Shape measurement device, shape measurement method, and wafer processing system

Abstract

Provided is a shape measurement method for measuring the shape of a surface subject to measurement at an end part of a wafer, the shape measurement method comprising: generating measurement data indicating the shape of a notch part formed on the surface subject to measurement, the measurement data being generated on the basis of the coordinates of a point cloud obtained by repeatedly imaging the notch part by using an imaging part when an optical unit (104) is moved relative to the surface subject to measurement, the optical unit (104) having a light source part that has an optical axis parallel to the main surface of the wafer and irradiates the surface subject to measurement with measurement light along the optical axis, and the imaging part, which is used in imaging reflected light from the surface subject to measurement; and performing shape analysis of the notch part on the basis of the measurement data.

Description

Shape measurement device, shape measurement method, and wafer processing system

[0001] The present invention relates to a shape measuring device, a shape measuring method, and a wafer processing system, and more particularly to a shape measuring device, a shape measuring method, and a wafer processing system for measuring the shape of an edge of a wafer.

[0002] When a disk-shaped wafer is subjected to surface processing using a polishing device, the edge of the wafer is processed into a sharp point, which can cause the wafer to crack or chip. For this reason, the wafer is subjected to a grinding process (also called a chamfering process) to remove the sharp point from the edge of the wafer and make the edge into a rounded or chamfered shape (see Patent Document 1).

[0003] The shape and dimensions of the edge of the wafer formed by grinding are regulated by standards set by industry organizations or by client requests, and the edge must be ground to fall within the regulated range.

[0004] Furthermore, to produce many chips from a single wafer, it is desirable to form a pattern all the way to the outermost periphery of the wafer. To achieve this, the resist film thickness d1 of the resist PR (photoresist, see FIG. 45 ) applied to the wafer W must be constant all the way to the outermost periphery of the wafer W. The resist film thickness d1 depends on the surface tension of the coated surface W1 of the wafer W, which in turn depends on the electrostatic force at the outer periphery of the wafer W (the edge portion 80 and its vicinity). The electrostatic force at the outer periphery of the wafer W depends on the angle θ1 of the edge portion 80 relative to the coated surface W1 and the nominal diameter R1 of the edge portion 80. Therefore, to maintain a constant resist film thickness d1, the angle θ1 and diameter R1 must be formed as designed, and it is important to process, measure, and manage the shape of the edge portion 80 as designed.

[0005] For this reason, in the wafer manufacturing process, shape measurement is performed to measure the shape of the edge of the wafer after grinding to check whether the shape of the edge is within a specified range.

[0006] Patent Document 2 discloses a shape measuring device that measures the shape of a wafer edge by an optical projection measurement method. This shape measuring device projects light onto the edge of a ground wafer from a direction approximately parallel to both the front and back surfaces of the wafer, captures a projected image of the wafer edge from a direction opposite to the light projection direction using a camera, and measures the shape of the wafer edge based on the projected image.

[0007] JP 2009-78326 A JP 2009-168634 A

[0008] An object of the present invention is to provide a shape measuring device, a shape measuring method, and a wafer processing system that are capable of measuring the shape of the edge of a wafer with high accuracy.

[0009] In order to achieve the above object, the present invention comprises the following aspects.

[0010] A shape measuring device according to a first aspect of the present invention is a shape measuring device that measures the shape of a measurement surface at the edge of a wafer, and is equipped with an optical unit having an optical axis parallel to the main surface of the wafer, a light source unit that irradiates measurement light along the optical axis onto the measurement surface, and an imaging unit that images reflected light from the measurement surface, a relative movement unit that moves the optical unit relatively to the measurement surface, a calculation unit that generates measurement data indicating the shape of the notch portion based on the coordinates of the point cloud obtained by the imaging unit repeatedly imaging a notch portion formed on the measurement surface by moving the optical unit relatively, and an analysis unit that performs shape analysis of the notch portion based on the measurement data.

[0011] A shape measuring instrument according to a second aspect of the present invention is the first aspect, wherein the analysis unit obtains an approximation curve from coordinates of the point cloud.

[0012] A shape measuring device according to a third aspect of the present invention is the second aspect, wherein the imaging unit images the notch portion of the wafer to obtain coordinates of a point cloud, and the analysis unit calculates at least two curves obtained by shifting the approximation curve along a direction perpendicular to the front or back surface of the wafer, thereby determining an approximation curve of the notch portion along a direction perpendicular to the front or back surface of the wafer that passes through a saddle point of the notch portion.

[0013] A shape measuring instrument according to a fourth aspect of the present invention is the shape measuring instrument of any one of the first to third aspects, further comprising an output unit that outputs a determination result as to whether or not there is an abnormality in the wafer based on the measurement data.

[0014] A shape measuring device according to a fifth aspect of the present invention is any of the first to fourth aspects, in which the analysis unit determines whether or not there is an abnormality in the three-dimensional shape corresponding to the area data based on area data extracted from the three-dimensional shape of the edge of the wafer.

[0015] A shape measuring device according to a sixth aspect of the present invention is any of the first to fifth aspects, in which the analysis unit determines an analysis coordinate system for analyzing the notch portion based on the coordinates of the point cloud obtained by moving the optical unit relative to a master workpiece having a known angle between each surface and repeatedly imaging the measured surface of the master workpiece with the imaging unit.

[0016] A seventh aspect of the present invention is a shape measurement method for measuring the shape of a measurement surface at the edge of a wafer, in which an optical unit having an optical axis parallel to the main surface of the wafer, a light source unit that irradiates measurement light along the optical axis onto the measurement surface, and an imaging unit that images reflected light from the measurement surface is moved relative to the measurement surface, and measurement data indicating the shape of the notch portion is generated based on the coordinates of a point cloud obtained by the imaging unit repeatedly imaging a notch portion formed on the measurement surface, and shape analysis of the notch portion is performed based on the measurement data.

[0017] The shape measuring device of the eighth aspect is a shape measuring device that measures the three-dimensional shape of the measurement surface at the edge of a wafer, and is equipped with an optical unit having an optical axis parallel to the main surface of the wafer, a light source unit that irradiates the measurement surface with coaxial incident illumination light along the optical axis, and an imaging unit that is arranged coaxially with the optical axis and images the reflected light from the measurement surface, a relative movement unit that moves the optical unit relative to the measurement surface in a direction along the optical axis, a side illumination unit that irradiates the measurement surface with side illumination light from a direction perpendicular to the optical axis, and a shape data generation unit that generates three-dimensional shape data indicating the three-dimensional shape of the measurement surface based on multiple captured images repeatedly captured by the imaging unit while the optical unit is moving relatively.

[0018] A ninth aspect of the present invention is the shape measuring instrument of the eighth aspect, wherein the side lighting unit has a rod-shaped light emitter whose longitudinal direction is parallel to the optical axis.

[0019] A tenth aspect of the present invention is a shape measuring instrument according to the ninth aspect, wherein the side illumination unit has a pair of rod-shaped light emitters provided on both sides of the edge of the wafer in a direction perpendicular to the optical axis.

[0020] The shape measuring instrument according to an eleventh aspect is the eighth aspect, further comprising a light amount control section that controls the amount of side illumination light emitted from the side illumination unit.

[0021] A shape measuring device according to a twelfth aspect is the shape measuring device of the tenth aspect, further comprising a light amount control section that controls the amount of light emitted by the pair of rod-shaped light emitters independently of each other.

[0022] A thirteenth aspect of the present invention is the shape measuring instrument of the eighth aspect, wherein the side lighting unit has a surface light emitter that emits light in a plane parallel to the main surface.

[0023] The shape measuring device according to the fourteenth aspect is the shape measuring device of the eighth aspect, which has a measurement table configured to hold a wafer and be rotatable around a rotation axis perpendicular to the main surface of the wafer, and is equipped with a measurement control unit that rotates the measurement table so that the surface to be measured at the edge of the wafer is positioned opposite the optical unit.

[0024] A shape measuring device according to a 15th aspect is any of the 8th to 14th aspects, wherein the shape data generation unit includes a first shape data generation unit that generates first shape data indicating the three-dimensional shape of the surface to be measured using a white light interferometry method based on a plurality of captured images, a second shape data generation unit that generates second shape data indicating the three-dimensional shape of the surface to be measured using a focus variation method based on the plurality of captured images, and an integrated calculation unit that generates integrated shape data by selectively combining the first shape data and the second shape data for each pixel or for each region based on an index value obtained from at least one of the first shape data and the second shape data.

[0025] A shape measurement method according to a sixteenth aspect is a shape measurement method for measuring the three-dimensional shape of a measurement surface at the edge of a wafer, and includes a scanning step in which an optical unit having an optical axis parallel to the main surface of the wafer is moved relative to the measurement surface in a direction along the optical axis; an imaging step in which, while the scanning step is being performed, the measurement surface is irradiated with coaxial incident illumination light from the optical unit along the optical axis, and the reflected light from the measurement surface is captured by an imaging unit arranged coaxially with the optical axis in the optical unit; a side illumination step in which, while the imaging step is being performed, side illumination light is irradiated onto the measurement surface from a direction perpendicular to the optical axis; and a shape data generation step in which three-dimensional shape data indicating the three-dimensional shape of the measurement surface is generated based on a plurality of captured images captured by the imaging unit in the imaging step.

[0026] The wafer processing system according to the seventeenth aspect includes a base plate, a grinding unit mounted on the base plate for grinding the edge of the wafer, a measuring unit mounted on the base plate for measuring the shape of the edge of the ground wafer, a transport unit for transporting the wafer between the grinding unit and the measurement unit, and a vibration isolation table arranged between the base plate and the measurement unit.

[0027] The wafer processing system of the 18th aspect is the 17th aspect, wherein the grinding unit has a grinding table on which a wafer is placed and which rotates the wafer, and a grinding wheel which comes into relative contact with the edge of the wafer placed on the grinding table to grind the edge, and the measuring unit has a measuring table on which a wafer is placed and which rotates the wafer, and a shape measuring device which measures the shape of the edge of the wafer placed on the measuring table.

[0028] A wafer processing system according to a 19th aspect is the 18th aspect, further comprising a first sensor for measuring the diameter of the wafer and the center position of the wafer relative to the measurement table, the surface plate having a second sensor for measuring the center position of the wafer relative to the surface plate, and a control device for controlling the amount of wafer transport by the transport unit based on the difference between the two center positions measured by the first sensor and the second sensor and the preset relative positions of the centers of rotation of the measurement table and the grinding table.

[0029] A wafer processing system according to a twentieth aspect is the wafer processing system of any one of the seventeenth to nineteenth aspects, wherein the measurement section is provided with a shape measurement device, and the shape measurement device includes an optical unit that is a white light interference microscope.

[0030] A wafer processing system according to a 21st aspect is any of the 17th to 19th aspects, in which the vibration isolation table is moved between a seated position, which is a non-operating position, and a floating position, which is an operating position located above the seated position, and has a locking member that fixes the vibration isolation table at the floating position and releases the fixation.

[0031] The shape measuring device and shape measuring method according to the present invention can measure the shape of the edge of a wafer with high accuracy, and the wafer processing system according to the present invention can improve throughput.

[0032] 1 is a plan view showing a schematic configuration of a wafer processing system. FIG. 1 is a schematic configuration diagram showing a schematic configuration of a grinding device (chamfering device) installed in a grinding section. FIG. 2 is a side view showing a schematic configuration of a shape measuring device. FIG. 3 is a plan view showing a schematic configuration of a shape measuring device. FIG. 4 is a schematic diagram showing details of the configuration of an optical unit. FIG. 5 is a functional block diagram of a control device in the shape measuring device. FIG. 6 is a diagram for explaining a procedure for shape measurement of a notch portion. FIG. 7 is a perspective view for explaining shape analysis according to Example 2. FIG. 8 is a diagram showing a user interface for accepting input of a deviation amount of an approximation curve. FIG. 9 is a perspective view showing a notch portion (saddle portion). FIG. 10 is a diagram showing a user interface for accepting input of a range designation for extracting a surface shape. FIG. 11 is a perspective view showing an example of determining an analysis coordinate system using a master workpiece. FIG. 12 is a diagram showing an example of determining an analysis coordinate system using a master workpiece. FIG. 13 is a schematic diagram showing an example of a wafer. FIG. 14 is a diagram for explaining problems in the prior art. FIG. 15 is a side view showing a schematic configuration of a shape measuring device. FIG. 16 is a plan view showing a schematic configuration of a shape measuring device. FIG. 17 is a schematic diagram showing details of the configuration of the optical unit. FIG. 18 is a schematic diagram showing the configuration of a side illumination unit. FIG. 19 is a diagram showing a state when the surface to be measured is switched between a notch portion and an edge portion. FIG. 20 is a schematic diagram showing an example of the configuration of a side light emitter. 1 is a schematic diagram showing the configuration of a side lighting unit according to a comparative example; a diagram for explaining the effect of the side lighting unit of the present embodiment; a functional block diagram of a control device; a flowchart showing the flow of a shape measuring method using the shape measuring device of the embodiment; a schematic diagram showing the configuration of a side lighting unit of a first modified example of the second embodiment; a schematic diagram showing the configuration of a side lighting unit of a second modified example of the second embodiment; a schematic diagram showing the configuration of a side lighting unit of a third modified example of the second embodiment; a schematic diagram showing the configuration of a side lighting unit of a fourth modified example of the second embodiment; an explanatory diagram showing the configuration of a grinding device installed in a grinding unit; a plan view of a wafer; an explanatory diagram showing the configuration of a measuring unit; an explanatory diagram showing the configuration of a shape measuring device; a functional block diagram of a control device in a surface shape measuring device; a flowchart showing an example of a grinding method and a shape measuring method; a schematic diagram showing the configuration when a grinding unit and a measuring unit are mounted on a surface plate;FIG. 43 is an explanatory diagram for explaining the features of the wafer processing system of this embodiment. FIG. 44 is an explanatory diagram showing a diameter sensor and an outer diameter sensor that perform first and second alignment processes. FIG. 45 is an explanatory diagram showing the attitudes of two wafers placed on a measurement table. FIG. 46 is an explanatory diagram showing a state in which a vibration isolation table positioned in a floating position is locked. FIG. 47 is an explanatory diagram showing that a dead zone exists within the return range of an active vibration isolation table. FIG. 48 is a schematic plan view of a wafer processing system showing a first modified example of the third embodiment. FIG. 49 is a schematic side view of the wafer processing system shown in FIG. 42. FIG. 49 is a schematic plan view of a wafer processing system showing a second modified example of the third embodiment. FIG. 49 is a cross-sectional view showing an edge portion of a wafer.

[0033] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0034] 1 is a plan view showing a schematic configuration of a wafer processing system 10. In the following description, of the three mutually orthogonal directions X, Y, and Z shown in the figure, the X and Z directions refer to the horizontal direction, and the Y direction refers to the up-down direction (vertical direction).

[0035] 1, the wafer processing system 10 includes a cassette unit 12, a load unit 14, a grinding unit 16, a cleaning unit 18, a measurement unit 20, and a transport unit 22. The load unit 14, the grinding unit 16, and the measurement unit 20 are examples of the transport unit, the grinding unit, and the measurement unit of the present invention, respectively.

[0036] The loading unit 14 transports wafers W (shown in FIGS. 2 and 3, etc.) between the cassette unit 12, the grinding unit 16, and the measuring unit 20. This operation is performed by a supply / recovery robot. The cassette unit 12 is provided with a wafer cassette that stores a large number of wafers W to be chamfered. The supply / recovery robot takes out wafers W one by one from the wafer cassette and stores the chamfered wafers W back into the wafer cassette.

[0037] The supply and recovery robot is equipped with a three-axis rotating transfer arm, and this transfer arm is equipped with a suction pad (not shown) on its upper surface. The transfer arm holds the wafer W by vacuum suctioning the underside of the wafer W with this suction pad. That is, the transfer arm of this supply and recovery robot can move back and forth, up and down, and rotate while holding the wafer W, and the wafer W is transported by combining these movements.

[0038] The grinding section 16 performs grinding of the edge of the wafer W, that is, performs processes from rough grinding to finish grinding.

[0039] 2 is a schematic diagram showing the schematic configuration of the grinding device (chamfering device) 30 installed in the grinding section 16. As shown in FIG. 2, the grinding device 30 includes a grinding table 32 that holds the wafer W, a grinding wheel 34, and a spindle motor 36 that rotates the grinding wheel 34.

[0040] The grinding table 32 has an upper surface that is a holding surface 32a that suction-holds the wafer W. The grinding table 32 is configured to be rotatable about a rotation axis P that is parallel to the Y direction by various actuators such as a motor drive mechanism (not shown). The grinding table 32 is an example of the grinding table of the present invention.

[0041] The grinding wheel 34 is configured to be rotatable about a rotation axis parallel to the Y direction by a spindle motor 36. The grinding wheel 34 is also moved forward and backward in the Z direction relative to the edge of the wafer W held on the grinding table 32. When the grinding wheel 34 is moved forward and backward, the rotating grinding wheel 34 is pressed relatively against the outer periphery (edge ​​portion 80), which is the edge of the rotating wafer W, thereby grinding the outer periphery of the wafer W. The grinding wheel 34 in this example is a formed grinding wheel having grinding grooves 34a on its outer periphery, and the shape of the grinding grooves 34a is transferred to the outer periphery of the wafer W during grinding.

[0042] The grinding device 30 is provided with a fine grinding wheel (not shown) in addition to the grinding wheel (rough grinding wheel) 34. As a result, the outer periphery of the wafer W is roughly ground with the grinding wheel 34, and then the fine grinding wheel is used to perform chamfering for finish grinding of the outer periphery of the wafer W. The grinding device 30 is also provided with a notch rough grinding wheel and a notch fine grinding wheel for grinding a notch portion 82 (see FIG. 4). As a result, the notch portion 82 is roughly ground with the notch rough grinding wheel, and then the fine notch grinding wheel is used to perform chamfering as finish grinding. Note that a plurality of grinding devices 30 may be installed in the grinding section 16.

