Wafer processing equipment

Abstract

The present invention provides a wafer processing apparatus capable of measuring the chamfer width in the chamfered portion with high precision and efficiency. [Solution] The wafer processing apparatus performs chamfering on the outer peripheral edge 42 of the wafer 40 using a grinding wheel to form a chamfered slope that slopes from the boundary of the wafer 40 surface toward the outermost edge of the outer peripheral edge 42. The wafer processing apparatus includes a measuring table 82 that supports the surface of the wafer 40, a second sensor 86 that detects the position of the surface of the wafer 40, and a shape measuring unit 90 that measures the three-dimensional shape of the outer peripheral edge 42 of the wafer 40 using multiple imaging data captured from the radially outside the wafer 40, intersecting the height direction of the wafer 40, with different focal positions. Based on the measurement results of the shape measuring unit 90 and the detection results of the second sensor 86, the wafer processing apparatus calculates the chamfer width, which is the radial distance from the boundary to the outermost edge.

Description

Technical Field

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

Background Art

[0002] Wafers are used as raw 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 sharp due to the surface processing, which can cause cracking and chipping. For this reason, wafers are subjected to a grinding process called chamfering to remove sharp portions at the edges. Patent Document 1 discloses a wafer chamfering apparatus that chamfers a wafer.

[0003] The shape and dimensions of the chamfered portion formed by chamfering are specified by standards established by industry associations or requirements of clients. The shape and dimensions of the chamfered portion are important for controlling the film thickness when coating the surface of a wafer after chamfering. In particular, the chamfer width, which is the dimension of the chamfered portion in the radial direction of the wafer, is very important.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of Invention

Problem to be Solved by the Invention

[0005] An object of the present invention is to provide a wafer processing apparatus capable of acquiring the shape and dimensions of a chamfered portion with high accuracy and efficiency.

Means for Solving the Problem

[0006] A wafer processing apparatus that solves the above problems performs chamfering on the outer edge of a wafer using a grinding wheel to form a chamfered slope that slopes from the boundary of the wafer surface toward the outermost edge of the outer edge. The wafer processing apparatus comprises a measuring table that supports the surface of the wafer, a sensor that detects the position of the wafer surface, and a shape measuring device that measures the three-dimensional shape of the outer edge of the wafer using a plurality of imaging data captured from the outside of the wafer in the radial direction intersecting the height direction of the wafer, with different focal positions. Based on the measurement results of the shape measuring device and the detection results of the sensor, the wafer processing apparatus calculates the chamfer width, which is the radial distance from the boundary to the outermost edge. [Effects of the Invention]

[0007] According to this disclosure, the chamfer width of the chamfered portion can be measured with high precision and efficiency. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a plan view showing a schematic configuration of one embodiment of a wafer processing apparatus. [Figure 2] Figure 2 is a block diagram showing the schematic configuration of the wafer processing apparatus shown in Figure 1. [Figure 3] Figure 3 is an explanatory diagram showing the schematic configuration of the processing section in Figure 1. [Figure 4] Figure 4 is a schematic plan view showing the wafer measurement points in the measurement section of Figure 1, as well as the arrangement of the shape measurement section and each sensor. [Figure 5] Figure 5 is an explanatory diagram of wafer detection by the first and second sensors. [Figure 6] Figure 6 is an explanatory diagram of the shape measurement unit and the detection of the wafer by the third sensor. [Figure 7] Figure 7 is a block diagram showing the schematic configuration of the shape measuring unit. [Figure 8] Figure 8 is a block diagram showing the schematic configuration of the optical unit. [Figure 9]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] Figure 10 is an explanatory diagram of the wafer's appearance as detected by the third sensor. [Figure 11] Figure 11 is an explanatory diagram of the shape of the outer edge of the wafer. [Figure 12] Figure 12 shows a flowchart of the wafer inspection method. [Figure 13] Figure 13 shows the imaging range of the optical unit when the amount of deflection is a positive value in the modified example. [Figure 14] Figure 14 shows the imaging range of the optical unit when the amount of deflection is a negative value in the modified example. [Figure 15] Figure 15 shows the imaging range of the optical unit moved to the upper surface of the wafer in the modified example. [Figure 16] Figure 16 shows the imaging range of the optical unit moved to the underside of the wafer in the modified example. [Modes for carrying out the invention]

[0009] 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 solely to distinguish between objects and do not rank them.

[0010] (One embodiment) An embodiment of the wafer processing apparatus 10 will be described below with reference to Figures 1 to 12.

[0011] (Overview of wafer processing equipment) FIG. 1 is a plan view showing the schematic configuration of a wafer processing apparatus 10. In the following description, among the mutually orthogonal XYZ axes shown in the drawing, the X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is the height direction (vertical direction). In the following description, the Z-axis direction may be referred to as the height direction.

[0012] As shown in FIG. 1, the wafer processing apparatus 10 includes a supply and recovery unit 12, a processing unit 16, a cleaning unit 18, a measurement unit 20 that performs 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 that accommodates wafers 40 is placed on the cassette table 32. The wafer cassette 36 accommodates unprocessed wafers 40.

