Processing method and cutting apparatus

Abstract

To suppress breakage during grinding of a processing object wafer.SOLUTION: A processing method includes: a holding step 101 of holding the wafer side of a bonded wafer by a holding table to expose a processing object wafer; a non-attached region detection step 102 if imaging the bonded wafer held by the holding table by an imaging unit to detect a non-attached region at an outer peripheral part of the bonded wafer; a cut scheduled line setting step 103 of setting a cut scheduled line that separates the detected non-attached region from the center side of the processing object wafer and storing the orientation of the holding table to position the cut scheduled line parallel to the cutting feed direction; and a separation step 104 of positioning the cut scheduled line parallel to the X-axis direction, dividing the processing object wafer by cutting it along the cut scheduled line by a cutting blade, and forming a division groove 230 that separates the outer side including the non-attached region.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a machining method for machining a bonded wafer in which a workpiece wafer is laminated on a wafer by a cutting apparatus, and to the cutting apparatus.

Background Art

[0002] In back grinding of a wafer, a carrier wafer may be attached to the front side of the wafer for the purpose of protecting the front surface or facilitating handling during grinding and after the wafer is thinned by grinding (for example, see Patent Document 1).

[0003] In addition, there is a case where wafers are laminated to form a bonded wafer like an SOI (Silicon-On-Insulator Wafer) wafer (for example, see Patent Document 2).

[0004] Further, there is a case where a bonded wafer called WoW (Wafer on Wafer) in which a plurality of wafers are adhered and laminated is formed (for example, see Patent Document 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of Invention

Problems to be Solved by the Invention

[0006] However, in the above-described bonded wafer, the bonding between the wafers may be insufficient, and an unbonded region (that is, a bubble) may be formed.

[0007] If an unbonded area exists on the outer edge of the bonded wafer, a portion of the wafer may detach from the unbonded area during grinding, potentially causing the wafer to crack. The extent of the detachment cannot be controlled, and cracks may also spread to the remaining portion of the wafer that does not detach.

[0008] Devices in areas where delamination or cracking occurs during grinding cannot be commercialized, which could significantly reduce the number of devices that can be produced per wafer.

[0009] The object of the present invention is to provide a processing method and a cutting apparatus that can suppress damage to a wafer during grinding. [Means for solving the problem]

[0010] To solve the above-mentioned problems and achieve the objective, the present invention provides a cutting apparatus comprising: a holding table that includes a holding surface for holding a workpiece and is rotatable about a rotation axis passing through the center of the holding surface; a cutting unit having a spindle on which a cutting blade for cutting the workpiece held by the holding table is mounted; a cutting feed unit that moves the holding table relative to the cutting unit in the cutting feed direction; an indexing feed unit that moves the holding table relative to the cutting unit in an indexing feed direction perpendicular to the cutting feed direction; and an imaging unit that images the workpiece held by the holding table, wherein the wafer side of the bonded wafer is held by the holding table. The apparatus is characterized by comprising: a holding step of exposing the wafer to be processed; an unbonded area detection step of imaging the bonded wafer held by the holding table with an imaging unit and detecting an unbonded area on the outer periphery of the bonded wafer; a cutting line setting step of setting a cutting line to separate the detected unbonded area from the center of the wafer to be processed and storing the orientation of the holding table for positioning the cutting line parallel to the cutting feed direction; and a separation step of, after performing the cutting line setting step, positioning the cutting line parallel to the cutting feed direction, cutting the wafer to be processed of the bonded wafer along the cutting line with the cutting blade to separate it and form a separation groove that separates the outer part including the unbonded area.

[0011] The above processing method may also include a grinding step in which, after performing the separation step, the wafer to be processed in the bonded wafer is ground with a grinding wheel to thin it to a predetermined thickness.

[0012] The cutting apparatus of the present invention comprises: a holding table that includes a holding surface for holding a bonded wafer in which a wafer to be processed is stacked on a wafer and is rotatable about a rotation axis passing through the center of the holding surface; a cutting unit having a spindle on which a cutting blade for cutting the bonded wafer held by the holding table is mounted; a cutting feed unit that moves the holding table relative to the cutting unit in the cutting feed direction; an indexing feed unit that moves the holding table relative to the cutting unit in an indexing feed direction perpendicular to the cutting feed direction; an imaging unit that images the bonded wafer held by the holding table; and a controller that controls each component, wherein the controller comprises a storage unit that stores the position of a planned cutting line that is located towards the center of the unbonded area on the outer periphery of the bonded wafer held on the holding surface of the holding table and extends in a straight line; and a cutting control unit that causes each component to cut the planned cutting line stored in the storage unit of the bonded wafer held on the holding surface of the holding table.

