Wafer processing system and wafer processing method

Abstract

To provide a wafer processing system and a wafer processing method capable of suppressing occurrence of a defect in a shape of an end of a wafer after grinding.SOLUTION: A wafer processing system (10) includes: a grinding unit (16) that grinds an end portion of a wafer; a measurement unit (20) that measures a shape of an end portion of the ground wafer and measures a shape of an end portion of a truer used for grinding; and a feedback calculation unit (152) that performs feedback to the grinding based on a measurement result of the shape of the end portion of the truer.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] When a disk-shaped wafer is surface-processed by a polishing apparatus, the edge of the wafer is processed into a sharp shape, which may cause the wafer to crack or chip. Therefore, a grinding process (also referred to as chamfering) is performed on the wafer to remove the sharp portion at the edge of the wafer and make the edge into a round shape or a chamfered shape (see Patent Document 1).

[0003] The shape and dimensions of the edge of the wafer formed by the grinding process are defined by the standards set by industry associations or the requirements of clients. Therefore, it is necessary to grind the edge within the defined range. For this reason, in the wafer manufacturing process, after the grinding process, the shape of the edge of the wafer is measured, and shape measurement is performed to inspect whether the shape of the edge is within the defined range.

[0004] Patent Document 2 discloses a shape measurement apparatus for measuring the shape of the edge of a wafer by a light projection measurement method. This shape measurement apparatus projects light onto the edge of the ground wafer from directions substantially parallel to each of the front and back surfaces of the wafer, and images the projection image of the edge of the wafer with a camera from a direction opposite to the light projection direction, and measures the shape of the edge of the wafer based on the projection image.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the grinding process as described above, defects (for example, deviations from the processing target) may occur in the shape of the end portion of the wafer. For example, the grinding wheel used in the grinding process is processed into the target shape by shaving the surface of the grinding wheel (adjusting the cross-sectional (groove) shape) with a dresser. Such a dresser deteriorates (wears) when repeatedly used. When the dresser deteriorates, the dressing of the grinding wheel cannot be sufficiently performed, which becomes a factor in the occurrence of defects in the shape of the end portion of the wafer.

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a wafer processing system and a wafer processing method capable of suppressing the occurrence of defects in the shape of the end portion of the wafer after grinding.

Means for Solving the Problems

[0008] The present invention comprises the following aspects in order to achieve the above object.

[0009] A wafer processing system according to a first aspect of the present invention includes a grinding unit that grinds an end portion of a wafer, a measuring unit that measures the shape of the end portion of the ground wafer, and a measuring unit that measures the shape of an end portion of a dresser for maintenance of a grinding wheel used in the grinding process, and a feedback calculation unit that performs feedback to the grinding process based on the measurement result of the shape of the end portion of the dresser.

[0010] A wafer processing system according to a second aspect of the present invention is, in the first aspect, the feedback calculation unit determines the quality of the dresser when the wear amount of the dresser exceeds a threshold value.

[0011] In the wafer processing system according to the third aspect of the present invention, in the first or second aspect, when the feedback calculation unit determines that the shape of the end portion of the wafer is defective, the measurement unit measures the shape of the end portion of the turret, and when the feedback calculation unit determines that the shape of the end portion of the turret is defective, an output prompting maintenance of the turret is performed, and when the feedback calculation unit determines that the shape of the end portion of the turret is good, an output prompting maintenance of the grindstone using the turret is performed.

[0012] The wafer processing system according to the fourth aspect of the present invention includes an output unit that superimposes and displays the measurement results of the wafer and the turret in any of the first to third aspects.

[0013] In the wafer processing system according to the fifth aspect of the present invention, in any of the first to fourth aspects, the feedback calculation unit compares the measured value of the shape of the turret with the design value, and calculates the correction amount of the shape of the turret and the relative movement amount between the wafer and the grindstone.

[0014] In the wafer processing system according to the sixth aspect of the present invention, in any of the first to fifth aspects, the measurement unit measures the measurement result of the surface roughness of the ground surface of the wafer, and the feedback calculation unit adjusts the depth of cut of the grindstone with respect to the wafer according to the measurement result of the surface roughness of the ground surface.

[0015] In the wafer processing system according to the seventh aspect of the present invention, in any of the first to sixth aspects, the feedback calculation unit adjusts the helical angle of the grindstone according to the measurement result of the wafer.

[0016] In the wafer processing method according to the eighth aspect of the present invention, in the measurement unit that measures the shape of the end portion of the ground wafer, the shape of the end portion of the turret used for grinding is measured, and feedback to the grinding process is performed based on the measurement result of the shape of the end portion of the turret.

