50, the Z-axis motor 54 rotates the Z-axis ball screw 52, ​​thereby causing the Z-axis moving table 53 to move along the Z-axis guide rail 51 in the Z-axis direction. As a result, the support 56 mounted on the Z-axis moving table 53 and the grinding mechanism 70 held on the support 56 move together with the Z-axis moving table 53 in the Z-axis direction.

[0039] In addition, the position of the Z-axis moving stage 53 is identified by detecting the rotation angle of the Z-axis motor 54 through the Z-axis encoder 55.

[0040] like Figure 1 As shown, the grinding mechanism 70 includes: a spindle housing 71 fixed to the support 56; a spindle 72 rotatably held in the spindle housing 71; a spindle motor 73 that drives the spindle 72 to rotate; a grinding wheel mounting seat 74 mounted on the lower end of the spindle 72; and a grinding wheel 75 supported on the grinding wheel mounting seat 74.

[0041] The spindle housing 71 is held in place by the support 56. The spindle 72 extends along the Z-axis and is supported in the spindle housing 71 in such a way that it can rotate about an axis in the direction of extension.

[0042] The spindle motor 73 is connected to the upper end of the spindle 72, causing the spindle 72 to rotate.

[0043] The grinding wheel mounting base 74 is formed in the shape of a circular plate and is fixed to the lower end (front end) of the spindle 72. The grinding wheel mounting base 74 supports the grinding wheel 75.

[0044] The grinding wheel 75 is formed with an outer diameter substantially the same as that of the grinding wheel mount 74. The grinding wheel 75 includes an annular grinding wheel base (ring base) 76 formed of metal. Figure 3 As shown, a processing water passage 761 is formed inside the grinding wheel base 76 for supplying processing water from a water source (not shown) to the grinding wheel 77.

[0045] like Figure 1 As shown, an annular grinding wheel 77, consisting of multiple grinding wheels arranged in a ring, is fixed on the lower surface of the grinding wheel base 76, covering the entire circumference. The annular grinding wheel 77 has an inner diameter such that, when positioned on the holding surface 32 of the chuck table 31, the annular grinding wheel 77 protrudes horizontally from the holding surface 32.

[0046] The annular grinding wheel 77 is formed on the grinding wheel base 76 in a manner that extends along the center of the spindle 72. Therefore, the grinding wheel 77 rotates along a central axis (grind wheel rotation axis 701; see reference). Figure 3 Centered on the spindle 72, the grinding wheel mounting base 74 and the grinding wheel base 76 are rotated by the spindle motor 73 to grind the plate-shaped workpiece 100 held by the chuck table 31 arranged in the grinding area.

[0047] In this way, the grinding mechanism 70 rotates the grinding wheel 77 around the grinding wheel rotation axis 701 passing through the center of the annular grinding wheel 77, thereby grinding the front surface 101 of the plate-shaped workpiece 100 held by the holding surface 32 of the chuck table 31 in the workpiece holding mechanism 30 arranged in the grinding area.

[0048] Furthermore, in this embodiment, the extension direction of the spindle 72 is set to the Z-axis direction, which is perpendicular to the holding surface 32 of the chuck table 31. Also, as described above, the extension direction of the spindle 72 is consistent with the direction of the grinding wheel rotation axis 701, which serves as the rotation axis of the grinding wheel 77. Therefore, in this embodiment, the direction of the grinding wheel rotation axis 701 (its inclination relative to the holding surface 32) is set to be perpendicular to the holding surface 32.

[0049] In addition, such as Figure 1 As shown, a thickness measuring mechanism 60 is provided on the side of the opening 13 in the base 10. The thickness measuring mechanism 60 is capable of measuring the thickness of the plate-shaped workpiece 100 held by the holding surface 32 in a contact manner.

[0050] That is, the thickness measuring mechanism 60 contacts the first contact 61 and the second contact 62 with the holding surface 32 of the chuck table 31 and the plate-shaped workpiece 100, respectively. Thus, the thickness measuring mechanism 60 can measure the height of the holding surface 32 of the chuck table 31 and the height of the plate-shaped workpiece 100. The thickness measuring mechanism 60 can calculate the thickness of the plate-shaped workpiece 100 based on the difference between the measured height of the holding surface 32 and the height of the plate-shaped workpiece 100.