[0013] In the cutting apparatus described above, the controller may include a detection unit that detects an unbonded area on the outer periphery of a bonded wafer from an image obtained by the imaging unit from the bonded wafer held on the holding surface of the holding table, and a setting unit that sets a cutting line for separating the unbonded area detected by the detection unit from the center side of the wafer to be processed, and stores the position of the cutting line set in the storage unit. [Effects of the Invention]

[0014] This invention has the effect of suppressing damage to the wafer during grinding. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a perspective view showing an example of the configuration of a cutting apparatus according to Embodiment 1. [Figure 2] Figure 2 is a schematic perspective view showing an example of a bonded wafer to be processed by the cutting device shown in Figure 1. [Figure 3] Figure 3 is a plan view schematically showing the non-bonded region of the bonded wafer shown in Figure 2. [Figure 4] Figure 4 is a perspective view schematically showing another example of the bonded wafer shown in Figure 2. [Figure 5] Figure 5 is a flowchart showing the flow of the processing method according to Embodiment 1. [Figure 6] Figure 6 is a cross-sectional view schematically showing the holding step of the processing method shown in Figure 5. [Figure 7] Figure 7 is a cross-sectional view schematically showing the non-bonded region detection step of the processing method shown in Figure 5. [Figure 8] Figure 8 is a plan view schematically showing a state of setting a planned cutting line in the planned cutting line setting step of the processing method shown in Figure 5. [Figure 9] Figure 9 is a plan view schematically showing a state of setting another planned cutting line in the planned cutting line setting step of the processing method shown in Figure 5. [Figure 10] Figure 10 is a cross-sectional view schematically showing the separation step of the processing method shown in Figure 5. [Figure 11] Figure 11 is a plan view schematically showing the bonded wafer after the separation step of the processing method shown in Figure 5. [Figure 12] Figure 12 is a side view schematically showing the grinding step of the processing method shown in Figure 5 with a partial cross-section. [Figure 13] Figure 13 is a perspective view showing a configuration example of the cutting apparatus according to Embodiment 2. [Modes for Carrying Out the Invention]

[0016] Embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by those skilled in the art, and those that are substantially the same. In addition, the components described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the present invention.

[0017] [Embodiment 1] A cutting apparatus according to Embodiment 1 of the present invention will be described based on the drawings. Figure 1 is a perspective view showing an example of the configuration of the cutting apparatus according to Embodiment 1. Figure 2 is a schematic perspective view showing an example of a bonded wafer to be processed by the cutting apparatus shown in Figure 1. Figure 3 is a schematic plan view showing the unbonded region of the bonded wafer shown in Figure 2. Figure 4 is a schematic perspective view showing another example of the bonded wafer shown in Figure 2.

[0018] (Bonded wafers) The cutting apparatus 1 shown in Figure 1 according to Embodiment 1 is a processing apparatus that holds the bonded wafer 200, which is the workpiece shown in Figure 2 etc., on a holding table 10 and cuts the bonded wafer 200. The bonded wafer 200 to be processed by the cutting apparatus 1 shown in Figure 1 is constructed by stacking a workpiece wafer 202 on a wafer 201 and bonding the workpiece wafer 202 to the wafer 201, as shown in Figure 2.

[0019] In the example shown in Figure 2, the wafer 201 is made of glass of a uniform thickness and is formed in a disc shape. Although the wafer 201 is made of glass in the example shown in Figure 2, in the present invention it may be made of silicon or the like.

[0020] The wafer to be processed 202 is a disc-shaped semiconductor wafer or optical device wafer, etc., with a substrate 203 made of silicon, LT (lithium tantalate: LiTaO3), LN (lithium niobate: LiNbO3), sapphire, GaN (gallium nitride), etc. However, in this invention, the material constituting the substrate 203 of the wafer to be processed 202 is not limited to silicon, LT, LN, sapphire, or GaN.

[0021] The wafer 202 to be processed has multiple intersecting division lines 205 set on its surface 204, and a device 206 is formed in the region demarcated by the division lines 205. The device 206 is, for example, an integrated circuit such as an IC (Integrated Circuit) or LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor), or various types of memory (semiconductor memory device).

[0022] In Embodiment 1, the outer diameter of the wafer 202 to be processed is equal to the outer diameter of the wafer 201. In Embodiment 1, the substrate 203 of the wafer 202 to be processed is made of silicon. In Embodiment 1, the wafer 202 to be processed has a notch 207 formed on its outer edge that indicates the crystal orientation of the substrate 203.

[0023] In Embodiment 1, the bonded wafer 200 is constructed by bonding the surface 204 of the wafer to be processed 202 to the wafer 201 via a temporary adhesive. However, in the present invention, the wafer may be constructed by directly bonding the surface 204 of the wafer to be processed 202 to the wafer 201.

[0024] Since the bonded wafer 200 is constructed by bonding the surface 204 of the wafer to be processed 202 to wafer 201, an unbonded region 210 may occur between these wafers 201 and 202, as shown in Figure 3. The unbonded region 210 is a region between wafers 201 and 202 that is not bonded to each other, and in Embodiment 1, it is an air bubble between wafers 201 and 202.

[0025] Furthermore, as shown in Figure 4, the bonded wafer 200 may have a wafer 201 made of silicon and a substrate 203 of the wafer to be processed 202 made of LT. Note that the wafer to be processed 202 shown in Figure 4 may or may not have a device formed on its surface 204. Also, the wafer to be processed 202 shown in Figure 4 has an orientation flat 208 formed on its outer edge indicating the crystal orientation of the substrate 203.