[0043] 1 , the cleaning unit 18 cleans the wafer W after chamfering. This cleaning unit 18 includes a spin cleaning device (not shown). The spin cleaning device sprays a cleaning liquid onto the upper surface (front surface) of the wafer W while rotating the wafer W held on a cleaning table, thereby peeling off and removing contaminants adhering to the upper surface of the wafer W.

[0044] The transfer unit 22 transfers the wafer W between the grinding unit 16 and the cleaning unit 18. The transfer unit 22 includes a transfer robot configured to be capable of linear motion in the Z direction and vertical motion in the Y direction (vertical direction). The transfer robot includes an arm unit, the tip of which is provided with a suction pad. The transfer robot transfers the wafer W while suctioning the top surface of the wafer W with the suction pad of the arm unit. As a result, in the transfer unit 22, the transfer robot transfers the wafer W that has been chamfered in the grinding unit 16 to the cleaning unit 18, and transfers the wafer W that has been cleaned in the cleaning unit 18 to the grinding unit 16.

[0045] The measurement unit 20 measures the thickness of the wafer W to be chamfered and performs pre-alignment. To measure the thickness of the wafer W and perform pre-alignment, the measurement unit 20 includes a measurement table (denoted by reference numeral 102 in FIG. 3), a thickness sensor, and an orientation flat / notch detection sensor.

[0046] The measurement table rotates the wafer W around its central axis. The thickness sensor is, for example, a capacitance sensor, which measures the distance from the top surface to the bottom surface of the wafer W. The measurement results of the capacitance sensor are output to a computing device (not shown), which determines the thickness of the wafer W. The orientation flat / notch detection sensor is, for example, a laser sensor, which detects the position of the orientation flat or notch of the wafer W. Here, the orientation flat is an abbreviation for orientation flat, which is a flat portion formed on the edge of the wafer W to indicate the crystal orientation of the wafer W, and the notch portion 82 is a cutout portion formed to indicate the crystal orientation of the wafer. Examples of thickness sensors include capacitance-type and interference-type sensors, and the orientation flat / notch detection sensor includes an image sensor.

[0047] The measuring unit 20 also includes a diameter measuring device (not shown) that measures the diameter of the chamfered wafer W, and a shape measuring device 100 (an example of the "shape measuring device" of the present invention) that measures the three-dimensional shape of the edge of the chamfered wafer W. The configuration of the shape measuring device 100 will be described in detail later.

[0048] Next, an outline of the operation of the wafer processing system 10 of the embodiment will be described.

[0049] First, the wafer W is taken out of the cassette attached to the cassette unit 12 by the supply / recovery robot of the loading unit 14 and transported to the measurement unit 20. The wafer W transported to the measurement unit 20 is placed on the measurement table of the measurement unit 20.

[0050] Next, in the measurement unit 20, a thickness sensor and an orientation flat / notch detection sensor are used to measure the thickness and pre-align the wafer W. Also, a diameter measuring instrument is used to measure the diameter of the wafer W.

[0051] Next, the wafer W that has undergone various measurements in the measuring section 20 is transported to the grinding section 16 by the supply / recovery robot of the loading section 14. The wafer W transported to the grinding section 16 is placed on the grinding table 32 of the grinding device 30.

[0052] Next, in the grinding section 16, the grinding device 30 performs grinding (chamfering) on ​​the edge of the wafer W. Specifically, after the edge portion 80, which is the outer periphery of the wafer W, is roughly ground with the grindstone 34, chamfering is performed with a precision grindstone for finish grinding of the outer periphery of the wafer W. Furthermore, the notch portion 82 of the wafer W is roughly ground with a notch rough grindstone, and then chamfering is performed as finish grinding with a notch precision grindstone.

[0053] Next, the wafer W that has been subjected to grinding (chamfering) in the grinding unit 16 is transferred from the grinding unit 16 to the cleaning unit 18 by the transfer robot of the transfer unit 22. Then, in the cleaning unit 18, the wafer W is cleaned by a spin cleaning device.

[0054] Next, the wafer W that has been cleaned in the cleaning unit 18 is transferred from the cleaning unit 18 to the grinding unit 16 by the transfer robot of the transfer unit 22. Thereafter, the wafer W is transferred from the grinding unit 16 to the measurement unit 20 by the supply / recovery robot of the loading unit 14. The wafer W transferred to the measurement unit 20 is placed on a measurement table.

[0055] Next, in the measuring unit 20, the diameter of the wafer W is measured using a diameter measuring device, and the three-dimensional shape of the edge of the wafer W is measured by the shape measuring device 100. The measurement results of the measuring unit 20 (the diameter of the wafer W and the three-dimensional shape of the edge of the wafer W) are output to an output unit (denoted by reference numeral 114 in FIG. 24). Note that the control device 110, which will be described later, may calculate a determination result indicating whether or not the measurement result of the measuring unit 20 is within a predetermined specified range, and output the determination result to the output unit (reference numeral 114 in FIG. 6).

[0056] Next, the wafer W that has been measured in the measuring section 20 is transported from the measuring section 20 to the cassette section 12 by the supply and recovery robot of the loading section 14, and is stored in a wafer cassette.

[0057] First Embodiment Incidentally, a cutout portion called a notch may be formed at the edge of a wafer W to indicate the crystal orientation of the wafer W. If a defect such as a scratch exists in the notch of the wafer W (particularly, a saddle portion that is recessed like a horse's saddle), this may trigger damage to the wafer W. For this reason, it is also necessary to measure the shape of the notch of the wafer W to detect defects such as scratches.

[0058] The light projection measurement method described in Patent Document 2 projects light from a direction approximately parallel to the front and back surfaces of the wafer, which creates a shadow at the saddle of the notch, making it impossible to measure the shape of the saddle of the notch.

[0059] The first embodiment provides a shape measuring device and a shape measuring method that can accurately analyze the shape of a notch formed at the edge of a wafer.

[0060] [Shape Measuring Apparatus] Next, a description will be given of the configuration of the shape measuring apparatus 100. This shape measuring apparatus 100 is an example of a shape measuring apparatus of the present invention, and calculates three-dimensional shape data indicating height information (surface shape, surface roughness, etc.) of the measurement surface of the edge of the wafer W, which is the measurement object, based on a plurality of captured images captured at a fixed pitch while scanning an optical unit 104 (white light interference microscope) described later in the scanning direction (Z direction).

[0061] Fig. 3 is a side view (viewed from the X direction) showing a schematic configuration of the shape measuring device 100. Fig. 4 is a plan view (viewed from the Y direction) showing a schematic configuration of the shape measuring device 100.

[0062] As shown in FIGS. 3 and 4, the shape measuring apparatus 100 includes a measuring table 102, an optical unit 104, and a control device 110.

[0063] The measuring table 102 has a holding surface 102a on its upper surface that suction-holds the wafer W. The measuring table 102 is configured to be rotatable about a rotation axis G that is parallel to the Y direction. The table driving unit 116 is configured with various actuators such as a motor driving mechanism, and rotates the measuring table 102 about the rotation axis G under the control of a control device 110, which will be described later. As a result, the wafer W suction-held on the holding surface 102a of the measuring table 102 rotates and moves about the rotation axis G.

[0064] The optical unit 104 is configured by a white light interference microscope. This optical unit 104 is provided adjacent to one side of the measurement table 102 in the Z direction (the left side in FIG. 3 ). Specifically, the optical unit 104 is disposed so that its optical axis R (corresponding to the optical axis of the interference objective lens 124) is parallel (including approximately parallel) to the main surface (top or bottom surface) of the wafer W. In other words, the optical axis R of the optical unit 104 is disposed so that it is parallel (including approximately parallel) to a direction perpendicular to the rotation axis G of the measurement table 102 (preferably, so that it intersects with the rotation axis G of the measurement table 102). The optical unit 104 then captures an image of the edge of the wafer W (edge ​​portion 80 or notch portion 82) from a position facing the edge of the wafer W held on the measurement table 102.

[0065] Next, a detailed description will be given of the configuration of the optical unit 104. FIG.

[0066] The optical unit 104 is a Michelson-type white light interference microscope. As shown in Fig. 5, the optical unit 104 includes a light source unit 120, a beam splitter 122, an interference objective lens 124, an imaging lens 126, and a camera 128. The interference objective lens 124, the beam splitter 122, the imaging lens 126, and the camera 128 are arranged in this order along the left side in the Z direction from the surface to be measured at the edge of the wafer W, which is the measurement object. The light source unit 120 is also arranged at a position opposite the beam splitter 122 in the Y direction.

[0067] Under the control of the control device 110, the light source unit 120 emits a parallel beam of white light (low-coherence light) as measurement light L1 toward the beam splitter 122. Although not shown, the light source unit 120 includes a light source capable of emitting measurement light L1, such as a light-emitting diode, a semiconductor laser, a halogen lamp, or a high-intensity discharge lamp, and a collector lens that converts the measurement light L1 emitted from the light source into a parallel beam.

[0068] A half mirror, for example, is used as the beam splitter 122. The beam splitter 122 reflects a portion of the measurement light L1 incident from the light source unit 120 toward the interference objective lens 124 on the right side in the Z direction. The beam splitter 122 also transmits a portion of the combined light L3 (described below) incident from the interference objective lens 124 to the left side in the Z direction, and emits this combined light L3 toward the imaging lens 126.

[0069] The interference objective lens 124 is a Michelson type and includes an objective lens 124A, a beam splitter 124B, and a reference surface 124C. The beam splitter 124B and the objective lens 124A are arranged in this order along the left side in the Z direction from the measured surface side. The reference surface 124C is arranged opposite the beam splitter 124B in the Y direction. While the following description will be given using a Michelson type interference optical system, the interference optical system is not limited to the Michelson type, and known interference optical systems such as a Mirau type or Linnik type can also be used.

[0070] The objective lens 124A has a light-condensing function, and condenses the measurement light L1 incident from the beam splitter 122 onto the surface to be measured through the beam splitter 124B.

[0071] The beam splitter 124B is, for example, a half mirror. The beam splitter 124B splits a portion of the measurement light L1 incident from the objective lens 124A as reference light L2, transmits the remaining measurement light L1 and emits it toward the surface to be measured, and reflects the reference light L2 toward the reference surface 124C. The measurement light L1 transmitted through the beam splitter 124B is irradiated onto the surface to be measured, and is then reflected by the surface to return to the beam splitter 124B.

[0072] The reference surface 124C is, for example, a reflecting mirror, and reflects the reference light L2 incident from the beam splitter 124B toward the beam splitter 124B. The position of this reference surface 124C in the Y direction can be manually adjusted by a position adjustment mechanism (e.g., a ball screw mechanism, an actuator, etc.) not shown. This makes it possible to adjust the optical path length (reference optical path length) of the reference light L2.

[0073] The beam splitter 124B generates a combined light L3 from the measurement light L1 returning from the surface to be measured and the reference light L2 returning from the reference surface 124C, and emits this combined light L3 toward the objective lens 124A on the left side in the Z direction. This combined light L3 passes through the objective lens 124A and the beam splitter 122 and enters the imaging lens 126.

[0074] The imaging lens 126 forms an image of the combined light L3 incident from the beam splitter 122 on an imaging plane (not shown) of the camera 128. Specifically, the imaging lens 126 forms an image of a point on the focal plane of the objective lens 124A as an image point on the imaging plane of the camera 128.

[0075] Although not shown, the camera 128 has a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) imaging element. The camera 128 captures an image of the combined light L3 formed on the imaging surface of the imaging element by the imaging lens 126, processes the imaging signal of the combined light L3 obtained by this imaging, and outputs an imaging signal. The camera 128 is an example of an imaging unit.

[0076] The optical unit driving unit 106 is composed of various actuators such as a linear motor or a motor driving mechanism, and holds the optical unit 104 so that it can move freely in the Z direction, which is the scanning direction. Under the control of the control device 110, the optical unit driving unit 106 scans the optical unit 104 in the Z direction, i.e., along a direction parallel to the optical axis R of the optical unit 104. The optical unit driving unit 106 is an example of a relative moving unit.

[0077] Furthermore, the optical unit driving unit 106 holds the optical unit 104 so that it can move not only in the Z direction but also in the Y and X directions. This makes it possible to adjust the relative position (relative position in the X and Y directions) of the optical unit 104 with respect to the edge of the wafer to be measured. Furthermore, if there is a limit to the measurement field of view of the measurement surface that can be measured in one run due to limitations such as the measurement field of view of the interference objective lens 124, it is possible to perform multiple measurements while moving the optical unit 104 in the X or Y direction. Note that instead of moving the optical unit 104 in the X, Y, or Z directions, the measurement table 102 may be moved in the X, Y, or Z directions.

[0078] The scale 130 is a position detection sensor, such as a linear scale, that detects the Z-direction position of the optical unit 104. The scale 130 repeatedly detects the Z-direction position of the optical unit 104 and repeatedly outputs the position detection result to the control device 110.

[0079] 6 is a functional block diagram of the control device 110 in the shape measuring device 100. The light source unit 120 and camera 128 of the optical unit 104, the scale 130, the table driving unit 116, the optical unit driving unit 106, the operation unit 112, and the output unit 114 are connected to the control device 110.

[0080] The operation unit 112 includes an input device (for example, a keyboard and a mouse) for receiving operation inputs from an operator to the control device 110 .

[0081] The output unit 114 is a device for outputting the results of program execution by the control device 110, data on the results of calculations, etc. The output unit 114 includes, for example, an operation UI (User Interface) and a monitor (for example, a liquid crystal display) for displaying the detection results. The output unit 114 may also include a printer, a speaker, etc. in addition to or instead of the monitor.

[0082] The control device 110 controls the measurement operation of the three-dimensional shape of the measurement surface (edge ​​portion 80 or notch portion 82) by the shape measurement device 100 in response to operation input from the operation unit 112, and performs calculations of the three-dimensional shape of the measurement surface. The control device 110 includes a processor (e.g., a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc.) that executes various calculations, memory (e.g., a ROM (Read Only Memory) and a RAM (Random Access Memory)), etc.) that serves as a working area for the processor, and a storage device (e.g., an SSD (Solid State Drive) or an HDD (Hard Disk Drive), etc.) for storing various programs and data.

[0083] The control device 110 functions as a measurement control unit 160, a calculation unit 162, and an analysis unit 164 by executing a program stored in a storage device using a processor.

[0084] The measurement control unit 160 controls the table driving unit 116, the optical unit driving unit 106, the light source unit 120, and the camera 128 to scan the optical unit 104 in the scanning direction (Z direction), while repeatedly capturing images of the measurement surface (edge ​​portion 80 or notch portion 82) of the measurement object using the camera 128 at a constant pitch. Specifically, the measurement control unit 160 controls the table driving unit 116 to rotate the measurement table 102 so that the measurement surface (edge ​​portion 80 or notch portion 82) of the measurement object is positioned opposite the optical unit 104. Furthermore, after starting emission of the measurement light L1 from the light source unit 120, the measurement control unit 160 controls the optical unit driving unit 106 to scan the optical unit 104 in the Z direction. In addition, while the optical unit driving unit 106 scans the optical unit 104 in the Z direction, the measurement control unit 160 repeatedly causes the camera 128 to capture the combined light L3 and output the captured image to the control device 110 each time the optical unit 104 moves a certain pitch in the Z direction, based on the detection result of the Z direction position of the optical unit 104 by the scale 130.

[0085] Each time the camera 128 captures an image of the combined light L3, the calculation unit 162 acquires the captured image output from the camera 128 and generates three-dimensional shape data of the measurement surface of the measurement target object. Specifically, the calculation unit 162 compares the brightness values ​​of each pixel at the same coordinates in each captured image. Next, the calculation unit 162 determines the Z-direction position at which the brightness value of each pixel at the same coordinates in each captured image is maximized, thereby calculating height information indicating the height position (Z-direction position) of each part of the measurement surface corresponding to each pixel. This generates three-dimensional shape data indicating the three-dimensional shape (height distribution) of the measurement surface.

[0086] The analysis unit 164 performs a shape analysis of the edge portion 80 (e.g., notch portion 82) of the wafer W based on the three-dimensional shape data of the measurement surface generated by the calculation unit 162. The analysis unit 164 determines whether the shape of the notch portion 82 is acceptable, for example, based on the three-dimensional shape of the notch portion 82. Specifically, the analysis unit 164 determines that there is a defect such as a scratch when the notch portion 82 includes a portion that deviates from the design value of the notch portion 82 by a threshold value or more, or a portion with a stepped shape or a roughness parameter (e.g., surface roughness (ISO 25178-2), etc.) that is a threshold value or more.

[0087] [Measuring the Shape of the Notch] Figure 7 is a diagram for explaining the procedure for measuring the shape of the notch portion 82. Figure 7(a) is a plan view of the wafer W, and Figure 7(b) is an enlarged plan view of part VIIb in Figure 7(a). Figure 7(c) is a YZ cross section (plane X = x ｉ ) is a cross-sectional view showing

[0088] In this embodiment, the analysis unit 164 determines the shape of the notch portion 82 shown in FIG. 7C (for example, the vertex in the Z direction (the coordinate of the point where the Z coordinate is maximum)). Then, based on the determined shape of the notch portion 82, a shape analysis of the notch portion 82 (for example, determining whether the shape of the notch portion 82 is good or bad, detecting defects such as scratches, etc.) is performed.

[0089] Incidentally, the measurement data Di of the coordinates of the surface of the notch portion 82 measured by the shape measuring device 100 may contain random noise-like components. In the example shown in FIG. 7(d), the measurement data Di (X=x ｉ7(d) shows an example of a trajectory obtained from measurement data Di viewed from the Z direction. In the example shown in FIG. 7(d), the trajectory obtained from measurement data Di is not a smooth curve (including straight lines, line segments, and half-lines), and the influence of random noise-like components appears.

[0090] Therefore, in this embodiment, as shown in FIG. 7E, an approximation curve Li (including a straight line, a line segment, and a half-line) is calculated from the measurement data Di, and the shape of the notch portion 82 is analyzed.

