Wafer processing device

Abstract

Provided is a wafer processing device that can highly accurately and efficiently measure defects occurring at an outer circumferential edge of a wafer through chamfering that uses a grindstone. The wafer processing device chamfers a wafer 40. The wafer processing device comprises: a measurement table 82 that supports the wafer 40 and is configured to be rotatable about a rotation axis; a third sensor 88 that detects the appearance of an outer circumferential edge 42 of the wafer 40; and a shape measurement unit 90 that measures the three-dimensional shape of the outer circumferential edge 42 of the wafer 40 by using a plurality of pieces of imaging data obtained by imaging the outer circumferential edge 42 of the wafer 40 from the radially outer side of the measurement table 82 at different focal positions. The shape measurement unit 90 measures the position of a defect, on the outer circumferential edge 42, as detected by the third sensor 88.

Description

Wafer processing apparatus

[0001] The present disclosure relates to a wafer processing apparatus that processes an outer peripheral edge of a wafer.

[0002] Wafers are used as materials for semiconductor devices, electronic components, and the like. The surface of a wafer is processed by a polishing apparatus. The edge of a surface-processed wafer becomes sharpened due to the surface processing, which can cause cracking and chipping. For this reason, the wafer is subjected to a grinding process called chamfering, in which the edge is ground using a grindstone so as to remove the sharpened portion of the edge. On the other hand, defects such as chipping and cracks may occur on the outer peripheral edge of a chamfered wafer. These defects cause problems in processes after the chamfering process. Therefore, Patent Document 1 discloses an apparatus that uses an electron microscope to detect the appearance of the outer peripheral edge of a wafer from vertically above and obliquely above.

[0003] Japanese Patent Application Laid-Open No. 2007-158099

[0004] An object of the present invention is to provide a wafer processing apparatus capable of highly accurately and efficiently measuring the shape and the like of defects occurring on an outer peripheral edge of a wafer.

[0005] A wafer processing apparatus that solves the above problems chamfers a wafer. The wafer processing apparatus includes: a measurement table that supports the wafer and is configured to be rotatable about a rotation axis; a detection unit that detects an appearance of an outer peripheral edge of the wafer; and a shape measuring device that measures a three-dimensional shape of the outer peripheral edge of the wafer from a plurality of pieces of imaging data obtained by imaging the outer peripheral edge of the wafer from the radially outer side of the measurement table at different focal positions. The shape measuring device measures the position of a defect on the outer peripheral edge detected by the detection unit.

[0006] According to the present disclosure, defects occurring on the outer peripheral edge of a wafer due to chamfering using a grindstone can be measured with high accuracy and efficiently.

[0007] Figure 1 is a plan view showing the schematic configuration of one embodiment of a wafer processing apparatus. Figure 2 is a block diagram showing the schematic configuration of the wafer processing apparatus of Figure 1. Figure 3 is an explanatory diagram showing the schematic configuration of the processing section of Figure 1. Figure 4 is a schematic plan view showing the wafer measurement points in the measurement section of Figure 1, and the arrangement of the shape measurement section and each sensor. Figure 5 is an explanatory diagram of wafer detection by the first and second sensors. Figure 6 is an explanatory diagram of wafer detection by the shape measurement section and the third sensor. Figure 7 is a block diagram showing the schematic configuration of the shape measurement section. Figure 8 is a block diagram showing the schematic configuration of the optical unit. Figure 9 is an explanatory diagram showing the relationship between the imaging range of the optical unit and the outer edge of the wafer. Figure 10 is an explanatory diagram of the appearance of the wafer detected by the third sensor. Figure 11 is a diagram showing the optical unit facing the defect location. Figure 12 is an explanatory diagram of the shape of the outer edge of the wafer. Figure 13(a) is an enlarged plan view to explain an example of size parameters, and Figure 13(b) is an enlarged cross-sectional view to explain an example of size parameters. Figure 14 is a flowchart of the wafer inspection method. Figure 15 shows the positional relationship between the third sensor and the shape measuring unit in a modified example.

[0008] Embodiments and modifications of the wafer processing apparatus 10 of this disclosure will be described below with reference to the attached drawings. The attached drawings are merely illustrative of embodiments of this disclosure and should not be considered as limiting this disclosure. Terms such as "first," "second," and "third" in this disclosure are used simply to distinguish objects and do not rank them.

[0009] (One Embodiment) Hereinafter, one embodiment of the wafer processing apparatus 10 will be described with reference to Figures 1 to 14.

[0010] (Overview of Wafer Processing Apparatus) Figure 1 is a plan view showing the schematic configuration of the wafer processing apparatus 10. In the following description, of the mutually orthogonal XYZ axes shown in the figure, the X-axis and Y-axis directions will be considered as horizontal, and the Z-axis direction will be considered as height (vertical). In the following description, the Z-axis direction may be considered as height.

[0011] As shown in Figure 1, the wafer processing apparatus 10 includes a supply and recovery unit 12, a processing unit 16, a cleaning unit 18, a measuring unit 20 for alignment and measurement, and a transport unit 22. The supply and recovery unit 12 includes a cassette table 32 and a supply and recovery robot 34. A wafer cassette 36 for housing wafers 40 is placed on the cassette table 32. The wafer cassette 36 contains wafers 40 before processing.

[0012] The supply and retrieval unit 12 uses the supply and retrieval robot 34 to supply the wafer 40 before processing from the wafer cassette 36 to the measurement unit 20. The supply and retrieval unit 12 also uses the supply and retrieval robot 34 to store the processed wafer 40 from the measurement unit 20 into the wafer cassette 36.

[0013] The transport unit 22 is configured to transport the wafer 40 to the processing unit 16, the cleaning unit 18, and the measurement unit 20. In one example, the transport unit 22 is configured to transport the wafer 40 to the processing unit 16, the cleaning unit 18, and the measurement unit 20 in the order of measurement unit 20, processing unit 16, cleaning unit 18, and measurement unit 20. In other words, the transport unit 22 is configured to transport the wafer 40 before processing from the measurement unit 20 to the processing unit 16. Next, the transport unit 22 is configured to transport the processed wafer 40 from the processing unit 16 to the cleaning unit 18. Finally, the transport unit 22 is configured to transport the wafer 40 from the cleaning unit 18 to the measurement unit 20.

[0014] The measurement unit 20 measures the wafer 40. The measurement unit 20 is configured to perform measurements to align the center of the wafer 40 with the rotation center of the grinding table 64 that holds the wafer 40 in the processing unit 16. The measurement unit 20 is also configured to measure the state of the wafer 40 after it has been processed by the processing unit 16. The configuration of the measurement unit 20 will be described later.

[0015] The wafer processing apparatus 10 includes two processing sections 16 having the same configuration. In the following description, when the two processing sections 16 are distinguished, they will be referred to as the first processing section 16A and the second processing section 16B.

[0016] The first processing section 16A and the second processing section 16B are arranged in parallel on the surface of the wafer processing apparatus 10. The first processing section 16A and the second processing section 16B are configured to perform grinding of the edges of the wafer 40. The grinding process includes rough grinding and fine grinding. The first processing section 16A and the second processing section 16B include a wafer feeding device 62 and an outer edge grinding device 66. The outer edge grinding device 66 includes a grinding wheel for grinding the outer edge 42 of the wafer 40. The wafer feeding device 62 is configured to move the held wafer 40 relative to the outer edge grinding device 66.

[0017] The wafer feeding device 62 includes a grinding table 64 that holds the wafer 40. In one example, the transport unit 22 transports the wafer 40 from the measuring unit 20 to the first processing unit 16A and the second processing unit 16B. In one example, the transport unit 22 transports the wafer 40 so that the center of the wafer 40 detected by the measuring unit 20 is aligned with the rotation axis of the grinding table 64 of the processing unit 16. The processing unit 16 grinds the outer peripheral edge 42 of the wafer 40 held on the grinding table 64 using an outer peripheral grinding device 66. Then, the transport unit 22 transports the wafer 40 processed in the first processing unit 16A to the cleaning unit 18, and transports the wafer 40 processed in the second processing unit 16B to the cleaning unit 18. By providing two processing units 16 in this way, the processing time for one wafer 40 in the grinding process is shortened.

[0018] The cleaning unit 18 is configured to clean the processed wafer 40. In one example, the cleaning unit 18 includes a spin cleaning device. The cleaning unit 18 includes a cleaning table 72, which rotates the wafer 40 held on the cleaning table 72 and sprays cleaning fluid toward the surface of the wafer 40 to remove dirt adhering to the surface of the wafer 40. The wafer 40 cleaned by the cleaning unit 18 is transported to the measuring unit 20.