[0026] (cutting equipment) Next, the cutting apparatus 1 will be described. In Embodiment 1, the cutting apparatus 1 is a processing apparatus that holds a wafer 202 to be processed in a holding table 10 and cuts it with a cutting blade 21. As shown in Figure 1, the cutting apparatus 1 comprises a holding table 10 including a holding surface 11 for holding the wafer 202 to be processed, a cutting unit 20 having a spindle 23 on which a cutting blade 21 for cutting the bonded wafer 200 held in the holding table 10 is mounted, an imaging unit 30 for imaging the bonded wafer 200 held in the holding table 10, and a control unit 50 which is a controller.

[0027] Furthermore, the cutting apparatus 1 includes a moving unit 40 that moves the holding table 10 and the cutting unit 20 relative to each other. The moving unit 40 includes at least a cutting feed unit 41 that feeds the holding table 10 in the X-axis direction parallel to the horizontal direction, an indexing feed unit 42 that feeds the cutting unit 20 in the Y-axis direction parallel to the horizontal direction and perpendicular to the X-axis direction, a cutting feed unit 43 that feeds the cutting unit 20 in the Z-axis direction parallel to the vertical direction perpendicular to both the X-axis and Y-axis directions, and a rotational moving unit 44 that rotates the holding table 10 around a rotation axis 12 parallel to the Z-axis direction and passing through the center of the holding surface 11. In other words, the moving unit 40 moves the holding table 10 and the cutting unit 20 relative to each other in the X-axis direction, Y-axis direction, Z-axis direction and around the rotation axis 12.

[0028] The cutting feed unit 41 moves the holding table 10 and the rotational movement unit 44 in the X-axis direction, which is the cutting feed direction, thereby moving the holding table 10 relative to the cutting unit 20 in the X-axis direction. The indexing feed unit 42 moves the cutting unit 20 in the Y-axis direction, which is the indexing feed direction, thereby moving the holding table 10 relative to the cutting unit 20 in the Y-axis direction.

[0029] The cutting feed unit 43 moves the cutting unit 20 in the Z-axis direction, which is the cutting feed direction, thereby moving the holding table 10 relative to the cutting unit 20 in the Z-axis direction. The rotational movement unit 44 is supported by the cutting feed unit 41 and supports the holding table 10, and is arranged to move together with the holding table 10 in the X-axis direction. The rotational movement unit 44 rotates the holding table 10 around a rotation axis 12 parallel to the Z-axis direction.

[0030] The cutting feed unit 41, indexing feed unit 42, and depth-of-cut feed unit 43 are equipped with a well-known ball screw rotatably mounted around its axis, a well-known motor for rotating the ball screw around its axis, and a well-known guide rail for supporting the holding table 10 or cutting unit 20 so that it can move in the X-axis, Y-axis, or Z-axis direction. The rotary movement unit 44 is equipped with a motor for rotating the holding table 10 around the rotation axis 12.

[0031] The holding table 10 is disc-shaped, and a flat holding surface 11 along the horizontal direction for holding the bonded wafer 200 is formed from a porous material such as porous ceramic. The holding table 10 is also provided by a cutting feed unit 41 so as to be movable in the X-axis direction across the processing area below the cutting unit 20 and the loading / unloading area where the bonded wafer 200 is loaded and unloaded, separated from below the cutting unit 20. The holding table 10 is provided by a rotational movement unit 44 so as to be rotatable around a rotation axis 12 parallel to the Z-axis direction. For this reason, the holding table 10 is rotatable around the rotation axis 12.

[0032] The holding table 10 has a holding surface 11 connected to a vacuum suction source (not shown), and the bonded wafer 200 placed on the holding surface 11 is held in place by suction from the vacuum suction source. In Embodiment 1, the holding table 10 holds the wafer 201 of the bonded wafer 200 to the holding surface 11 by suction.

[0033] The cutting unit 20 is a processing unit in which a cutting blade 21 is mounted on a spindle 23 and cuts a workpiece wafer 202 held on a holding table 10. The cutting unit 20 is provided to move in the Y-axis direction by an indexing feed unit 42 and to move in the Z-axis direction by a cutting feed unit 43 relative to the bonded wafer 200 held on the holding table 10. As shown in Figure 1, the cutting unit 20 is provided on a support frame 3 erected from the main body 2 of the apparatus via the indexing feed unit 42 and the cutting feed unit 43. The cutting unit 20 allows the cutting blade 21 to be positioned at any position on the holding surface 11 of the holding table 10 by the indexing feed unit 42 and the cutting feed unit 43.

[0034] The cutting unit 20 includes a cutting blade 21, a spindle housing 22 that is movable in the Y-axis and Z-axis directions by indexing feed unit 42 and depth feed unit 43, a spindle 23 that is rotatable around its axis in the spindle housing 22 and has the cutting blade 21 mounted at its tip, a spindle motor (not shown) that rotates the spindle 23 around its axis, and a cutting fluid supply nozzle 24 that supplies cutting fluid to the cutting blade 21.