[0013] The supply and recovery unit 12 supplies unprocessed wafers 40 from the wafer cassette 36 to the measurement unit 20 by the supply and recovery robot 34. Further, the supply and recovery unit 12 causes the supply and recovery robot 34 to accommodate processed wafers 40 from the measurement unit 20 into the wafer cassette 36.

[0014] The transport unit 22 is configured to transport wafers 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 wafers 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. That is, the transport unit 22 is configured to transport unprocessed wafers 40 from the measurement unit 20 to the processing unit 16. Next, the transport unit 22 is configured to transport processed wafers 40 from the processing unit 16 to the cleaning unit 18. Then, the transport unit 22 is configured to transport wafers 40 from the cleaning unit 18 to the measurement unit 20.

[0015] 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.

[0016] 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.

[0017] 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 grind 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.

[0018] 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 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.

[0019] 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 onto 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.

[0020] 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.

[0021] 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 edge 42 in the height direction intersecting the radial direction, and a third sensor 88 for detecting the appearance of the outer edge 42. The measuring table 82 is configured to hold the wafer 40 and to be rotatable. 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 edge 42 of the chamfered wafer 40.

[0022] (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 unit 16.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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 (truer) (not shown). The truer 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 truer.

[0027] (Configuration of the measurement unit) Next, the measurement unit 20 will be described in accordance with Figures 4 to 8. The measuring unit 20 measures the processed wafer 40. 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.

[0028] 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.

[0029] 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.

[0030] 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 radially from the measurement table 82. 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.

[0031] 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.

[0032] 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. Furthermore, the second sensor 86 may be fixed in a position that can accommodate wafers 40 of all sizes that are to be processed by the wafer processing apparatus 10. Furthermore, the second sensor 86 may be configured to move radially according to the size of the wafer 40.

[0033] 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.

[0034] 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 top surface of the wafer 40 as the appearance of the wafer 40. The second imaging unit 88B images the bottom 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.

[0035] 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 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 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 edge 42 of the wafer 40 using multiple imaging data obtained by imaging the outer edge 42 of the wafer 40 from the radial outside with different focal positions.

[0036] Figure 4 shows the measurement points 220 on 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 wafer 40 in the circumferential direction. The measuring unit 20 sets a plurality of measurement points 220 in the circumferential direction with respect to the center O1 of the wafer 40. In one example, the plurality of measurement points 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 measurement points 220 may be set so as not to include the notch portion 42B.

[0037] The measurement unit 20 sets multiple measurement points 220 at predetermined measurement intervals in the circumferential direction. In one example, the measurement interval is the central angle with respect to the center O1 of the wafer 40. Figure 4 shows the state where 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 measurement points 220 so that the measurement 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 as to measure the shape of the wafer 40 at each of the set measurement points 220.

[0038] 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 measurement table 82 (wafer 40), viewed from the height direction (above).

[0039] 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.

[0040] 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. In one example, the shape measuring unit 90 is located between the second sensor 86 and the first sensor 84.

[0041] Preferably, the shape measuring unit 90 and the third sensor 88 are positioned at a distance of an integer multiple of the measurement 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 measurement 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 measurement point 220 on the wafer 40, for example, measurement point 220A, is positioned relative to the third sensor 88, another measurement point 220B on the wafer 40 is positioned relative to the shape measuring unit 90.

[0042] Furthermore, it is preferable that the third sensor 88 and the shape measuring unit 90 are arranged in the rotational direction in the order described above. Therefore, for each measurement point 220 of the wafer 40, the external appearance is detected by the third sensor 88, and then the three-dimensional shape is measured by the shape measuring unit 90.

[0043] 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 at a central angle of 180 degrees with respect to the rotation axis G2 of the measurement table 82.

[0044] 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 measurement table 82. In another example, the third sensor 88 is positioned midway between the third sensor 88 and the shape measuring unit 90 in the rotational direction of the measurement table 82. In other words, the second sensor 86 is positioned at a central angle of 45 degrees with respect to the rotation axis G2 of the measurement table 82.

[0045] 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 in the area inside the outer edge 42, but closer to the outer edge 42.

[0046] 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 measurement 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 measurement table 82. That is, the first sensor 84, second sensor 86, third sensor 88, and shape measuring unit 90 of the measurement unit 20 are positioned biased toward the side of the measurement table 82 where the shape measuring unit 90 is located, in the Y-axis direction. As shown in Figure 1, the shape measuring unit 90 is positioned on the opposite side of the measurement table 82 from the transport unit 22.

[0047] (Configuration of the shape measurement unit) The configuration of the shape measuring unit 90 will now be described. Figure 7 shows the schematic configuration of the shape measuring unit 90.

[0048] The shape measuring unit 90 includes an optical unit 132, an optical unit drive unit 134, and a control unit 160. As shown in Figure 2, the control unit 160 includes a measurement control unit 162 and a shape / roughness analysis unit 164 as functional blocks related to the shape measuring unit 90.