[0019] The measuring unit 20 measures the wafer 40 after processing. The measuring unit 20 is configured to measure the diameter of the wafer 40, the thickness of the wafer 40, the shape of the edge of the wafer 40, the roughness of the edge of the wafer 40, and so on.

[0020] The measuring unit 20 includes a measuring table 82, a first sensor 84 for detecting the relative position of the wafer 40 with respect to the measuring table 82, a second sensor 86 for detecting the height of the outer peripheral edge 42 in the height direction intersecting the radial direction, and a third sensor 88 for detecting the appearance of the outer peripheral edge 42. The measuring table 82 is configured to hold the wafer 40 and to be rotatable about a rotation axis. The third sensor 88 functions as a detection unit. The measuring unit 20 also includes a shape measuring unit 90, which is a shape measuring device for measuring the shape of the outer peripheral edge 42 of the chamfered wafer 40.

[0021] (Configuration of the processing section) Figure 2 is a block diagram showing the schematic configuration of the wafer processing apparatus 10. Figure 3 shows the schematic configuration of the processing section 16.

[0022] As shown in Figure 3, the processing unit 16 includes a wafer feeding device 62 and an outer circumference grinding device 66. The wafer feeding device 62 includes a grinding table 64, a table drive unit 102, and a position control unit 104.

[0023] The grinding table 64 has a holding surface 64A for holding the wafer 40. The grinding table 64 is configured to rotate around a rotation axis G1 parallel to the Z-axis direction. The table drive unit 102 is composed of various actuators such as a motor drive mechanism. The table drive unit 102 rotates the grinding table 64 around the rotation axis G1 under the control of the control unit 160. As a result, the wafer 40 held on the grinding table 64 rotates around the rotation axis G1.

[0024] The position control unit 104 is composed of various actuators such as motor drive mechanisms and moving mechanisms such as linear sliders. The actuators and moving mechanisms are provided corresponding to the X, Y, and Z axes. The position control unit 104 moves the grinding table 64 along each of the X, Y, and Z axes under the control of the control unit 160. As a result, the wafer 40 held on the grinding table 64 moves along each of the X, Y, and Z axes.

[0025] The outer circumference grinding device 66 includes grinding wheels 112 and 114. The outer circumference grinding device 66 includes a grinding wheel drive unit 106. The grinding wheel drive unit 106 rotates the grinding wheels 112 and 114. In one example, grinding wheel 112 rough grinds the outer circumference edge 42 of the wafer 40. In another example, grinding wheel 114 fine grinds the outer circumference edge 42 of the wafer 40. The grinding wheels 112 and 114 have grinding grooves on their outer circumference for grinding the outer circumference edge 42 of the wafer 40. The grinding grooves are formed and shaped by a truing wheel (truing wheel) (not shown). The truing wheel deteriorates (wears) due to repeated formation and shaping of the grinding grooves. In one example, grinding wheel 112 has a master groove for shaping the truing wheel.

[0026] (Configuration of the measurement unit) Next, the measurement unit 20 will be described in reference to Figures 4 to 8. The measurement unit 20 measures the processed wafer 40. The measurement unit 20 is configured to measure the diameter of the wafer 40, the thickness of the wafer 40, the shape of the edge of the wafer 40, the roughness of the edge of the wafer 40, etc.

[0027] As shown in Figures 4 to 7, the measuring unit 20 includes a measuring table 82. The measuring table 82 has a holding surface 82A. In one example, the measuring table 82 adsorbs and holds a wafer 40 placed on the holding surface 82A. The measuring table 82 is configured to be rotatable around its rotation axis G2.

[0028] As shown in Figure 7, the measuring unit 20 includes a table drive unit 122. The table drive unit 122 is composed of various actuators, such as a motor drive mechanism. The table drive unit 122 rotates the measuring table 82 in one direction around the rotation axis G2 under the control of the control unit 160. As a result, the wafer 40 held on the holding surface 82A of the measuring table 82 rotates around the rotation axis G2 of the measuring table 82.

[0029] As shown in Figures 4 and 5, the measurement unit 20 includes a first sensor 84. The first sensor 84 is configured to detect the diameter, reference position, center position, and eccentricity of a wafer 40, etc. In one example, the reference position of the wafer 40 is a notch provided on the wafer 40. The notch is a cutout portion provided on a part of the circumferential edge of the outer edge of the wafer 40. In one example, the first sensor 84 is a laser sensor or a laser alignment sensor. As shown in Figure 5, the first sensor 84 includes an emission unit 84A and a light receiving unit 84B. The emission unit 84A and the light receiving unit 84B are arranged facing each other in the Z-axis direction on the radially outside of the measurement table 82. The emission unit 84A is configured to emit a line-shaped detection light extending in the radial direction of the measurement table. The light receiving unit 84B is configured to receive the detection light. The light-emitting unit 84A and the light-receiving unit 84B are positioned such that a portion of the detected light is blocked by the wafer 40 held on the measurement table 82. The light-receiving unit 84B is configured to detect the position of the outer edge 42 of the wafer 40 by the portion that receives the detected light and the portion that receives the detected light but is blocked by the wafer 40. The measurement result of the first sensor 84 is output to the measurement control unit 162 of the control unit 160 shown in Figure 2. The measurement control unit 162 calculates the center position of the wafer 40, the diameter of the wafer 40, the eccentricity of the wafer 40, the depth of the notch of the wafer 40, etc., based on the measurement result of the first sensor 84.

[0030] As shown in Figures 4 and 5, the measurement unit 20 includes a second sensor 86. The second sensor 86 is configured to detect the thickness of the wafer 40, etc. In one example, the second sensor 86 is a distance sensor. As shown in Figure 5, the second sensor 86 includes a first sensor unit 86A and a second sensor unit 86B. The first sensor unit 86A and the second sensor unit 86B are arranged to sandwich the wafer 40 at a predetermined distance apart in the height direction. The first sensor unit 86A and the second sensor unit 86B are arranged to measure the same position in the XY plane. The first sensor unit 86A measures the distance to the surface (top surface) of the wafer 40. The second sensor unit 86B measures the distance to the surface (bottom surface) of the wafer 40. The measurement results of the first sensor unit 86A and the second sensor unit 86B are output to the measurement control unit 162 shown in Figure 2. The measurement control unit 162 calculates the thickness of the wafer 40 and the truar based on the distance between the first sensor unit 86A and the second sensor unit 86B and the measurement results of the first sensor unit 86A and the second sensor unit 86B. Alternatively, the measurement control unit 162 may calculate the thickness of the wafer 40 and the truar based on the measurement results of the second sensor 86.

[0031] Furthermore, the second sensor 86 is configured to detect the height position (or warp) of the outer edge 42 of the wafer 40 in the height direction. In one example, the height position of the outer edge 42 is the center position of the wafer 40 in the height direction at the detection position of the second sensor 86. Note that the height position of the outer edge 42 may be the height position of the bottom surface of the wafer 40, the height position of the top surface of the wafer 40, or the height position of another part of the wafer 40. For example, the measurement control unit 162 calculates the height position of the outer edge 42 of the wafer 40 based on the height of the holding surface 82A of the measurement table 82 and the measurement result of the second sensor 86, for example, the thickness of the wafer 40. The second sensor 86 may be a capacitance sensor, a confocal sensor, a spectroscopic interference laser displacement meter, etc.

[0032] The measurement unit 20 uses the first sensor 84 and the second sensor 86 to measure the thickness of the wafer 40 before processing and to perform pre-alignment. The measurement unit 20 also uses the first sensor 84 and the second sensor 86 to measure the thickness, center position, diameter, etc., of the wafer 40 after processing.

[0033] As shown in Figures 4 and 6, the measurement unit 20 includes a third sensor 88. The third sensor 88 is configured to detect the appearance of the wafer 40. In one example, the third sensor 88 is a camera that images the appearance of the wafer 40. The camera has a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) type image sensor. As shown in Figure 6, the third sensor 88 includes a first imaging unit 88A and a second imaging unit 88B. The first imaging unit 88A images the upper surface of the wafer 40 as the appearance of the wafer 40. The second imaging unit 88B images the lower surface of the wafer 40 as the appearance of the wafer 40. The third sensor 88 includes an illumination unit (not shown). The illumination unit is configured to irradiate the wafer 40 in the area imaged by the first imaging unit 88A and the second imaging unit 88B with suitable light. The imaging data from the first imaging unit 88A and the second imaging unit 88B are output to the shape and roughness analysis unit 164 shown in Figure 2. Based on the imaging data from the third sensor 88, the shape and roughness analysis unit 164 analyzes the roughness of the wafer 40 and the presence or absence of defects 412 (see Figure 10) on the outer edge 42.