[0091] It should be noted that when measuring the shape of the notch portion 82, it is assumed that the wafer W alignment process (alignment process) and the process of determining the position (angular position) of the notch portion 82 using the orientation flat / notch detection sensor have been completed in advance.

[0092] In the alignment process, the center C0 of the wafer W is aligned with the center (rotation axis G) of the measuring table 102. The alignment process is performed using, for example, a diameter measuring instrument including a camera (including, for example, an imaging element such as a CCD or CMOS). Specifically, the wafer W is placed on the measuring table 102 and images are taken while being rotated. The analysis unit 164 detects changes in the position of the edge portion 80 of the wafer W from the captured images for each rotation angle. The analysis unit 164 calculates the distance between each of the end points of the multiple edge portions 80 detected for each rotation angle and the center (G) of the measuring table 102, and calculates the diameter of the wafer W and the amount of misalignment of the center C0 of the wafer W with respect to the center (G) of the measuring table 102 based on these distances. This allows the center C0 of the wafer W to be aligned with the center (rotation axis G) of the measuring table 102.

[0093] First, a coordinate system for analyzing the notch portion 82 (hereinafter referred to as the analytical coordinate system) is created. For example, the analysis unit 164 acquires the front or back surface of the wafer W (an approximate plane; for example, a surface determined by least-squares approximation from the coordinates of the front or back surface of the wafer W), and creates the analytical coordinate system based on the front or back surface of the wafer W. Specifically, the direction perpendicular to the front or back surface of the wafer W can be defined as the Y direction. Furthermore, for rotation around the Y axis, for example, the Z direction of the shape measuring apparatus 100 can be defined as the Z direction of the analytical coordinate system. This allows the X, Y, and Z directions of the analytical coordinate system to be determined.

[0094] Next, a YZ section (plane X = x ｉ ), the maximum value of the Z coordinate and the Y coordinate at that time are obtained from the measurement data Di by the shape measuring device 100. Note that the calculation of the maximum value may be performed after applying the filter.

[0095] If there is design information or the like about the shape of the tip of the notch portion 82, the measurement data Di may be fitted using the shape based on the design information or the like, and the apex of the approximation curve Li obtained by fitting may be found. For example, as shown in FIG. 7C, the Z-direction region of the notch portion 82 (for example, the design dimension z ｃ ), the measurement range of the actual shape by the shape measuring device 100 (or the extraction range of the measurement data Di from the measurement results by the shape measuring device 100) is set to the design dimension z ｃ The range may be limited to a range defined by

[0096] An example of approximating the measurement data Di with a quadratic curve will be described below. For example, the approximation curve near the apex of the notch 82 in the Z direction is expressed as Z=-k(Y-a). ２ +b, and the parameters k, a, and b are determined by approximating the measurement data Di (for example, by the least squares method), where the parameter a is the coordinate of the vertex in the Z direction.

[0097] plane X=x ｉ The sequence of points obtained by measuring the shape of the notch portion 82 along (i=1 to nx) is called (x １ , y １ , z １), ..., (x ｉ , y ｉ , z ｉ ), ..., (x ｎｘ , y ｎｙ , z ｎｚ ) The least squares curve Li (i = 1 to nx) is calculated from this sequence of points. For simplicity, let us consider the plane X = x ｉ Let's say there is a point on the plane X = x ｉ If there is no point on the ｉ You can calculate the above points.

[0098] The obtained least squares curve Li (i = 1 to nx) is expressed as (x ｉ , y ２，１ , z ２，１ ), ..., (x ｉ , y ２，ｉ , z ２，ｉ ), ..., (x ｉ , y ２，ｎｙ , z ２，ｎｚ )

[0099] In the above example, the sequence of points (x ｉ , y ２，１ , z ２，１ ), ..., (x ｉ , y ２，ｉ , z ２，ｉ ), ..., (x ｉ , y ２，ｎｙ , z ２，ｎｚ ) shows an example in which Y is regressed on Z (linear regression), but the method for obtaining the approximation curve is not limited to this.

[0100] Furthermore, the target of shape measurement and shape analysis is not limited to the notch portion 82. For example, the shape measurement according to this embodiment can also be applied to the edge portion 80 of the wafer W where no notch portion 82 is formed, or to an orientation flat, etc.

[0101] [Shape Analysis Example 1] In this embodiment, a shape analysis of the notch portion 82 is performed using the least-squares curve Li obtained as described above. For example, the least-squares curve Li is compared with the design values ​​of the notch portion 82 of the wafer W. Note that, instead of or in addition to the design values, the object to be compared with the least-squares curve Li may be the result of measuring a wafer master work whose shape and dimensions are known, or the result of measurement using the optical projection measurement method described in Patent Document 2. Furthermore, a process of superimposing the least-squares curve Li on the object to be compared (best-fit process) may be performed to compare the shapes of the two.

[0102] If the comparison result does not satisfy a predetermined standard (for example, if it exceeds a threshold), the analysis unit 164 determines that there is an abnormality (NG) in the notch portion 82. Then, the analysis unit 164 outputs the determination result to the output unit 114 (for example, by displaying it on a monitor or providing audio guidance).

[0103] For example, the analysis unit 164 calculates the plane X=x obtained from the least squares curve Li. ｉ If the difference or absolute value of the difference between the position of the vertex in the Z direction (Y coordinate) and the design value is greater than or equal to a threshold value, it may be determined that there is an abnormality in the notch portion 82 (NG), and if it is less than the threshold value, it may be determined that there is no abnormality (OK).

[0104] Furthermore, when determining the least squares curve Li, the nominal shape may be removed by the least squares method, or a short wavelength pass filter of an appropriate length may be applied, and then roughness parameter analysis (ISO21920-2, ISO12085 (ISO: International Organization for Standardization), etc.) may be performed.

[0105] [Embodiment 2 of Shape Analysis] FIG. 8 is a perspective view for explaining shape analysis according to embodiment 2. As shown in FIG.

[0106] In Example 1, the plane X=x ｉ Similarly, the plane Y = y ｋ If we focus on (k=1 to ny), we can see that the sequence of points (x ３，ｉ , y ｋ , z ３，１ ), ..., (x ３，ｉ , yｋ , z ３，ｉ ), ..., (x ｎｘ , y ｋ , z ２，ｎｚ ) can be obtained, and the following processes (1) to (3) are performed on this curve. ｋ Although the parameter a in the first embodiment may be used, the design information may also be used and the present invention is not limited to this.

[0107] (1) For the curve Ls corresponding to the above-mentioned sequence of points, a cross section shifted by α and β in the Y direction and a cross section of the original shape are obtained. In Fig. 8, two curves Lα and Lβ are obtained by shifting the curve Ls, but the number of shifted curves is not limited to two and may be three or more.

[0108] (2) The lowest points P0, Pα, and Pβ in the Z direction (points with the smallest Z coordinates) of the three curves Ls, Lα, and Lβ are found.

[0109] Here, the deviation amounts α and β may be manually input by, for example, displaying a user interface illustrated in FIG. 9 on the output unit 114. Alternatively, the deviation amounts α and β may be automatically set by the analysis unit 164. For example, when the reference curve Ls is biased near the front or back surface of the wafer W, the deviation amounts α and β may be set so that the three curves are not biased with respect to the center in the thickness direction of the wafer W, or the number of curves may be increased. For example, when the curve Ls is close to the front surface of the wafer W, the curves Lα and Lβ may be set near the back surface and in the vicinity of the saddle point SP (see FIG. 10).

[0110] (3) A curve LY connecting the three points P0, Pα, and Pβ is determined. Here, the curve LY is determined by, for example, polynomial approximation, piecewise polynomial approximation, or a B-spline curve.

[0111] From the above analysis, the curve LY of the outer peripheral surface that passes through the saddle point SP of the notch portion 82 and runs along a direction (Y direction) substantially perpendicular to the front or back surface of the wafer W can be obtained.

[0112] In Example 2, the shape of the notch portion 82 is analyzed using the curve LY obtained as described above. For example, the curve LY is compared with the design value of the notch portion 82 of the wafer W. Note that, instead of or in addition to the design value, the object to be compared with the curve LY may be the result of measuring a wafer master work whose shape and dimensions are known, or the result of measurement using the optical projection measurement method described in Patent Document 2. Furthermore, a process of superimposing the curve LY and the object to be compared (best fit process) may be performed to compare the shapes of the two.

[0113] If the comparison result does not satisfy a predetermined standard (for example, if it exceeds a threshold), the analysis unit 164 determines that there is an abnormality (NG) in the notch portion 82. Then, the analysis unit 164 outputs the determination result to the output unit 114 (for example, by displaying it on a monitor or providing audio guidance).

[0114] For example, the analysis unit 164 may determine that there is an abnormality (NG) in the notch portion 82 if the difference or absolute value of the difference between the position (Y coordinate) of the saddle point obtained from the curve LY and the design value is greater than or equal to a threshold value, and may determine that there is no abnormality (OK) if it is less than the threshold value.

[0115] Furthermore, when determining the least squares curve Li and the curve LY, the nominal shape may be removed by the least squares method, or a short wavelength pass filter of an appropriate length may be applied, and then roughness parameter analysis (ISO 21920-2, ISO 12085, etc.) may be performed.

[0116] [Modification of Second Embodiment of Shape Analysis] In the second embodiment, curves LX and LY in two directions, X and Y, that pass through the saddle point SP can be determined, as shown in Fig. 10. Then, by interpolating or extrapolating using the curves LX and LY, it is possible to generate the surface shape of a region specified with the region including the saddle point SP as the reference (center), and the generated region can be extracted.

[0117] This region may be manually input by displaying a user interface shown in Fig. 11 on the output unit 114, where the range in the X and Y directions is based on the saddle point SP (center). The region may be designated as a band-shaped region based on the curve LX or LY by leaving ±X or ±Y blank. Instead of inputting numerical values, the shape of the saddle in Fig. 10 may be displayed and designated with a pointing device such as a mouse.

[0118] In the second embodiment, the area specification based on the saddle point SP is designed to specify an area that is rectangular when projected onto the XY plane. However, this is not limiting. For example, an area of ​​any shape other than a rectangle (e.g., a polygon, a circle, or an oval (e.g., an ellipse, an oval, etc.)) may be specified when projected onto the XY plane. Specifically, the radius of a circle based on the saddle point SP, or the major and minor axes of an oval shape, may be input numerically. Furthermore, a UI (e.g., a button or an icon) for selecting the shape of the area (e.g., a rectangle, a polygon, an oval, or any other shape) may be provided, and an area of ​​the selected shape may be specified using a pointing device.

[0119] Furthermore, the area designation is not limited to the example in which it is performed based on a projection surface onto the XY plane, but may be performed three-dimensionally. For example, the area designation may be performed using three-dimensional coordinates. Furthermore, the area designation may be performed by using a pointing device to designate voxels of the three-dimensional image displayed on the output unit 114.

[0120] Shape analysis of the notch portion 82 is performed using the surface shape of the notch portion 82 in the extracted region as described above. For example, the extracted region is compared with the design values ​​of the notch portion 82 of the wafer W. Note that, instead of or in addition to the design values, the results of measuring a wafer master work whose shape and dimensions are known, or the results of measurement using the optical projection measurement method described in Patent Document 2, may be used as the object to be compared with the extracted region. A process (best-fit process) may be performed to superimpose the curve LY and the object to be compared, and the shapes of the two may be compared. Shape analysis may also be performed on area data obtained by extracting a desired region from the three-dimensional shape of the edge of the wafer W, not limited to the notch portion 82.

[0121] If the comparison result does not satisfy a predetermined standard (for example, if it exceeds a threshold), the analysis unit 164 determines that there is an abnormality (NG) in the notch portion 82. Then, the analysis unit 164 outputs the determination result to the output unit 114 (for example, by displaying it on a monitor or providing audio guidance).

[0122] Alternatively, the nominal shape may be removed from the extracted region using design values, or a short-wavelength pass filter of an appropriate length may be applied, and then the surface shape may be quantified and compared using three-dimensional surface texture parameters (ISO 25178-2) or the like.

[0123] According to this embodiment, by using the shape measuring device 100, it is possible to analyze the shape of the notch portion 82 (saddle portion), and to quantify the shape or roughness of the saddle portion. Furthermore, by quantifying the shape or roughness of the saddle portion, it is possible to determine whether or not there is an abnormality in the notch portion 82 (pass / fail judgment) based on a threshold value. Furthermore, it is possible to perform analysis and pass / fail judgment similar to those of the light projection measurement method.

[0124] Furthermore, in this embodiment, the numerical values ​​are recorded for multiple wafers W. If the numerical abnormalities for a series of wafers W show the same tendency, it can be determined that there is a problem with the grinding wheel. Detecting abnormalities in the grinding wheel is particularly effective for areas that are shaded by the light projection measurement method. It is also possible to feed back the results of grinding wheel abnormality detection to the processing conditions.

[0125] [Others] In the above-described shape analysis, in addition to the measurement data Di of the notch portion 82 (saddle portion), data on the front or back surface of the wafer W is used. If the tilt sensitivity of the shape measuring device 100 is low, it is difficult to simultaneously obtain the measurement data of the saddle portion and the data on the front or back surface.

[0126] 12 is a perspective view showing an example of determining an analytical coordinate system using a master workpiece. As shown in FIG. 12, a master workpiece M is placed on the measurement table 102 instead of the wafer W. The master workpiece M is a workpiece in which the angles between the surfaces that make up the master workpiece M are known, and for example, a right-angle gauge or the like can be used. The master workpiece M is fixed on the measurement table 102 by, for example, suction or its own weight.

[0127] For example, if the master work M has a substantially rectangular parallelepiped shape, it is placed so that the normal direction of one face is substantially oriented toward the center (rotation axis G) of the measurement table 102. The rotation axis G of the measurement table 102 and the Y direction of the optical unit 104 are made substantially coincident (substantially parallel). The position of the optical unit 104 in the Y direction is adjusted so that the optical unit 104 faces the surface to be measured of the master work M. The angle of the rotation axis of the optical unit 104 is also adjusted so that the reflected light to the optical unit 104 is maximized.

[0128] After the above adjustments, the master workpiece M is measured. Specifically, while the optical unit 104 is scanned in the Z direction, the coordinates of multiple points on the measurement surface of the master workpiece are detected based on the images captured by the camera 128 at predetermined intervals. A least-squares plane is then calculated from the coordinates of the point cloud consisting of these multiple points, and an XY plane is determined from the least-squares plane of the master workpiece M. Regarding the degree of freedom of rotation in the Z-axis direction, for example, the Y direction of the shape measuring device 100 can be determined as the Y direction of the analytical coordinate system. This allows the analytical coordinate system to be determined.

[0129] Since the rotation axis G of the measurement table 102 and the Y direction of the profile measuring device 100 are substantially aligned (adjusted to be substantially parallel), defining the Y direction of the profile measuring device 100 as the Y direction of the analytical coordinate system does not pose any practical problems in the profile analysis described above. Furthermore, when comparing with design values, etc., a best fit with the surface profile (measured profile) of the notch portion 82 is performed, so no practical problems in the profile analysis described above arise.

[0130] Here, if the measurement range MR of the shape measuring device 100 includes the edge portion ME of the master work M (for example, data near the edge), the data near the edge may be removed to obtain the least squares plane MS (XY plane), as shown in Figure 13.

[0131] As described above, by using a master work M in which the angles between each surface are known, the XY plane can be determined even when it is difficult to obtain data on the front or back surface of the wafer W.

[0132] In the above embodiment, the measuring unit 20 is described as being equipped with a shape measuring device having a white light interference microscope, but this is not limited to this, and the measuring unit 20 may be equipped with a shape measuring device having a microscope such as a focus variation microscope or a laser confocal microscope.

[0133] Second Embodiment As shown in FIG. 14 , an edge portion 80 is formed along the circumferential direction of the outer periphery of a chamfered wafer W at the end of the wafer W, and a notch portion 82, which is a cutout portion, is formed in a portion of the circumferential direction of the outer periphery. The edge portion 80 and the notch portion 82 each have a chamfered portion 84. As shown in the enlarged view in the upper left of FIG. 14 , the notch portion 82 has a generally U-shaped or V-shaped configuration and is broadly divided into linear portions 82a, 82a on both sides and a bottom portion 82b. The bottom portion 82b is located at the back of the notch portion 82 and is a curved portion having a predetermined curvature. The linear portions 82a, 82a are linear portions, one end of each of which is connected to both ends of the bottom portion 82b. The other end of each of the linear portions 82a, 82a is connected to the edge portion 80, which constitutes the outer periphery of the wafer W.

[0134] The cross-sectional shape of the edge portion 80 is provided with an inclined surface S and a flat surface F, as shown in the enlarged view at the lower right of Fig. 14. Specifically, two inclined surfaces S, S that are inclined obliquely with respect to the thickness direction of the wafer W are formed on the upper surface Wu side and the lower surface Wd side of the wafer W, respectively, and a flat surface F that is approximately perpendicular to the thickness direction of the wafer W is formed between the two inclined surfaces S, S. Although not shown, the cross-sectional shape of the notch portion 82 is also a shape common to the cross-sectional shape of the edge portion 80. Note that, although the cross-sectional shape shown in Fig. 14 is shown here as an example of the cross-sectional shapes of the edge portion 80 and the notch portion 82, the cross-sectional shapes are not limited to this, and may be rounded shapes with rounded corners or other shapes.

[0135] In the wafer manufacturing process, it is important to check that there are no scratches or chips on the edge of the chamfered wafer, and to accurately measure the shape of the edge and check that the shape is within the tolerance range for the design shape.

[0136] For example, Japanese Patent Laid-Open Publication No. 2001-4341 discloses a shape measuring device that measures the shape of a wafer edge by an optical projection measurement method. This shape measuring device projects light onto the edge of a chamfered wafer from a direction approximately parallel to both the front and back surfaces of the wafer, captures a projected image of the wafer edge from a direction opposite to the light projection direction using a camera, and measures the shape of the wafer edge based on the projected image. The outline of the projected image obtained by this method is the cross-sectional shape of the wafer edge (the shape of a cross section cut in the thickness direction).