Effects of the Invention

[0017] According to the present invention, by performing feedback according to the measurement result of measuring the chamfer in the measurement unit that measures the wafer, it is possible to suppress the occurrence of defects in the shape of the end portion of the wafer after grinding.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

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Figure 6

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Figure 8

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Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0020] [Wafer Processing System] FIG. 1 is a plan view showing a schematic configuration of a wafer processing system 10. In the following description, among the three mutually orthogonal XYZ directions shown in the figure, the X direction and the Z direction refer to the horizontal direction, and the Y direction refers to the vertical direction (perpendicular direction).

[0021] As shown in FIG. 1, the wafer processing system 10 includes a cassette unit 12, a load unit 14, a grinding unit 16, a cleaning unit 18, a measuring unit 20, and a transfer unit 22.

[0022] The load unit 14 transfers a wafer W (illustrated 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 / retrieval robot. The cassette unit 12 is provided with a wafer cassette in which a large number of wafers W to be chamfered are stored. The supply / retrieval robot takes out the wafers W one by one from the wafer cassette or stores the chamfered wafers W in the wafer cassette.

[0023] The supply / retrieval robot is provided with a three-axis rotating transfer arm, and this transfer arm is provided with a suction pad (not shown) on its upper surface portion. The transfer arm holds the wafer W by vacuum-sucking the lower surface of the wafer W with this suction pad. That is, the transfer arm of this supply / retrieval robot can move back and forth, up and down, and rotate while holding the wafer W, and transfers the wafer W by combining these operations.

[0024] The grinding unit 16 performs grinding processing on the edge of the wafer W, that is, from rough processing to finish processing.

[0025] FIG. 2 is a schematic configuration diagram showing a schematic configuration of a grinding device (chamfering device) 30 installed in the grinding unit 16. As shown in FIG. 2, the grinding device 30 includes a grinding table 32 for holding the wafer W, a grinding wheel 34, and a spindle motor 36 for rotating the grinding wheel 34.

[0026] The grinding table 32 has a holding surface 32a on its upper surface for adsorbing and holding the wafer W. The grinding table 32 is configured to be rotatable about a rotation axis P parallel to the Y direction by various actuators such as a motor drive mechanism (not shown).

[0027] The grinding wheel 34 is configured to be rotatable about a rotation axis parallel to the Y direction by a spindle motor 36. Further, the grinding wheel 34 is moved forward and backward in the Z direction relative to the end of the wafer W held by the grinding table 32. When the grinding wheel 34 is moved forward, the rotating grinding wheel 34 is relatively pressed against the outer peripheral portion (edge portion 80), which is the end of the rotating wafer W, and the outer peripheral portion of the wafer W is ground. The grinding wheel 34 in this example is a total grinding wheel having grinding grooves 34a on its outer peripheral portion, and the shape of the grinding grooves 34a is transferred to the outer peripheral portion of the wafer W during grinding.

[0028] The grinding apparatus 30 is provided with, in addition to the above-described grinding wheel (coarse grinding wheel) 34, a fine grinding wheel (not shown). Thereby, after the outer peripheral portion of the wafer W is roughly processed with the grinding wheel 34, chamfering for finish grinding of the outer peripheral portion of the wafer W is performed with the fine grinding wheel. Further, the grinding apparatus 30 is provided with a notch rough grinding wheel and a notch fine grinding wheel for grinding the notch portion 82 (see FIG. 4). Thereby, for the notch portion 82, after rough processing with the notch rough grinding wheel, chamfering as finish grinding is performed with the notch fine grinding wheel. Note that a plurality of grinding apparatuses 30 may be installed in the grinding unit 16.

[0029] Returning to FIG. 1, the cleaning unit 18 cleans the wafer W after chamfering. The 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, and peels off and removes the dirt adhering to the upper surface of the wafer W.

[0030] 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 lifting motion in the Y direction (vertical direction). The transfer robot includes an arm portion, and a suction pad is provided at the tip thereof. The transfer robot transfers the wafer W while sucking the upper surface of the wafer W with the suction pad of the arm portion. Thus, in the transfer unit 22, the transfer robot transfers the wafer W chamfered in the grinding unit 16 to the cleaning unit 18, or transfers the wafer W cleaned in the cleaning unit 18 to the grinding unit 16.

[0031] The measurement unit 20 measures the thickness and performs pre-alignment of the wafer W to be chamfered. The measurement unit 20 includes a measurement table (denoted by reference numeral 102 in FIG. 4), a thickness sensor, and an orifla-notch detection sensor in order to measure the thickness and perform pre-alignment of the wafer W.