[0049] The optical unit 132 consists of a white light interference microscope. The optical unit 132 is positioned radially adjacent to the measurement table 82. Specifically, the optical unit 132 is positioned such that its optical axis LA is parallel (including approximately parallel) to the holding surface 82A of the measurement table 82. The optical unit 132 is positioned such that its optical axis LA is parallel (including approximately parallel) to the direction perpendicular to the rotation axis G2 of the measurement table 82. The optical unit 132 then images the outer edge 42 of the wafer 40 held on the measurement table 82 from a position facing the outer edge 42 of the wafer 40 in the radial direction of the wafer 40.

[0050] Next, the configuration of the optical unit 132 will be described. Figure 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, interference objective lens 140, imaging lens 142, and camera 144 are arranged on the optical axis LA of the interference objective lens 140. The interference objective lens 140, beam splitter 138, imaging lens 142, and camera 144 are arranged in this order from the surface to be measured at the outer edge 42 of the wafer 40 which is the object to be measured. The light source unit 136 is positioned 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.

[0051] The light source unit 136 emits measurement light L1, which is white light in a parallel beam, under the control of the control unit 160. White light is low-coherence light with low coherence. The light source unit 136 includes a light source such as a light-emitting diode, semiconductor laser, halogen lamp, and high-intensity discharge lamp, and a collector lens that converts the measurement light L1 emitted from the light source into a parallel beam.

[0052] In one example, the beam splitter 138 is a half-mirror. The beam splitter 138 reflects a portion of the measurement light L1 incident from the light source 136 toward the interference objective lens 140. The beam splitter 138 also transmits a portion of the combined light L4, described later, incident from the interference objective lens 140.

[0053] The interference objective lens 140 is, in one example, a Michelson-type interference optical system. Therefore, the optical unit 132 of this embodiment can be described as a Michelson-type white-light interference microscope. However, the interference optical system is not limited to the Michelson type; known interference optical systems such as the Mirau type or Linik type can also be used.

[0054] 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.

[0055] 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.

[0056] The objective lens 146 has a light-gathering 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 a 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.

[0057] The reference light L2 reflected by the beam splitter 148 is reflected by the reference plane 150A and incident on the beam splitter 148. The beam splitter 148 transmits a portion of the measurement light L3 reflected from 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 from 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 enters the imaging lens 142.

[0058] 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.

[0059] Camera 144 includes a CCD or CMOS type image sensor. Camera 144 captures the multiplexed light L4 imaged on the image sensor's imaging surface by an imaging lens 142, and outputs an image signal by signal processing of the image signal of the multiplexed light L4 obtained by this capture. Camera 144 is an example of an imaging unit.

[0060] 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 photodetectors). 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.

[0061] 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 that it can move 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 edge 42 of the wafer 40 which is the object to be measured. The optical unit drive unit 134 then 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, under the control of the control unit 160. The optical unit drive unit 134 is an example of a relative movement unit.

[0062] 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.

[0063] 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.

[0064] [Functions of wafer processing equipment] Figure 2 is a functional block diagram of the control unit 160 in the wafer processing apparatus 10. Note that Figure 2 shows the portion of the control unit 160 related to the processing unit 16 and the measurement unit 20 in the wafer processing apparatus 10. In the following description, functional blocks will sometimes be explicitly described, and sometimes multiple functional blocks will be collectively referred to as the control unit 160.

[0065] 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.

[0066] 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.

[0067] 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. Furthermore, the control unit 160 is 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, mouse, etc. Non-contact devices such as sensors may also be used as input devices. The output unit 174 is a device for outputting data such as the execution results of a program and calculation results by 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, etc.) for displaying detection results. In addition to the monitor, or instead of the monitor, the output unit 174 may also include a printer or speaker, etc. The operation unit 172 and the output unit 174 may be composed of a personal computer or a portable terminal such as a tablet. Furthermore, in addition to the operation unit 172 and the output unit 174, a portable terminal may also be connected to the control unit 160.

[0068] The control unit 160 performs processing and measurement processing on the wafer 40 by the wafer processing apparatus 10 in response to the operation input from the operation unit 172. The control unit 160 includes a processor that performs various processes (e.g., a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc.), memory that serves as the processor's workspace (e.g., ROM (Read Only Memory) and RAM (Random Access Memory), etc.), and a storage device for saving various programs and data (e.g., an SSD (Solid State Drive) or an HDD (Hard Disk Drive), etc.).

[0069] 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.

[0070] 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, chamfering 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).

[0071] 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 up a plurality of measurement points 220. The plurality of measurement points 220 are set at predetermined measurement intervals in the circumferential direction of the wafer 40, which is the object to be measured.

[0072] The measurement control unit 162 controls the table drive unit 122 to rotate the wafer 40 held on the measurement table 82 at measurement intervals. This rotational movement positions the multiple measurement points 220 on the wafer 40 at positions corresponding to the third sensor 88 and the shape measurement unit 90, respectively, with each rotation. Specifically, the multiple measurement points 220 on the wafer 40 are positioned at positions where the appearance can be detected by the third sensor 88 with each rotation. Similarly, the multiple measurement points 220 on the wafer 40 are positioned at positions where the three-dimensional shape can be measured by the shape measurement unit 90 with each rotation. Therefore, it is possible to simultaneously perform appearance detection of the wafer 40 by the third sensor 88 and measurement of the three-dimensional shape of the outer edge 42 of the wafer 40 by the shape measurement unit 90.