[0034] As shown in Figures 4, 6, and 7, the measurement unit 20 includes a shape measurement unit 90. The shape measurement unit 90 is configured to measure the shape of the outer peripheral edge 42 of the wafer 40. As shown in Figure 6, the shape measurement unit 90 is configured to be movable in the radial direction of the measurement table 82. The shape measurement unit 90 is also configured to be movable in the height direction relative to the measurement table 82. The shape measurement unit 90 is configured to measure the shape of the outer peripheral edge 42 of the wafer 40 from the radial outside. Specifically, the shape measurement unit 90 is configured to measure the three-dimensional shape of the outer peripheral edge 42 of the wafer 40 using multiple imaging data obtained by imaging the outer peripheral edge 42 of the wafer 40 from the radial outside with different focal positions.

[0035] Figure 4 shows the detection locations 220 of the wafer 40. The wafer 40 is circular in shape when viewed from the height direction in a plan view. The outer edge 42 of the wafer 40 includes a circular outer portion 42A and a notch portion 42B, which is a cutout portion provided in a part of the circumferential direction of the wafer 40. The measuring unit 20 sets a plurality of detection locations 220 in the circumferential direction with respect to the center O1 of the wafer 40. In one example, the plurality of detection locations 220 are set with respect to the notch portion 42B as the reference point, and are set at equal angular intervals in the circumferential direction from the notch portion 42B. However, the plurality of detection locations 220 may be set so as not to include the notch portion 42B.

[0036] The measurement unit 20 sets multiple detection points 220 at predetermined detection intervals in the circumferential direction. In one example, the detection interval is the central angle with respect to the center O1 of the wafer 40. Figure 4 shows the state in which the center O1 of the wafer 40 coincides with the rotation axis G2 of the measurement table 82. In one example, the measurement unit 20 sets multiple detection points 220 so that the detection intervals are equal, that is, so that the central angle θ11 is equal with respect to the center O1 of the wafer 40. In one example, the central angle θ11 is 45 degrees. Note that the central angle θ11 can be changed arbitrarily, for example, 90 degrees. The measurement unit 20 rotates the wafer 40 so that the appearance of the wafer 40 is detected by the third sensor 88 at the set detection points 220.

[0037] Figure 4 also shows an example of the arrangement of the first sensor 84, second sensor 86, third sensor 88, and shape measuring unit 90 relative to the measuring table 82 (wafer 40), viewed from the height direction (above).

[0038] As shown in Figure 4, the measurement table 82 rotates in one direction indicated by arrow AR1 by the table drive unit 122 shown in Figure 2. Therefore, the wafer 40 held on the measurement table 82 rotates in one direction indicated by arrow AR1.

[0039] As shown in Figure 4, the first sensor 84, the second sensor 86, the third sensor 88, and the shape measuring unit 90 are arranged along the rotational direction of the measuring table 82. The first sensor 84, the third sensor 88, and the second sensor 86 are arranged in the rotational direction in the order described above. In one example, the shape measuring unit 90 is located between the second sensor 86 and the first sensor 84.

[0040] The shape measuring unit 90 and the third sensor 88 may be positioned at a distance of an integer multiple of the detection interval in the circumferential direction of the measuring table 82 with respect to the rotation axis G2, which is the center of the measuring table 82. In one example, the shape measuring unit 90 and the third sensor 88 are positioned at a distance of twice the central angle θ11, which is the detection interval. That is, with respect to the rotation axis G2 of the measuring table 82, the shape measuring unit 90 and the third sensor 88 are positioned so that the central angle θ12 is 90 degrees. Therefore, when one detection point 220 on the wafer 40, for example detection point 220A, is positioned relative to the third sensor 88, another detection point 220B on the wafer 40 is positioned relative to the shape measuring unit 90.

[0041] Furthermore, the third sensor 88 and the shape measuring unit 90 are arranged in the rotational direction in the order described above. Therefore, for each detection point 220 of the wafer 40, the external appearance is detected by the third sensor 88, and then the three-dimensional shape can be measured by the shape measuring unit 90.

[0042] The first sensor 84 and the third sensor 88 are positioned on a straight line passing through the rotation axis G2 of the measurement table 82, with the measurement table 82 in between, when viewed from the height direction (above). In other words, the first sensor 84 and the third sensor 88 are positioned so that their central angle with respect to the rotation axis G2 of the measurement table 82 is 180 degrees.

[0043] In one example, the second sensor 86 is positioned between the third sensor 88 and the shape measuring unit 90 in the rotational direction of the measuring table 82. The second sensor 86 detects the thickness of the wafer 40. In one example, the second sensor 86 is positioned to detect the thickness of the wafer 40 inward from the outer peripheral edge 42, but closer to the outer peripheral edge 42.

[0044] The second sensor 86 and the shape measuring unit 90 are arranged between the third sensor 88 and the first sensor 84 in the rotation direction of the measurement table 82, that is, the rotation direction of the wafer 40. In other words, no sensor or the like is arranged between the first sensor 84 and the third sensor 88 in the rotation direction of the measurement table 82. That is, it can be said that the first sensor 84, the second sensor 86, the third sensor 88, and the shape measuring unit 90 of the measuring unit 20 are arranged biased toward the side where the shape measuring unit 90 is arranged relative to the measurement table 82 in the Y-axis direction. As shown in FIG. 1, the shape measuring unit 90 is arranged on the opposite side of the measurement table 82 from the conveying unit 22.

[0045] (Configuration of Shape Measuring Unit) The configuration of the shape measuring unit 90 will be described. FIG. 7 shows a schematic configuration of the shape measuring unit 90.

[0046] The shape measuring unit 90 includes an optical unit 132, an optical unit driving section 134, and a control section 160. As shown in FIG. 2, the control section 160 includes a measurement control section 162 and a shape / roughness analysis section 164 as functional blocks related to the shape measuring unit 90.

[0047] The optical unit 132 is configured by a white light interference microscope. The optical unit 132 is arranged at a position radially adjacent to the measurement table 82. Specifically, the optical unit 132 is arranged such that its optical axis LA is parallel (including substantially parallel) to the holding surface 82A of the measurement table 82. The optical unit 132 is arranged such that its optical axis LA is parallel (including substantially parallel) to a direction orthogonal to the rotation axis G2 of the measurement table 82. Then, the optical unit 132 images the outer peripheral edge 42 of the wafer 40 held by the measurement table 82 from a position facing the outer peripheral edge 42 in the radial direction of the wafer 40.

[0048] Next, the configuration of the optical unit 132 will be described. FIG. 8 shows the configuration of the optical unit 132. In one example, the optical unit 132 is a white light interference microscope. The optical unit 132 includes a light source unit 136, a beam splitter 138, an interference objective lens 140, an imaging lens 142, and a camera 144. The beam splitter 138, the interference objective lens 140, the imaging lens 142, and the camera 144 are arranged on the optical axis LA of the interference objective lens 140. The interference objective lens 140, the beam splitter 138, the imaging lens 142, and the camera 144 are arranged in this order starting from the surface to be measured of the outer peripheral end 42 of the wafer 40 that is an object to be measured. The light source unit 136 is arranged in a direction intersecting the optical axis LA of the interference objective lens 140, such that the measurement light L1 emitted from the light source unit 136 is incident on the beam splitter 138.

[0049] Under the control of the control unit 160, the light source unit 136 emits measurement light L1 that is white light in the form of a parallel light flux. White light is low-coherence light with low coherence. The light source unit 136 includes a light source such as a light-emitting diode, a semiconductor laser, a halogen lamp, and a high-intensity discharge lamp, and a collector lens that converts the measurement light L1 emitted from the light source into a parallel light flux.

[0050] In one example, the beam splitter 138 is a half mirror. The beam splitter 138 reflects part of the measurement light L1 incident from the light source unit 136 toward the interference objective lens 140. Further, the beam splitter 138 transmits part of combined light L4 (described later) incident from the interference objective lens 140.