[0051] Alternatively, the thickness measuring mechanism 60 can replace the first contact 61 and the second contact 62 with a non-contact distance measuring device, such as a laser-type distance measuring device. This distance measuring device, for example, irradiates the plate-shaped workpiece 100 with laser light having a wavelength that transmits through the plate-shaped workpiece 100, receives reflected light from the bottom surface of the plate-shaped workpiece 100 and reflected light from the top surface of the plate-shaped workpiece 100, and measures the thickness of the plate-shaped workpiece 100 based on these reflected light and reflected light.

[0052] Alternatively, a non-contact distance measuring device can be used, for example, light or sound waves of wavelengths that are impermeable to the plate-shaped workpiece 100 and the holding surface 32. This allows for the measurement of the height of the holding surface 32 and the height of the upper surface of the plate-shaped workpiece 100. The thickness of the plate-shaped workpiece 100 can be calculated based on the difference between the measured height of the holding surface 32 and the height of the plate-shaped workpiece 100.

[0053] In addition, the control unit 7 includes a CPU and a storage medium such as a memory for performing calculations according to a control program. The control unit 7 controls the above-mentioned components of the grinding apparatus 1 to perform grinding operations on the plate-shaped workpiece 100.

[0054] The grinding method in grinding apparatus 1 will be described below.

[0055] The grinding method of this embodiment is a grinding method for plate-shaped workpiece 100, in which the plate-shaped workpiece 100 held by the holding surface 32 of the chuck table 31 is ground by an annular grinding tool 77.

[0056] [Maintaining process]

[0057] In this process, such as Figure 3 As shown, the plate-shaped workpiece 100 is held by the holding surface 32 of the chuck table 31 of the workpiece holding mechanism 30. That is, the control unit 7 or the operator holds the plate-shaped workpiece 100 on the holding surface 32 of the chuck table 31 of the workpiece holding mechanism 30, which is located in the workpiece placement area, with the front 101 facing upwards. Then, the control unit 7 controls the Y-axis direction movement mechanism 40 to move the workpiece holding mechanism 30, which includes the chuck table 31, toward the grinding area in the +Y direction.

[0058] [Infeed Grinding Process]

[0059] In this process, the control unit 7 first controls the chuck table motor 34 of the workpiece holding mechanism 30, such as... Figure 3 As shown, the chuck table 31 is rotated around the table rotation axis 301, which is centered on the holding surface 32 of the plate-shaped workpiece 100, as indicated by arrow 601.

[0060] Next, the control unit 7 controls the Y-axis movement mechanism 40 to position the grinding wheel 77 above the holding surface 32, with the lower surface of the grinding wheel 77 of the grinding mechanism 70 passing through the center of the holding surface 32. Furthermore, the control unit 7 controls the spindle motor 73 of the grinding mechanism 70 to rotate the spindle 72, thereby causing the grinding wheel 77 to rotate about the wheel rotation axis 701 as shown by arrow 602.

[0061] Next, the control unit 7 controls the grinding feed mechanism 50 to move the rotating grinding wheel 77 and the rotating chuck table 31 relative to each other in a direction perpendicular to the holding surface 32. In this embodiment, the control unit 7 uses the grinding feed mechanism 50 to move the grinding wheel 77 relative to the chuck table 31. In this way, the control unit 7 grinds the upper surface, i.e., the front surface 101, of the plate-shaped workpiece 100 held by the holding surface 32 through the lower surface of the grinding wheel 77.

[0062] Therefore, as Figure 2 As shown in (b), on the front side 101, the portion of the molding resin layer 113 covering the Si chip 111 and the electrode 112 is removed, exposing the Si chip 111 and the electrode 112. Then, the Si chip 111, the electrode 112, and the molding resin layer 113 are ground according to a predetermined depth of cut. This predetermined depth of cut is the amount of grinding required to achieve a predetermined first target thickness for the thickness of the plate-shaped workpiece 100 after depth of cut.

[0063] In addition, during this process, the control unit 7 can be controlled by... Figure 1 The thickness measuring mechanism 60 shown measures the thickness of the plate workpiece 100 during grinding and performs infeed grinding until the thickness of the plate workpiece 100 reaches the first target thickness.

[0064] [Grinding process with creep feed]

[0065] This process is performed after the entry grinding process. In this process, the control unit 7 first... Figure 4 As shown, the lower surface of the grinding tool 77 used in the cutting-in grinding is positioned outside the outer periphery of the plate workpiece 100 and lower than the upper surface, i.e., the front surface 101, of the plate workpiece 100 (positioning process).