[0032] The measurement table rotates the wafer W around its central axis. The thickness sensor is, for example, a capacitance sensor, and measures the distance from the upper surface to the lower surface of the wafer W. The measurement result of the capacitance sensor is output to an arithmetic unit (not shown), and the thickness of the wafer W is obtained. The orifla-notch detection sensor is, for example, a laser sensor, and detects the position of the orifla or notch of the wafer W. Here, the orifla is substantially an orientation flat, which is a flat portion formed at the end of the wafer W to indicate the crystal orientation of the wafer W, and the notch portion 82 is a notch portion formed to indicate the crystal orientation of the wafer. Examples of the thickness sensor include an interference type in addition to the capacitance type, and examples of the orifla-notch detection sensor include an image sensor.

[0033] Further, the measurement unit 20 includes a diameter measuring instrument (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 end portion of the chamfered wafer W. The configuration of the shape measuring device 100 will be described in detail later.

[0034] Next, an overview of the operation of the wafer processing system 10 of the embodiment will be described.

[0035] First, the wafer W is taken out from the cassette attached to the cassette unit 12 by the supply / retrieval robot of the load unit 14 and conveyed to the measurement unit 20. The wafer W conveyed to the measurement unit 20 is placed on the measurement table of the measurement unit 20.

[0036] Next, in the measurement unit 20, the thickness of the wafer W is measured and pre-alignment is performed using a thickness sensor and an orifice-notch detection sensor. Also, the diameter of the wafer W is measured using a diameter measuring instrument.

[0037] Next, the wafer W on which various measurements have been performed in the measurement unit 20 is conveyed to the grinding unit 16 by the supply / retrieval robot of the load unit 14. The wafer W conveyed to the grinding unit 16 is placed on the grinding table 32 of the grinding device 30.

[0038] Next, in the grinding unit 16, grinding processing (chamfering) of the edge of the wafer W is performed by the grinding device 30. Specifically, after the edge portion 80, which is the outer peripheral portion of the wafer W, is roughly processed with the grinding wheel 34, chamfering for finish grinding of the outer peripheral portion of the wafer W is performed with a finish grinding wheel. Also, for the notch portion 82 of the wafer W, after rough processing with a notch rough grinding wheel, chamfering as finish grinding is performed with a notch finish grinding wheel.

[0039] As shown in FIG. 1, the grinding unit 16 is provided with a grinding wheel motor 24 and a wafer / grinding wheel position control unit 26. The grinding wheel motor 24 is a motor for rotating the grinding wheel 34 and the fine grinding wheel in response to a control signal from the apparatus control unit 200. The wafer / grinding wheel position control unit 26 includes an actuator or the like for adjusting the relative position of the wafer W and the grinding wheel 34 and the fine grinding wheel (the XYZ-direction position and the inclination (helical angle) of the grinding wheel 34 and the fine grinding wheel with respect to the wafer W) in response to a control signal from the apparatus control unit 200. Note that the apparatus control unit 200 shown in FIG. 1 may be included in the control device 110 including the measurement control unit 160 or the like, or may be included in a circuit or a control device different from the control device 110. The measurement control unit 160 or the like will be described later.

[0040] Next, the wafer W that has completed the grinding process (chamfering process) in the grinding unit 16 is transported from the grinding unit 16 to the cleaning unit 18 using the transfer robot of the transfer unit 22. Then, in the cleaning unit 18, the wafer W is cleaned by a spin cleaning device.

[0041] Next, the wafer W that has been cleaned in the cleaning unit 18 is transported from the cleaning unit 18 to the grinding unit 16 by the transfer robot of the transfer unit 22. Thereafter, the wafer W is transported from the grinding unit 16 to the measurement unit 20 by the supply / retrieval robot of the load unit 14. The wafer W transported to the measurement unit 20 is placed on the measurement table.

[0042] Next, in the measurement unit 20, the diameter of the wafer W is measured using a diameter measuring instrument, and the three-dimensional shape of the end portion of the wafer W is measured by the shape measuring device 100. The measurement results of the measurement unit 20 (the diameter of the wafer W and the three-dimensional shape of the end portion of the wafer W) are output to an output unit (reference numeral 114 in FIG. 6). Note that the control device 110 described later may calculate a determination result indicating whether or not the measurement results of the measurement unit 20 are within a predetermined specified range, and output the determination result to the output unit.

[0043] Next, the wafer W for which the measurement has been completed in the measurement unit 20 is transported from the measurement unit 20 to the cassette unit 12 by the supply / retrieval robot of the load unit 14 and is accommodated in the cassette.

[0044] [Shape Measuring Device] Next, the configuration of the shape measuring device 100 will be described. This shape measuring device 100 calculates three-dimensional shape data indicating height information (such as surface shape and surface roughness) of the measured surface at the edge of the wafer W, which is the measurement object, based on a plurality of captured images captured at regular pitches while scanning an optical unit 104 (white interference microscope) described later in the scanning direction (Z direction).

[0045] FIG. 3 is a side view (viewed from the X direction) showing the schematic configuration of the shape measuring device 100. FIG. 4 is a plan view (viewed from the Y direction) showing the schematic configuration of the shape measuring device 100.