[0073] [Visual inspection using a 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 measurement 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 measurement 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 from the upper surface 201 side of the wafer 40 and imaging data of the outer edge 42 from the lower surface 202 side of the wafer 40.

[0074] Figure 4 shows the imaging ranges 402 and 404 by the third sensor 88 as dotted rectangles. The imaging range 402 at measurement point 220A and the imaging range 404 at measurement point 220C, which is located a distance equal to the measurement interval in the rotational direction of the wafer 40 from measurement 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.

[0075] 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 using 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 the number of defect 412s on the wafer 40. The shape and roughness analysis unit 164 also calculates the area of ​​the defect 412s on the wafer 40. The control unit 160 stores the presence, number, and area of ​​the defect 412s detected by the shape and roughness analysis unit 164 in a storage device for each wafer 40. The control unit 160 also outputs the presence, number, and area of ​​the defect 412s to the output unit 174.

[0076] [Measurement by 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 edge 42 of the wafer 40 using multiple imaging data obtained by imaging the outer edge 42 of the wafer 40 from the radially outer side with different focal positions.

[0077] More specifically, the measurement control unit 162 of the shape measurement unit 90 controls the table drive unit 122 to sequentially bring each measurement point 220 of the wafer 40 into contact with 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 in the radial direction (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.

[0078] Specifically, the measurement control unit 162 controls the table drive unit 122 to rotate the measurement table 82 so that the measurement point 220 on the wafer 40 is positioned opposite the optical unit 132. After the measurement control unit 162 starts emitting measurement light L1 from the light source unit 136, it controls the optical unit drive unit 134 to scan the optical unit 132 radially across 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.

[0079] 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 of the wafer 40 at the measurement location 220 using the three-dimensional shape data.

[0080] Figure 11 shows the cross-sectional shape of the outer edge 42 of the wafer 40 and an example of the measurement results of the outer 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 upper curved surface 206 between the upper sloping surface 204 and the end surface 203, and a lower curved surface 207 between the lower sloping surface 205 and the end surface 203. The surface including the end surface 203 is the surface that indicates the outermost edge of the wafer 40 in the radial direction. The upper sloping surface 204 and the upper curved surface 206 constitute an upper surface bevel slope that slopes from the upper surface 201 to the end surface 203. The lower inclined surface 205 and the lower curved surface 207 constitute a lower side bevel slope that slopes from the lower surface 202 toward the end surface 203. The upper inclined surface 204 is the inclined portion of the upper side bevel slope and extends linearly from the end of the upper surface 201 in the cross-section of the outer peripheral end 42. The lower inclined surface 205 is the inclined portion of the lower side bevel slope and extends linearly from the end of the lower surface 202 in the cross-section of the outer peripheral end 42. The upper curved surface 206 is the curved portion on the upper surface 201 side, and the lower curved surface 207 is the curved portion on the lower surface 202 side.

[0081] The shape and roughness analysis unit 164, shown in Figure 2, uses the three-dimensional shape data obtained as a result of the measurement by the shape measurement unit 90 to determine the upper intersection point 211 between the extension of the upper inclined surface 204 and the extension of the end face 203, and the lower intersection point 212 between the extension of the lower inclined surface 205 and the extension of the end face 203. The upper intersection point 211 is defined as the outermost radial end on the upper surface 201 side, and the lower intersection point 212 is defined as the outermost radial end on the lower surface 202 side. The shape and roughness analysis unit 164 then calculates the distance between the upper intersection point 211 and the lower intersection point 212 in the height direction (Z-axis direction) as the end face height X3 of the end face 203. The end face height X3 is the second height.

[0082] The shape and roughness analysis unit 164 calculates the distance between the holding surface 82A of the measurement table 82 and the center position of the end face 203 in the height direction, using the three-dimensional shape data, as the central height P. In Figure 11, the center position of the end face 203 coincides with the optical axis LA of the optical unit 132. The central height P is the third height.

[0083] The shape and roughness analysis unit 164 calculates the inclination angle θ1 of the upper inclined surface 204 relative to the upper surface 201 and the inclination angle θ2 of the lower inclined surface 205 relative to the lower surface 202 based on the three-dimensional shape data. The shape and roughness analysis unit 164 also calculates the radius of curvature R1 of the upper curved surface 206 and the radius of curvature R2 of the lower curved surface 207 based on the three-dimensional shape data.

[0084] Furthermore, the shape and roughness analysis unit 164 functions as a calculation unit that calculates the chamfer width A1 (first chamfer width) and chamfer width A2 (second chamfer width) in Figure 11. The shape and roughness analysis unit 164 calculates the chamfer width A1 and chamfer width A2 based on the measurement results of the shape measurement unit 90 and the detection results of the second sensor 86. The chamfer width A1 is the distance between the first boundary point 216 and the upper intersection point 211, which is the outermost point in the radial direction (Y-axis direction) on the upper surface 201 side. The first boundary point 216 is the boundary between the upper surface 201 and the upper inclined surface 204. The chamfer width A2 is the distance between the second boundary point 217 and the lower intersection point 212 in the radial direction (Y-axis direction) on the lower surface 202 side. The second boundary point 217 is the boundary between the lower surface 202 and the lower inclined surface 205.