[0051] In one example, the interference objective lens 140 is a Michelson-type interference optical system. Therefore, the optical unit 132 of the embodiment can be referred to as a Michelson-type white light interference microscope. Note that the interference optical system is not limited to the Michelson type, and any known interference optical system such as a Mirau type or a Linnik type can be employed.

[0052] The interference objective lens 140 includes an objective lens 146, a beam splitter 148, and a reference mirror 150. The objective lens 146 and the beam splitter 148 are positioned on the optical axis LA of the interference objective lens 140. The objective lens 146 and the beam splitter 148 are positioned in this order toward the surface to be measured at the outer edge 42 of the wafer 40, which is the object to be measured.

[0053] The reference mirror 150 is positioned in a direction intersecting the optical axis LA of the interference objective lens 140, and is where the reference light L2 is incident. In one example, the reference mirror 150 is a reflective mirror and has a reference surface 150A that reflects light. The reference mirror 150 is positioned so that the reference light L2 is incident on the reference surface 150A. It can be said that the reference mirror 150 is positioned so that the reference surface 150A faces the beam splitter 148. The distance between the beam splitter 148 and the reference surface 150A of the reference mirror 150 can be adjusted by an adjustment mechanism (not shown). The adjustment mechanism consists of a ball screw mechanism, an actuator, etc. This allows the optical path length of the reference light L2, i.e., the reference optical path length, to be adjusted.

[0054] The objective lens 146 has a focusing function. The objective lens 146 focuses the incident measurement light L1 onto the surface to be measured through the beam splitter 148. The beam splitter 148 splits a portion of the incident measurement light L1 into reference light L2. In one example, the beam splitter 148 is a half mirror. The beam splitter 148 reflects a portion of the incident measurement light L1 as reference light L2 in a direction intersecting the optical axis LA, and transmits the remaining measurement light L3. The measurement light L3 that has passed through the beam splitter 148 is irradiated onto the surface to be measured. The measurement light L3 is reflected from the surface to be measured and incident on the beam splitter 148.

[0055] The reference light L2 reflected by the beam splitter 148 is reflected by the reference surface 150A and incident on the beam splitter 148. The beam splitter 148 transmits a portion of the measurement light L3 reflected from the surface of the outer edge 42 of the wafer 40, which is the surface to be measured, and reflects a portion of the reference light L2 reflected by the reference surface 150A. This generates a combined light L4 of the measurement light L3 and the reference light L2. This combined light L4 can be described as interference light of the measurement light L3 and the reference light L2. The combined light L4 passes through the objective lens 146 and the beam splitter 138 and is incident on the imaging lens 142.

[0056] The imaging lens 142 forms an image of the incident multiplexed light L4 on the imaging surface of the camera 144. Specifically, the imaging lens 142 forms an image of a point on the focal plane of the objective lens 146 as an image point on the imaging surface of the camera 144.

[0057] The camera 144 includes a CCD or CMOS type image sensor. The camera 144 captures the multiplexed light L4 imaged on the image sensor's imaging surface using an imaging lens 142, and outputs an image signal by signal processing the image signal of the multiplexed light L4 obtained from this capture. The camera 144 is an example of an imaging unit.

[0058] Figure 9 shows the relationship between the imaging range 420 of the optical unit 132 and the outer edge 42 of the wafer 40. The imaging range 420 is shown by a dotted line. The imaging range 420 of the optical unit 132 is set to correspond to the thickness T1 of the wafer 40. In one example, the imaging range 420 of the optical unit 132 is set by the magnification of the interference objective lens 140 shown in Figure 8 and the size of the image sensor of the camera 144 (size of the imaging surface, number of light-receiving elements). In one example, the imaging range 420 of the optical unit 132 is set so that imaging data of the entire outer edge 42 of the wafer 40 can be obtained in one shot in the height direction. If the imaging range 420 in the height direction is too large compared to the thickness T1 of the wafer 40, the measurement accuracy of the three-dimensional shape obtained from the imaging data will be low. On the other hand, if the imaging range 420 in the height direction is smaller than the thickness T1 of the wafer 40, more detailed imaging data can be obtained, but the position of the optical unit 132 must be changed in the height direction, which increases the measurement time.

[0059] The optical unit drive unit 134 is composed of various actuators such as a linear motor or a motor drive mechanism. The optical unit drive unit 134 holds the optical unit 132 so as to be movable in the Y-axis direction, which is the scanning direction. This makes it possible to adjust the relative position of the optical unit 132 in the radial direction (Y-axis direction) of the measurement table 82 with respect to the outer peripheral edge 42 of the wafer 40 which is the object to be measured. Then, under the control of the control unit 160, the optical unit drive unit 134 scans the optical unit 132 in the Y-axis direction, that is, in a direction parallel to the optical axis LA of the optical unit 132. The optical unit drive unit 134 is an example of a relative movement unit.

[0060] Furthermore, the optical unit drive unit 134 holds the optical unit 132 so that it can move not only in the Y-axis direction but also in the Z-axis direction, which is the height direction. The optical unit drive unit 134 may also hold the optical unit 132 so that it can move not only in the Y-axis direction and the Z-axis direction but also in the X-axis direction. This makes it possible to adjust the relative position of the optical unit 132 in the height direction with respect to the outer edge 42 of the wafer 40 which is the object to be measured. In addition, it is possible to take multiple images while moving the optical unit 132 in the Z-axis direction or the X-axis direction. This makes it possible to image a wider range than the limitations of the measurement field of view of the interference objective lens 140.

[0061] The scale 152 is a position detection sensor that detects the position of the optical unit 132 in the Y-axis direction. The scale 152 is, for example, a linear scale. This scale 152 repeatedly detects the position of the optical unit 132 in the Y-axis direction and repeatedly outputs the position detection result to the control unit 160.

[0062] [Functions of the Wafer Processing Apparatus] Figure 2 is a functional block diagram of the control unit 160 in the wafer processing apparatus 10. Figure 2 shows the portion of the control unit 160 related to the processing unit 16 and the measuring unit 20 in the wafer processing apparatus 10. In the following description, functional blocks will sometimes be explicitly described, and sometimes functional blocks will be described collectively as the control unit 160.

[0063] The control unit 160 includes a machining control unit 168 for controlling the machining unit 16. The machining control unit 168 is connected to the table drive unit 102, the position control unit 104, and the grinding wheel drive unit 106 of the machining unit 16.

[0064] The control unit 160 includes a measurement control unit 162 for controlling each part of the measurement unit 20, and a shape / roughness analysis unit 164 for obtaining measurement results of the object to be measured. The measurement control unit 162 is connected to a table drive unit 122, a first sensor 84, a second sensor 86, a third sensor 88, an optical unit drive unit 134, an optical unit 132, and a scale 152. The shape / roughness analysis unit 164 is connected to the camera 144 of the optical unit 132 and the third sensor 88.

[0065] Furthermore, the control unit 160 includes a feedback calculation unit 166 for providing feedback to the processing unit 16 based on the measurement results from the measurement unit 20. The control unit 160 is also connected to an operation unit 172 and an output unit 174. The operation unit 172 includes an input device for receiving operator input to the control unit 160. The input device may be, for example, a touch panel, keyboard, or mouse. A non-contact device such as a sensor may also be used as the input device. The output unit 174 is a device for outputting data such as the execution results of a program and calculation results from the control unit 160. The output unit 174 includes, for example, an operation UI (User Interface) and a monitor (for example, a liquid crystal display) for displaying detection results. The output unit 174 may also include a printer or speaker in addition to, or instead of, the monitor. The operation unit 172 and the output unit 174 may be configured as personal computers or portable terminals such as tablets. In addition to the operation unit 172 and the output unit 174, a portable terminal may also be connected to the control unit 160.

[0066] The control unit 160 performs processing and measurement processing on the wafer 40 by the wafer processing apparatus 10 in response to operation input from the operation unit 172. The control unit 160 includes a processor (e.g., CPU (Central Processing Unit), GPU (Graphics Processing Unit), etc.) that executes various processes, memory (e.g., ROM (Read Only Memory) and RAM (Random Access Memory), etc.) that serves as the processor's workspace, and a storage device (e.g., SSD (Solid State Drive) or HDD (Hard Disk Drive), etc.) for storing various programs and data.

[0067] The control unit 160 functions as a measurement control unit 162, a shape / roughness analysis unit 164, a feedback calculation unit 166, and a machining control unit 168 by executing a program stored on a storage device using a processor.