[0066] That is, the control unit 7 first controls the Y-axis direction moving mechanism 40 to position the workpiece holding mechanism 30, including the chuck table 31, at the forward (-Y direction side) creep-feed grinding start position. The creep-feed grinding start position is, for example, the position closest to the -Y direction side in the grinding area, such as... Figure 4 The image shows the position where the grinding wheel 77 is not in contact with the plate-shaped workpiece 100 held by the chuck table 31. At this time, the lower surface of the grinding wheel 77 is located horizontally outside the outer periphery of the plate-shaped workpiece 100 and the outer periphery of the holding surface 32.

[0067] Next, the control unit 7 determines the height position (grinding height position) of the lower surface of the grinding tool 77 that gives the plate-shaped workpiece 100 a predetermined thickness after feed grinding. This grinding height position is a position lower than the front surface 101 of the plate-shaped workpiece 100 before feed grinding. For example, the control unit 7 determines the grinding height position based on the preset thickness of the plate-shaped workpiece 100 after feed grinding (the final target thickness of the plate-shaped workpiece 100; the second target thickness) and the height of the pre-obtained holding surface 32.

[0068] Then, the control unit 7 uses the grinding feed mechanism 50 to feed the grinding mechanism 70, which includes the grinding wheel 77, downwards, and sets the height position of the lower surface of the grinding wheel 77 to the aforementioned grinding height position. Furthermore, regarding the grinding height position, the Z-axis encoder 55 can pre-identify and store the height of the lower surface of the grinding wheel 77 at the end of the cutting-in grinding process. The grinding mechanism 70, which includes the grinding wheel 77, is then fed downwards from this stored height according to the difference between the first target thickness and the second target thickness, and the height position of the lower surface of the grinding wheel 77 is set to the aforementioned grinding height position.

[0069] Simultaneously with or at any time before or after the position control of the grinding wheel 77, the control unit 7 controls the chuck table motor 34 to stop the rotation of the chuck table 31.

[0070] Furthermore, the control unit 7 moves the plate-shaped workpiece 100 and the grinding wheel 77 relative to each other in a direction parallel to the holding surface 32. In this embodiment, the control unit 7 uses the Y-axis direction movement mechanism 40 to move the workpiece holding mechanism 30, which includes the chuck table 31 holding the plate-shaped workpiece 100, as follows: Figure 4 The chuck table moves relative to the grinding wheel 77 as indicated by the middle arrow 611.

[0071] In this way, the control unit 7 grinds the front surface 101 of the upper surface of the plate-shaped workpiece 100 by means of the side of the rotating grinding wheel 77. Thus, as... Figure 2 As shown in (c), on the front side 101, the Si chip 111, electrode 112 and molding resin layer 113 are further ground according to thickness d1 starting from the entry grinding. The thickness of the plate-shaped workpiece 100 becomes the second target thickness mentioned above.

[0072] In addition, in this process, the control unit 7 passes through Figure 1The thickness measuring mechanism 60 shown measures the thickness of the plate-shaped workpiece 100 during grinding. The control unit 7 confirms that the measured thickness of the plate-shaped workpiece 100 has reached the second target thickness and ends the creep-feed grinding. That is, if the measured thickness of the plate-shaped workpiece 100 has not reached the second target thickness, the control unit 7 performs creep-feed grinding again.

[0073] As described above, in this embodiment, the same grinding wheel 77 is used in both plunge grinding and creep grinding. Therefore, it is not necessary to position the chuck table 31 holding the plate-shaped workpiece 100 relative to two different grinding wheels. As a result, grinding time can be shortened.

[0074] Furthermore, the lower surface of the grinding wheel 77 is used in plunge grinding, and the side surface of the grinding wheel 77 is used in creep grinding. Therefore, compared to grinding the plate-shaped workpiece 100 to a predetermined thickness solely by plunge grinding or creep grinding, the consumption of the grinding wheel 77 can be reduced, and clogging of the grinding wheel 77 can be suppressed. Thus, the lifespan of the grinding wheel 77 can be extended.

[0075] Furthermore, in this embodiment, a gradual feed grinding process is performed after the entry grinding process, thus achieving the following effect. That is, in this embodiment, when the annular grinding wheel 77 performs entry grinding on the plate-shaped workpiece 100 held on the holding surface 32 of the chuck table 31, such as... Figure 5 As shown, it is configured to extend horizontally from the plate-shaped workpiece 100.