[0137] Furthermore, Japanese Patent Laid-Open Publication No. 2023-139925 discloses a three-dimensional shape measuring device that optically measures three-dimensional shapes such as the surface shape and surface roughness shape of a measurement surface of a measurement target. This three-dimensional shape measuring device measures the three-dimensional shape of a measurement surface by combining the WLI (White Light Interferometry) method (white light interferometry) and the FV (Focus Variation) method (focus variation method) based on multiple captured images taken by a camera at a fixed pitch while scanning a white light interferometer in a direction perpendicular to the measurement surface (Z direction).

[0138] Here, the WLI method is a method for calculating three-dimensional shape data indicating height information of the measurement target surface of the measurement object based on the Z direction position where the brightness value in the Z direction is maximum for each pixel at the same coordinates in each captured image. The FV method is a method for calculating the focus degree for each pixel in each captured image, and for calculating three-dimensional shape data indicating height information of the measurement target surface of the measurement object based on the Z direction position where the focus degree is maximum for each pixel at the same coordinates in each captured image.

[0139] The WLI method has the advantage of having high resolution in the height direction of the surface to be measured (nm or less) and being good at measuring the roughness of surfaces that are nearly perpendicular to the scanning direction (Z direction) parallel to the optical axis of the white light interference microscope (interference objective lens), but has the disadvantage of low measurement sensitivity for inclined surfaces that are inclined with respect to the scanning direction.On the other hand, the FV method has the disadvantage of having lower resolution in the height direction of the surface to be measured compared to the WLI method, but has the advantage of high measurement sensitivity for inclined surfaces and being good at measuring the shape of inclined surfaces.

[0140] The three-dimensional shape measuring device disclosed in JP 2023-139925 A takes advantage of the advantages of the two methods, and generates three-dimensional shape data of the surface to be measured by selecting the result of three-dimensional shape calculation by the WLI method or the result of three-dimensional shape calculation by the FV method, whichever has the higher accuracy for each pixel.

[0141] The shape measurement device disclosed in JP 2001-4341 A uses an optical projection measurement method, which, by its very nature, is unable to acquire shape data for areas that are shaded by the camera. Therefore, even if scratches or chips exist on the edge of the wafer, they may not be detected. Furthermore, while surface roughness is an important factor in determining the quality of the wafer edge, it is impossible to measure surface roughness using the optical projection measurement method.

[0142] In response to this, it is conceivable to apply the three-dimensional shape measuring device disclosed in Japanese Patent Laid-Open Publication No. 2023-139925 to measure the three-dimensional shape of the edge (edge ​​or notch) of a chamfered wafer. However, this three-dimensional shape measuring device has the following problems.

[0143] 15, a white light interference microscope 900 used in the three-dimensional shape measuring apparatus disclosed in Japanese Patent Laid-Open No. 2023-139925 uses a coaxial epi-illumination method to capture an image of a measurement surface 902. The coaxial epi-illumination method is an illumination method in which the optical axis of the illumination light (measurement light) irradiating the measurement surface 902 is aligned with the optical axis of the white light interference microscope 900 (the optical axis of the camera), and reflected light from the measurement surface 902 of the measurement target is obtained.

[0144] The three-dimensional shape measurement device disclosed in Japanese Patent Application Laid-Open Publication No. 2023-139925 uses both the WLI method and the FV method to calculate three-dimensional shape data. However, as shown in FIG. 15 , when the measurement surface 902 contains a mixture of flat and inclined surfaces, it is necessary to irradiate the inclined surfaces with illumination light as uniformly as possible. If the intensity of the light reflected from the inclined surface and directed toward the camera of the white light interference microscope 900 becomes uneven, the sensitivity will be insufficient in the low-reflected light area (inclined surface). In this case, the FV method may result in a decrease in the calculation accuracy of the three-dimensional shape data of the inclined surface, or may even be unable to perform the calculation at all. In this case, the camera gain and integration time must be adjusted to fit the maximum intensity of the reflected light from the inclined surface within the dynamic range.

[0145] However, if such adjustments are made, with illumination light from the coaxial incident-light illumination method, the reflected light will be too strong in the area corresponding to the flat surface (specular reflection area) that is the front facing part of the white light interference microscope 900 in the captured image 904 captured by the camera of the white light interference microscope 900, resulting in a bright area (high-brightness area), and the sensitivity of other areas, i.e., areas corresponding to the inclined surface, will be insufficient and result in a dark area. In this case, with the WLI method, it will be impossible to obtain information on interference fringes in the area of ​​high reflected light intensity (i.e., the front facing part) in the captured image 904 (i.e., the preset measurement range will be exceeded), and the calculation accuracy of the three-dimensional shape data will decrease.

[0146] As such, there is room for improvement in applying the three-dimensional shape measuring device disclosed in JP 2023-139925 A to measuring the three-dimensional shape of the measurement surface at the end (edge ​​portion or notch portion) of a chamfered wafer.

[0147] Therefore, in the second embodiment, a shape measuring device and a shape measuring method are provided that can measure the three-dimensional shape of the measurement surface at the edge of a wafer with high accuracy.

[0148] The second embodiment will be described below with reference to the accompanying drawings. Note that the wafer processing system 10 is the same as that of the first embodiment (FIG. 1), and therefore a description thereof will be omitted.

[0149] [Shape Measuring Apparatus] Next, a description will be given of the configuration of the shape measuring apparatus 100. This shape measuring apparatus 100 is an example of the shape measuring apparatus of the present invention, and uses both the WLI method and the FV method in combination to calculate three-dimensional shape data indicating height information (surface shape, surface roughness, etc.) of the measurement surface of the edge of the wafer W, which is the measurement object, based on a plurality of captured images captured at a constant pitch while scanning an optical unit 104 (white light interference microscope) described below in the scanning direction (Z direction).

[0150] Fig. 16 is a side view (viewed from the X direction) showing a schematic configuration of the shape measuring device 100. Fig. 17 is a plan view (viewed from the Y direction) showing a schematic configuration of the shape measuring device 100.

[0151] As shown in FIGS. 16 and 17, the shape measuring apparatus 100 mainly comprises a measuring table 102, an optical unit 104, a side illumination unit 108, and a control device 110.

[0152] The measuring table 102 has a holding surface 102a on its upper surface that suction-holds the wafer W. The measuring table 102 is configured to be rotatable about a rotation axis G that is parallel to the Y direction. The table driving unit 116 is configured with various actuators such as a motor driving mechanism, and rotates the measuring table 102 about the rotation axis G under the control of a control device 110, which will be described later. As a result, the wafer W suction-held on the holding surface 102a of the measuring table 102 rotates and moves about the rotation axis G.

[0153] The optical unit 104 is provided at a position adjacent to one side in the Z direction (the left side in FIG. 16 ) of the measurement table 102. This optical unit 104 has an optical axis R (corresponding to the optical axis of an interference objective lens 124 (see FIG. 18 ) described later) parallel (including approximately parallel) to the main surface (upper surface Wu or lower surface Wd) of the wafer W, and includes a light source unit (depicted by reference numeral 120 in FIG. 18 ) that irradiates a measurement surface (depicted by reference numeral T in FIG. 18 ) of the measurement target (the edge of the wafer W) with coaxial epi-illumination light (measurement light L1 described later) along the optical axis R, and a camera (depicted by reference numeral 128 in FIG. 18 ) that is provided coaxially with the optical axis R and captures an image of reflected light from the measurement surface. That is, the optical axis R of the optical unit 104 is arranged so as to be parallel (including approximately parallel) to a direction perpendicular to the rotation axis G of the measurement table 102 (preferably so as to intersect with the rotation axis G of the measurement table 102). The optical unit 104 then captures an image of the edge (edge ​​portion 80 or notch portion 82) of the wafer W from a position facing the edge of the wafer W held on the measurement table 102. The configuration of the optical unit 104 will be described later.

[0154] The side illumination unit 108 irradiates the edge of the wafer W, which is imaged by the camera of the optical unit 104, with side illumination light M from a direction (Y direction) perpendicular to the optical axis R of the optical unit 104. The configuration of the side illumination unit 108 will be described later.

[0155] Next, a detailed description will be given of the configuration of the optical unit 104. Fig. 18 is a schematic diagram showing the configuration of the optical unit 104 in detail.

[0156] The optical unit 104 is a Michelson-type white light interference microscope. As shown in Fig. 18, the optical unit 104 includes a light source unit 120, a beam splitter 122, an interference objective lens 124, an imaging lens 126, and a camera 128. The interference objective lens 124, the beam splitter 122, the imaging lens 126, and the camera 128 are arranged in this order along the left side in the Z direction from the measurement surface T at the edge of the wafer W, which is the measurement object. The light source unit 120 is also arranged at a position opposite the beam splitter 122 in the Y direction.

[0157] Under the control of the control device 110, the light source unit 120 emits a parallel beam of white light (low-coherence light) as measurement light L1 toward the beam splitter 122. Although not shown, the light source unit 120 includes a light source capable of emitting measurement light L1, such as a light-emitting diode, a semiconductor laser, a halogen lamp, or a high-intensity discharge lamp, and a collector lens that converts the measurement light L1 emitted from the light source into a parallel beam.

[0158] A half mirror, for example, is used as the beam splitter 122. The beam splitter 122 reflects a portion of the measurement light L1 incident from the light source unit 120 toward the interference objective lens 124 on the right side in the Z direction. The beam splitter 122 also transmits a portion of the combined light L3 (described below) incident from the interference objective lens 124 to the left side in the Z direction, and emits this combined light L3 toward the imaging lens 126.

[0159] The interference objective lens 124 is a Michelson type and includes an objective lens 124A, a beam splitter 124B, and a reference surface 124C. The beam splitter 124B and the objective lens 124A are arranged in this order along the left side in the Z direction from the side of the surface T to be measured. Furthermore, the reference surface 124C is arranged at a position opposite the beam splitter 124B in the Y direction. While the following description will be given using a Michelson type interference optical system, the interference optical system is not limited to the Michelson type, and known interference optical systems such as a Mirau type or a Linnik type can also be used.

[0160] The objective lens 124A has a light-condensing function, and condenses the measurement light L1 incident from the beam splitter 122 onto the measurement surface T through the beam splitter 124B.

[0161] The beam splitter 124B is, for example, a half mirror. The beam splitter 124B splits a portion of the measurement light L1 incident from the objective lens 124A as reference light L2, transmits the remaining measurement light L1, and emits it toward the measurement surface T, while reflecting the reference light L2 toward the reference surface 124C. The measurement light L1 transmitted through the beam splitter 124B is irradiated onto the measurement surface T, and is then reflected by the measurement surface T and returns to the beam splitter 124B.

[0162] The reference surface 124C is, for example, a reflecting mirror, and reflects the reference light L2 incident from the beam splitter 124B toward the beam splitter 124B. The position of this reference surface 124C in the Y direction can be manually adjusted by a position adjustment mechanism (e.g., a ball screw mechanism, an actuator, etc.) not shown. This makes it possible to adjust the optical path length (reference optical path length) of the reference light L2.

[0163] The beam splitter 124B generates a combined light L3 from the measurement light L1 returning from the measurement surface T and the reference light L2 returning from the reference surface 124C, and emits this combined light L3 toward the objective lens 124A on the left side in the Z direction. This combined light L3 passes through the objective lens 124A and the beam splitter 122 and enters the imaging lens 126.

[0164] The imaging lens 126 forms an image of the combined light L3 incident from the beam splitter 122 on an imaging plane (not shown) of the camera 128. Specifically, the imaging lens 126 forms an image of a point on the focal plane of the objective lens 124A as an image point on the imaging plane of the camera 128.

[0165] Although not shown, the camera 128 has a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) imaging element. The camera 128 captures an image of the combined light L3 formed on the imaging surface of the imaging element by the imaging lens 126, processes the imaging signal of the combined light L3 obtained by this imaging, and outputs an imaging signal. The camera 128 is an example of an imaging unit.

[0166] The optical unit driving unit 106 is composed of various actuators such as a linear motor or a motor driving mechanism, and holds the optical unit 104 so that it can move freely in the Z direction, which is the scanning direction. Under the control of the control device 110, the optical unit driving unit 106 scans the optical unit 104 in the Z direction, i.e., along a direction parallel to the optical axis R of the optical unit 104. The optical unit driving unit 106 is an example of a relative moving unit.

[0167] Furthermore, the optical unit driving unit 106 holds the optical unit 104 so that it can move not only in the Z direction but also in the Y and X directions. This makes it possible to adjust the relative position (relative position in the X and Y directions) of the optical unit 104 with respect to the edge of the wafer to be measured. Furthermore, if there is a limit to the measurement field of view of the measurement surface T that can be measured in one measurement due to limitations such as the measurement field of view of the interference objective lens 124, it is possible to perform multiple measurements while moving the optical unit 104 in the X or Y direction. Note that instead of moving the optical unit 104 in the X, Y, or Z directions, the measurement table 102 may be moved in the X, Y, or Z directions.

[0168] The scale 130 is a position detection sensor, such as a linear scale, that detects the Z-direction position of the optical unit 104. The scale 130 repeatedly detects the Z-direction position of the optical unit 104 and repeatedly outputs the position detection result to the control device 110.

[0169] Next, the configuration of the side lighting unit 108 will be described in detail. Fig. 19 is a schematic diagram showing the configuration of the side lighting unit 108. In Fig. 19, 1006A is a top view of the side lighting unit 108 (viewed from the Y direction), 1006B is a side view of the side lighting unit 108 (viewed from the X direction), and 1006C is a front view of the side lighting unit 108 (viewed from the Z direction). Fig. 20 is a diagram (corresponding to 1006B in Fig. 19) showing a state when the measurement surface T is switched between the notch portion 82 and the edge portion 80.

[0170] 19 and 20 , the side illumination unit 108 includes a pair of side light emitters 150A, 150B that are arranged facing each other on both sides of the edge of the wafer W, which is the measurement object, in a direction perpendicular to the optical axis R (Y direction). Of the pair of side light emitters 150A, 150B, one side light emitter 150A is arranged on the upper surface Wu side of the wafer W, and the other side light emitter 150B is arranged on the lower surface Wd side of the wafer W. Each side light emitter 150A, 150B has a rod-like shape (e.g., a cylindrical or prismatic shape) whose longitudinal direction is along the optical axis R of the optical unit 104 (Z direction). Each side light emitter 150A, 150B is an example of a rod-shaped light emitter.

[0171] Fig. 21 is a schematic diagram showing an example of the configuration of the side light emitter 150. In Fig. 21, the side light emitters 150A and 150B are collectively indicated by the reference numeral 150.

[0172] As shown in 1008A of FIG. 21 , side light emitter 150 of a first configuration example has a plurality of small LEDs (Light Emitting Diodes) 152 arranged in a line along the Z direction. Also, as shown in 1008B of FIG. 21 , side light emitter 150 of a second configuration example has a configuration in which a plurality of small LEDs 152 are arranged in a line along the Z direction, and further has a light scatterer 154 on the emission surface of each LED 152. In this case, light emitted from each LED 152 is irradiated as diffused light toward the edge of wafer W via light scatterer 154. Also, as shown in 1008C of FIG. 21 , side light emitter 150 of a third configuration example has an elongated light guide 156 whose longitudinal direction is the Z direction and an LED 152 provided at one end of light guide 156, and light emitted from LED 152 is irradiated toward the edge of wafer W through light guide 156. The side light emitters 150 (150A, 150B) are not limited to the configurations of the first to third configuration examples described above, and may have other configurations.

[0173] As shown in FIGS. 19 and 20 , the length of each side light emitter 150A, 150B in the longitudinal direction (Z direction) is longer than the edge of the wafer W. Specifically, as shown by 1006A in FIG. 19 , each side light emitter 150A, 150B is configured to be at least longer than the depth D of the notch portion 82 (the radial length of the wafer W). Regardless of whether the measurement surface T is the notch portion 82 or the edge portion 80, when the edge of the wafer W is viewed from one side in the Y direction, each side light emitter 150A, 150B is positioned so as to overlap the measurement surface T (the notch portion 82 or the edge portion 80). This allows the optical unit 104 to uniformly irradiate the inclined surface S of each portion with side illumination light M when imaging the measurement surface T, regardless of whether the measurement surface T is the notch portion 82 (shown by the solid line in FIG. 20 ) or the edge portion 80 (shown by the dashed line in FIG. 20 ).

[0174] 19 , when notch portion 82 is viewed from the front side (i.e., the side where optical unit 104 is disposed, in the Z direction), notch portion 82 has inclined surfaces S that expand in a funnel shape toward both the upper surface Wu and the lower surface Wd of wafer W. According to side illumination unit 108 of the present embodiment, each side light emitter 150A, 150B has a rod-like shape with the longitudinal direction in the Z direction, and the outer width H in the X direction is formed smaller than the opening width Q of notch portion 82, thereby adopting a configuration that makes it easy to irradiate the side illumination light M onto the inclined surface S of notch portion 82. Generally, the inner wall surface (inclined surface S, etc.) of a concave portion such as notch portion 82 is easily shaded and therefore difficult to measure. However, the configuration of the present embodiment makes it easy to uniformly irradiate the side illumination light M onto the inclined surface S, enabling highly sensitive measurement.

[0175] Fig. 22 is a schematic diagram showing the configuration of a side illumination unit 910 according to a comparative example. As shown in Fig. 22, the side illumination unit 910 according to the comparative example includes a pair of point light emitters 912A and 912B positioned opposite each other across the edge of the wafer W. In the side illumination unit 910 according to the comparative example having such a configuration, the relative position of the measurement surface T with respect to each point light emitter 912A and 912B changes in the Z direction depending on whether the measurement surface T is the notch portion 82 (shown by the solid line in Fig. 22) or the edge portion 80 (shown by the dashed line in Fig. 22). As a result, there are cases in which the side illumination light M emitted from each point light emitter 912A and 912B does not sufficiently strike the inclined surface S. In this case, the ratio between the amount of light reflected from the flat surface F, which is the directly opposite part of the measurement light L1, which is coaxial incident illumination light, and the amount of light reflected from the inclined surface S, which is the side illumination light M, changes depending on the position of the measurement surface T, making it difficult to perform highly accurate calculation processing of three-dimensional shape data using both the WLI method and the FV method.