[0068] The machining control unit 168 controls the table drive unit 122, the position control unit 104, and the grinding wheel drive unit 106 to perform grinding on the wafer 40, that is, to chamfer the outer edge 42 of the wafer 40. The machining control unit 168 also controls the table drive unit 122, the position control unit 104, and the grinding wheel drive unit 106 to perform maintenance on the grinding wheels 112 and 114 shown in Figure 3. The machining control unit 168 also controls the table drive unit 122, the position control unit 104, and the grinding wheel drive unit 106 to perform maintenance on a truar (not shown).

[0069] The measurement control unit 162 controls the table drive unit 122, the first sensor 84, and the second sensor 86 to detect the relative position of the outer edge 42 of the wafer 40 held on the measurement table 82, as well as the diameter, thickness, and height of the wafer 40. Based on the detection results, the measurement control unit 162 sets a plurality of detection points 220. The plurality of detection points 220 are set at predetermined detection intervals in the circumferential direction of the wafer 40, which is the object to be measured.

[0070] The measurement control unit 162 controls the table drive unit 122 to rotate the wafer 40 held on the measurement table 82. For example, the measurement control unit 162 controls the table drive unit 122 so that the detection point 220 is positioned to correspond to the third sensor 88.

[0071] [Visual Inspection by Third Sensor] The measurement control unit 162 controls the table drive unit 122 and the third sensor 88 to detect the appearance of the outer edge 42 of the wafer 40. Specifically, the measurement control unit 162 controls the table drive unit 122 to rotate the measurement table 82 so that the detection point 220 of the wafer 40 is in a position corresponding to the third sensor 88. In one example, the measurement control unit 162 rotates the wafer 40 so that the detection point 220 of the wafer 40 is located on a straight line passing through the center of the imaging range of the third sensor 88 and the rotation axis G2 of the measurement table 82. The measurement control unit 162 controls the table drive unit 122 and the third sensor 88 to obtain imaging data of the outer edge 42 of the wafer 40 taken from the upper surface 201 side of the wafer 40 and imaging data of the outer edge 42 taken from the lower surface 202 side of the wafer 40.

[0072] Figure 4 shows the imaging ranges 402 and 404 by the third sensor 88 as dotted rectangles. The imaging range 402 at detection point 220A and the imaging range 404 at detection point 220C, which is located a distance equal to the detection interval in the rotational direction of the wafer 40 from detection point 220, overlap in part. In other words, the imaging range of the third sensor 88 is configured so that a portion of the imaging range overlaps before and after the wafer 40 is rotated by the measurement table 82. With this imaging range setting, the third sensor 88 can obtain imaging data that captures the entire outer edge 42 of the wafer 40 in the circumferential direction.

[0073] The shape and roughness analysis unit 164 shown in Figure 2 detects the presence or absence of defects such as cracks and chipping on the outer edge 42 of the wafer 40 based on imaging data obtained by the third sensor 88. Figure 10 shows imaging data 410 of a wafer 40 in which a defect 412 has occurred. In one example, a defect 412 on the wafer 40 can be detected as a region with a different brightness from the rest of the wafer. The shape and roughness analysis unit 164 shown in Figure 2 detects a defect 412 on the wafer 40.

[0074] As shown in Figure 10, the shape and roughness analysis unit 164 detects the defect location, which is the position of the defect 412. If the shape and roughness analysis unit 164 detects multiple defects 412, it detects the defect location for each of the multiple defects 412. The defect location can be represented, for example, by central angles θd1 and θd2 with respect to the detection location 220. The control unit 160 stores the defect locations detected by the shape and roughness analysis unit 164 in a storage device.

[0075] [Measurement by the shape measuring unit] The shape measuring unit 90 controls the table drive unit 122, the optical unit drive unit 134, the light source unit 136, and the camera 144 to measure the three-dimensional shape of the outer peripheral edge 42 at the defect location.

[0076] As shown in Figure 11, the measurement control unit 162 of the shape measurement unit 90 controls the table drive unit 122 based on the defect location to face the defect 412 toward the optical unit 132. The measurement control unit 162 then controls the optical unit drive unit 134, the light source unit 136, and the camera 144 to scan the optical unit 132 radially (Y-axis direction) of the wafer 40, while repeatedly imaging the surface of the object to be measured, i.e., the outer edge 42 of the wafer 40, with the camera 144 at regular intervals. This results in obtaining multiple image data with the focal position of the optical unit 132 changed at regular intervals.

[0077] Specifically, the measurement control unit 162 controls the table drive unit 122 to rotate the measurement table 82 so that the defect 412 on the wafer 40 is positioned opposite the optical unit 132. After starting to emit measurement light L1 from the light source unit 136, the measurement control unit 162 controls the optical unit drive unit 134 to scan the optical unit 132 in the radial direction of the wafer 40. Based on the detection result of the Y-axis position of the optical unit 132 by the scale 152, the measurement control unit 162 repeatedly performs imaging of multiplexed light L4 by the camera 144 and outputs the imaging data to the control unit 160 each time the optical unit 132 moves by a certain pitch in the Y-axis direction.

[0078] The shape and roughness analysis unit 164 acquires imaging data output from the camera 144 each time the camera 144 captures multiplexed light L4, and generates three-dimensional shape data of the outer edge 42 of the wafer 40. The shape and roughness analysis unit 164 measures the three-dimensional shape of the outer edge 42, including defects 412, using the three-dimensional shape data.

[0079] Figure 12 shows an example of the cross-sectional shape of the outer peripheral edge 42 without defects 412, and an example of various parameters obtained as measurement results of the outer peripheral edge 42. The wafer 40 has an upper surface 201 and a lower surface 202 opposite to the upper surface 201. The outer peripheral edge 42 of the wafer 40 has an end surface 203 that is substantially perpendicular to the upper surface 201 and the lower surface 202, an upward sloping surface 204 extending from the upper surface 201 to the end surface 203, and a downward sloping surface 205 extending from the lower surface 202 to the end surface 203. The wafer 40 also has an upward curved surface 206 between the upward sloping surface 204 and the end surface 203, and a downward curved surface 207 between the downward sloping surface 205 and the end surface 203.

[0080] The shape and roughness analysis unit 164 shown in Figure 2 uses the three-dimensional shape data obtained by the shape measurement unit 90 to determine the upper intersection point 211 between the extension line of the upper inclined surface 204 and the extension line of the end face 203, and the lower intersection point 212 between the extension line of the lower inclined surface 205 and the extension line of the end face 203. The shape and roughness analysis unit 164 then calculates the distance between the upper intersection point 211 and the upper surface 201 as the height dimension X1 of the upper inclined surface 204, the distance between the upper intersection point 211 and the lower intersection point 212 as the length dimension X3 of the end face 203, and the distance between the lower intersection point 212 and the lower surface 202 as the height dimension X2 of the lower inclined surface 205. The shape and roughness analysis unit 164 calculates the width dimension A1 of the upper inclined surface 204 as the distance from the upper intersection 211 to the upper surface 201 in the radial direction (Y-axis direction), and the width dimension A2 of the lower inclined surface 205 as the distance from the lower intersection 212 to the lower surface 202. The width dimensions A1 and A2 may also be determined from the imaging data obtained by the third sensor 88 (see Figure 10). The shape and roughness analysis unit 164 calculates the inclination angle θ1 of the upper inclined surface 204 with respect to the upper surface 201, and the inclination angle θ2 of the lower inclined surface 205 with respect to the lower surface 202. The shape and roughness analysis unit 164 also calculates the radius R1 of the upper curved surface 206 and the radius R2 of the lower curved surface 207.

[0081] Furthermore, the shape and roughness analysis unit 164 obtains the size and shape of the defect 412 as measurement results of the outer peripheral edge 42 at the defect location. The size includes size parameters that indicate the size of the defect 412. For example, as shown in Figure 13(a), the size parameters include parameters that serve as indicators of the size of the defect 412 in the horizontal direction (X-axis direction and Y-axis direction). The horizontal parameters are, for example, the area, maximum length L, and maximum width W (< maximum length L) of the defect 412 on the surface of the outer peripheral edge 42. Also, as shown in Figure 13(b), the size parameters include parameters that serve as indicators of the size of the defect 412 in the depth direction. For defects 412 formed above the optical axis LA, the depth direction is, for example, the normal direction of the upper inclined surface 204. For defects 412 formed below the optical axis LA, the depth direction is, for example, the normal direction of the lower inclined surface 205. The parameter in the depth direction is, for example, the maximum depth D of the defect 412.