[0035] The cutting blade 21 is an extremely thin cutting wheel having a substantially ring shape. The cutting blade 21 is fixed to the tip of the spindle 23. In Embodiment 1, the cutting blade 21 is a so-called hub blade comprising an annular circular base and an annular cutting edge disposed on the outer edge of the circular base for cutting the wafer 202 to be processed. The cutting edge is made up of abrasive grains such as SiC, alumina, diamond, or CBN (Cubic Boron Nitride) and a bond (binding material) that fixes the abrasive grains such as metal or resin, and is formed to a predetermined thickness. In this invention, the cutting blade 21 may also be a so-called washer blade composed only of a cutting edge. The axes of the cutting blade 21 and spindle 23 of the cutting unit 20 are set parallel to the Y-axis direction.

[0036] The imaging unit 30 is fixed to the cutting unit 20 so as to move integrally with the cutting unit 20. The imaging unit 30 is equipped with an image sensor that images the bonded wafer 200 before cutting, which is held on the holding table 10. The image sensor is, for example, a CCD (Charge-Coupled Device) image sensor or a CMOS (Complementary MOS) image sensor, and in Embodiment 1, it receives visible light or infrared light to image the bonded wafer 200. The imaging unit 30 images the bonded wafer 200 held on the holding table 10 to obtain an image and outputs the obtained image to the control unit 50. In Embodiment 1, the image obtained by the imaging unit 30 is a grayscale image in which the brightness of each pixel is defined by multiple gradations (for example, 256 gradations). Also in Embodiment 1, in the image obtained by the imaging unit 30, the brightness of the unbonded area 210 and the area where wafers 201 and 202 are bonded to each other differ significantly.

[0037] Furthermore, the cutting device 1 includes an X-axis position detection unit (not shown) for detecting the position of the holding table 10 in the X-axis direction, a Y-axis position detection unit (not shown) for detecting the position of the cutting unit 20 in the Y-axis direction, a Z-axis position detection unit for detecting the position of the cutting unit 20 in the Z-axis direction, and an angle detection unit for detecting the angle of the holding table 10 around the rotation axis 12. The X-axis position detection unit and the Y-axis position detection unit can be configured with a linear scale parallel to the X-axis direction or the Y-axis direction and a reading head. The Z-axis position detection unit detects the position of the cutting unit 20 in the Z-axis direction using motor pulses. The X-axis position detection unit, the Y-axis position detection unit, and the Z-axis position detection unit output the position of the holding table 10 in the X-axis direction and the position of the lower end of the cutting edge of the cutting unit 20 in the Y-axis direction or the Z-axis direction to the control unit 50. The rotation angle detection unit outputs the angle around the rotation axis 12, which is the detected orientation of the holding table 10, to the control unit 50.

[0038] In Embodiment 1, the X-axis, Y-axis, and Z-axis positions of the holding table 10 and cutting unit 20 of the cutting device 1 are determined based on a predetermined reference position (not shown) (in Embodiment 1, the distance in the X-axis, Y-axis, and Z-axis directions from the reference position). Also in Embodiment 1, the angle around the rotation axis 12 of the holding table 10 is determined by the angle from a predetermined reference position (not shown).

[0039] The control unit 50 controls each component of the cutting device 1 to cause the cutting device 1 to perform processing operations on the bonded wafer 200. The control unit 50 is a computer having an arithmetic processing unit with a microprocessor such as a CPU (central processing unit), a storage device with memory such as ROM (read-only memory) or RAM (random access memory), and an input / output interface device. The arithmetic processing unit of the control unit 50 performs calculations according to the computer program stored in the storage device and outputs control signals for controlling the cutting device 1 to each component of the cutting device 1 via the input / output interface device.

[0040] Furthermore, the cutting device 1 includes a display unit 60, which consists of a liquid crystal display device that displays the status of the machining operation and images, and an input unit 70 used by the operator to register machining conditions, etc. The display unit 60 and the input unit 70 are connected to the control unit 50. The input unit 70 consists of a touch panel or the like provided on the display unit 60.

[0041] Furthermore, as shown in Figure 1, the control unit 50 includes a storage unit 51 and a cutting control unit 52. The storage unit 51 stores the position of the planned cutting line 220 (shown as a dashed line in Figure 3), which is located on the central side of the unbonded region 210 on the outer periphery of the bonded wafer 200 held on the holding surface 11 of the holding table 10 and extends in a straight line. The unbonded region 210 on the outer periphery refers to the unbonded region 210 that extends to the outer edge of the wafer 202 to be processed (hereinafter referred to as reference numeral 211).

[0042] The planned cutting line 220 divides the wafer 202 of the bonded wafer 200 into an outer region 212 that includes the unbonded region 211 and is closer to the center of the planned cutting line 220 and is not included in the unbonded region 211. The position of the planned cutting line 220 is the angle around the rotation axis 12 of the holding table 10 so that the planned cutting line 220 is parallel to the X-axis direction, and the distance of the planned cutting line 220 from the reference point (center in Embodiment 1) of the holding surface 11 of the holding table 10.