[0176] In contrast, the side lighting unit 108 of this embodiment, as shown in Figures 19 and 20, is equipped with a pair of side light emitters 150A, 150B whose longitudinal direction is the optical axis R of the optical unit 104, and therefore has the following effects.

[0177] Fig. 23 is a diagram for explaining the effect of the side lighting unit 108 of this embodiment. 1010A in Fig. 23 shows a case where the measurement surface T is an edge portion 80. 1010B in Fig. 23 shows a case where the measurement surface T is a notch portion 82.

[0178] As shown by reference numerals 1010A and 1010B in FIG. 23 , the light density of the side illumination light M emitted from each side light emitter 150A, 150B is approximately uniform across the Z direction, which is the longitudinal direction of each side light emitter 150A, 150B. Therefore, even if the position of the measurement surface T changes in the Z direction as the measurement surface T switches between the edge portion 80 and the notch portion 82, the side illumination light M is irradiated with a uniform light density onto each inclined surface S of the edge portion 80 and the notch portion 82. That is, the amount of irradiation of the side illumination light M contributing to the reflected light from each inclined surface S is approximately equal whether the measurement surface T is the edge portion 80 or the notch portion 82. Therefore, the ratio between the amount of light reflected from the flat surface F, which is the directly opposite portion of the measurement light L1 (coaxial incident illumination light), and the amount of light reflected from the inclined surface S of the side illumination light L is approximately constant.

[0179] When calculating three-dimensional shape data of the measurement surface T using the WLI method, the side illumination light M becomes a noise source. On the other hand, when calculating three-dimensional shape data of the measurement surface T using the FV method, the measurement sensitivity of the inclined surface S is low with coaxial incident illumination light. Therefore, to improve measurement accuracy for the inclined surface S, it is necessary to illuminate the inclined surface S with side illumination light M. To achieve stable quality calculation of three-dimensional shape data of the measurement surface T by using both of these methods, it is important that the ratio of the side illumination light M to the light intensity of the coaxial incident illumination light (measurement light L1) does not change. In the side illumination unit 108 of this embodiment, each side light emitter 150A, 150 has a rod-like shape with the optical axis R of the optical unit 104 as its longitudinal direction. Therefore, the light density of the side illumination light M does not depend on the position of the measurement surface T, making it possible to maintain optimal illumination conditions regardless of the position of the measurement surface T. Therefore, three-dimensional shape data can be stably calculated using the two methods.

[0180] Therefore, according to the side illumination unit 108 of this embodiment, even if the position of the measurement surface T of the measurement target (edge ​​of the wafer W) changes in the direction (Z direction) along the optical axis R of the optical unit 104, it is possible to uniformly irradiate the side illumination light M onto the inclined surface S that constitutes a part of the measurement surface T. As a result, regardless of the position of the measurement surface T, the ratio between the amount of light reflected from the flat surface F, which is the directly opposite part of the measurement light L1, which is coaxial epi-illumination light, and the amount of light reflected from the inclined surface S of the side illumination light M, does not change, and it is possible to perform highly accurate arithmetic processing of three-dimensional shape data using both the WLI method and the FV method.

[0181] Next, the configuration of the control device 110 will be described. Fig. 24 is a functional block diagram of the control device 110. As shown in Fig. 24, the light source section 120 and camera 128 of the optical unit 104, the scale 130, the table driving section 116, the optical unit driving section 106, the side lighting unit 108, the operation section 112, and the output section 114 are connected to the control device 110.

[0182] The operation unit 112 includes operation members (for example, a keyboard and a mouse) for receiving operation inputs from an operator to the control device 110 .

[0183] The output unit 114 is a device for outputting the results of program execution by the control device 110, data on the results of calculations, etc. The output unit 114 includes, for example, an operation UI (User Interface) and a monitor (for example, a liquid crystal display) for displaying the detection results. The output unit 114 may also include a printer, a speaker, etc. in addition to or instead of the monitor.

[0184] The control device 110 controls the measurement operation of the three-dimensional shape of the measurement target surface T by the shape measurement device 100 in response to operation input from the operation unit 112, and performs calculations, etc., of the three-dimensional shape of the measurement target surface T. The control device 110 includes a processor (e.g., a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc.) that executes various calculations, memory (e.g., a ROM (Read Only Memory) and a RAM (Random Access Memory)), etc.) that serves as a working area for the processor, and a storage device (e.g., an SSD (Solid State Drive) or an HDD (Hard Disk Drive), etc.) for storing various programs and data.

[0185] The control device 110 functions as a measurement control unit 160 and a shape data generation unit 165 by executing a program stored in a storage device using a processor. The shape data generation unit 165 also functions as a first shape data generation unit 166, a second shape data generation unit 167, and an integrated calculation unit 168, which will be described later.

[0186] The measurement control unit 160 controls the table driving unit 116, the optical unit driving unit 106, the light source unit 120, the camera 128, and the side lighting unit 108 to scan the optical unit 104 in the scanning direction (Z direction), while repeatedly capturing images of the measurement target surface T (edge ​​portion 80 or notch portion 82) of the measurement target object using the camera 128 at a constant pitch. Specifically, the measurement control unit 160 controls the table driving unit 116 to rotate the measurement table 102 so that the measurement target surface T (edge ​​portion 80 or notch portion 82) of the measurement target object is positioned opposite the optical unit 104. Furthermore, the measurement control unit 160 starts emitting the measurement light L1 from the light source unit 120 and starts emitting the side lighting light M from the side lighting unit 108, and then controls the optical unit driving unit 106 to scan the optical unit 104 in the Z direction. In addition, while the optical unit driving unit 106 scans the optical unit 104 in the Z direction, the measurement control unit 160 repeatedly causes the camera 128 to capture the combined light L3 (including the reflected light of the side illumination light M) and output the captured image to the control device 110 each time the optical unit 104 moves a certain pitch in the Z direction, based on the detection result of the Z direction position of the optical unit 104 by the scale 130.

[0187] Furthermore, the measurement control unit 160 functions as a light intensity control unit that controls the intensity of the side illumination light M emitted from the side illumination unit 108 (side light emitters 150A, 150B). This allows the ratio of the intensity of the side illumination light M to the intensity of the measurement light L1 to be changed, making it possible to optimize the illumination conditions according to the shape of the measurement surface T of the measurement object, etc.

[0188] The shape data generation unit 165 acquires the captured image output from the camera 128 each time the camera 128 captures an image of the combined light L3, and generates three-dimensional shape data of the measurement surface T of the measurement target. The shape data generation unit 165 functions as a first shape data generation unit 166 that generates three-dimensional shape data (first shape data) of the measurement surface T using the WLI method, a second shape data generation unit 167 that generates three-dimensional shape data (second shape data) of the measurement surface T using the FV method, and an integration calculation unit 168 that calculates three-dimensional shape data (integrated shape data) of the measurement surface T by integrating the first shape data and second shape data generated by the two methods. The captured image output from the camera 128 may be acquired via a storage device (memory, storage device, etc.) provided in the control device 110.

[0189] The first shape data generation unit 166 calculates the three-dimensional shape of the measurement surface T using the WLI method based on multiple captured images taken by the camera 128 at a constant pitch while scanning the optical unit 104 in the Z direction. Specifically, the first shape data generation unit 166 compares the brightness values ​​of each pixel at the same coordinates in each captured image. Next, the first shape data generation unit 166 determines the Z-direction position at which the brightness value of each pixel at the same coordinates in each captured image is maximized, thereby calculating height information indicating the height position (Z-direction position) of each part of the measurement surface T corresponding to each pixel. This generates three-dimensional shape data (first shape data) indicating the three-dimensional shape (height distribution) of the measurement surface T.

[0190] The second shape data generation unit 167 calculates the three-dimensional shape of the measurement surface T using the FV method based on multiple captured images captured by the camera 128 at regular intervals while scanning the optical unit 104 in the Z direction. Specifically, the second shape data generation unit 167 calculates the focus level (contrast, sharpness) for each pixel in each captured image. For example, the second shape data generation unit 167 sets the pixel for which the focus level is to be calculated as a pixel of interest, and calculates the focus level using a known method based on the luminance value of this pixel of interest and the luminance values ​​of each pixel within a focus level calculation range based on the pixel of interest. The second shape data generation unit 167 repeatedly performs the focus level calculation process for all pixels in each captured image, thereby calculating the focus level for each pixel in each captured image.

[0191] After calculating the focus degree, the second shape data generation unit 167 compares the focus degree for each pixel at the same coordinates in each captured image and determines the Z-direction position at which the focus degree is maximized for each pixel at the same coordinates.The second shape data generation unit 167 then determines the focal position of the camera 128 with respect to the measurement surface T for each pixel at the same coordinates, thereby calculating height information indicating the height position (Z-direction position) of each part of the measurement surface T corresponding to each pixel.This generates three-dimensional shape data (second shape data) indicating the three-dimensional shape (height distribution) of the measurement surface T.

[0192] It should be noted that the three-dimensional shape calculation processing by the WLI method and the three-dimensional shape calculation processing by the FV method are well-known techniques, and therefore detailed explanations thereof will be omitted (see, for example, Japanese Patent Application Laid-Open No. 2023-139925).

[0193] After processing by the first shape data generation unit 166 and the second shape data generation unit 167, the integrated calculation unit 168 compares the first shape data with the second shape data and generates three-dimensional shape data (integrated shape data) of the measurement surface T by selectively combining the shape data with the higher accuracy.

[0194] The integrated shape data may be generated by, for example, the method disclosed in Japanese Patent Application Laid-Open Publication No. 2014-1964. In this method, the tilt angle (an example of an index value) of each pixel is calculated based on the second shape data generated by the FV method. The tilt angle for each pixel is compared with a preset tilt angle threshold. The first shape data is selected for pixels whose tilt angle is equal to or less than the tilt angle threshold, and the second shape data is selected for pixels whose tilt angle exceeds the tilt angle threshold. This generates integrated shape data in which the first shape data is selected for surfaces with small tilt angles and the second shape data is selected for surfaces with large tilt angles. As a result, the surface shape and surface roughness of the flat surface F of the measurement surface T can be measured with high accuracy, while the inclined surface S can be measured with high sensitivity.

[0195] Alternatively, the tilt angle of each pixel may be calculated based on the first shape data generated by the WLI method, and the tilt angle of each pixel may be compared with a preset tilt angle threshold, and the first shape data may be selected for pixels whose tilt angle is equal to or less than the tilt angle threshold, and the second shape data may be selected for pixels whose tilt angle is greater than the tilt angle threshold. Furthermore, the above processes may be performed not only for each pixel, but also for each region consisting of multiple pixels.

[0196] Another method for generating integrated shape data is the method disclosed in Japanese Patent Application Laid-Open No. 2023-139925. This method calculates the S / N ratio (signal-to-noise ratio) of the first shape data and the second shape data for each pixel, and generates integrated shape data by selecting, for each pixel, the shape data with the higher S / N ratio based on the S / N ratio calculated for each pixel.

[0197] In the method disclosed in Japanese Patent Application Laid-Open No. 2023-139925, the S / N ratio is calculated for each pixel of each shape data and compared, but this is not limited to this. The S / N ratio may be calculated for each region consisting of multiple pixels and compared. Also, in this method, the above-mentioned processes may be performed for each region consisting of multiple pixels, not just for each pixel. Furthermore, in each of the above-mentioned methods, the tilt angle or S / N ratio is used as an index value for comparing the accuracy of each shape data, but other index values ​​may be used as long as they can evaluate the accuracy of each shape data.

[0198] In this way, in the shape data generation unit 165, the first shape data generation unit 166 generates first shape data (three-dimensional shape data by the WLI method), the second shape data generation unit 167 generates second shape data (three-dimensional shape data by the FV method), and the integrated calculation unit 168 generates integrated shape data by selecting, for each pixel or each region, the first shape data or the second shape data that has higher accuracy. Then, the shape data generation unit 165 outputs the integrated shape data generated by the integrated calculation unit 168 to the output unit 114 as the measurement result of the three-dimensional shape of the measurement target surface T. As a result, the measurement result of the three-dimensional shape of the measurement target surface T is displayed on the monitor of the output unit 114, etc., in accordance with the operation of the operation unit 112.

[0199] [Shape Measuring Method] Next, a shape measuring method using the shape measuring device 100 of this embodiment will be described.

[0200] 25 is a flowchart showing the flow of a shape measuring method using the shape measuring apparatus 100 of this embodiment. At the start of this measurement process, it is assumed that a wafer W is placed on the holding surface 102a of the measuring table 102. In addition, here, a case where the three-dimensional shape of a notch portion 82 at the edge of the wafer W is measured will be described as an example.

[0201] 25 , when the measurement process by the profile measuring apparatus 100 is started, first, the notch portion 82 of the wafer W and the optical unit 104 are relatively aligned (aligned) (step S10). Specifically, the measurement control unit 160 drives the table driving unit 116 to rotate the measurement table 102, thereby positioning the notch portion 82 of the wafer W at a position facing the optical unit 104. The measurement control unit 160 also drives the optical unit driving unit 106 to move the optical unit 104 in the X direction or the Y direction, thereby aligning the optical unit 104 with the notch portion 82 so that the notch portion 82 is positioned in a direction along the optical axis R of the optical unit 104. This alignment may be performed using the camera 128 of the optical unit 104 or using a known alignment technique.

[0202] After the notch portion 82 of the wafer W and the optical unit 104 are relatively aligned, the measurement control unit 160 starts emitting the measurement light L1 from the light source unit 120 and starts emitting the side illumination light M from the side illumination unit 108 (side light emitters 150A and 150B) (step S12, side illumination step). As a result, combined light L3 (including the reflected light of the side illumination light M reflected by the inclined surface S of the measurement surface T), which is the combination of the measurement light L1 reflected by the measurement target surface T and the reference light L2 reflected by the reference surface 124C and which includes interference fringes, is incident on the camera 128. Then, the measurement control unit 160 controls the optical unit drive unit 106 to start scanning the optical unit 104 in the Z direction (step S14, scanning step).

[0203] Furthermore, the measurement control unit 160 causes the camera 128 to repeatedly capture images of the combined light L3 each time the optical unit 104 moves by a certain pitch in the Z direction, based on the detection result of the Z direction position of the optical unit 104 by the scale 130 (step S16, NO in step S18, step S20, imaging step). As a result, while the optical unit 104 is scanning, captured images are repeatedly input from the camera 128 to the shape data generation unit 165, and the shape data generation unit 165 repeatedly acquires the captured images.

[0204] When scanning of the optical unit 104 is completed (YES in step S18), the first shape data generation unit 166 detects the brightness value for each pixel of the multiple captured images taken by the camera 128, determines the Z-direction position where the brightness value is maximum for each pixel at the same coordinates in each captured image, and calculates the height information of the measured surface T for each pixel at the same coordinates, thereby generating three-dimensional shape data (first shape data) indicating the three-dimensional shape of the measured surface T (step S22).

[0205] In addition, the second shape data generation unit 167 calculates the degree of focus for each pixel in the multiple captured images taken by the camera 128, and generates three-dimensional shape data (second shape data) indicating the three-dimensional shape (height distribution) of the measured surface T based on the results of comparing the degree of focus for each pixel at the same coordinates in each captured image (step S24).

[0206] After the processing by the first shape data generating unit 166 and the second shape data generating unit 167, the integrated calculation unit 168 generates three-dimensional shape data (integrated shape data) of the measurement surface T by selectively combining, for each pixel or region of each shape data, the shape data with higher accuracy between the first shape data and the second shape data (step S26, shape data generating step). The integrated shape data generated in this manner is output to the output unit 114. This concludes the flowchart shown in FIG.

[0207] Effect of the Present Embodiment According to the profile measuring apparatus 100 of the present embodiment, when the camera 128 repeatedly captures images of the measurement surface T at regular intervals while the optical unit 104 is scanning in the scanning direction (Z direction), the side illumination light M is irradiated from the side illumination unit 108 onto the edge of the wafer W. In particular, in the present embodiment, each of the side light emitters 150A, 150B constituting the side illumination unit 108 is formed in a rod shape with its longitudinal direction aligned with the optical axis R of the optical unit 104. This allows the reflected light from the flat surface F and the inclined surface S of the measurement surface T to be optimized regardless of whether the edge portion 80 or the notch portion 82 of the wafer W is being measured. Therefore, even if the position of the measurement surface T changes, both the flat surface F and the inclined surface S can be measured under the best optical conditions. This makes it possible to measure the three-dimensional shapes of both the edge portion 80 and the notch portion 82 of the wafer W with similar quality.

[0208] Furthermore, according to the profile measuring apparatus 100 of this embodiment, the provision of the side illumination unit 108 configured as described above enables the maintenance of optimal illumination conditions regardless of the position of the measurement target surface T, thereby enabling stable calculation of three-dimensional profile data by two methods (WLI method and FV method). This allows for highly accurate measurement of the surface shape, surface roughness, etc. of a surface (flat surface F) that is nearly perpendicular to the optical axis R of the optical unit 104, while also enabling highly sensitive measurement of a surface (inclined surface S) that is tilted with respect to the optical axis R of the optical unit 104. This enables roughness measurement of the bottom 82b of the notch portion 82 (see FIG. 14 ), which is particularly important in measuring the three-dimensional profile of the measurement target surface T. Because the bottom 82b of the notch portion 82 is configured as a surface that is nearly perpendicular to the optical axis R of the optical unit 104, the surface shape, surface roughness, etc. of the bottom 82b of the notch portion 82 can be measured with high accuracy by the WLI method.