[0082] The shape includes shape parameters that describe the shape of the defect 412. For example, the shape parameters include parameters that indicate the shape of the defect 412 in the horizontal direction (X-axis and Y-axis direction). These parameters are, for example, the ratio of the maximum length L to the maximum width W. The shape also includes parameters that indicate the shape of the defect 412 in the depth direction. These parameters are, for example, the ratio of the maximum length L to the maximum depth D.

[0083] The determination unit 170 determines whether the wafer 40 is good or bad based on the three-dimensional shape of the defect 412, that is, the size and shape of the defect 412. In one example of determining whether the wafer 40 is good or bad, the determination unit 170 stores tolerance values ​​for various parameters related to the size and shape of the defect 412 in a predetermined storage area. The determination unit 170 determines the wafer 40 is "good" when all of the parameters of the defect 412 are below the tolerance value. The determination unit 170 determines the wafer 40 is "bad" when at least one of the parameters of the defect 412 is greater than the tolerance value.

[0084] In another example of determining the quality of wafer 40, the determination unit 170 determines the shape of the defect 412 based on shape parameters, and then determines the quality of wafer 40 using an acceptable value for the size parameter corresponding to the determination result. Specifically, the determination unit 170 determines the shape of the defect 412 (e.g., chipping or cracking) based on shape parameters. The determination unit 170 stores an acceptable value for the size parameter for each shape of defect 412 in a predetermined storage area and selects an acceptable value according to the determination result. For example, if the determination unit 170 determines that the shape of the defect 412 is chipping, it selects an acceptable value for chipping determination. Then, the determination unit 170 determines the quality of wafer 40 based on the result of comparing the selected acceptable value with the size parameter obtained by measurement.

[0085] Regarding the quality determination of the wafers 40, the wafer processing apparatus 10 is configured so that the types of parameters used for various determinations and the allowable values ​​for each parameter can be arbitrarily set by the operator's operation of the operation unit 172. The control unit 160 outputs the result of the quality determination of the wafers 40 by the determination unit 170 to the output unit 174. The wafer processing apparatus 10 may also be configured to exclude wafers 40 that are determined to be "not good" from the processing process.

[0086] Incidentally, the aforementioned defects 412 are often caused by deterioration of the grinding wheel, such as wear and clogging. As the deterioration of the grinding wheel progresses, the defects 412 tend to become larger, and the proportion of wafers 40 that are judged as "failure" in the quality judgment of the wafers 40 increases.

[0087] Conventionally, a quantity-based management system was in place where maintenance of the grinding wheel was performed when the number of wafers 40 ground by the grinding wheel reached a predetermined number. This maintenance of the grinding wheel included shaping the grinding grooves with a tool (not shown) and replacing the grinding wheel itself. However, when grinding wheels are maintained uniformly based on quantity management, regardless of the actual deterioration of the grinding wheel, grinding wheels that are less deteriorated may end up being the ones targeted for maintenance.

[0088] Therefore, the determination unit 170 determines the condition of the grinding wheels 112 and 114, that is, whether or not maintenance of the grinding wheels 112 and 114 is necessary, based on the result of the quality determination of the wafer 40.

[0089] In an example of determining the state of the grinding wheels 112 and 114, the determination unit 170 determines the state of the grinding wheels 112 and 114 based on the size of the defect 412. Specifically, the determination unit 170 stores determination values ​​for each of the various parameters related to the size of the defect 412 in a predetermined storage area. The determination values ​​for each parameter are greater than their respective allowable values. When all of the various parameters related to the size of the defect 412 are less than or equal to the determination values, the determination unit 170 determines that maintenance of the grinding wheels 112 and 114 is "unnecessary". On the other hand, when at least one of the various parameters related to the size of the defect 412 is greater than the determination value, the determination unit 170 determines that maintenance of the grinding wheels 112 and 114 is "necessary". In other words, the determination unit 170 determines that maintenance of the grinding wheels 112 and 114 is necessary when a defect 412 occurs that deviates significantly from the allowable range in size.

[0090] In another example of determining the state of the grinding wheels 112 and 114, the determination unit 170 determines the state of the grinding wheels 112 and 114 based on the frequency of defect 412 occurrence. Specifically, the determination unit 170 records defect information in a predetermined area of ​​the storage device, for example, whether or not a defect 412 was detected for each of a predetermined number of wafers 40 in the most recent period. The determination unit 170 resets the defect information in conjunction with maintenance of the grinding wheels 112 and 114. After the reset, the determination unit 170 records the detection results of a predetermined number of wafers 40 as defect information and updates the defect information based on the detection results of new wafers 40. Based on the defect information, the determination unit 170 calculates the defect frequency, which is the percentage of wafers 40 in which a defect 412 was detected. The determination unit 170 stores in a predetermined memory area the determination frequency at which maintenance of the grinding wheels 112 and 114 is deemed necessary. When the defect frequency is less than or equal to the determination frequency, it determines that maintenance of the grinding wheels 112 and 114 is "unnecessary". On the other hand, when the defect frequency is greater than the determination frequency, the determination unit 170 determines that maintenance of the grinding wheels 112 and 114 is "necessary". In other words, the determination unit 170 determines that maintenance of the grinding wheels 112 and 114 is necessary when the frequency of defect 412 occurrences increases.

[0091] In another example of determining the state of the grinding wheels 112 and 114, the determination unit 170 determines the state of the grinding wheels 112 and 114 based on defect measurement information, which associates the measurement results of defects 412 with the defect information described above.

[0092] Specifically, the determination unit 170 calculates an average value for each of the various parameters related to the size and shape of the defect 412 based on the defect measurement information. The determination unit 170 stores in a predetermined memory area an average determination value for each of the average values ​​of the various parameters, which is the value at which maintenance of the grinding wheels 112 and 114 is determined to be necessary. This average determination value is smaller than the above-mentioned tolerance value. The determination unit 170 determines that maintenance of the grinding wheels 112 and 114 is "unnecessary" when all of the average values ​​of the various parameters are less than or equal to the average determination value. On the other hand, the determination unit 170 determines that maintenance of the grinding wheels 112 and 114 is "necessary" when at least one of the average values ​​of the various parameters is greater than the average determination value. In other words, even if a defect 412 within the tolerance range occurs, the determination unit 170 determines that maintenance of the grinding wheels 112 and 114 is necessary when the defect 412 becomes larger.

[0093] Regarding the condition determination of the grinding wheels 112 and 114, the wafer processing apparatus 10 is configured so that the types of parameters used for various determinations and the determination values ​​for each parameter can be arbitrarily set by the operator's operation of the operation unit 172. When the determination unit 170 determines that maintenance of the grinding wheels 112 and 114 is "required", the control unit 160 outputs to the output unit 174 that maintenance of the grinding wheels 112 and 114 is required.

[0094] Referring to Figure 14, a wafer inspection method using the wafer processing apparatus 10 will be described. As shown in Figure 14, the control unit 160 performs wafer detection (step S21) to detect the wafer 40 using the first sensor 84 and the second sensor 86, and appearance detection (step S22) to detect the appearance of the outer peripheral edge 42 of the wafer 40 using the third sensor 88.

[0095] In wafer detection (step S21), the control unit 160 uses the first sensor 84 and the second sensor 86 to obtain the thickness of the wafer 40, the relative position of the outer edge 42 of the wafer 40 in the radial direction, and the height of the outer edge 42 of the wafer 40 in the height direction. The control unit 160 also sets up a plurality of detection locations 220.

[0096] In appearance detection (step S22), the control unit 160 uses the third sensor 88 to detect the appearance of the outer edge 42 of the wafer 40 at the detection location 220. If a defect 412 is detected in appearance detection (step S22), the control unit 160 performs shape measurement (step S23).

[0097] In the shape measurement (step S23), the control unit 160 uses the shape measurement unit 90 to measure the three-dimensional shape of the outer edge 42 of the wafer 40 at the defect location. The control unit 160 also determines the quality of the wafer 40 and the condition of the grinding wheels 112 and 114 based on the measurement results. The shape measurement (step S23) may be performed after the visual detection (step S22) has been completed for all detection locations 220, or it may be performed while the measurement table 82 is being rotated toward the undetected detection locations 220.