[0046] As shown in FIGS. 3 and 4, the shape measuring device 100 includes a measurement table 102, an optical unit 104, and a control device 110.

[0047] The measurement table 102 has a holding surface 102a for sucking and holding the wafer W on its upper surface. Further, the measurement table 102 is configured to be rotatable about a rotation axis G parallel to the Y direction. The table drive unit 116 is composed of various actuators such as a motor drive mechanism, and rotates the measurement table 102 about the rotation axis G under the control of the control device 110 described later. Thereby, the wafer W sucked and held on the holding surface 102a of the measurement table 102 rotates and moves about the rotation axis G.

[0048] The optical unit 104 is composed of a white light interference microscope. This optical unit 104 is provided at a position adjacent to one side in the Z direction (the left side in FIG. 3) with respect to the measurement table 102. Specifically, the optical unit 104 is arranged such that its optical axis R (corresponding to the optical axis of the interference objective lens 124) is parallel (including substantially parallel) to the main surface (upper surface or lower surface) of the wafer W. In other words, the optical axis R of the optical unit 104 is arranged to be parallel (including substantially parallel) to the direction orthogonal to the rotation axis G of the measurement table 102 (preferably, to intersect the rotation axis G of the measurement table 102). Then, the optical unit 104 images the end portion (edge portion 80 or notch portion 82) of the wafer W from a position facing the end portion of the wafer W held on the measurement table 102.

[0049] Next, the configuration of the optical unit 104 will be described in detail. FIG. 5 is a schematic diagram showing the details of the configuration of the optical unit 104.

[0050] The optical unit 104 is a Michelson type white light interference microscope. As shown in FIG. 5, this 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. Along the left side in the Z direction from the measured surface of the end portion of the wafer W to be measured, the interference objective lens 124, the beam splitter 122, the imaging lens 126, and the camera 128 are arranged in this order. Also, the light source unit 120 is arranged at a position facing the beam splitter 122 in the Y direction.

[0051] The light source unit 120 emits white light (low coherence light with low interferability) in the form of a parallel light beam as measurement light L1 toward the beam splitter 122 under the control of the control device 110. Although not shown in the figure, the light source unit 120 has a light source capable of emitting the measurement light L1 such as a light emitting diode, a semiconductor laser, a halogen lamp, and a high-intensity discharge lamp, and a collector lens for converting the measurement light L1 emitted from this light source into a parallel light beam.

[0052] The beam splitter 122 is, for example, a half mirror. The beam splitter 122 reflects a part 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. Also, the beam splitter 122 transmits a part of the combined light L3 (described later) incident from the interference objective lens 124 to the left side in the Z direction and emits the combined light L3 toward the imaging lens 126.

[0053] The interference objective lens 124 is of the 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 order from the measured surface side along the left side in the Z direction. Also, the reference surface 124C is arranged at a position facing the beam splitter 124B in the Y direction. Hereinafter, the explanation will be made using a Michelson type interference optical system, but the interference optical system is not limited to the Michelson type, and a known interference optical system such as the Mirau type or the Linnik type can be adopted.

[0054] The objective lens 124A has a condensing action and condenses the measurement light L1 incident from the beam splitter 122 onto the measured surface through the beam splitter 124B.

[0055] The beam splitter 124B is, for example, a half mirror. The beam splitter 124B splits a part of the measurement light L1 incident from the objective lens 124A as reference light L2, transmits the remaining measurement light L1, emits it to the measured surface, 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 measured surface and then reflected by the measured surface and returns to the beam splitter 124B.

[0056] The reference surface 124C is, for example, a reflection mirror and reflects the reference light L2 incident from the beam splitter 124B toward the beam splitter 124B. This reference surface 124C can be manually adjusted in the Y direction by a position adjustment mechanism (not shown) (for example, a ball screw mechanism, an actuator, etc.). Thereby, the optical path length (reference optical path length) of the reference light L2 can be adjusted.

[0057] The beam splitter 124B generates a combined light beam L3 of 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 beam L3 toward the objective lens 124A on the left side in the Z direction. This combined light beam L3 passes through the objective lens 124A and the beam splitter 122 and enters the imaging lens 126.

[0058] The imaging lens 126 forms an image of the combined light beam L3 incident from the beam splitter 122 on the imaging surface (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 surface of the camera 128.

[0059] The camera 128 has an imaging element of a CCD (Charge Coupled Device) type or a CMOS (Complementary Metal Oxide Semiconductor) type, although not shown. The camera 128 images the combined light beam L3 formed on the imaging surface of the imaging element by the imaging lens 126, and processes the imaging signal of the combined light beam L3 obtained by this imaging to output an imaging signal. The camera 128 is an example of an imaging unit.