[0209] [Modifications] Next, modifications of this embodiment will be described.

[0210] (First Modification) Measurement control unit 160 (an example of a light intensity control unit) in this embodiment may be capable of independently controlling the intensity of side surface illumination light M emitted by each of side light emitters 150A and 150B constituting side illumination unit 108. For example, as shown in FIG. 26 , when the inclination angles of the inclined surface S on the upper surface Wu side and the inclined surface S on the lower surface Wd side are different on the measurement surface T at the edge of wafer W, the amount of light reflected by each inclined surface S and toward optical unit 104 may differ among the side surface illumination light M emitted from side light emitters 150A and 150B. In such a case, the amount of light emitted by side light emitter 150A on the upper surface Wu side, where the amount of reflected light is relatively large, is relatively small compared to the amount of light reflected by side light emitter 150B on the lower surface Wd side, where the amount of reflected light is relatively small (preferably, so that the light reflected from both inclined surfaces S is approximately uniform). This makes it possible to perform stable calculation processing using the FV method, since the reflected light of the side illumination light M reflected by each inclined surface S is uniform without being affected by differences in the inclination angle of each inclined surface S.

[0211] (Second Modification) Although the side illumination unit 108 of the present embodiment has been shown to have a configuration including a pair of side light emitters 150A, 150B on both sides of the edge of the wafer W, the configuration is not limited thereto, and the side illumination unit 108 may include only one of the pair of side light emitters 150A, 150B. For example, as shown in FIG. 27 , if an inclined surface S is formed only on the upper surface Wu side of the wafer W, the side light emitter 150A may be disposed only on the side of the edge of the wafer W where the inclined surface S is formed. According to the second modification, the side illumination unit 108 can be realized at low cost.

[0212] (Third Modification) In the preferred embodiment, side illumination unit 108 has been described with each side light emitter 150A, 150B formed in a rod shape with its longitudinal direction aligned along optical axis R of optical unit 104 (Z direction). However, the present invention is not limited to this configuration. For example, as shown by 1015A to 1015C in FIG. 28 , each side light emitter 158A, 158B may be configured in a planar shape parallel to the main surface (upper surface Wu or lower surface Wd) of wafer W. Each side light emitter 158A, 158B has a plurality of light sources two-dimensionally arranged along the Y and Z directions, which are parallel to the main surface of wafer W, and emits side illumination light M in a planar shape parallel to the main surface of wafer W. Each side light emitter 158A, 158B is an example of a planar light emitter. 28 is configured, as an example, to have a rectangular shape in a plan view, with the longitudinal direction being the direction along the optical axis R of the optical unit 104 (Z direction) and the lateral direction being the direction orthogonal to the optical axis R (X direction). The length of the lateral direction of each of the side light emitters 158A, 158B is configured to be equal to or longer than the opening width Q of the notch portion 82. With this configuration, even if the opening width Q of the notch portion 82 is large, it is possible to irradiate the entire notch portion 82 with side illumination light M.

[0213] (Fourth Modification) Each of the side light emitters 150A, 150B (or side light emitters 158A, 158B) constituting the side illumination unit 108 may be configured to be movable in the Y direction. As a result, for example, as shown in FIG. 29 , when the inclination angles of the inclined surface S on the upper surface Wu side and the inclined surface S on the lower surface Wd side are different on the measurement surface T at the edge of the wafer W, the side light emitter 150A is moved to one side in the Y direction (upper side in FIG. 29 ) so that the distance between the side light emitter 150A on the upper surface Wu side, which has a larger inclination angle, and the edge of the wafer W is relatively larger than the distance between the side light emitter 150B on the lower surface Wb side, which has a smaller inclination angle, and the edge of the wafer W. Note that instead of moving the side light emitter 150A to one side in the Y direction, the side light emitter 150B may be moved to the other side in the Y direction (lower side in FIG. 29 ). This makes it possible to uniformize the amount of light reflected by each inclined surface S of the side illumination light M. As a result, similar to the first modification, the reflected light of the side illumination light M reflected by each inclined surface can be made uniform without being affected by differences in the inclination angle of each inclined surface S, and therefore it is possible to stably perform calculation processing using the FV method. Note that the first modification and the fourth modification may also be combined.

[0214] (Fifth Modification) The optical unit 104 used in the profile measuring apparatus 100 of this embodiment includes the interference objective lens 124. However, instead of the interference objective lens 124, a non-interference objective lens (a bright-field observation objective lens) used in general FV-type measurements may be included. In this case, in the flowchart shown in Fig. 25, the first profile data is not generated by the WLI method (step S22), and only the second profile data is generated by the FV method (step S24). The integrated calculation unit 168 then outputs the second profile data generated in step S24 to the output unit 114 as three-dimensional profile data (integrated profile data) of the measurement surface T.

[0215] According to the fifth variant, the three-dimensional shape data of the measurement surface T is obtained by calculation using the FV method, so the measurement accuracy of the flat surface F is inferior to that of the present embodiment described above. However, the side illumination unit 108 can optimize the reflected light from the flat surface F and the inclined surface S on the measurement surface T regardless of whether the edge portion 80 or the notch portion 82 of the wafer W is being measured, so that the three-dimensional shape of the inclined surface S can be measured with high sensitivity.

[0216] (Sixth Modification) In the form measuring apparatus 100 of this embodiment, a measurement operation is performed only once, in which the optical unit 104 is scanned in the scanning direction (Z direction) while repeatedly capturing images with the camera 128 at a fixed pitch. However, this is not limited to this. For example, a first measurement operation in which measurement is performed with the interference objective lens 124 attached to the optical unit 104 and a second measurement operation in which measurement is performed with a non-interference objective lens attached to the optical unit 104 may be performed. That is, the measurement operation may be performed in two separate steps, in which the objective lens attached to the optical unit 104 is switched for each measurement. In this case, in the flowchart shown in FIG. 25 , the first shape data is generated by the WLI method based on the multiple captured images obtained in the first measurement operation (step S22). The second shape data is generated by the FV method based on the multiple captured images obtained in the second measurement operation (step S24). Then, the integrated calculation unit 168 generates three-dimensional shape data (integrated shape data) of the measurement surface T by selectively combining the two shape data for each pixel or each region, and outputs the data to the output unit 114 (step S26).

[0217] According to the sixth modification, since the measurement operation is performed twice, the measurement time is longer than in the above-described embodiment, but it is possible to perform measurements under measurement conditions suitable for each of the first and second measurement operations, and therefore it is possible to measure the three-dimensional shape of the measurement surface T with higher accuracy.

[0218] Third Embodiment Generally, wafer grinding is performed by a grinding device installed at a processing site. Furthermore, shape measurement of the wafer edge after grinding is performed by a shape measurement device installed in a precision measurement room located at a different location from the processing site. The reason for this is that floor vibrations are smaller in the precision measurement room than in the processing site, and measurement errors caused by floor vibrations can be avoided.

[0219] As described above, conventionally, grinding and shape measurement are performed in separate locations. This requires the wafer transport process, which transports wafers between the processing site and the precision measurement room, to be included in the wafer manufacturing process, resulting in a problem of reduced wafer production per unit time (throughput). Specifically, conventionally, ground wafers are sequentially stored in a cassette, and a plurality of wafers for one lot are stored in this cassette. Then, this cassette must be transported from the processing site to the precision measurement room, where the wafers are removed from the cassette and their shapes are measured using a shape measurement device. In this case, even if there is insufficient grinding, it takes additional time to return the wafers from the shape measurement device to the grinding device.

[0220] Therefore, in the third embodiment, a wafer processing system capable of improving throughput is provided.

[0221] The third embodiment will be described below with reference to the accompanying drawings. Note that the wafer processing system 10 is the same as that of the first embodiment (FIG. 1), and therefore a description thereof will be omitted.

[0222] 30 is a schematic diagram showing the schematic configuration of a grinding device (chamfering device) 30 installed in the grinding section 16. As shown in FIG. 30, the grinding device 30 includes a grinding table 32 that holds the wafer W, a grinding wheel 34, and a spindle motor 36 that rotates the grinding wheel 34.

[0223] The grinding table 32 has an upper surface that is a holding surface 32a that suction-holds the wafer W. The grinding table 32 is configured to be rotatable about an axis P1 that is parallel to the Y direction of the rotation shaft 38 by various actuators such as a motor drive mechanism (not shown). The grinding table 32 is an example of the grinding table of the present invention.

[0224] The wafer W is held on the grinding table 32 with the center P2 of the wafer W aligned with the axis P1 of the rotation shaft 38. The alignment process for aligning the center P2 of the wafer W with the axis P1 of the rotation shaft 38 is carried out in the measuring unit 20 or the like, which will be described later.

[0225] The grinding wheel 34 is configured to be rotatable about an axis parallel to the Y direction by a spindle motor 36. The grinding wheel 34 is moved forward and backward in the Z direction relative to the end WA (including an edge portion WB and a notch portion WC, which will be described later; the same applies hereinafter) of the wafer W held on the grinding table 32. When the grinding wheel 34 is moved forward and backward, the rotating grinding wheel 34 is pressed relatively against the outer periphery, i.e., the end WA, of the rotating wafer W, thereby grinding the outer periphery of the wafer W. The grinding wheel 34 in this example is a formed grinding wheel having grinding grooves 34a on its outer periphery, and the shape of the grinding grooves 34a is transferred to the outer periphery of the wafer W during grinding. The grinding wheel 34 is an example of a grinding wheel of the present invention.

[0226] The grinding unit 16 is provided with a fine grinding stone (not shown) in addition to the grinding stone (rough grinding stone) 34. As a result, the outer periphery of the wafer W is roughly ground with the grinding stone 34, and then chamfering is performed with the fine grinding stone for finish grinding of the outer periphery of the wafer W.

[0227] The grinding device 30 is also provided with a notch rough grinding wheel and a notch fine grinding wheel for grinding the notch portion WC (see FIG. 31). As a result, the notch portion WC is roughly ground with the notch rough grinding wheel, and then chamfered as a finish grinding with the notch fine grinding wheel. Note that a plurality of grinding devices 30 may be installed in the grinding section 16.

[0228] 1 , the cleaning unit 18 cleans the wafer W after chamfering. This cleaning unit 18 includes a spin cleaning device (not shown). The spin cleaning device sprays a cleaning liquid onto the upper surface (front surface) of the wafer W while rotating the wafer W held on a cleaning table, thereby peeling off and removing contaminants adhering to the upper surface of the wafer W.

[0229] The transfer unit 22 transfers the wafer W between the grinding unit 16 and the cleaning unit 18. The transfer unit 22 includes a transfer robot configured to be capable of linear motion in the Z direction and vertical motion in the Y direction (vertical direction). The transfer robot includes an arm unit, the tip of which is provided with a suction pad. The transfer robot transfers the wafer W while suctioning the top surface of the wafer W with the suction pad of the arm unit. As a result, in the transfer unit 22, the transfer robot transfers the wafer W that has been chamfered in the grinding unit 16 to the cleaning unit 18, and transfers the wafer W that has been cleaned in the cleaning unit 18 to the grinding unit 16.

[0230] 31 is a plan view of a wafer W. As shown in Fig. 31, an edge portion WB is formed along the circumferential direction on the outer periphery, which is the edge portion WA of the wafer W, and a notch portion WC is formed in part of the outer periphery. The notch portion WC is a cutout portion for indicating the silicon crystal orientation of the wafer W, and is subject to grinding and shape measurement in the same way as the edge portion WB.

[0231] 32 is an explanatory diagram showing the configuration of the measurement unit 20. The above-mentioned alignment process is carried out in the measurement unit 20, which will be described later. First, the configuration for measuring the shape of the end WA (edge ​​portion WB and notch portion WC) of the wafer W will be described.

[0232] 32, the measuring unit 20 of this example is provided with a shape measuring device 54. This shape measuring device 54 calculates three-dimensional shape data indicating height information (surface shape, surface roughness, etc.) of the measurement surface of the end WA (edge ​​portion WB and notch portion WC) of the wafer W, which is the measurement object, based on a plurality of captured images captured at a fixed pitch while an optical unit 60, which will be described later, is scanned in the scanning direction (Z direction).

[0233] The shape measuring device 54 is roughly divided into an optical unit 60 , a measuring table 52 , and a control device 170 .

[0234] The measuring table 52 has a holding surface 52a on its upper surface that suction-holds the wafer W. The measuring table 52 is configured to be rotatable about an axis P3 parallel to the Y direction by a table driving unit 65. The table driving unit 65 is configured by various actuators such as a motor driving mechanism. The measuring table 52 is an example of the measuring table of the present invention.

[0235] The optical unit 60 is disposed on the left side in the Z direction of the measuring table 52. This optical unit 60 captures images of the edge WA of the wafer W at predetermined pitches while scanning the edge WA of the wafer W relatively in the Z direction (the left-right direction in FIG. 32 ). The shape measuring device 54 is an example of a shape measuring device of the present invention.

[0236] Next, a description will be given of the configuration of the optical unit 60. Fig. 33 is a schematic diagram showing the details of the configuration of the optical unit 60.

[0237] The optical unit 60 is a Michelson-type white light interference microscope. The optical unit 60 includes a camera 66, a light source 68, a beam splitter 70, an interference objective lens 72, and an imaging lens 74. The optical unit 60 is an example of the optical unit of the present invention.

[0238] 33, an interference objective lens 72, a beam splitter 70, an imaging lens 74, and a camera 66 are arranged in this order along the left side in the Z direction from the edge WA of the wafer W. In addition, a light source unit 68 is arranged at a position opposite the beam splitter 70 in the Y direction.

[0239] Under the control of the control device 170, the light source unit 68 emits a parallel beam of white light (low-coherence light) as measurement light L1 toward the beam splitter 70. The light source unit 68 includes a light source capable of emitting measurement light L1, such as a light-emitting diode, a semiconductor laser, a halogen lamp, or a high-intensity discharge lamp (not shown), and a collector lens that converts the measurement light L1 emitted from the light source into a parallel beam.

[0240] A half mirror, for example, is used as the beam splitter 70. The beam splitter 70 reflects a portion of the measurement light L1 incident from the light source unit 68 toward an interference objective lens 72 on the right side in the Z direction. The beam splitter 70 also transmits combined light L3 (described below) incident from the interference objective lens 72 to the left side in the Z direction, and emits this combined light L3 toward an imaging lens 74.

[0241] The interference objective lens 72 is a Michelson type and includes an objective lens 72A, a beam splitter 72B, and a reference surface 72C.

[0242] 33, a beam splitter 72B and an objective lens 72A are arranged in this order along the left side in the Z direction from the edge WA of the wafer W. Furthermore, a reference surface 72C is arranged at a position opposite the beam splitter 72B in the Y direction. Although the following description will be given using a Michelson-type interference optical system, the interference optical system is not limited to the Michelson type, and known interference optical systems such as a Mirau-type or Linnik-type can also be used.

[0243] The objective lens 72A has a light-collecting effect, and collects the measurement light L1 incident from the beam splitter 70 onto the measurement surface of the edge WA of the wafer W through the beam splitter 72B.

[0244] The beam splitter 72B is, for example, a half mirror. The beam splitter 72B splits a portion of the measurement light L1 incident from the objective lens 72A as reference light L2, transmits the remaining measurement light L1 to emit it toward the edge WA of the wafer W, and reflects the reference light L2 toward the reference surface 72C. The measurement light L1 transmitted through the beam splitter 72B is irradiated onto the measurement surface of the edge WA of the wafer W, and is then reflected by the measurement surface and returns to the beam splitter 72B.

[0245] The reference surface 72C is, for example, a reflecting mirror, and reflects the reference light L2 incident from the beam splitter 72B toward the beam splitter 72B. The position of this reference surface 72C in the Y direction can be manually adjusted by a position adjustment mechanism (not shown). This makes it possible to adjust the optical path length of the reference light L2 between the beam splitter 72B and the reference surface 72C. The optical path length of the reference light L2 is adjusted to match (or approximately match) the optical path length of the measurement light L1 between the beam splitter 72B and the surface to be measured.

[0246] The beam splitter 72B generates a combined light L3 from the measurement light L1 returning from the measured surface and the reference light L2 returning from the reference surface 72C, and emits this combined light L3 toward the objective lens 72A on the left side in the Z direction. This combined light L3 passes through the objective lens 72A and the beam splitter 70 and enters the imaging lens 74. In the case of a white light interference microscope, the combined light L3 becomes interference light containing interference fringes.

[0247] The imaging lens 74 forms an image of the combined light L3 incident from the beam splitter 70 on the imaging plane (not shown) of the camera 66. Specifically, the imaging lens 74 forms an image of a point on the focal plane of the objective lens 72A as an image point on the imaging plane of the camera 66.

[0248] The camera 66 has a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) imaging element (not shown), and captures an image of the combined light L3 formed on the imaging surface by the imaging lens 74 while the optical unit 60 is being driven (scanned) by the optical unit driving section 62.

[0249] The optical unit driving unit 62 is composed of various actuators such as a linear motor or a motor driving mechanism, and holds the optical unit 60 so that it can move freely in the Z direction, which is the scanning direction. This optical unit driving unit 62 scans the optical unit 60 along the Z direction under the control of the control device 170. In addition, the optical unit driving unit 62 holds the optical unit 60 so that it can move freely in the Y direction and the X direction, and is able to adjust the position of the optical unit 60 relative to the wafer W.

[0250] The scale 64 is a position detection sensor, for example a linear scale, that detects the Z direction position of the optical unit 60 relative to the wafer W. The scale 64 repeatedly detects the Z direction position of the optical unit 60 and repeatedly outputs the position detection result to the control device 170.

[0251] [Control Device] Next, the configuration of the control device 170 will be described. Fig. 34 is a functional block diagram of the control device 170. As shown in Fig. 34, the light source unit 68 and camera 66 of the optical unit 60, the scale 64, the table driving unit 65, the optical unit driving unit 62, the operation unit 172, and the output unit 174 are connected to the control device 170.