[0043] The cutting control unit 52 causes each component of the cutting device 1 to cut along the planned cutting lines 220 stored in the storage unit 51 of the bonded wafer 200 held on the holding surface 11 of the holding table 10. The cutting control unit 52 controls each component of the cutting device 1 to cut the workpiece wafer 202 of the bonded wafer 200 along each planned cutting line 220 based on the position of the planned cutting lines 220 stored in the storage unit 51, thereby dividing the workpiece wafer 202 into regions 212 and 213.

[0044] The functions of the memory unit 51 are realized by the memory device described above. The functions of the cutting control unit 52 are realized by the arithmetic processing unit performing calculations according to the computer program stored in the memory device and outputting control signals for controlling the cutting device 1 to each component of the cutting device 1 via the input / output interface device.

[0045] (Processing method) Next, the processing method according to Embodiment 1 will be described based on the drawings. Figure 5 is a flowchart showing the flow of the processing method according to Embodiment 1. The processing method according to Embodiment 1 is also a method of cutting the bonded wafer 200 with the cutting device 1 with the configuration described above. As shown in Figure 5, the processing method comprises a holding step 101, an unbonded area detection step 102, a cutting line setting step 103, a separation step 104, and a grinding step 105.

[0046] (Holding step) Figure 6 is a schematic cross-sectional view showing the holding step of the processing method shown in Figure 5. The holding step 101 is a step in which the wafer 201 side of the bonded wafer 200 is held by the holding table 10 to expose the wafer 202 to be processed.

[0047] In Embodiment 1, during the holding step 101, the cutting device 1 places the wafer 201 side of the bonded wafer 200 on the holding surface 11 of the holding table 10 located in the loading / unloading area. In Embodiment 1, during the holding step 101, when the cutting device 1 receives a processing start instruction from the operator after the processing conditions have been registered in the control unit 50 by the operator, it uses suction to hold the wafer 201 of the bonded wafer 200 on the holding surface 11 of the holding table 10, as shown in Figure 6, thereby exposing the wafer 201 of the wafer 202 to be processed.

[0048] (Unattached area detection step) Figure 7 is a schematic cross-sectional view showing the unbonded area detection step of the processing method shown in Figure 5. The unbonded area detection step 102 is a step in which the bonding wafer 200 held by the holding table 10 is imaged by the imaging unit 30 and the unbonded area 211 on the outer periphery of the bonding wafer 200 is detected.

[0049] In Embodiment 1, during the unbonded area detection step 102, the cutting device 1 moves the holding table 10 and the cutting unit 20 to the cutting feed unit 41 and the indexing feed unit 42, and as shown in Figure 7, the imaging unit 30 images the bonded wafer 200 on the holding table 10, and the control unit 50 displays the image obtained from the imaging on the display unit 60. In this way, in Embodiment 1, during the unbonded area detection step 102, the image obtained from the imaging unit 30 is displayed on the display unit 60, allowing the operator to detect the unbonded area 211.

[0050] (Step to set the line to be cut) Figure 8 is a schematic plan view showing the state of setting the cutting line in the cutting line setting step of the processing method shown in Figure 5. Figure 9 is a schematic plan view showing the state of setting other cutting lines in the cutting line setting step of the processing method shown in Figure 5.

[0051] The cutting line setting step 103 is a step in which the operator sets a cutting line 220 that separates the detected unbonded region 211 from the center of the wafer 201, and stores the angle around the rotation axis 12 of the holding table 10 for positioning the cutting line 220 parallel to the X-axis direction, and the distance from the reference point (center in Embodiment 1) of the holding surface 11 of the holding table 10 (distance in the Y-axis direction in Embodiment 1). In Embodiment 1, in the cutting line setting step 103, the operator operates the input unit 70 while checking the image of the workpiece wafer 202 of the bonded wafer 200 displayed on the display unit 60 to identify both ends 221,222 of the cutting line 220 that passes through the center of the workpiece wafer 202 beyond the unbonded region 211, and positions the cutting line 220 parallel to the X-axis direction as shown in Figures 8 and 9.

[0052] In Embodiment 1, in the cutting line setting step 103, the operator checks the image of the workpiece wafer 202 of the bonded wafer 200 displayed on the display unit 60 and confirms that the cutting line 220 passes through the center of the workpiece wafer 202 of the bonded wafer 200 beyond the unbonded area 211. Then, the operator operates the input unit 70 to store the position of the confirmed cutting line 220 in the storage unit 51. In Embodiment 1, in the cutting line setting step 103, the positions of the cutting lines 220 that pass through the center beyond each unbonded area 211 are sequentially stored in the storage unit 51 until all positions of the cutting lines 220 that pass through the center beyond the unbonded area 211 are stored in the storage unit 51. In Embodiment 1, in the cutting line setting step 103, if the operator determines that there are no unbonded areas 211 extending to the outer edge of the unbonded area 210, the operator operates the input unit or the like to move the holding table 10 to the loading / unloading area, stops the suction holding of the bonded wafer 200 by the holding table 10 in the loading / unloading area, and proceeds to the grinding step 105 without performing the separation step 104.

[0053] (Separation step) Figure 10 is a schematic cross-sectional view showing the separation step of the processing method shown in Figure 5. Figure 11 is a schematic plan view showing the bonded wafer after the separation step of the processing method shown in Figure 5.