[0076] When implemented in this state Figure 3 During the plunge grinding process shown, a grinding process is performed on the front surface 101 of the grinding surface of the plate-shaped workpiece 100. Figure 6 The shown is a 120mm indentation grinding mark. (See figure.) Figure 6 As shown, the closer to the outer periphery of the front surface 101 of the plate-shaped workpiece 100, the wider the spacing of the cutting marks 120. Therefore, a larger unevenness is generated on the front surface 101 of the plate-shaped workpiece 100 after cutting, which is closer to the outer periphery.

[0077] Therefore, in the plate-shaped workpiece 100 after infeed grinding, the strength tends to vary in each portion. Consequently, when manufacturing a semiconductor chip containing a Si chip 111 by cutting the plate-shaped workpiece 100 after infeed grinding into smaller pieces using cutting tools or the like, it is difficult to make the bending strength of the semiconductor chip uniform.

[0078] On the other hand, when implementing Figure 4 During the feed-feed grinding process shown, a grinding process is performed on the front surface 101 of the plate-shaped workpiece 100. Figure 7 The circular, gradual feed grinding marks 121 are shown. (See example...) Figure 7 As shown, the feed grinding marks 121 are generated continuously at almost equal intervals on the front side 101 of the plate-shaped workpiece 100. Therefore, by performing feed grinding after infeed grinding, the bending strength of the semiconductor chip obtained by cutting the ground plate-shaped workpiece 100 into smaller pieces can be made uniform.

[0079] In addition, in this embodiment, the control unit 7 can perform the following pre-feed grinding process before the above-mentioned entry grinding process.

[0080] [Pre-feed grinding process]

[0081] In the pre-feed process of this embodiment, the front surface 101 is ground until the Si chip 111 and the electrode 112 are exposed on the front surface 101 of the plate workpiece 100 in a predetermined proportion.

[0082] The pre-cash feed grinding process includes a portion of the same process as the aforementioned pre-cash feed grinding process. That is, in the pre-cash feed grinding process, the control unit 7 first, as described above... Figure 4 The lower surface of the grinding tool 77 is positioned outside the outer periphery of the plate workpiece 100 and lower than the front surface 101, which is the upper surface of the plate workpiece 100 (positioning process).

[0083] That is, the control unit 7 uses the Y-axis direction moving mechanism 40 to position the workpiece holding mechanism 30, which includes the chuck table 31, at the aforementioned forward (-Y direction side) creep-feed grinding start position. As a result, the lower surface of the grinding wheel 77 is located horizontally outward from the outer periphery of the plate-shaped workpiece 100 and the outer periphery of the holding surface 32.

[0084] Furthermore, the control unit 7 uses the grinding feed mechanism 50 to set the height of the lower surface of the grinding wheel 77 to a grinding height position that is lower than the front surface 101 of the plate-shaped workpiece 100. This grinding height position is lower than the front surface 101 of the plate-shaped workpiece 100 before grinding. The control unit 7 determines this grinding height position, for example, based on the height of the plate-shaped workpiece 100 before grinding and a predetermined advance feed grinding amount (the amount ground in advance feed grinding).

[0085] Next, the control unit 7 moves the plate-shaped workpiece 100 and the grinding wheel 77 relative to each other in a direction parallel to the holding surface 32. That is, the control unit 7 uses the Y-axis direction movement mechanism 40 to move the workpiece holding mechanism 30, which includes the chuck table 31 holding the plate-shaped workpiece 100, as... Figure 4 As shown by the middle arrow 611, it moves relative to the grinding wheel 77 along the Y-axis (chuck table movement process).

[0086] In this way, the control unit 7 grinds the front surface 101 of the upper surface of the plate-shaped workpiece 100 by means of the side of the rotating grinding wheel 77. Thus, the surface in the previous grinding stage... Figure 8 The plate-shaped workpiece 100 in the state shown in (a) Figure 8 It is ground as shown in (b).

[0087] That is, by pre-feed grinding, the molding resin layer 113 is mainly ground on the front side 101 of the plate workpiece 100, so that the Si chip 111 and the electrode 112 are exposed in a specified ratio.

[0088] Then, control unit 7 performs the aforementioned plunge grinding process. Thus, as... Figure 8 As shown in (c), after the previous feed grinding process, the front side 101 of the plate workpiece 100 is further ground according to the thickness d2, and the thickness of the plate workpiece 100 is, for example, the first target thickness mentioned above.