[0085] The shape and roughness analysis unit 164 calculates the chamfer width A1 based on the end face height X3 and inclination angle θ1 obtained from the three-dimensional data, as well as the first distance t1, the second distance t2, and the thickness T1 of the wafer 40 detected by the second sensor 86.

[0086] Specifically, the shape and roughness analysis unit 164 calculates the deflection amount Δt of the wafer 40 from the first distance t1 and the second distance t2 using (t1-t2) / 2. The deflection amount Δt is 0 if the outer edge 42 of the wafer 40 is not inclined with respect to the holding surface 82A of the measurement table 82. The deflection amount Δt is shown as a positive value if the outer edge 42 of the wafer 40 is inclined upward with respect to the measurement table 82. Conversely, if the outer edge 42 of the wafer 40 is inclined downward with respect to the measurement table 82, the deflection amount Δt is shown as a negative value. The shape and roughness analysis unit 164 also calculates the chamfer height X1 (first chamfer height) in Figure 10. The chamfer height X1 is the distance between the upper intersection point 211 and the first boundary point 216 in the height direction. The shape and roughness analysis unit 164 calculates the chamfer height X1 using the formula X1 = T1 - P + Δt - X3 ÷ 2. Then, the shape and roughness analysis unit 164 calculates the chamfer width A1 using the formula A1 = X1 × tanθ1.

[0087] In other words, the shape and roughness analysis unit 164 calculates the chamfer width A1 by applying trigonometric ratios to a right triangle in which the side extending from the first boundary point 216 along the radial direction of the measurement table 82 to the position of the end face 203 is the base, the side from the first boundary point 216 to the upper intersection point 211 is the hypotenuse, and the angle of inclination θ1 is the distance between the base and the hypotenuse.

[0088] The shape and roughness analysis unit 164 calculates the chamfer width A2 based on the end face height X3 and inclination angle θ2 obtained from the three-dimensional data, as well as the first distance t1 and second distance t2 detected by the second sensor 86.

[0089] Specifically, the shape and roughness analysis unit 164 calculates the deflection amount Δt and the chamfer height X2 (second chamfer height) in Figure 10. The chamfer height X2 is the distance between the lower intersection point 212 and the second boundary point 217 in the height direction. The shape and roughness analysis unit 164 calculates the chamfer height X2 using the formula X2 = P + Δt - X3 ÷ 2. Then, the shape and roughness analysis unit 164 calculates the chamfer width A2 using the formula A2 = (P + Δt - X3 ÷ 2) × tanθ².

[0090] Specifically, the shape and roughness analysis unit 164 calculates the chamfer width A2 by applying trigonometric ratios to a right triangle where the side extending the lower surface 202 from the second boundary point 217 along the radial direction of the measurement table 82 to the position of the end face 203 is the base, the side from the second boundary point 217 to the lower intersection point 212 is the hypotenuse, and the angle of inclination between the base and the hypotenuse is θ2. The chamfer heights X1 and X2 are the first heights.

[0091] The control unit 160 stores the measurement results and calculation results of the outer edge 42 detected by the shape and roughness analysis unit 164, as well as the detection results of the measurement control unit 162, etc., in a storage device for each wafer 40. The control unit 160 also outputs the measurement results and calculation results of the outer edge 42, as well as the detection results of the measurement control unit 162, etc., to the output unit 174.

[0092] The feedback calculation unit 166 calculates a value to be fed back to the machining control unit 168 based on the analysis results from the shape and roughness analysis unit 164. Specifically, the feedback calculation unit 166 calculates the amount of position correction in the height direction between the grinding wheels 112, 114 and the wafer 40 during machining so that the chamfer widths A1, A2 become the target values. For example, the feedback calculation unit 166 calculates the position correction amount based on the difference between the target value and the chamfer widths A1, A2, and outputs the calculated position correction amount to the machining control unit 168. Based on the position correction amount output by the feedback calculation unit 166, the machining control unit 168 corrects the positional relationship between the grinding wheels 112, 114 and the wafer 40 during machining. Through this feedback, even if the grinding wheels 112, 114 wear down, the deviation between the target value and the chamfer widths A1, A2 can be suppressed.

[0093] Referring to Figure 12, a wafer inspection method using the wafer processing apparatus 10 will be described. As shown in Figure 12, the control unit 160 performs wafer detection (step S31) to detect the wafer 40 using the first sensor 84 and the second sensor 86, and appearance detection (step S32) to detect the appearance of the outer edge 42 of the wafer 40 using the third sensor 88.