[0060] The optical unit drive unit 106 is composed of various actuators such as a linear motor or a motor drive mechanism, and holds the optical unit 104 movably in the Z direction, which is the scanning direction. Under the control of the control device 110, the optical unit drive unit 106 scans the optical unit 104 in the Z direction, that is, along the direction parallel to the optical axis R of the optical unit 104. The optical unit drive unit 106 is an example of a relative movement unit.

[0061] In addition, the optical unit drive unit 106 holds the optical unit 104 so as to be movable not only in the Z direction but also in the Y and X directions. Thereby, it becomes possible to adjust the relative position (relative positions in the X and Y directions) of the optical unit 104 with respect to the end portion of the wafer to be measured. Further, when there is a limitation in the measurement field of the surface to be measured that can be measured at one time due to limitations such as the measurement field of the interference objective lens 124, it becomes possible to perform measurement a plurality of times 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 direction, the measurement table 102 may be moved in the X, Y, or Z direction.

[0062] The scale 130 is a position detection sensor that detects the Z-direction position of the optical unit 104, and for example, a linear scale is used. This 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.

[0063] FIG. 6 is a functional block diagram of the control device 110 in the shape measurement device 100. The control device 110 is connected to the light source unit 120 and the camera 128 of the optical unit 104, the scale 130, the table drive unit 116, the optical unit drive unit 106, the operation unit 112, and the output unit 114.

[0064] The operation unit 112 includes an input device (for example, a keyboard and a mouse, etc.) for receiving an operator's operation input to the control device 110.

[0065] The output unit 114 is a device for outputting the execution result of a program, data of calculation results, etc. by the control device 110. The output unit 114 includes, for example, an operation UI (User Interface) and a monitor (for example, a liquid crystal display, etc.) for displaying detection results. Further, in addition to or instead of the monitor, the output unit 114 may include a printer or a speaker, etc.

[0066] The control device 110 controls the measurement operation of the three-dimensional shape of the surface to be measured (edge portion 80 or notch portion 82) by the shape measurement device 100 according to the operation input from the operation unit 112, and performs operations such as calculation of the three-dimensional shape of the surface to be measured. The control device 110 includes a processor that executes various operations (for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc.), a memory that serves as a working area for the processor (for example, a ROM (Read Only Memory) and a RAM (Random Access Memory), etc.), and a storage device for storing various programs and data (for example, an SSD (Solid State Drive) or an HDD (Hard Disk Drive), etc.).

[0067] The control device 110 functions as a shape / roughness analysis unit 150, a feedback calculation unit 152, and a measurement control unit 160 by executing the program stored in the storage device by the processor.

[0068] The measurement control unit 160 controls the table drive unit 116, the optical unit drive unit 106, the light source unit 120, and the camera 128, and repeatedly captures an image of the surface to be measured (edge portion 80 or notch portion 82) of the measurement object by the camera 128 at a constant pitch while scanning the optical unit 104 in the scanning direction (Z direction). Specifically, the measurement control unit 160 controls the table drive unit 116 to rotate the measurement table 102 so that the surface to be measured (edge portion 80 or notch portion 82) of the measurement object faces the optical unit 104. Further, after starting the emission of the measurement light L1 from the light source unit 120, the measurement control unit 160 controls the optical unit drive unit 106 to scan the optical unit 104 in the Z direction. Further, while the optical unit drive unit 106 scans the optical unit 104 in the Z direction, the measurement control unit 160, based on the detection result of the Z-direction position of the optical unit 104 by the scale 130, repeatedly executes imaging of the combined light L3 by the camera 128 and output of the captured image to the control device 110 every time the optical unit 104 moves by a constant pitch in the Z direction.

[0069] Each time the camera 128 captures the combined light L3, the shape and roughness analysis unit 150 acquires the captured image output from the camera 128 and generates three-dimensional shape data of the measured surface of the object to be measured (wafer W). Further, the shape and roughness analysis unit 150 generates three-dimensional shape data of the end portion of the turret by placing the turret on the measurement table 102 of the measurement unit 20.

[0070] The feedback calculation unit 152 performs feedback control according to the measurement result by the shape and roughness analysis unit 150.

[0071] [Example 1] Conventionally, in order to detect the deterioration of the turret (measure the wear condition), off-machine measurement by a device separate from the wafer grinding unit was required, so the detection work of the turret deterioration was complicated. Therefore, in order to avoid the work becoming complicated, a replacement count management was implemented to replace the turret when the number of grinding wheels ground by the turret reached a predetermined number.

[0072] However, when the turret is uniformly replaced by count management regardless of the actual deterioration condition of the turret, there may be a case where a turret with no deterioration is targeted for replacement.