[0252] The operation unit 172 includes operation members (for example, a keyboard and a mouse) for receiving operation inputs from an operator to the control device 170 .

[0253] The output unit 174 is a device for outputting the results of program execution by the control device 170, data on the results of calculations, etc. The output unit 174 includes, for example, an operation UI (User Interface) and a monitor (for example, a liquid crystal display) for displaying the detection results. The output unit 174 may also include a printer, a speaker, etc. in addition to or instead of the monitor.

[0254] The control device 170 controls the measurement operation of the three-dimensional shape of the measurement surface by the shape measuring device 54 in response to operation input from the operation unit 172, and performs calculations of the three-dimensional shape of the measurement surface, etc. The control device 170 includes a processor (e.g., a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc.) that executes various calculations, memory (e.g., a ROM (Read Only Memory) and a RAM (Random Access Memory)), etc.) that serves as a working area for the processor, and a storage device (e.g., an SSD (Solid State Drive) or an HDD (Hard Disk Drive), etc.) for storing various programs and data.

[0255] The control device 170 functions as the measurement control unit 140 and the shape data generating unit 176 by executing a program stored in the storage device with a processor. The control device 170 also includes a storage unit 178 configured from the above-mentioned storage device (which may also be a memory).

[0256] The measurement control unit 140 controls the table driving unit 65, the optical unit driving unit 62, the camera 66, and the light source unit 68 to scan the optical unit 60 in the scanning direction (Z direction), while repeatedly capturing images of the edge WA of the wafer W with the camera 66 at a constant pitch. Specifically, the measurement control unit 140 controls the table driving unit 65 to rotate the measurement table 52 so that the edge WA of the wafer W to be measured is positioned opposite the optical unit 104. After starting emission of the measurement light L1 from the light source unit 68, the measurement control unit 140 controls the optical unit driving unit 62 to scan the optical unit 60 in the Z direction. While the optical unit driving unit 62 scans the optical unit 60 in the Z direction, the measurement control unit 140 repeatedly captures the combined light L3 with the camera 66 and outputs the captured image to the control device 170 each time the optical unit 60 moves a constant pitch in the Z direction, based on the detection result of the Z-direction position of the optical unit 60 by the scale 64.

[0257] Each time the camera 66 captures an image of the combined light L3, the shape data generation unit 176 acquires the captured image output from the camera 66 and generates three-dimensional shape data of the measurement surface of the edge WA of the wafer W. Specifically, the shape data generation unit 176 compares the brightness values ​​of each pixel at the same coordinates in each captured image. Next, the shape data generation unit 176 determines the Z-direction position at which the brightness value of each pixel at the same coordinates in each captured image is maximized, thereby calculating height information indicating the height position (Z-direction position) of each part of the measurement surface corresponding to each pixel. This generates three-dimensional shape data indicating the three-dimensional shape (height distribution) of the measurement surface W.

[0258] [Outline of Operation of Wafer Processing System] Next, an outline of the operation of the wafer processing system 10 of this embodiment will be described. Fig. 35 is a flowchart showing an outline of the operation of the wafer processing system 10.

[0259] First, the wafer W is taken out of the cassette attached to the cassette unit 12 by the supply / recovery robot of the loading unit 14 and transported to the measurement unit 20. The wafer W transported to the measurement unit 20 is placed on the measurement table 52 of the measurement unit 20 (step S1: wafer placement step).

[0260] Next, in the measuring unit 20, the diameter and misalignment amount of the wafer W placed on the measuring table 52 are measured (step S2: diameter and misalignment amount measuring step). The misalignment amount is the amount of misalignment of the center P1 of the wafer W with the axis P1 of the grinding table 32 when the wafer W is placed on the grinding table 32. The step S2 corresponds to an alignment step for aligning the center P2 of the wafer W with the axis P1 of the grinding table 32. This alignment step will be described later.

[0261] Next, the wafer W whose diameter and misalignment amount have been measured in the measuring unit 20 is transported from the measuring unit 20 to the grinding unit 16 by the supply / recovery robot of the loading unit 14. The wafer W transported to the grinding unit 16 is placed on the grinding table 32 of the grinding unit 16 (step S3: wafer placing step).

[0262] At this time, the control device 170 corrects the known distance (known relative position) between the axis P1 of the grinding table 32 and the axis P3 of the measuring table 52 using the misalignment amount obtained in step S2, and controls the transport amount of the wafer W by the supply and recovery robot based on this corrected distance (corrected relative position).

[0263] As a result, the wafer W is placed on the grinding table 32 with the center P2 of the wafer W aligned with the axis P1 of the grinding table 32. The above-mentioned known relative position is measured in advance and stored in the memory unit 178.

[0264] Next, in the grinding section 16, the grinding device 30 performs grinding (chamfering) on ​​the edge WA of the wafer W. Specifically, the edge portion WB, which is the outer periphery of the wafer W, is roughly ground with the grindstone 34, and then chamfering is performed with a precision grindstone for finish grinding of the outer periphery of the wafer W. In addition, the notch portion WC of the wafer W is roughly ground with a notch rough grindstone, and then chamfering is performed as finish grinding with a notch precision grindstone (step S4: grinding process).

[0265] Next, the wafer W that has been subjected to grinding (chamfering) in the grinding unit 16 is transferred from the grinding unit 16 to the cleaning unit 18 by the transfer robot of the transfer unit 22. Then, in the cleaning unit 18, cleaning of the wafer W is carried out by a spin cleaning device (step S5: cleaning step).

[0266] Next, the wafer W that has been cleaned in the cleaning unit 18 is transferred from the cleaning unit 18 to the grinding unit 16 by the transfer robot of the transfer unit 22. Thereafter, the wafer W is transferred from the grinding unit 16 to the measurement unit 20 by the supply / recovery robot of the loading unit 14. The wafer W transferred to the measurement unit 20 is placed on the measurement table 52 (step S6: transfer process to the measurement unit).

[0267] Next, in the measurement unit 20, the shape measurement device 54 measures the three-dimensional shape of the edge WA of the wafer W (step S7: shape measurement process). Specifically, the measurement control unit 140 controls each component to relatively scan the edge WA of the wafer W in the scanning direction (Z direction) with the optical unit 60, while capturing images of the edge WA of the wafer W with the camera 66 at predetermined intervals. Next, the shape data generation unit 176 generates three-dimensional shape data indicating the surface shape of the edge WA of the wafer W based on the multiple captured images captured by the camera 66. The measurement results of the measurement unit 20 (the three-dimensional shape of the edge WA of the wafer W) are output to the output unit 174. Note that the control device 170 may also calculate a determination result indicating whether the measurement results of the measurement unit 20 are within a predetermined range and output the determination result to the output unit 174.

[0268] Next, the inspected wafer W is transported from the measurement unit 20 to the cassette unit 12 by the supply / recovery robot of the loading unit and stored in the cassette (step S8: cassette storage step). Note that before the wafer W is transported from the measurement unit 20 to the cassette unit 12, it is preferable to measure the diameter and misalignment of the wafer W again in the measurement unit 20. This allows the wafer W to be stored in the correct position in the cassette. Furthermore, if the shape of the edge WA of the wafer W is outside the specified range, the wafer W may be returned to the grinding unit 16 and re-ground.

[0269] In order to improve throughput (productivity of wafers W), it is desirable to perform the grinding process and shape measurement of wafers W in the same system (on the same surface plate).

[0270] In other words, it is desirable to mount (side by side) the grinding unit 16 and the measuring unit 20 on the same surface plate, and to immediately measure the shape of the wafer W after grinding in the grinding unit 16 (via the cleaning unit 18) in the measuring unit 20. With this configuration, the wafer transport process between the grinding unit 16 and the measuring unit 20 (including the process of returning the wafer from the measuring unit 20 to the grinding unit 16 when grinding is insufficient) can be shortened, thereby improving throughput.

[0271] Before describing the configuration of the wafer processing system 10 of this embodiment, several comparative examples (Comparative Examples 1 and 2) will be described.

[0272] Comparative Example 1 Comparative Example 1 is shown in Fig. 36. Fig. 36 shows a configuration in which the grinding unit 16 and the measuring unit 20 are simply arranged side by side on the same surface plate 300.

[0273] However, in the configuration of Comparative Example 1, floor vibration A is transmitted from the floor surface 302 of the processing site to the measuring unit 20 via the surface plate 300. For this reason, floor vibration A is mixed into the measurement results of the measuring unit 20 as noise, resulting in a problem of deterioration in measurement accuracy (large error).

[0274] [Comparative Example 2] Although not shown in the figures, Comparative Example 2 is configured such that, in order to suppress the effects of floor vibration A, a vibration isolation table is installed between the floor surface 302 and the base plate 300, and the floor vibration A transmitted from the floor surface 302 to the measurement unit 20 via the base plate 300 is reduced (attenuated) by the vibration isolation table.

[0275] However, in the configuration of Comparative Example 2, although the effects of floor vibration A can be suppressed, the processing vibrations generated in the grinding section 16 are transmitted to the measuring section 20 via the surface plate 300, which also results in a problem of deterioration in measurement accuracy.

[0276] For these reasons, conventionally, wafer grinding and shape measurement are carried out in separate locations (systems), resulting in a problem of reduced throughput.

[0277] Therefore, the wafer processing system 10 of this embodiment has the following configuration to solve the above problem.

[0278] [Features of the Wafer Processing System of the Present Embodiment] FIG. 37 is an explanatory diagram for explaining features of the wafer processing system 10 of the present embodiment.

[0279] 37, in the wafer processing system 10 of this example, a grinding unit 16 and a measuring unit 20 are arranged side by side on a surface plate 300, and a vibration isolation table 90 is installed between the surface plate 300 and the measuring unit 20. In addition, the loading unit 14 shown in FIG. 1 and the like are installed on the surface plate 300. The surface plate 300 is an example of the surface plate of the present invention.

[0280] 37, the vibration isolation table 90 is a passive type vibration isolation table having a lower base 92 fixed to a surface plate 300, an upper base 94 to which the measuring unit 20 is fixed, and a spring element 96 and a damping element 98 provided between the lower base 92 and the upper base 94. The vibration isolation table 90 is one example of the vibration isolation table of the present invention.

[0281] According to the wafer processing system 10 of this embodiment, the above-mentioned configuration enables the vibration isolation table 90 to reduce floor vibration A transmitted from the floor surface 302 to the measurement section 20 via the surface plate 300 and processing vibration B transmitted from the grinding section 16 to the measurement section 20 via the surface plate 300.

[0282] As a result, the wafer processing system 10 of this embodiment can ensure measurement accuracy even when the grinding unit 16 and the measuring unit 20 are installed side by side on the same surface plate 300. In other words, measurement accuracy can be ensured even when grinding by the grinding unit 16 and shape measurement by the measuring unit 20 are performed simultaneously on the same surface plate 300. As a result, the wafer transport process performed between the grinding unit 16 and the measuring unit 20 can be shortened, thereby improving throughput.

[0283] The vibration isolation table 90 is not limited to a passive type, and may be an active type that uses a motor to cancel out external vibrations. Furthermore, the measurement table 52 mounted on the vibration isolation table 90 is a rotary stage with no center of gravity movement, and therefore tilting of the vibration isolation table 90 can be reduced compared to a linear stage with a center of gravity movement.

[0284] However, when the measuring unit 20 is mounted on the base plate 300 via the vibration isolation table 90, the originally known distance, i.e., the distance between the axis P3 of the measuring unit 20 and the axis P1 of the grinding unit 16 (hereinafter also referred to as the relative position), may no longer be constant due to a shift in the return position of the vibration isolation table 90.

[0285] In this case, even if only the misalignment of the center P2 of the wafer W relative to the axis P3 of the measuring section 20 is measured, it may not be possible to align the center P2 of the wafer W with the axis P1 of the grinding table 32 due to the deviation of the return position described above.

[0286] Therefore, in order to align the center P2 of the wafer W with the axis P1 of the grinding table 32, the following two alignment processes (first alignment process and second alignment process) must be performed in the measurement section 20.

[0287] <First Alignment Step> The first alignment step is a step of measuring the diameter of the wafer W and the amount of misalignment of the center P2 of the wafer W with respect to the axis P3 of the measuring table 52. In other words, it is a step of determining the center C1 of the wafer W in the vibration isolation table coordinate system (XZ coordinate system) based on the measuring table 52. Below, a brief description will be given of the configuration for performing the first alignment step.

[0288] First, the original purpose is to transport the wafer W from the measuring section 20 to the grinding section 16 so that the center P2 of the wafer W is aligned with the axis P1 of the grinding table 32.

[0289] Therefore, the relative position between the axis P1 of the grinding table 32 and the axis P3 of the measuring table 52 is measured in advance, and the relative position is stored in the memory unit 178 of the control device 170.

[0290] Thereafter, the wafer W is removed from the wafer cassette using the supply / recovery robot of the loading unit 14, transported to the measuring unit 20, and placed on the measuring table 52. However, since the position of the wafer W in the cassette is unknown, the wafer W is placed in a state where it is misaligned with respect to the measuring table 52. The misaligned state means that the center P2 of the wafer W is misaligned with the axis P3 of the measuring table 52.

[0291] 38 shows a diameter sensor 180 for performing the first alignment step. This diameter sensor 180 is installed on the upper base 94 of the vibration isolation table 90 and has a light receiving unit 182 and a light projecting unit 184. The light receiving unit 182 and the light projecting unit 184 are arranged opposite each other in the Y direction with the wafer W sandwiched between them. The diameter sensor 180 is an example of the first sensor of the present invention.

[0292] For example, a CCD camera is used as the light receiving unit 182. The CCD camera is capable of capturing an image of the outer periphery of the wafer W.

[0293] The CCD camera, which is the light receiving unit 182, captures images of a plurality of imaging points on the outer periphery of the wafer W while rotating the measuring table 52. In other words, the CCD camera is a sensor that detects the position of the outer periphery of the wafer W placed on the measuring table 52, and outputs to the control device 170 a change in the position of the outer periphery of the wafer W according to the rotation angle of the measuring table 52.

[0294] The images captured by the CCD camera are obtained as black and white binary images. The control device 170 processes the captured images and determines the coordinates of the outer periphery edge points (edges) in each image obtained by image processing, thereby determining the distance between the axis P3 of the measuring table 52 and the outer periphery edge points (edges). The control device 170 then rotates the measuring table 52 to determine the distances for multiple edge points in the circumferential direction of the wafer W, and based on these distances, determines the diameter of the wafer W and the amount of misalignment of the center P2 of the wafer W relative to the axis P3 of the measuring table 52 (the center C1 of the wafer W in the vibration isolation table coordinate system). This completes the first alignment process. The distance in the Z direction between the axis P3 of the measuring table 52 and the CCD camera (light receiving unit 182) is known.

[0295] <Second Alignment Step> The second alignment step is a step of measuring the position of the center P1 of the wafer W with reference to the surface plate 300. In other words, it is a step of determining the center C2 of the wafer W in the grinding unit coordinate system (XZ coordinate system) with reference to the surface plate 300. Below, a brief description will be given of the configuration for performing the second alignment step.

[0296] 38, an outer diameter sensor 190 for detecting the outer diameter position of the wafer W is disposed above the measurement table 52. The outer diameter sensor 190 has two sensors 192, 194 disposed spaced apart from each other on the XZ plane. These sensors 192, 194 are attached to a pole 196 installed on the surface plate 300 in order to determine the center C2 of the wafer W in the grinding unit coordinate system. The outer diameter sensor 190 is an example of the second sensor of the present invention.

[0297] 39 is an explanatory diagram showing the postures of two wafers W placed on the measuring table 52. The wafer W shown by the solid line in Fig. 39 is placed with the center P2 of the wafer W deviated from the axis P3 of the measuring table 52, while the imaginary wafer W shown by the dotted line is placed with the center P2 of the wafer W aligned with the axis P3 of the measuring table 52.

[0298] 39, the outer diameter positions of the wafer W detected by the two sensors 192 and 194 are indicated as D1 and D2. The diameter of the wafer W determined in the first alignment step is indicated as D.

[0299] When the outer diameter positions D1, D2 of the wafer W are detected by the two sensors 192, 194, the control device 170 determines the center C2 of the wafer W in the grinding unit coordinate system based on the two outer diameter positions D1, D2 detected by the sensors 192, 194 and the diameter D of the wafer W determined in the first alignment step. This completes the second alignment step.

[0300] Once the center C2 has been determined, the control device 170 calculates the difference between the center C1 determined in the first alignment step and the center C2 determined in the second alignment step in order to achieve the above-mentioned purpose (transporting the wafer W from the measurement unit 20 to the grinding unit 16 so that the center P2 of the wafer W is aligned with the axis P1 of the grinding table 32), corrects the relative position using this difference, and calculates the transport amount of the wafer W by the supply / recovery robot based on the corrected relative position (transport amount calculation step).Then, the wafer W is transported by the supply / recovery robot based on this transport amount (transport step).

[0301] As a result, even if the return position of the vibration isolation table 90 is misaligned, the wafer W can be transported so that the center P2 of the wafer W is aligned with the axis P1 of the grinding table 32.

[0302] In this embodiment, an example is shown in which the transport amount by the supply / recovery robot is corrected, but it is also possible to adopt a configuration in which the position of the grinding table 32 is moved based on the corrected relative position.

[0303] The first alignment step and the second alignment step implement step S2 (diameter and misalignment amount measuring step) shown in Fig. 35. The transport distance calculation step and transport step implement step S3 (wafer placing step).

[0304] [Characteristics of the Vibration Isolation Table] When the vibration isolation table 90 is stopped (OFF), the upper base 94 is located at a seated position, which is a non-operating position. When the vibration isolation table 90 is activated (ON), the upper base 94 rises from the seated position to a levitated position, which is an operating position. Shape measurement of the wafer W is performed at this levitated position. In this case, the wafer W is delivered from the supply / recovery robot to the measurement table 52 at a seated position that is more stable than the levitated position, and then shape measurement is performed at the levitated position.