[0054] The separation step 104 is a step in which, after performing the cutting line setting step 103, the cutting line 220 is positioned parallel to the X-axis direction, and the workpiece wafer 202 of the bonded wafer 200 is cut along the cutting line 220 with the cutting blade 21 to divide it, thereby forming a dividing groove 230 that separates the region 212 on the outer periphery of the cutting line 220, which includes the unbonded region 211, from the region 213 on the central side of the cutting line 220.

[0055] In Embodiment 1, during the separation step 104, when the cutting device 1 receives a start instruction for the separation step 104 from the operator, the cutting control unit 52 of the control unit 50 reads the position of one planned cutting line 220 stored in the storage unit 51 and positions the read planned cutting line 220 parallel to the X-axis direction. In Embodiment 1, during the separation step 104, as shown in Figure 10, the cutting control unit 52 of the control unit 50 controls the moving unit 40 to move the holding table 10 and the cutting unit 20 relative to each other, and based on the distance of the stored planned cutting line 220 from the reference point (center in Embodiment 1) of the holding surface 11 of the holding table 10, the cutting blade 21 rotated around its axis by the spindle 23 cuts into the wafer 202 until it reaches the wafer 201.

[0056] In the separation step 104, the cutting device 1 cuts the wafer 202 to be processed with the cutting blade 21 along the entire length of the planned cutting line 220. As a result, as shown in Figure 11, a dividing groove 230 is formed in the wafer 202 to be processed, dividing it into region 212 and region 213. In Embodiment 1, in the separation step 104, the cutting device 1 has the cutting control unit 52 of the control unit 50 make the cutting blade 21 cut into each planned cutting line 220, and sequentially forms dividing grooves 230 in each planned cutting line 220. In Embodiment 1, in the separation step 104, the cutting device 1 has the cutting control unit 52 of the control unit 50 make the cutting blade 21 cut into all planned cutting lines 220, and sequentially forms dividing grooves 230 in all planned cutting lines 220.

[0057] In Embodiment 1, in the separation step 104, once the cutting device 1 has formed separation grooves 230 in all the planned cutting lines 220, it moves the holding table 10 to the loading / unloading area and stops the suction holding of the bonded wafers 200 by the holding table 10 in the loading / unloading area.

[0058] (Grinding step) Figure 12 is a schematic side view showing a partial cross-section of the grinding step of the processing method shown in Figure 5. The grinding step 105 is a step in which, after performing the separation step 104, the workpiece wafer 202 of the bonded wafer 200 is ground with a grinding wheel 95 to thin it to a predetermined thickness.

[0059] In Embodiment 1, in grinding step 105, the grinding device 90 holds the wafer 201 of the bonded wafer 200 by suction to the holding surface 92 of the chuck table 91. In Embodiment 1, in grinding step 105, as shown in Figure 12, the grinding device 90 rotates the grinding wheel 94 around its axis with the spindle 93 and rotates the chuck table 91 around its axis, bringing the grinding wheel 95 of the grinding wheel 94 into contact with the workpiece wafer 202 of the bonded wafer 200 and bringing it closer to the chuck table 91 at a predetermined feed rate, thereby grinding the workpiece wafer 202 with the grinding wheel 95.

[0060] In Embodiment 1, in grinding step 105, the grinding device 90 grinds the wafer 202 of the bonded wafer 200 until the thickness of the wafer 202 of the bonded wafer 200 reaches a predetermined thickness. In Embodiment 1, when the grinding device 90 grinds the wafer 202 of the bonded wafer 200, even if the grinding wheel 95 collides with the region 212 including the unbonded region 211, causing the region 212 to detach from the wafer 201, a dividing groove 230 is formed between regions 212 and 213 that divides the wafer 202 of the bonded wafer 202. Therefore, it is possible to suppress the application of force to the region 213 on the central side of the dividing groove 230.

[0061] For this reason, in Embodiment 1, in the grinding step 105, even if the grinding wheel 95 collides with the region 212 including the unbonded region 211 and the region 212 including the unbonded region 211 peels off from the wafer 201, it is possible to suppress cracking of the region 213 on the central side of the dividing groove 230 of the workpiece wafer 202, or the occurrence of cracks in the region 213 on the central side of the dividing groove 230 of the workpiece wafer 202. In Embodiment 1, in the grinding step 105, when the thickness of the workpiece wafer 202 of the bonded wafer 200 reaches a predetermined thickness, the grinding device 90 moves the grinding wheel 94 away from the workpiece wafer 202 of the bonded wafer 200, and the processing method according to Embodiment 1 is terminated.

[0062] As described above, the processing method according to Embodiment 1 involves detecting an unbonded region 211 on the outer periphery of the bonded wafer 200, setting a cutting line 220 that separates the detected unbonded region 211 from the central region 213 of the wafer 202 to be processed, and forming a dividing groove 230 that divides the wafer 202 to be processed along the set cutting line 220.

[0063] For this reason, the processing method according to Embodiment 1 can prevent the peeling from reaching the central region 213 of the wafer 202, even if the region 212 including the unattached region 211 of the wafer 202 is peeled off from the wafer 201 in the grinding step 105.