[0094] The control unit 160 performs a shape measurement (step S33) using the shape measurement unit 90 to measure the three-dimensional shape of the outer edge 42 of the wafer 40. In the wafer processing apparatus 10, it is preferable that the third sensor 88 and the shape measuring unit 90 are positioned at a distance of an integer multiple of the measurement interval in the circumferential direction of the measuring table 82. This allows step S32 for one measurement location 220 and step S33 for another measurement location 220 to be performed in parallel. As a result, the efficiency of measuring the wafer 40 can be improved.

[0095] Furthermore, in the shape measurement (step S33), it is preferable that the control unit 160 adjusts the position of the shape measuring unit 90 while rotating the wafer 40, based on the relative position of the wafer 40 with respect to the measurement table 82 and the height position of the outer edge 42 obtained in step S31. This improves the efficiency of measuring the wafer 40.

[0096] The control unit 160 performs a dimension calculation (step S34) to calculate chamfer widths A1 and A2 based on the measurement results from the shape measuring unit 90 and the detection results from the second sensor 86. In the dimension calculation (step S34), the control unit 160 calculates the chamfer widths A1 and A2 for each measurement point 220 based on the measurement results from the shape measuring unit 90 (end face height X3, center height P, inclination angle θ1, θ2) and the detection results from the second sensor 86 (first distance t1, second distance t2, thickness T1). The control unit 160 outputs the measurement results, calculation results, detection results, etc. for each step to the output unit 174.

[0097] (Effects and Effects of the Embodiment) The operation and effects of this embodiment will now be described. (1) The wafer processing apparatus 10 performs chamfering to form a chamfered bevel on the outer edge 42 of the wafer 40 using grinding wheels 112 and 114. The wafer processing apparatus 10 includes a measuring table 82 that supports the lower surface 202 of the wafer 40, a second sensor 86 that detects the positions of the upper surface 201 and the lower surface 202 of the wafer 40, and a shape measuring unit 90 that measures the three-dimensional shape of the outer edge 42 of the wafer 40 using multiple imaging data captured from the outside of the radial direction intersecting the height direction of the wafer 40, with different focal positions. Based on the measurement results of the shape measuring unit 90 and the detection results of the second sensor 86, the wafer processing apparatus 10 calculates the chamfer widths A1 and A2, which are the radial distances from the boundary points 216 and 217 to the outermost edge.

[0098] With this configuration, the chamfer widths A1 and A2 are calculated based on the measurement results of the shape measuring unit 90 and the detection results of the second sensor 86. Compared to calculating the chamfer widths A1 and A2 based solely on the measurement results of the shape measuring unit 90, this configuration allows for more accurate and efficient calculation of the chamfer widths A1 and A2 in the chamfered portion. Furthermore, compared to, for example, a case where chamfer widths A1 and A2 are obtained by providing a shape measuring unit 90 that measures the outer peripheral edge 42 and the top surface 201 of the wafer 40 from an oblique upward side and a shape measuring unit 90 that measures the outer peripheral edge 42 and the bottom surface 202 of the wafer 40 from an oblique downward side, the configuration described in this embodiment can simplify the cost and structure.

[0099] (2) Based on the measurement results of the shape measuring unit 90 and the detection results of the second sensor 86, the wafer processing apparatus 10 calculates the chamfer heights X1 and X2, which are the heights of triangles where the sides extending radially from the boundary points 216 and 217 to the position of the end face 203 in the radial direction (Y-axis direction) are the base sides, and the sides extending along the inclined surfaces 204 and 205 from the boundary points 216 and 217 to the position of the end face 203 in the radial direction are the hypotenuses. With this configuration, the chamfer heights X1 and X2 can be calculated as dimensions of the chamfered portion.

[0100] (3) The shape measuring unit 90 measures the end face height X3, which is the distance between the upper intersection point 211 and the lower intersection point 212 in the height direction (Z-axis direction), the center height P, which is the distance from the measuring table 82 to the center position of the end face 203 in the height direction, and the inclination angles θ1 and θ2, which are the angles of the hypotenuse relative to the base, as measurement results. The second sensor 86 also detects the thickness T1 of the wafer 40 as a detection result based on the difference between the first distance t1 to the upper surface 201 of the wafer 40 and the second distance t2 to the lower surface 202 of the wafer 40.

[0101] With this configuration, the chamfer heights X1 and X2 and chamfer widths A1 and A2 can be calculated by geometric calculations using the end face height X3, the center height P, the inclination angles θ1 and θ2, the first distance t1, the second distance t2, and the thickness T1 of the wafer 40.

[0102] (4) The second sensor 86 has a first sensor unit 86A and a second sensor unit 86B. The first sensor unit 86A is positioned at a distance Ts from the reference position line 40C, which is at a height from the measurement table 82 that corresponds to half the thickness T1 of the wafer 40, in a first direction in the height direction (Z-axis direction). The second sensor unit 86B is positioned at a distance Ts from the reference position line 40C in a second direction opposite to the first direction in the height direction. The first sensor unit 86A detects a first distance t1 to the upper surface 201 of the wafer 40, and the second sensor unit 86B detects a second distance t2 to the lower surface 202 of the wafer 40.