[0098] In shape measurement (step S23), the control unit 160 adjusts the position of the shape measuring unit 90 in the radial direction based on the relative position of the wafer 40 with respect to the measurement table 82 and the defect location. More specifically, the control unit 160 adjusts the position of the optical unit 132 with respect to the outer peripheral edge 42 of the wafer 40 in the radial direction based on the relative position of the wafer 40 at the defect location with respect to the measurement table 82. The control unit 160 also adjusts the position of the shape measuring unit 90 in the height direction based on the defect location and the height of the outer peripheral edge 42 at the defect location. More specifically, the control unit 160 adjusts the position of the optical unit 132 with respect to the outer peripheral edge 42 of the wafer 40 in the height direction based on the height of the wafer 40 at the defect location.

[0099] As described above, the shape measuring unit 90 obtains multiple imaging data each time the optical unit 132, which includes an interference optical system, changes the focal position relative to the surface of the outer edge 42 of the wafer 40 by a certain pitch in the radial direction of the wafer 40. For this reason, the optical unit 132 has a shallow depth of field and a short focal length.

[0100] When a wafer 40 is transported to the measurement table 82 by the transport unit 22, the center of the wafer 40 may not coincide with the rotation axis G2 of the measurement table 82. In this case, the distance between the outer edge 42 of the wafer 40 and the measurement table 82 in the radial direction of the measurement table 82 changes due to the rotational movement of the measurement table 82 and the wafer 40. For this reason, before rotating the wafer 40, it is necessary to move the optical unit 132 away from the measurement table 82 to a position where it does not interfere with the wafer 40. The time required for such movement of the optical unit 132 increases the time required for measurement at the defect location and affects the throughput of the wafer processing apparatus 10.

[0101] The shape measuring unit 90 needs to move the optical unit 132 to a position where the wafer 40 can be imaged before starting to measure the location of defects. One possible method for moving the optical unit 132 is to use the image data of the defect location obtained by the optical unit 132. However, this method takes time to acquire the image data and to determine whether or not the surface of the outer edge 42 of the wafer 40 is being imaged, so the movement speed of the optical unit 132 must be slowed down. For this reason, the method using image data requires a lot of time to move the optical unit 132 to a position where the wafer 40 can be imaged. Furthermore, if multiple defects 412 are detected, the movement of the optical unit 132 using image data is required for each defect location. As a result, the method using image data takes a long time to measure at the defect location.

[0102] In contrast, the control unit 160 (shape measuring unit 90) of this embodiment adjusts the position of the optical unit 132 in the radial direction based on the relative position of the outer peripheral edge 42 of the wafer 40 with respect to the measuring table 82, which is obtained by the first sensor 84 during wafer detection (step S21). This allows the movement speed of the optical unit 132 to be increased. Furthermore, the optical unit 132 can be easily moved to a position where the wafer 40 can be imaged. Consequently, the time required to move the optical unit 132 to a position where the wafer 40 can be imaged is shortened. In this way, the wafer processing apparatus 10 of this embodiment can improve the efficiency of measurement at defect locations.

[0103] Furthermore, in this embodiment, the control unit 160 adjusts the position of the optical unit 132 in the radial direction based on the relative position of the outer peripheral edge 42 at the defect location while the measuring table 82 and wafer 40 are rotated by the table drive unit 122. In other words, there is a period in which the rotation of the measuring table 82 and the adjustment of the position of the optical unit 132 in the radial direction are performed in parallel. Therefore, the time required to start measurement is shortened compared to the case where the relative position of the optical unit 132 is adjusted after the optical unit 132 is positioned facing the defect location. In this way, the wafer processing apparatus 10 of this embodiment can improve the efficiency of measuring the wafer 40. Furthermore, the time required to measure at one defect location can be shortened, and the throughput of the wafer processing apparatus 10 can be improved.

[0104] The outer edge 42 of the wafer 40 may move in the height direction due to warping or undulation of the wafer 40. Furthermore, the height position of the outer edge 42 of the wafer 40 may differ in the circumferential direction of the wafer 40 due to warping or undulation. In such cases, a portion of the wafer 40 may fall outside the imaging range of the optical unit 132 in the height direction, making measurement impossible or requiring adjustment of the height position of the optical unit 132 after measurement has started. This can increase the time required for measurement at defect locations.

[0105] In this embodiment, the control unit 160 adjusts the position of the optical unit 132 in the height direction based on the height position of the wafer 40 obtained by the second sensor 86 during wafer detection (step S21), specifically the height position of the outer edge 42 at the defect location. This prevents the outer edge 42 of the wafer 40 from moving out of the imaging range of the optical unit 132. Furthermore, the height position of the optical unit 132 does not need to be adjusted after measurement of the outer edge 42 has started. This reduces the time required for measurement at the defect location, thus improving the efficiency of measurement at the defect location. This also improves the throughput of the wafer processing apparatus 10.

[0106] Furthermore, in this embodiment, the control unit 160 adjusts the position of the optical unit 132 based on the height position of the outer edge 42 at the defect location while the table drive unit 122 rotates the measurement table 82 and the wafer 40. In other words, there is a period in which the rotation of the measurement table 82 and the adjustment of the position of the optical unit 132 in the height direction are performed in parallel. The height position of the optical unit 132 is adjusted so that the outer edge 42 of the wafer 40 is within the imaging range of the optical unit 132 in the height direction. Therefore, the time required to start measurement is shortened compared to when the height position of the optical unit 132 is adjusted after the defect location is facing the optical unit 132. As a result, the time required for measurement at the defect location can be shortened, that is, the efficiency of measurement at the defect location can be improved. And the throughput of the wafer processing apparatus 10 can be improved.

[0107] (Operation and Effects of the Embodiment) The operation and effects of this embodiment will now be described. (1) The wafer processing apparatus 10 chamfers the wafer 40. The wafer processing apparatus 10 includes a measuring table 82 that supports the wafer 40 and is configured to rotate around a rotation axis, a third sensor 88 which is a detection unit that detects the appearance of the outer peripheral edge 42 of the wafer 40, and a shape measuring unit 90 which measures the three-dimensional shape of the outer peripheral edge 42 of the wafer 40 using a plurality of imaging data obtained by imaging the outer peripheral edge 42 of the wafer 40 from the radially outside with different focal positions. The shape measuring unit 90 measures the position of defects 412 on the outer peripheral edge 42 detected by the third sensor 88.

[0108] With this configuration, the shape measuring unit 90 measures the outer peripheral edge 42 of the wafer 40 from the radial outside, thereby enabling the measurement of both defects 412 occurring on the upper surface 201 side and defects 412 occurring on the lower surface 202 side of the outer peripheral edge 42. Furthermore, the measurement position by the shape measuring unit 90 is limited to the position of the defect 412 detected by the third sensor 88. As a result, the time required for measurement by the shape measuring unit 90 can be shortened, allowing for efficient measurement of defects 412 occurring on the outer peripheral edge 42 of the wafer 40.

[0109] (2) The shape measuring unit 90 is configured to measure the three-dimensional shape of the defect 412. With this configuration, the shape of the defect 412 can be determined with high precision. (3) The wafer processing apparatus 10 includes a determination unit 170 configured to determine whether the wafer 40 is good or bad based on the three-dimensional shape of the defect 412. With this configuration, since the quality of the wafer 40 is determined based on the three-dimensional shape of the defect 412, the accuracy of the quality determination of the wafer 40 can be improved.

[0110] (4) The determination unit 170 is configured to perform a good or bad determination of the wafer 40 based on the size of the defect 412. With this configuration, wafers 40 having a defect 412 of an unacceptable size can be determined to be "bad".

[0111] (5) The determination unit 170 is configured to perform a quality determination of the wafer 40 based on the shape of the defect 412. With this configuration, even if the size of the defect 412 is within an acceptable range, the quality determination of the wafer 40 can be performed according to the shape of the defect 412.

[0112] (6) The determination unit 170 is configured to determine the state of the grinding wheels 112 and 114 that chamfer the wafer 40 based on the result of the quality determination of the wafer 40. With this configuration, the state of the grinding wheels 112 and 114 can be determined based on the actual processing state of the wafer 40 by the grinding wheels 112 and 114. As a result, maintenance of the grinding wheels 112 and 114 can be performed at an appropriate time.

[0113] (7) The third sensor 88 and the shape measuring unit 90 are arranged in order in the rotational direction of the measurement table 82. That is, the shape measuring unit 90 is located downstream of the third sensor 88 in the rotational direction of the measurement table 82. With this configuration, measurements by the shape measuring unit 90 can be performed while the measurement table 82 is rotating toward an undetected detection point 220. As a result, for wafers 40 that are judged as "fail" by the wafer quality judgment, the detection of appearance by the third sensor 88 and measurement by the shape measuring unit 90 can be minimized, and maintenance of the grinding wheels 112 and 114 can be performed early if necessary.