[0064] As a result, the processing method according to Embodiment 1 has the effect of suppressing damage to the wafer 202 during grinding.

[0065] Furthermore, the cutting apparatus 1 according to Embodiment 1 stores the position of the planned cutting line 220 that separates the unattached region 211 from the central region 213 of the wafer 202 to be processed in the storage unit 51, and forms a dividing groove 230 that divides the wafer 202 to be processed along the stored planned cutting line 220. Therefore, even if region 212 peels off from the wafer 201, it is possible to prevent the peeling from reaching the central region 213 of the wafer 202 beyond the dividing groove 230, thereby suppressing damage to the wafer 202 during grinding.

[0066] [Embodiment 2] A cutting apparatus according to Embodiment 2 will be described based on the drawings. Figure 13 is a perspective view showing an example of the configuration of the cutting apparatus according to Embodiment 2. Note that in Figure 13, the same reference numerals are used for the same parts as in Embodiment 1, and their descriptions are omitted.

[0067] As shown in Figure 13, the cutting apparatus 1 according to Embodiment 2 includes a control unit 50 comprising a detection unit 53 and a setting unit 54. The detection unit 53 detects an unbonded region 211 on the outer periphery of the bonded wafer 200 held on the holding surface 11 of the holding table 10 from an image obtained by the imaging unit 30. The setting unit 54 sets a cutting line 220 for separating the unbonded region 211 detected by the detection unit 53 from the central region 213 of the wafer 202 to be processed, and stores the position of the set cutting line 220 in the storage unit 51.

[0068] The functions of the detection unit 53 and the setting unit 54 are realized by the arithmetic processing unit performing calculations according to the computer program stored in the memory device.

[0069] The processing method according to Embodiment 2 is the same as in Embodiment 1, and includes a holding step 101, an unattached area detection step 102, a cutting line setting step 103, a separation step 104, and a grinding step 105.

[0070] In the holding step 101 of the processing method according to Embodiment 2, similar to Embodiment 1, the cutting apparatus 1 holds the wafer 201 side of the bonded wafer 200 with the holding table 10 to expose the wafer 202 to be processed.

[0071] In the unbonded area detection step 102 of the processing method according to Embodiment 2, similar to Embodiment 1, the cutting apparatus 1 moves the holding table 10 and the cutting unit 20 to the cutting feed unit 41 and the indexing feed unit 42, and the imaging unit 30 images the bonded wafer 200 on the holding table 10. In the unbonded area detection step 102 of the processing method according to Embodiment 2, the cutting apparatus 1's control unit 50 acquires the image obtained by the imaging unit 30.

[0072] In the unattached area detection step 102 of the processing method according to Embodiment 2, the cutting device 1 detects the unattached area 210 from the image captured by the imaging unit 30 using the detection unit 53 of the control unit 50. In Embodiment 2, when detecting the unattached area 210, the detection unit 53 of the control unit 50 performs binarization processing or the like on the image captured by the imaging unit 30 using a predetermined threshold to detect the unattached area 210.

[0073] In the unbonded area detection step 102 of the processing method according to Embodiment 2, the cutting device 1 uses the detection unit 53 of the control unit 50 to detect the unbonded area 211 extending from the unbonded area 210 to the outer edge. In Embodiment 2, if the detection unit 53 determines that there is no unbonded area 211 extending to the outer edge of the unbonded area 210, the holding table 10 is moved to the loading / unloading area, the suction holding of the bonded wafer 200 by the holding table 10 is stopped in the loading / unloading area, and the process proceeds to the grinding step 105 without performing the cutting line setting step 103 and the separation step 104.

[0074] In the cutting line setting step 103 of the processing method according to Embodiment 2, the cutting device 1 sets a cutting line 220 for each unattached area 211 detected by the detection unit 53 in the unattached area detection step 102 using the setting unit 54 of the control unit 50, and stores the position of the set cutting line 220 in the storage unit 51. In the cutting line setting step 103 of the processing method according to Embodiment 2, when setting each cutting line 220, for example, first, the cutting device 1 sets a plurality of cutting lines 220 at different positions on the central side of the unattached area 211 using the setting unit 54 of the control unit 50.

[0075] In the cutting line setting step 103 of the processing method according to Embodiment 2, when setting each cutting line 220, the cutting device 1 has the setting unit 54 of the control unit 50 calculate the area of ​​the region 212 that includes the unattached region 211 on the outer periphery of each set cutting line 220 and select the region 212 with the smallest area. In the cutting line setting step 103 of the processing method according to Embodiment 2, when setting each cutting line 220, the cutting device 1 has the setting unit 54 of the control unit 50 detect the position of the cutting line 220 on the central side of the selected region 212 with the smallest area, and stores the detected position of the cutting line 220 in the storage unit 51.

[0076] In the separation step 104 of the processing method according to Embodiment 2, similar to Embodiment 1, the cutting device 1 cuts the wafer 202 of the bonded wafer 200 along the cutting line 220 whose position is stored in the storage unit 51, thereby forming a dividing groove 230 that divides the wafer 202.