[0089] In addition, control unit 7 performs the aforementioned feed-and-grind process. Therefore, as... Figure 8 As shown in (d), after the cutting grinding process, the front side 101 of the plate workpiece 100 is further ground according to the thickness d3, and the thickness of the plate workpiece 100 is, for example, the second target thickness mentioned above.

[0090] Here, the pre-grate grinding amount, which is the grinding amount in the pre-grate grinding process, will be explained. As described above, in the pre-grate grinding process, the molding resin is ground until the Si chip 111 and the electrode 112 are exposed on the front side 101 of the plate workpiece 100 in a predetermined proportion.

[0091] Therefore, the control unit 7 measures the total thickness of the plate-shaped workpiece 100 before starting the pre-feed grinding process. Furthermore, regarding the plate-shaped workpiece 100, the control unit 7 compares the thickness of the substrate 110 (design value) + the thickness of the Si chip 111 (design value) with the thickness of the substrate 110 (design value) + the height of the electrode 112 (design value) and selects the larger value. The control unit 7 then subtracts the selected value from the total thickness (measured value) of the plate-shaped workpiece 100 as the pre-feed grinding amount.

[0092] That is, the control unit 7 calculates the forward feed grinding amount based on the design values ​​of the thickness of the substrate 110, the Si chip 111, and the electrode 112, and the measured value of the total thickness of the plate-shaped workpiece 100. According to the amount corresponding to this grinding amount, the front side 101 of the plate-shaped workpiece 100 is ground by forward feed grinding. As a result, the Si chip 111 and the electrode 112 are exposed from the front side 101 in a predetermined ratio by forward feed grinding.

[0093] Thus, by performing a pre-feed grinding process before the entry grinding process, the following effects are achieved: When the amount of molding resin layer 113 in the plate-shaped workpiece 100 is large (when the total thickness of the plate-shaped workpiece 100 is thick, and the molding resin layer 113 on the front side has relatively large unevenness), the excess molding resin layer 113 can be removed in one pass by pre-feed grinding. Therefore, the grinding amount and grinding time in the entry grinding process can be reduced. Consequently, the overall grinding time can be shortened.

[0094] In addition, during the forward feed grinding process, the control unit 7 can use a camera (not shown) to photograph the front side 101 of the plate-shaped workpiece 100 after forward feed grinding, and confirm whether the Si chip 111 and the electrode 112 are exposed from the front side 101 in a specified proportion based on the photographing results.

[0095] Furthermore, in a camera-based configuration, the control unit 7 can perform multiple feed grinding operations during the pre-feed grinding process. In this case, the control unit 7 sets the grinding amount for at least one feed grinding operation and performs multiple feed grinding operations on the front surface 101 of the plate-shaped workpiece 100. During each feed grinding operation, the control unit 7 uses the camera to photograph the front surface 101 and identifies the proportion of the Si chip 111 and electrode 112 exposed from the front surface 101. The control unit 7 terminates the pre-feed grinding process when the identified exposure proportion reaches a predetermined ratio.

[0096] In addition, in this embodiment, the grinding mechanism 70 of the grinding apparatus 1 may have a grinding wheel rotation axis adjustment mechanism (not shown) for adjusting the tilt (relative to the holding surface 32) of the grinding wheel rotation axis 701 of the grinding wheel 77. The grinding wheel rotation axis adjustment mechanism adjusts the tilt of the grinding wheel rotation axis 701, for example, by adjusting the extension direction (tilt) of the spindle 72.

[0097] In this structure, during the entry grinding process, the control unit 7 controls the grinding wheel rotation axis adjustment mechanism to adjust the tilt of the grinding wheel rotation axis 701 of the grinding wheel 77 to be perpendicular to the holding surface 32 of the chuck table 31. In this structure, the control unit 7 can perform the following tilt change process after the entry grinding process and before the start of the creep grinding.

[0098] [Tilt Change Process]

[0099] In this process, the control unit 7 controls the adjustment mechanism of the grinding wheel rotation axis, such as... Figure 9As shown, relative to the direction of relative movement (direction of arrow 611) between the plate-shaped workpiece 100 and the grinding wheel 77 in the creep-feed grinding process, the rotation axis 701 of the grinding wheel 77 is tilted slightly towards the movement direction relative to the holding surface 32 than the vertical direction. Thus, the grinding wheel 77 is tilted relative to the chuck table 31 in the movement direction (Y-axis direction). Furthermore, in this state, the grinding wheel 77 performs creep-feed grinding on the front surface 101 of the plate-shaped workpiece 100 on the holding surface 32 in a subsequent creep-feed grinding process.