[0073] Therefore, in Example 1, the turret is measured regularly in the wafer processing system 10. For example, at regular intervals from the start of operation of the wafer processing system 10, each time the number of times of processing the grinding wheel 34 or the fine grinding wheel using the turret reaches a predetermined number, the turret is transported to the measurement unit 20 to measure the shape of the end portion of the turret.

[0074] FIG. 7 is a cross-sectional view showing an example of the shape of the end portion of the turret. The actually measured shape T of the turret TR measured by the shape measuring device 100 A is the target shape T T Let the magnitude of the wear amount (deviation in the Y direction, maximum value of the deviation) with respect to be dy.

[0075] The shape and roughness analysis unit 150 generates three-dimensional shape data of the tip of the turret TR and calculates the wear amount dy.

[0076] When the wear amount dy exceeds a threshold value (for example, 5 μm) according to the measurement result by the shape and roughness analysis unit 150, the feedback calculation unit 152 outputs (for example, displays) to the output unit 114 that the turret TR needs to be replaced, or stops the processing of the wafer W. Note that the threshold value is not limited to the above. For example, when the ratio of dy to the thickness Dy of the wafer W is equal to or greater than the threshold value (1% in one example), the turret TR may be determined as defective (NG).

[0077] According to the first embodiment, by periodically measuring the turret, the wear condition of the turret can be parameterized and numerically evaluated. Thereby, the waste of maintenance of the turret TR can be reduced, and the replacement of the turret TR that has not deteriorated can be prevented. Further, according to the first embodiment, the probability of occurrence of processing defects of the wafer W can be reduced, and the reliability of processing can be improved.

[0078] [Second Embodiment] When the measurement result of the shape of the wafer W is defective (NG), it is necessary to quickly investigate the cause and recover. When the shape of the wafer W is NG, for example, the following countermeasures can be considered. That is, after grinding the grinding wheel 34 or the lapping wheel with the turret TR, the wafer W is ground again to measure the wafer W. And when the determination result of the second time is also NG, the turret TR is replaced or the like.

[0079] However, in the above countermeasures, when there is a defect in the turret TR, the steps from the maintenance of the grinding wheel to the re-judgment are wasted.

[0080] Therefore, in the second embodiment, when the shape of the wafer W is NG, the turret TR is measured. Thereby, the waste of the maintenance of the grinding wheel can be eliminated.

[0081] FIG. 8 is a flowchart showing a wafer processing method according to the second embodiment.

[0082] As shown in FIG. 8, in the second embodiment, first, the shape measuring device 100 measures the shape of the end portion of the wafer W (step S10). Then, when the measurement result of the wafer W is NG, the turret TR used for the maintenance (truing) of the grinding wheel 34 or the lapping wheel for the wafer W is transported to the measuring unit 20, and the shape measuring device 100 measures the shape of the end portion of the turret TR (step S12).

[0083] Next, when the shape of the end portion of the turret TR is good (OK), the maintenance of the grinding wheel 34 or the lapping wheel is performed using this turret TR (step S14). On the other hand, when the shape of the end portion of the turret TR is defective (NG), the maintenance of the turret TR is performed (step S16). For example, the feedback calculation unit 152 notifies the operator via the output unit 114 (for example, a display prompting the replacement of the turret TR, etc.) to prevent truing from being performed.

[0084] According to the second embodiment, since the process of re-measuring the wafer W can be omitted from truing, the cause of the shape defect of the wafer W can be identified at an early stage. Further, according to the second embodiment, since truing by the defective turret TR is not performed, the grinding wheel 34 or the lapping wheel is not damaged. Therefore, the running cost of the wafer processing system 10 can be reduced.

[0085] [Third Embodiment] As described above, in the wafer processing system 10, the shape of the turret TR is transferred to the grinding wheel 34 or the lapping wheel, and the grinding process of the wafer W is performed using this grinding wheel 34 or the lapping wheel. Therefore, it is preferable that the wafer W and the turret TR have shapes as close as possible, and more preferably, the same shape.

[0086] Therefore, in the third embodiment, a user interface (UI) is provided that overlays and displays the measurement results of the wafer W and the turret TR on the output unit 114.

[0087] In the example shown in FIG. 9, the measurement results (cross-sectional shapes) of the wafer W and the turret TR are superimposed and displayed. Note that the dimensions of the wafer W and the turret TR (for example, the dimension in the Y direction, the tilt angle, etc.) or the numerical value of the deviation amount δ (for example, the maximum value of the deviation) in the Y direction may be displayed.

[0088] According to Example 3, the operator can check the difference between the shape of the wafer W and the shape of the turret TR based on the above UI. Thereby, it can be determined whether the shape of the turret TR is accurately transferred to the wafer W. Further, when the shape of the wafer W is disturbed, it can be determined whether there is a problem with the turret TR.