[0077] In the grinding step 105 of the processing method according to Embodiment 2, similar to Embodiment 1, the grinding apparatus 90 thins the workpiece wafer 202 of the bonded wafer 200 to a predetermined thickness.

[0078] The processing method and cutting apparatus 1 according to Embodiment 2, similar to Embodiment 1, detects an unbonded region 211 on the outer periphery of the bonded wafer 200, sets a cutting line 220 that separates the detected unbonded region 211 from the central region 213 of the wafer 202 to be processed, and forms a dividing groove 230 that divides the wafer 202 to be processed along the set cutting line 220. Therefore, even if region 212 peels off from the wafer 201 in grinding step 105, it is possible to prevent the peeling from reaching the central region 213 of the wafer 202 beyond the dividing groove 230, thereby suppressing damage to the wafer 202 during grinding.

[0079] Furthermore, the cutting device 1 according to Embodiment 2 includes a detection unit 53 that detects the unattached area 211 and a setting unit 54 that sets the planned cutting line 220, so that the planned cutting line 220 can be set to the center of the area 212 that includes the unattached area 211, regardless of the operator's skill level.

[0080] Furthermore, the cutting apparatus 1 according to Embodiment 2 includes a detection unit 53 that detects the unattached area 211 and a setting unit 54 that sets the planned cutting line 220, so that the planned cutting line 220 that minimizes the area of ​​the region 212 can be set regardless of the operator's skill level.

[0081] It should be noted that the present invention is not limited to the embodiments described above. That is, it can be implemented with various modifications without departing from the core principles of the present invention. [Explanation of Symbols]

[0082] 1 Cutting equipment 10 Retention Table 11 Holding surface 12 Rotation axes 20 cutting units 21 Cutting blades 23 spindles 30 imaging units 41 Cutting feed unit 42 Indexing feed unit 50 Control Unit (Controller) 51 Storage section 52 Cutting control unit 53 Detection unit 54 Settings Section 95 Grinding Wheel 101 Holding step 102 Unattached Area Detection Step 103 Setting the planned cutting line step 104 Detachment Step 105 Grinding Steps 200 Bonded wafers (workpieces) 201 wafer 202 Wafer to be processed 211 Unattached area 220 Cutting lines 230 Dividing Grooves X Cutting feed direction Y Indexing feed direction

Claims

1. A cutting apparatus comprising: a holding table that includes a holding surface for holding a workpiece and is rotatable about a rotation axis passing through the center of the holding surface; a cutting unit having a spindle on which a cutting blade for cutting the workpiece held by the holding table is mounted; a cutting feed unit for moving the holding table relative to the cutting unit in the cutting feed direction; an indexing feed unit for moving the holding table relative to the cutting unit in an indexing feed direction perpendicular to the cutting feed direction; and an imaging unit for imaging the workpiece held by the holding table, wherein a laminated wafer is formed by stacking wafers on a wafer, and the apparatus comprises: A holding step in which the wafer side of the bonded wafer is held by the holding table to expose the wafer to be processed, An unbonded region detection step involves imaging the bonded wafer held on the holding table with an imaging unit to detect an unbonded region on the outer periphery of the bonded wafer, A cutting line setting step includes setting a cutting line to separate the detected unattached area from the center of the wafer to be processed, and storing the orientation of the holding table to position the cutting line parallel to the cutting feed direction. A processing method comprising: performing the cutting line setting step, positioning the cutting line parallel to the cutting feed direction, cutting the wafer to be processed of the bonded wafer along the cutting line with the cutting blade to divide it and form a dividing groove that separates the outer part including the unbonded area.

2. The processing method according to claim 1, further comprising: after performing the separation step, a grinding step of grinding the wafer to be processed in the bonded wafer with a grinding wheel to thin it to a predetermined thickness.

3. A holding table that includes a holding surface for holding a bonded wafer in which a wafer to be processed is stacked on a wafer, and is rotatable about a rotation axis passing through the center of the holding surface, A cutting unit having a spindle on which a cutting blade for cutting a bonded wafer held in the holding table is mounted, A cutting feed unit that moves the holding table relative to the cutting unit in the cutting feed direction, An indexing feed unit that moves the holding table relative to the cutting unit in an indexing feed direction perpendicular to the cutting feed direction, An imaging unit for imaging the bonded wafer held on the holding table, A cutting apparatus comprising a controller for controlling each component, The controller is, A storage unit that stores the position of a planned cutting line that is located on the holding surface of the holding table, and is located towards the center of the unbonded area on the outer periphery of the bonded wafer, and extends in a straight line, A cutting apparatus characterized by comprising: a cutting control unit that causes the cutting line stored in the storage unit of a bonded wafer held on the holding surface of the holding table to be cut by each component.

4. The controller is, A detection unit detects an unbonded area on the outer periphery of a bonded wafer from an image obtained by the imaging unit from the image of the bonded wafer held on the holding surface of the holding table, A setting unit sets a cutting line for separating the unattached area detected by the detection unit from the center side of the wafer to be processed, and stores the position of the cutting line set in the storage unit. The cutting apparatus according to claim 3, comprising:

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