[0114] (8) The first sensor 84 detects the relative position of the wafer 40 with respect to the measurement table 82. The control unit 160 adjusts the position of the radial shape measuring unit 90 based on the relative position. In the wafer processing apparatus 10 of this embodiment, the time required to move the optical unit 132 to a position where the wafer 40 can be imaged is short. In this way, the wafer processing apparatus 10 of this embodiment can improve the efficiency of measurement at defect locations.

[0115] (9) The second sensor 86 detects the height position of the outer peripheral edge 42 in the height direction. The shape measuring unit 90 is provided so as to be movable in the height direction, and the control unit 160 adjusts the position of the shape measuring unit 90 in the height direction based on the height position detected by the second sensor 86. The height position of the optical unit 132 can be adjusted so that the outer peripheral edge 42, which moves in the height direction due to warping or undulation in the wafer 40, is within the imaging range of the optical unit 132. Therefore, compared to the case where the height position of the optical unit 132 is adjusted after it is positioned facing the optical unit 132, the time required to start measurement is shortened, and the efficiency of measurement at defect locations can be improved.

[0116] (10) The control unit 160 adjusts the position of the radial shape measuring unit 90 while the wafer 40 is rotating. This shortens the time required to start measurement compared to the case where the optical unit 132 is positioned opposite the outer edge 42 at the defect location and then the relative position of the optical unit 132 is adjusted. In this way, the wafer processing apparatus 10 of this embodiment can improve the efficiency of measurement at the defect location.

[0117] (11) The control unit 160 adjusts the position of the shape measuring unit 90 in the height direction while the wafer 40 is rotated. As a result, the time required to start measurement is shortened compared to the case in which the height position of the optical unit 132 is adjusted after the optical unit 132 is positioned facing the outer edge 42 at the defect location. As a result, the time required for measurement at the defect location can be shortened, that is, the efficiency of measurement at the defect location can be improved.

[0118] (12) The measuring table 82 rotates in one direction by the table drive unit 122. In a mechanical mechanism, changing the rotation direction of the measuring table 82 can cause backlash. Backlash in the measuring table 82 causes a discrepancy between the desired measurement position and the actual measurement position. In contrast, in the measuring unit 20 of the wafer processing apparatus 10 of this embodiment, the wafer 40 held on the measuring table 82 rotates in one direction. As a result, the position of the shape measuring unit 90 relative to the defect location can be adjusted with high precision.

[0119] (13) In the measuring unit 20, the first sensor 84 and the third sensor 88 are positioned on a straight line passing through the rotation axis G2 of the measuring table 82, with the measuring table 82 in between, when viewed from the height direction (above). In other words, the first sensor 84 and the third sensor 88 are positioned so that their central angle with respect to the rotation axis G2 of the measuring table 82 is 180 degrees.

[0120] The second sensor 86 and the shape measuring unit 90 are positioned between the third sensor 88 and the first sensor 84 in the rotational direction of the measuring table 82, that is, in the rotational direction of the wafer 40. In other words, no sensors are positioned between the first sensor 84 and the third sensor 88 in the rotational direction of the measuring table 82. Therefore, the wafer 40 can be easily placed on the holding surface 82A of the measuring table 82 from the side where no sensors are positioned.

[0121] (Example of modification) This embodiment can be implemented with the following modifications. This embodiment and the following examples of modifications can be combined with each other to the extent that they do not contradict each other technically.

[0122] In the above embodiment, the diameter and other properties of the wafer 40 before processing were detected by the measuring unit 20. However, a separate unit for measuring the wafer 40 before processing may be provided in addition to the measuring unit 20.

[0123] The positions of the first sensor 84, the second sensor 86, the third sensor 88, and the shape measuring unit 90 may be changed as appropriate. For example, the second sensor 86 may be positioned between the shape measuring unit 90 and the first sensor 84. Also, the shape measuring unit 90 and the third sensor 88 may be positioned in this order in the rotational direction of the measuring table 82.

[0124] In particular, as shown in Figure 15, the shape measuring unit 90 may be positioned so that measurements are taken at a location adjacent to the imaging range 402 of the third sensor 88 in the rotational direction of the measurement table 82. With this configuration, measurements by the shape measuring unit 90 can be performed while the wafer 40 is being rotated to the next detection location 220. As a result, for wafers 40 that are judged as "not good" by the wafer quality judgment, the detection of their appearance by the third sensor 88 and measurements by the shape measuring unit 90 can be minimized, and maintenance of the grinding wheels 112 and 114 can be performed earlier if necessary.

[0125] In the above embodiment, the measurement unit 20 was described using as an example a configuration in which a shape measuring device having a white light interference microscope is provided. However, it is not limited to this, and for example, a shape measuring device having a microscope such as a focus variation type microscope or a laser confocal type microscope may be provided, or a shape measuring device using optical projection measurement may be provided.

[0126] 10...Wafer processing apparatus, 12...Supply and recovery unit, 16...Processing unit, 16A...First processing unit, 16B...Second processing unit, 18...Cleaning unit, 20...Measurement unit, 22...Transportation unit, 32...Cassette table, 34...Supply and recovery robot, 36...Wafer cassette, 40...Wafer, 42...Outer edge, 42A...Outer edge portion, 42B...Notch portion, 62...Wafer feeding device, 64...Grinding table, 64A...Holding surface, 66...Outer edge grinding device, 72...Cleaning table, 82...Measurement table, 82A...Holding surface, 84...First sensor, 84A ...Emitting unit, 84B...Light receiving unit, 86...Second sensor, 86A...First sensor unit, 86B...Second sensor unit, 88...Third sensor, 88A...First imaging unit, 88B...Second imaging unit, 90...Shape measuring unit, 102...Table drive unit, 104...Position control unit, 106...Grinding wheel drive unit, 112...Grinding wheel, 114...Grinding wheel, 122...Table drive unit, 132...Optical unit, 134...Optical unit drive unit, 136...Light source unit, 138...Beam splitter, 140...Interference objective lens, 142...Imaging lens, 144...Camera, 146...Objective lens, 148...Beam splitter, 150...Reference mirror, 150A...Reference surface, 152...Scale, 160...Control unit, 162...Measurement control unit, 164...Shape / roughness analysis unit, 166...Feedback calculation unit, 168...Processing control unit, 170...Determination unit, 172...Operation unit, 174...Output unit, 201...Top surface, 202...Bottom surface, 203...End surface, 204...Upper inclined surface, 205...Lower inclined surface, 206...Upper curved surface, 207...Lower curved surface, 211...Upper intersection, 212...Lower intersection, 220...Detection location, 220A...Detection Location, 220B...Detection location, 220C...Detection location, 402...Imaging range, 404...Imaging range, 410...Imaging data, 412...Defect, 420...Imaging range, θ1...Incline angle, θ2...Incline angle, A1...Width dimension, A2...Width dimension, L1...Measurement light, L2...Reference light, L3...Measurement light, L4...Multiply wave light, LA...Optical axis, R1...Radius, R2...Radius, T1...Thickness, T2...Thickness, UI...Operation, X1...Height dimension, X2...Height dimension, X3...Length dimension, AR1...Arrow, G1, G2...Rotation axis, O1...Center, θ11, θ12...Central angle.

Claims

1. A wafer processing apparatus for chamfering a wafer, comprising: a measuring table that supports the wafer and is configured to rotate about a rotation axis; a detection unit that detects the appearance of the outer edge of the wafer; and a shape measuring device that measures the three-dimensional shape of the outer edge of the wafer using a plurality of imaging data obtained by imaging the outer edge of the wafer from the radially outside of the measuring table at different focal positions, wherein the shape measuring device measures the location of defects in the outer edge detected by the detection unit.

2. The wafer processing apparatus according to claim 1, wherein the shape measuring device measures the three-dimensional shape of the defect.

3. The wafer processing apparatus according to claim 2, further comprising a determination unit that determines whether the wafer is good or bad based on the three-dimensional shape of the defect.

4. The wafer processing apparatus according to claim 3, wherein the determination unit performs a quality determination of the wafer based on the size of the defect.

5. The wafer processing apparatus according to claim 3, wherein the determination unit performs a quality determination of the wafer based on the shape of the defect.

6. The wafer processing apparatus according to claim 4 or 5, wherein the determination unit determines the state of the grinding wheel used to chamfer the wafer based on the result of the quality determination.

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