[0089] Note that the processing conditions of the wafer W (for example, the feed amount in the Z direction) etc. may be displayed together. In this case, by comparing the information on the shape of the turret TR and the feed amount in the Z direction with the wafer W, the cause of the defect of the wafer W can be determined.

[0090] [Modification Example 1] By the way, there is a case where the upper and lower surfaces of the edge portion 80 of the wafer W are processed separately by moving (up and down) the relative position of the grinding wheel 34 and the wafer W in the Y direction. In this case, it cannot be determined whether the defect in the shape of the wafer W is caused by the operation in the Y direction or the shape of the grinding wheel 34 (dress). For example, if truing is performed in the case of a defect caused by the operation in the Y direction, the actual shapes of the turret TR and the wafer W will deviate, and the processing accuracy of the wafer W will decrease.

[0091] FIG. 10 is a diagram for explaining the cause of the defect in the shape of the wafer. FIG. 10(a) shows an example in which the actual shape W of the wafer W A deviates from the target shape W T due to wear of the turret TR. FIG. 10(b) shows an example in which the wafer W deviates from the target shape (becomes thinner) because the actual movement amount 34 T is excessive with respect to the relative target movement amount 34 A of the grinding wheel with respect to the wafer W.

[0092] Therefore, in Modification 1, the feedback calculation unit 152 calculates the correction amount and the Y-direction movement amount of the turret TR independently by comparing the measured value and the designed value of the shape of the turret TR. For example, when a defect in the shape of the wafer W is detected, the turret TR is measured by the measuring unit 20. Then, when it is determined by the feedback calculation unit 152 that the difference between the measured value and the designed value of the shape is equal to or greater than the threshold value, the shape of the turret TR may be corrected or the turret TR may be replaced according to this difference. On the other hand, when it is determined by the feedback calculation unit 152 that the difference is less than the threshold value, the wafer / grinding wheel position control unit 26 may be controlled via the apparatus control unit 200 to adjust the relative movement amount between the wafer W and the grinding wheel according to this difference. And after performing these adjustments, the quality of the shape of the wafer W may be determined again.

[0093] According to Modification 1, the correction of the shape of the turret TR and the correction of the relative movement amount between the wafer W and the grinding wheel can be appropriately performed respectively.

[0094] Also, as described above, in the present embodiment, since the same measuring unit 20 is used to measure the wafer W and the turret TR, systematic errors are less likely to be included in the measurement results, and high-precision correction of the movement amount becomes possible.

[0095] [Modification 2] By the way, as the cutting amount (movement amount in the Z direction) of the grinding wheel 34 with respect to the wafer W increases, the processing efficiency increases, but the grinding surface of the wafer W (hereinafter referred to as the processing surface) becomes rougher.

[0096] Therefore, in Modification 2, the roughness of the processed surface of the wafer W is measured by the shape measuring device 100. Then, the feedback calculation unit 152 performs feedback to the depth of cut of the grindstone 34 or the like according to the measurement result of the roughness. For example, when the roughness of the processed surface of the wafer W increases, the feedback calculation unit 152 controls the wafer / grindstone position control unit 26 via the device control unit 200 to perform at least one of adjustment to reduce the depth of cut and adjustment to increase the rotation speed of the spindle motor 36.

[0097] According to Modification 2, by using the measurement result of the roughness of the wafer W, it is possible to perform processing with the maximum depth of cut that can achieve the target roughness according to the state of the grindstone. Thereby, it is possible to contribute to the improvement of the economic efficiency of the wafer processing system 10.

[0098] [Modification 3] FIG. 11 is a cross-sectional view of the wafer W after grinding. As shown in FIG. 11, in the edge portion 80 of the wafer W after grinding, a substantially flat portion W1 along the Y direction and inclined portions W2 extending from the Y-direction (up and down) ends of the substantially flat portion W1 toward the front and back surfaces of the wafer W are formed following the shape of the grindstone 34.

[0099] In Modification 3, the feedback calculation unit 152 compares the roughness of the inclined portion W2 with the roughness of the substantially flat portion W1 and feeds back the comparison result to the processing conditions of the wafer W. For example, since the inclined portion W2 of the wafer W is likely to be subjected to processing stress, the grindstone surface is likely to be roughened. On the other hand, the substantially flat portion W1 tends to have relatively stable roughness.

[0100] In view of the above properties, when the roughness of the substantially flat portion W1 increases, the feedback calculation unit 152 controls the wafer / grindstone position control unit 26 via the device control unit 200 to adjust the depth of cut of the grindstone 34 or the rotation speed of the spindle motor 36 or the like. Specifically, by reducing the depth of cut of the grindstone 34 or increasing the rotation speed of the spindle motor 36, it is possible to suppress the substantially flat portion W1 from becoming rough.