[0100] In this embodiment, such as Figure 9 As shown, the control unit 7 controls the grinding wheel rotation axis adjustment mechanism to tilt the grinding wheel 77 by raising it to the +Y direction side. Therefore, in the creep-feed grinding process, the portion of the grinding wheel 77 located on the -Y direction side grinds the plate-shaped workpiece 100. That is, the plate-shaped workpiece 100 is ground by the outer side of the grinding wheel 77.

[0101] In addition, when changing the chuck table 31, the grinding wheel 77 is tilted in the manner described above, with the +Y direction side raised, so that the part of the rotating grinding wheel 77 located on the -Y direction side contacts and grinds the upper surface of the chuck table 31 to form the retaining surface 32.

[0102] Furthermore, the control unit 7 can control the grinding wheel rotation axis adjustment mechanism to tilt the grinding wheel 77 by raising it to the -Y direction side. In this case, the portion of the grinding wheel 77 located on the +Y direction side grinds the plate-shaped workpiece 100. That is, the plate-shaped workpiece 100 is ground by the inner side of the grinding wheel 77. This tilting change process can also be performed before the preceding feed grinding process.

[0103] In this embodiment, the chuck table 31 is quadrilateral, and a quadrilateral retaining surface 32 is provided on the upper surface of the chuck table 31. However, the chuck table 31 and its retaining surface 32 can also be circular.

[0104] In this embodiment, a sheet-shaped workpiece 100 is held on the holding surface 32 of the chuck table 31. The holding surface 32 can be configured to hold multiple sheet-shaped workpieces 100.

[0105] In this embodiment, a quadrilateral plate-shaped workpiece 100 is shown as an example of a plate-shaped workpiece. In this regard, the grinding apparatus 1 of this embodiment can be configured to hold a polygonal or circular plate-shaped workpiece with different materials in the thickness direction by holding it by holding it by holding it by holding it by holding it by holding it by grinding it by grinding tool 77.

Claims

1. A grinding method for a plate-shaped workpiece, comprising grinding a plate-shaped workpiece held on the retaining surface of a chuck table using an annular grinding wheel, wherein... The grinding method for plate-shaped workpieces includes a plunge grinding process and a creep-feed grinding process. The infeed grinding process includes the following actions: The chuck table rotates about the table rotation axis that passes through the center of the holding surface holding the plate-shaped workpiece. The grinding wheel is positioned above the retaining surface such that its lower surface passes through the center of the retaining surface, allowing the grinding wheel to rotate about a rotation axis passing through the center of the grinding wheel; and The grinding wheel and the chuck table are moved relative to each other in a direction perpendicular to the holding surface, thereby grinding the upper surface of the plate-shaped workpiece through the lower surface of the grinding wheel. This creep-feed grinding process includes the following actions: After the infeed grinding process, the lower surface of the grinding wheel used in the infeed grinding is positioned outside the outer periphery of the plate workpiece and lower than the upper surface of the plate workpiece. To stop the rotation of the chuck table; as well as The plate-shaped workpiece and the grinding wheel are moved relative to each other in a direction parallel to the holding surface, thereby grinding the upper surface of the plate-shaped workpiece by the side of the rotating grinding wheel. The grinding method for plate-shaped workpieces also includes a pre-feed grinding process performed before the entry grinding process. The advance feed grinding process includes the following actions: The lower surface of the grinding wheel used in the infeed grinding is positioned outside the outer periphery of the plate-shaped workpiece and lower than the upper surface of the plate-shaped workpiece. as well as The plate-shaped workpiece and the grinding wheel are moved relative to each other in a direction parallel to the holding surface, thereby grinding the upper surface of the plate-shaped workpiece by the side of the rotating grinding wheel.

2. The grinding method for a plate-shaped workpiece according to claim 1, wherein, The grinding method for the plate-shaped workpiece also includes an inclination change process, which is performed after the entry grinding process and before the start of the feed grinding process. The inclination change process is performed such that, relative to the direction of relative movement of the plate-shaped workpiece and the grinding wheel in the feed grinding process, the axis of rotation of the grinding wheel is tilted slightly towards the direction of movement than the vertical direction.

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