[0305] However, such a measurement procedure has a problem in that it takes time for the upper base 94 to move from the seated position to the floating position.

[0306] Therefore, in order to shorten the above-mentioned time and stably transfer the wafer W to the measurement table 52, the upper base 94 of the vibration isolation table 90 is fixed (locked) so that it cannot move at the floating position, and in this locked state the wafer W is transferred to the measurement table 52, and then the lock is released and the shape of the wafer W is measured.

[0307] 40 shows a state in which the upper base 94 of the vibration isolation table 90, which is positioned at the levitated position, is locked so as to be unable to move at the levitated position by pressing the upper base 94 against a stopper wall 210 using an external lock pin 200. The lock pin 200 is an example of the locking member of the present invention.

[0308] The lock pin 200 and the stopper wall 210 are disposed opposite each other in the Z direction with the upper base 94 in between. The lock pin 200 is provided so as to be movable back and forth in the Z direction relative to the upper base 94.

[0309] When the lock pin 200 is advanced (see FIG. 40), the upper base 94 is pressed against the stopper wall 210 by the lock pin 200 and locked so as to be immovable. The wafer W is delivered to the measuring table 52 in this locked state.

[0310] With this configuration, it is possible to shorten (reduce) the time it takes for the upper base 94 to move from the seated position to the levitated position, while stably transferring the wafer W to the measurement table 52. Note that the vibration isolation table 90 may be stopped after the upper base 94 is locked. In this case, the upper base 94 is pressed against the stopper wall 210 and locked, so it will not return from the levitated position to the seated position.

[0311] Furthermore, when the lock pin 200 is retracted, the upper base 94 is released from being pressed (locked) against the stopper wall 210, and is therefore able to operate at the floating position. The shape of the wafer W is measured in this unlocked state. Naturally, the vibration isolation table 90 is activated before the lock pin 200 is retracted.

[0312] According to the configuration of this example, as described above, the time required for the upper base 94 to move from the seated position to the floating position can be shortened, which can contribute to improving throughput.

[0313] [When an active vibration isolation table is used as the vibration isolation table] An active vibration isolation table has a position feedback sensor. This position feedback sensor generally has a dead zone (see Figure 41) within its return range to prevent hunting. Due to the influence of this dead zone, the position of the vibration isolation table mounting part may not be precisely determined.

[0314] 41 is an explanatory diagram showing that a dead zone exists within the return range of an active vibration isolation table. The dead zone is a region in which no feedback occurs even if the position deviates from the neutral position within the dead zone.

[0315] Therefore, when transferring the wafer W, for example, the vibration isolation table is pushed from one side using a pressing member each time to return it to its original position (return position outside the dead zone: position E1 in Figure 41), thereby creating a structure that is not affected by the dead zone.

[0316] In this case, it is necessary that the speed at which the pressing member is released from the vibration isolation table does not exceed the return speed of the vibration isolation table. In other words, if the speed at which the pressing member is released exceeds the return speed, the vibration isolation table may overrun from position E2 in Figure 41 to position E3, which is the end of the dead zone, and enter the dead zone. Therefore, the speed at which the pressing member is released is set to a slow speed that does not exceed the return speed.

[0317] Also, if an axis (horizontal direction) is mounted on the vibration isolation table, it is possible to use the change in the center of gravity instead of pushing.Moreover, many vibration isolation tables have a feedback mechanism that returns the table to a neutral position when it receives external disturbance.

[0318] Hereinafter, several modifications (first and second modifications) of the third embodiment will be described.

[0319] [First Modification] Figure 42 is a schematic plan view of a wafer processing system 220 showing a first modification. Figure 43 is a schematic side view of the wafer processing system 220 shown in Figure 42. In explaining the first modification, members that are the same as or similar to those in the wafer processing system 10 of the present embodiment shown in Figure 1 will be described using the same reference numerals.

[0320] 42 and 43, in the wafer processing system 220 of the first modified example, the grinding unit 16 and the measuring unit 20 are also mounted on the same surface plate 300. Note that the loading unit 14 is also shown in FIG.

[0321] As shown in FIG. 43, in a wafer processing system 220 of the first modified example, the measuring unit 20 is installed above (in the Y direction) the grinding unit 16 .

[0322] Grinding debris 230 generated during grinding of the wafer W by the grinding unit 16 is scattered radially from the wafer W and falls onto the surface plate 300. As in the wafer processing system 220 of the second modified example, by installing the measurement unit 20 above (in the Y direction) the grinding unit 16, it is possible to prevent the grinding debris 230 from appearing in the measurement image when the optical unit 60 captures an image of the wafer W. It is also possible to prevent the grinding debris 230 from adhering to the wafer W placed on the measurement table 52 of the measurement unit 20 and to each sensor (diameter sensor 180 and outer diameter sensor 190) of the measurement unit 20. This ensures measurement accuracy.

[0323] Here, in the wafer processing system 10 of this embodiment, the measuring unit 20 is mounted on the surface plate 300 via the vibration isolation table 90, so that the measuring unit 20 is installed above (in the Y direction) the grinding unit 16. However, the member for installing the measuring unit 20 above (in the Y direction) the grinding unit 16 is not limited to the vibration isolation table 90, and another raising member 240 (see FIG. 43 ) may also be used.

[0324] That is, the configuration of the first modified example can be adopted in a wafer processing system in which the grinding unit 16 and the measuring unit 20 are mounted on the same surface plate 300, and which does not include a vibration isolation table 90. Even with this configuration, it is possible to prevent the grinding debris 230 from being reflected, and measurement accuracy can also be ensured.

[0325] 42, the shape measuring device 54 in the first modified example is preferably disposed at a position spaced apart from the corners 300A, 300A of the surface plate 300. Since grinding debris 230 is likely to accumulate in the corners 300A, by disposing the optical unit 60 at a position spaced apart from such corners 300A, it is possible to more reliably prevent the grinding debris 230 from being reflected in the image.

[0326] 44 is a schematic plan view of a wafer processing system 250 showing a second modified example. In explaining the second modified example, the same reference numerals will be used to denote components that are the same as or similar to those in the wafer processing system 10 of the present embodiment shown in FIG.

[0327] As shown in Fig. 44, in the wafer processing system 250 of the second modification, the grinding unit 16 and the measuring unit 20 are also mounted on the same surface plate 300. Note that Fig. 44 also shows the loading unit 14.

[0328] 44, processing vibrations B generated in the grinding unit 16 propagate along the rotation direction indicated by the arrow of the grinding table 32. The white light interference microscope, which is the optical unit 60, has the characteristic that its resolution in the direction along the optical axis (Z1) is superior to the resolution in the direction perpendicular to the optical axis (Z1).

[0329] Taking these characteristics into consideration, the white light interferometer is positioned on the XZ plane so that the optical axis (Z1) of the white light interferometer faces the grinding unit 16. In this way, since the processing vibration B propagates along a direction substantially perpendicular to the optical axis (Z1), it becomes possible to measure the shape of the wafer W without being affected by the processing vibration B. As a result, the measurement accuracy by the measurement unit 20 can be ensured.

[0330] Here, "so that the optical axis (Z1) of the white light interference microscope faces the grinding portion 16" means that the optical axis (Z1) faces within the arrangement area of ​​the measurement table 52, and preferably the optical axis (Z1) faces the axis center P1 of the measurement table 52. However, the optical axis (Z1) may face outside the arrangement area of ​​the measurement table 52 as long as it is within a range that is less susceptible to the effects of processing vibration B.

[0331] As with the configuration of the first modification, the configuration of the second modification can also be employed in a wafer processing system that does not have a vibration isolation table, in which the grinding unit 16 and the measuring unit 20 are mounted on the same surface plate 300. Even with this configuration, it is possible to measure the shape of the wafer W without being affected by the processing vibrations B.

[0332] As a reference example, the centering of the wafer W can be performed using the diameter sensor 180 shown in Fig. 38. Alternatively, the centering of the wafer W can be performed using a dedicated centering sensor. The dedicated centering sensor has, for example, two sensors that detect two spaced apart points on the outer periphery of the wafer W, and determines that the wafer W is centered when the two sensors simultaneously detect the outer periphery of the wafer W.

[0333] In the above embodiment, the measuring unit 20 is described as having a shape measuring device with a white light interference microscope as an example, but this is not limited to this. For example, the measuring unit 20 may be provided with a shape measuring device having a microscope such as a focus variation microscope or a laser confocal microscope, or may be provided with a shape measuring device using an optical projection measurement method.

[0334] Although the embodiments of the present invention have been described above, the present invention is not limited to the above examples, and various improvements or modifications may be made without departing from the spirit of the present invention.

[0335] 10...wafer processing system, 12...cassette section, 14...load section, 16...grinding section, 18...cleaning section, 20...measuring section, 22...transport section, 30...grinding device, 32...grinding table, 32a...holding surface, 34...grinding stone, 34a...grinding groove, 36...spindle motor, 38...rotating shaft, 52...measuring table, 52a...holding surface, 54...shape measuring device, 60...optical unit, 62...optical unit driving section, 64...scale, 65...table driving section, 66...camera, 68...light source section, 70...beam splitter, 72...interference objective lens, 72A...objective lens, 72B...beam splitter , 72C...reference surface, 74...imaging lens, 80...edge portion, 82...notch portion, 82a...straight portion, 82b...bottom portion, 84...chamfered portion, 100...shape measuring device, 102...measurement table, 102a...holding surface, 104...optical unit, 106...optical unit driving portion, 108...side illumination unit, 110...control device, 112...operation portion, 114...output portion, 116...table driving portion, 120...light source portion, 122...beam splitter, 124...interference objective lens, 124A...objective lens, 124B...beam splitter, 124C...reference surface, 126...imaging lens, 128...camera, 130...scale, 150...side light emitter, 150A...side light emitter, 150B...side light emitter, 152...LED, 154...light scattering body, 156...light guide, 158A...side light emitter, 158B...side light emitter, 160...measurement control unit, 162...calculation unit, 164...analysis unit, 165...shape data generation unit, 166...first shape data generation unit, 167...second shape data generation unit, 168...integrated calculation unit, 900...white light interference microscope, 902...measurement surface, 904...captured image, 910...side illumination unit, 912A...point light emitter, 912B...point light emitter, W...wafer, Wu...upper surface, Wb...lower surface, T...measurement surface, F...flat surface, S...inclined surface, L1...measurement light, L2...reference light, M...side illumination light, R...optical axis, G...rotation axis, 300...surface plate, 300A...corner portion, 90...vibration isolation table, 92...lower base, 94...upper base, 96...spring element, 98...damping element, 170...control device, 172...operation unit, 174...output unit, 176...shape data generation unit, 180...diameter sensor, 182...light receiving unit, 184...light projecting unit, 190...outer diameter sensor, 192...sensor, 194...sensor, 200...lock pin, 210...stopper wall, 220...wafer processing system, 230...grinding chips,240...raising member, 250...wafer processing system, A...floor vibration, B...processing vibration, D...diameter, D1...outer diameter position, D2...outer diameter position, E1...position of vibration isolation table, E2...position of vibration isolation table, E3...position of vibration isolation table, WA...end, WB...edge portion, WC...notch portion, P1...axis center, P2...center, P3...axis center,

Claims

1. A shape measuring device for measuring the shape of a measured surface at an edge of a wafer, comprising: an optical unit having an optical axis parallel to a main surface of the wafer, a light source unit for irradiating the measured surface with measurement light along the optical axis, and an imaging unit for imaging reflected light from the measured surface; a relative movement unit for moving the optical unit relatively to the measured surface; a calculation unit for generating measurement data indicating the shape of the notch portion based on the coordinates of a point cloud obtained when the imaging unit repeatedly images a notch portion formed on the measured surface by moving the optical unit relatively; and an analysis unit for performing a shape analysis of the notch portion based on the measurement data.

2. The shape measuring device according to claim 1, wherein the analysis unit determines an approximation curve from the coordinates of the point cloud.

3. The shape measuring device according to claim 2, wherein the imaging unit images a notch portion of the wafer to obtain coordinates of the point cloud, and the analysis unit calculates at least two curves obtained by shifting the approximation curve along a direction perpendicular to the front or back surface of the wafer, thereby determining an approximation curve of the notch portion along a direction perpendicular to the front or back surface of the wafer that passes through a saddle point of the notch portion.

4. A shape measuring device according to any one of claims 1 to 3, further comprising an output section which outputs a determination result as to whether or not the wafer has an abnormality based on the measurement data.

5. A shape measuring device as claimed in any one of claims 1 to 4, wherein the analysis unit determines the presence or absence of an abnormality in the three-dimensional shape corresponding to the area data extracted from the three-dimensional shape of the edge portion of the wafer based on the area data.

6. A shape measuring device as claimed in any one of claims 1 to 5, wherein the analysis unit determines an analysis coordinate system for analyzing the notch portion based on the coordinates of a point cloud obtained by moving the optical unit relative to a master workpiece having a known angle between each surface and repeatedly imaging the measured surface of the master workpiece with the imaging unit.

7. A shape measurement method for measuring the shape of a measured surface at an edge of a wafer, comprising: an optical unit having an optical axis parallel to a main surface of the wafer, a light source unit which irradiates the measured surface with measurement light along the optical axis, and an imaging unit which images reflected light from the measured surface; when an optical unit is moved relative to the measured surface, the imaging unit repeatedly images a notch formed on the measured surface, and based on the coordinates of a point cloud obtained, measurement data indicating the shape of the notch is generated; and a shape analysis of the notch is performed based on the measurement data.

8. A shape measuring device for measuring a three-dimensional shape of a measured surface at an edge of a wafer, comprising: an optical unit having an optical axis parallel to a main surface of the wafer, a light source unit for irradiating the measured surface with coaxial epi-illumination light along the optical axis, and an imaging unit arranged coaxially with the optical axis and imaging light reflected from the measured surface; a relative movement unit for moving the optical unit relatively to the measured surface in a direction along the optical axis; a side illumination unit for irradiating the measured surface with side illumination light from a direction perpendicular to the optical axis; and a shape data generation unit for generating three-dimensional shape data indicating the three-dimensional shape of the measured surface based on a plurality of captured images repeatedly captured by the imaging unit while the optical unit is moving relatively.

9. The shape measuring device according to claim 8, wherein the side lighting unit has a rod-shaped light-emitting body whose longitudinal direction is parallel to the optical axis.

10. The shape measuring device according to claim 9, wherein the side illumination unit has a pair of the rod-shaped light emitters provided on both sides of the edge of the wafer in a direction perpendicular to the optical axis.

11. The shape measuring device according to claim 8, further comprising a light amount control section that controls the amount of the side illumination light emitted from the side illumination unit.

12. The shape measuring device according to claim 10, further comprising a light amount control unit that controls the amount of light emitted by the pair of rod-shaped light emitters independently of each other.

13. The shape measuring device according to claim 8, wherein the side lighting unit has a surface light emitter that emits light in a plane parallel to the main surface.

14. A shape measuring device as described in claim 8, further comprising a measurement table configured to hold the wafer and be rotatable about an axis of rotation perpendicular to a main surface of the wafer, and a measurement control unit that rotates the measurement table so that the surface to be measured at the edge of the wafer is positioned opposite the optical unit.

15. A shape measuring device as described in any one of claims 8 to 14, wherein the shape data generation unit comprises: a first shape data generation unit that generates first shape data indicating the three-dimensional shape of the measured surface based on the multiple captured images using a white light interference method; a second shape data generation unit that generates second shape data indicating the three-dimensional shape of the measured surface based on the multiple captured images using a focus variation method; and an integrated calculation unit that generates integrated shape data by selectively combining the first shape data and the second shape data for each pixel or for each region based on an index value obtained from at least one of the first shape data and the second shape data.

16. A shape measuring method for measuring a three-dimensional shape of a measured surface at an edge of a wafer, comprising: a scanning step of moving an optical unit having an optical axis parallel to a main surface of the wafer relative to the measured surface in a direction along the optical axis; an imaging step of, while the scanning step is being performed, irradiating the measured surface with coaxial epi-illumination light along the optical axis from the optical unit, and imaging light reflected from the measured surface with an imaging section provided coaxially with the optical axis in the optical unit; a side illumination step of, while the imaging step is being performed, irradiating the measured surface with side illumination light from a direction perpendicular to the optical axis; and a shape data generation step of generating three-dimensional shape data indicating the three-dimensional shape of the measured surface based on a plurality of images captured by the imaging section in the imaging step.

17. A wafer processing system comprising: a surface plate; a grinding unit mounted on the surface plate for grinding an edge of a wafer; a measuring unit mounted on the surface plate for measuring a shape of the edge of the ground wafer; a transport unit for transporting the wafer between the grinding unit and the measurement unit; and a vibration isolation table disposed between the surface plate and the measurement unit.

18. The wafer processing system according to claim 17, wherein the grinding unit comprises: a grinding table on which the wafer is placed and which rotates the wafer; and a grindstone which comes into relative contact with an edge of the wafer placed on the grinding table to grind the edge; and the measuring unit comprises: a measuring table on which the wafer is placed and which rotates the wafer; and a shape measuring device which measures the shape of the edge of the wafer placed on the measuring table.

19. The wafer processing system described in claim 18, wherein the measurement unit has a first sensor for measuring the diameter of the wafer and the center position of the wafer with reference to the measurement table, the surface plate has a second sensor for measuring the center position of the wafer with reference to the surface plate, and the wafer processing system further comprises a control device for controlling the amount of transport of the wafer by the transport unit based on the difference between the two center positions measured by the first sensor and the second sensor and a preset relative position of the respective centers of rotation of the measurement table and the grinding table.

20. A wafer processing system according to any one of claims 17 to 19, wherein the measurement section is provided with a shape measuring device, and the shape measuring device has an optical unit which is a white light interference microscope.

21. A wafer processing system as described in any one of claims 17 to 19, wherein the vibration isolation table is moved between a seated position which is a non-operating position and a floating position which is located above the seated position and is an operating position, and the system has a locking member which fixes the vibration isolation table at the floating position and releases the fixation.

Images