[0101] On the other hand, when the roughness of the inclined surface portion W2 increases, the feedback calculation unit 152 performs at least one of the processes of performing truing and outputting to the output unit 114 prompting the operator to perform truing or replace the turret TR.

[0102] According to Modification 3, the wafer W can be processed under optimal processing conditions according to the roughness of the substantially flat surface portion W1 and the inclined surface portion W2 of the wafer W.

[0103] [Modification 4] Also, when the grindstone 34 is tilted with respect to the wafer W for processing, it is also possible to correct the helical angle according to the measurement result of the wafer W by the shape measurement device 100.

[0104] For example, when the helical angle is changed, it is conceivable that the shape of the processed surface (W1 and W2) of the wafer W changes or the roughness improves. Therefore, as shown in FIG. 12, when the shape or roughness of the processed surface of the wafer W deteriorates, the feedback calculation unit 152 controls the wafer / grindstone position control unit 26 via the device control unit 200 to adjust the helical angle.

[0105] According to the present embodiment, by performing feedback according to the measurement result of the wafer W or the turret TR, the wafer W can be processed under optimal conditions. In addition, since the necessity of maintenance can be immediately notified to the operator via the output unit 114, it is possible to reduce processing defects.

[0106] Furthermore, according to the present embodiment, since the turret TR and the wafer W are measured by the same measurement unit 20, the influence of the systematic error of the measurement unit 20 can be suppressed during feedback.

[0107] In the above-described embodiment, in the measurement unit 20, a configuration including a shape measurement device having a white light interference microscope has been described as an example. However, the present invention is not limited thereto. For example, a shape measurement device having a microscope such as a focus variation method microscope or a laser confocal method microscope may be provided, or a shape measurement device using a light projection measurement method may be provided.

[0108] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above examples, and various improvements and modifications may of course be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0109] 10... Wafer processing system, 12... Cassette unit, 14... Loading unit, 16... Grinding unit, 18... Cleaning unit, 20... Measurement unit, 22... Conveying unit, 24... Grinding wheel motor, 26... Wafer / grinding wheel position control unit, 30... Grinding device, 32... Grinding table, 32a... Holding surface, 34... Grinding wheel, 34a... Grinding groove, 36... Spindle motor, 80... Edge portion, 82... Notch portion, 100... Shape measurement device, 102... Measurement table, 102a... Holding surface, 104... Optical unit, 106... Optical unit drive unit, 110... Control device, 112... Operation unit, 114... Output unit, 116... Table drive unit, 120... Light source unit, 122... Beam splitter, 124... Interference objective lens, 124A... Objective lens, 124B... Beam splitter, 124C... Reference surface, 126... Imaging lens, 128... Camera, 130... Scale, 150... Shape / roughness analysis unit, 152... Feedback calculation unit, 160... Measurement control unit, 200... Device control unit

Claims

1. A grinding unit for grinding an end portion of a wafer, A measuring unit for measuring the shape of the end portion of the wafer after the grinding process, the measuring unit measuring the shape of the end portion of the dresser for maintenance of the grinding wheel used in the grinding process, A feedback calculation unit for performing feedback to the grinding process based on the measurement result of the shape of the end portion of the dresser, A wafer processing system comprising the same.

2. The wafer processing system according to claim 1, wherein the feedback calculation unit determines the quality of the dresser when the wear amount of the dresser exceeds a threshold value.

3. When the feedback calculation unit determines that the shape of the end portion of the wafer is defective, the measuring unit measures the shape of the end portion of the dresser, When the feedback calculation unit determines that the shape of the end portion of the dresser is defective, an output is provided to prompt maintenance of the dresser, The wafer processing system according to claim 1, wherein when the feedback calculation unit determines that the shape of the end portion of the dresser is good, an output is provided to prompt dressing of the grinding wheel using the dresser.

4. The wafer processing system according to any one of claims 1 to 3, further comprising an output unit for superimposed display of the measurement results of the wafer and the dresser.

5. The wafer processing system according to any one of claims 1 to 3, wherein the feedback calculation unit compares the measured value of the shape of the dresser with the design value and calculates the correction amount of the shape of the dresser and the relative movement amount between the wafer and the grinding wheel.

6. The measuring unit measures the measurement result of the surface roughness of the ground surface of the wafer, The wafer processing system according to any one of claims 1 to 3, wherein the feedback calculation unit adjusts the depth of cut of the grinding wheel with respect to the wafer according to the measurement result of the surface roughness of the ground surface.

7. The wafer processing system according to any one of claims 1 to 3, wherein the feedback calculation unit adjusts the helical angle of the grindstone according to the measurement result of the wafer.

8. In a measurement unit that measures the shape of the end portion of a ground wafer, the shape of the end portion of the turret used for the grinding is measured, A wafer processing method, wherein feedback to the grinding is performed based on the measurement result of the shape of the end portion of the turret.

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