[0103] With this configuration, it is possible to determine how the wafer 40 is supported by the measurement table 82 based on the first distance t1 and the second distance t2. That is, if the first distance t1 and the second distance t2 are different, it is possible to determine that the wafer 40 is supported by the measurement table 82 at an angle equal to the difference (deflection amount Δt). As a result, the chamfer widths A1 and A2 can be calculated taking into account the support state of the wafer 40 on the measurement table 82.

[0104] (5) When the first distance t1 and the second distance t2 are different, the shape and roughness analysis unit 164 corrects the chamfer widths A1 and A2 based on the deflection amount Δt, which is the difference value. Specifically, the shape and roughness analysis unit 164 calculates the chamfer height X1 by X1 = T1 - P + Δt - X3 ÷ 2 and the chamfer width A1 by A1 = X1 × tanθ1. Also, the shape and roughness analysis unit 164 calculates the chamfer height X2 by X2 = P + Δt - X3 ÷ 2 and the chamfer width A2 by A2 = (P + Δt - X3 ÷ 2) × tanθ2.

[0105] With this configuration, the chamfer widths A1 and A2 can be calculated by geometric calculations that take into account the support state of the wafer 40 on the measurement table 82. As a result, the chamfer widths A1 and A2 can be calculated with even higher accuracy.

[0106] (6) The shape measuring unit 90 is configured to measure the radii of curvature R1 and R2 of the curved surfaces 206 and 207 that are connected to the inclined surfaces 204 and 205 extending from the boundary points 216 and 217. With this configuration, the radii of curvature R1 and R2 can be measured as dimensions of the chamfered portion.

[0107] (Example of change) This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0108] 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 section for measuring the wafer 40 before processing may be provided in addition to the measuring unit 20.

[0109] 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.

[0110] 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.

[0111] If the wafer 40 is not warped or undulating (i.e., the deflection amount Δt is 0), the top surface 201 and bottom surface 202 are not included in the imaging range 420 of the optical unit 132. Therefore, even if the three-dimensional shape data is analyzed, it is difficult to detect the positions of the first boundary point 216 and the second boundary point 217 with high accuracy.

[0112] On the other hand, as shown in Figure 13, when the deflection amount Δt is a positive value, the wafer 40 is supported on the measurement table 82 with its outer peripheral edge 42 tilted downwards. Therefore, the imaging range 420 of the optical unit 132 includes the upper inclined surface 204 and the top surface 201, but does not include the bottom surface 202.

[0113] On the other hand, as shown in Figure 14, when the deflection amount Δt is a negative value, the wafer 40 is supported on the measurement table 82 with its outer peripheral edge 42 tilted upward. Therefore, the imaging range 420 of the optical unit 132 includes the downward inclined surface 205 and the bottom surface 202, but does not include the top surface 201.

[0114] Therefore, in the shape measurement (step S33), the measurement control unit 162 adjusts the relative position between the wafer 40 and the shape measurement unit 90, thereby performing measurements that include the upper inclined surface 204 and the top surface 201 within the imaging range 420 of the optical unit 132, and measurements that include the lower inclined surface 205 and the bottom surface 202 within the imaging range 420 of the optical unit 132. Then, in the dimension calculation (step S34), the shape and roughness analysis unit 164 calculates the chamfer width A1 based on the first three-dimensional data including the upper inclined surface 204 and the top surface 201, and calculates the chamfer width A2 based on the second three-dimensional data including the lower inclined surface 205 and the bottom surface 202.

[0115] (When the deflection Δt is 0) For example, as shown in Figure 15, the measurement control unit 162 moves the optical unit 132 in the height direction (Z-axis direction) to a position where the upper inclined surface 204 and the top surface 201 are included in the imaging range 420, and then performs measurement by the shape measurement unit 90. As a result, the shape and roughness analysis unit 164 obtains first three-dimensional data. Also, as shown in Figure 16, the measurement control unit 162 moves the optical unit 132 in the height direction to a position where the lower inclined surface 205 and the bottom surface 202 are included in the imaging range 420, and then performs measurement by the shape measurement unit 90. As a result, the shape and roughness analysis unit 164 obtains second three-dimensional data.

[0116] For example, as shown in Figure 13, the measurement control unit 162 tilts the measurement table 82 so that the upper inclined surface 204 and the top surface 201 are included in the imaging range 420, and then performs measurement by the shape measurement unit 90. As a result, the shape and roughness analysis unit 164 obtains the first three-dimensional data. Then, as shown in Figure 14, the measurement control unit 162 tilts the measurement table 82 to a position where the lower inclined surface 205 and the bottom surface 202 are included in the imaging range 420, and then performs measurement by the shape measurement unit 90. As a result, the shape and roughness analysis unit 164 obtains the second three-dimensional data.

[0117] (When the deflection amount Δt is a positive value) As shown in Figure 13, when the deflection amount Δt is a positive value, the outer edge 42 of the wafer 40 is tilted downwards. At this time, the imaging range 420 of the optical unit 132 includes the upper inclined surface 204 and the top surface 201. Therefore, the measurement control unit 162 first performs a measurement using the shape measurement unit 90 in this state. As a result, the shape and roughness analysis unit 164 obtains the first three-dimensional data. Next, the measurement control unit 162 tilts the measurement table 82 to a position where the lower inclined surface 205 and the bottom surface 202 are included in the imaging range 420, as shown in Figure 14, and then performs a measurement using the shape measurement unit 90. As a result, the shape and roughness analysis unit 164 obtains the second three-dimensional data.

[0118] (When the deflection amount Δt is a negative value) As shown in Figure 14, when the deflection amount Δt is a negative value, the outer edge 42 of the wafer 40 is tilted upward. At this time, the imaging range 420 of the optical unit 132 includes the downward inclined surface 205 and the bottom surface 202. Therefore, the measurement control unit 162 first performs a measurement using the shape measurement unit 90 in this state. As a result, the shape and roughness analysis unit 164 obtains second three-dimensional data. Next, the measurement control unit 162 tilts the measurement table 82 downward to a position where the upward inclined surface 204 and the top surface 201 are included in the imaging range 420, as shown in Figure 13, and then performs a measurement using the shape measurement unit 90. As a result, the shape and roughness analysis unit 164 obtains first three-dimensional data.

[0119] Specifically, the measurement control unit 162 detects the support state of the wafer 40 at the measurement location 220 based on the detection result of the second sensor 86. The measurement control unit 162 adjusts the measurement position of the shape measurement unit 90 and the inclination of the measurement table 82 so that the first boundary point 216 or the second boundary point 217 is included in the imaging range 420, according to the detected support state of the wafer 40, and then performs measurement with the shape measurement unit 90. The shape and roughness analysis unit 164 then calculates the chamfer width A1 by analyzing the shape of the outer edge 42 reproduced in the first three-dimensional data including the first boundary point 216. The shape and roughness analysis unit 164 then calculates the chamfer width A2 by analyzing the shape of the outer edge 42 reproduced in the second three-dimensional data including the second boundary point 217. Even with this configuration, the chamfer widths A1 and A2 can be calculated based on the measurement result of the shape measurement unit 90 and the detection result of the second sensor 86. [Explanation of Symbols]

[0120] 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...Transport 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...Ejection unit, 84 B...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, 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...Measurement location, 220A...Measurement location, 220B...Measurement location, 220C...Measurement location, 402... Image range, 404...Image range, 410...Image data, 412...Defect area, 420...Image range, θ1...Inclination angle, θ2...Inclination angle, A1...Chamfer width, A2...Chamfer width, L1...Measurement light, L2...Reference light, L3...Measurement light, L4...Multiply wave light, LA...Optical axis, P...Center height, R1...Radius of curvature, R2...Radius of curvature, t1...First distance, t2...Second distance, T1...Thickness, T2...Thickness, UI...Operation, X1...Chamfer height, X2...Chamfer height, X3...End face height, AR1...Arrow, G1, G2...Rotation axis, O1...Center, θ11, θ12...Center angle.

Claims

1. A wafer processing apparatus for chamfering a wafer, wherein a chamfered slope is formed on the outer edge of the wafer by grinding a wheel, and the chamfered slope is inclined from the boundary of the wafer surface toward the outermost edge of the outer edge, A measuring table that supports the surface of the wafer, A sensor for detecting the position on the surface of the wafer, The apparatus comprises a shape measuring device that measures the three-dimensional shape of the outer edge of the wafer using multiple imaging data obtained by imaging the outer edge of the wafer from the radially outer side intersecting the height direction of the wafer, with different focal positions. Based on the measurement results of the shape measuring device and the detection results of the sensor, the chamfer width, which is the radial distance from the boundary to the outermost end, is calculated. Wafer processing equipment.

2. Based on the measurement results of the shape measuring device and the detection results of the sensor, The first height of a triangle having a base extending radially from the boundary to the outermost end and a hypotenuse extending radially from the boundary to the outermost end along the chamfered slope is calculated. The wafer processing apparatus according to claim 1.

3. The shape measuring device measures, as the measurement results, a second height from the outermost end of the hypotenuse on the upper surface side of the wafer to the outermost end of the hypotenuse on the lower surface side of the wafer, a third height from the measuring table to the midpoint of the second height, and the angle of the hypotenuse with respect to the base. The sensor detects the thickness of the wafer as the detection result based on the difference between a first distance to the top surface of the wafer and a second distance to the bottom surface of the wafer. The wafer processing apparatus according to claim 2.

4. The sensor comprises a first sensor and a second sensor, which are positioned at the same distance from a reference position corresponding to half the thickness of the wafer from the measurement table, in a first direction in the height direction and in a second direction opposite to the first direction in the height direction. The wafer processing apparatus according to claim 3.

5. If the first distance and the second distance are different, the chamfer width is corrected based on the difference value. The wafer processing apparatus according to claim 4.

6. The shape measuring device measures the radius of curvature of the curved portion that curves from the outermost boundary to the outermost end of the inclined portion that extends linearly from the boundary portion on the chamfered slope. A wafer processing apparatus according to any one of claims 1 to 5.

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