JP2018170312A - Wafer positioning apparatus and chamfering apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer positioning apparatus and a chamfering apparatus using the same which can surely detect edge parts even for wafers that have been bonded or molded with glass, resin, or silicon.SOLUTION: A wafer positioning apparatus that detects the outer peripheral edge and detects the center of a wafer W includes a measurement table 66 on which the wafer W is mounted and that is rotatable while holding the wafer W and an optical sensor 1 that is installed in the vicinity of the outer peripheral edge of the mounted wafer W while maintaining a predetermined distance from the measurement table 66 and receives reflected light from the substantially disk-shaped surface of the wafer W, and the light receiving angle of the optical sensor 1 is narrowed such that the detection sensitivity is reduced on the surface inclined with respect to the horizontal plane of the wafer W.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wafer positioning apparatus bonded and molded with glass, resin, and silicon, and a chamfering apparatus using the same.

  In recent years, wafers that have been bonded or molded with glass, resin, or silicon have been proposed. For example, various applications such as projectors, high-frequency devices, and MEMS-applied products are expected due to substrate insulation and transparency. ing. In addition, notches called orientation flats (orientation flats (OF)) or notches are provided at predetermined positions on the outer peripheral edge of the wafer as marks for making the crystal orientation known in a later step. Yes.

  Therefore, when a wafer having such a configuration is put into various devices such as a chamfering device for further processing or an inspection machine for performing inspection, it is necessary to position the wafer based on the orientation flat. In particular, the processing state of the wafer end face (edge part) is regarded as important because of the demand for improving the quality of the wafer, and chamfering is performed by grinding the edge part in order to prevent chipping due to handling.

  As a technique for positioning a wafer, optically detecting a positioning reference part such as an orientation flat or a notch provided on the outer peripheral edge of a disk-shaped wafer, and positioning the wafer with reference to this positioning reference part It is known to optically measure the outer peripheral edge of a wafer by a line sensor while rotating the wafer after centering the wafer, and is described in Patent Document 1.

  When aligning semiconductor wafers stacked on top and bottom, an alignment mark formed on the surface of the semiconductor wafer disposed on the near side as viewed from the imaging means is imaged by an imaging means such as an infrared camera. Is known and described in US Pat.

JP 2011-181849 A Japanese Patent Laying-Open No. 2015-188042

  However, in the above prior art, when detecting the outer shape of the stacked wafers, the maximum outer shape of the entire wafer is detected, and it is difficult to correctly detect the outer shape corresponding to the bonded surface. In particular, in optical detection, because the depth of field is finite, the part other than the focal position is out of focus, the boundary of the shadow is blurred due to the spread of the light source, and the shadow is made with the round corner of the object, Since distortion is caused by local reflection in the vicinity of the edge, the edge obtained from the actual image is far from the ideal edge, and stable measurement is difficult.

  In particular, when aligning silicon and silicon with a glass-silicon wafer as a reference, normal line-type sensors and images have problems such as transparency of the glass part, dust and overlap, bubbles, swells, and dirt. Positioning was extremely difficult.

  The object of the present invention is to solve the above-described problems of the prior art, and even a wafer that has been bonded or molded with glass, resin, or silicon can be easily incorporated into a general-purpose chamfering apparatus and reliably. Another object of the present invention is to obtain a wafer positioning device capable of detecting an edge portion and a chamfering device using the same.

  In order to achieve the above object, the present invention provides a wafer positioning apparatus that detects an outer peripheral edge and detects the center of a wafer, and a measurement table that is rotatable while placing the wafer and holding the wafer. An optical sensor installed in the vicinity of the outer peripheral edge of the mounted wafer while maintaining a predetermined distance from the measurement table and receiving reflected light from a substantially disk-shaped surface of the wafer, The light receiving angle of the sensor is narrowed so that the detection sensitivity is reduced on the surface that is inclined with respect to the horizontal plane of the wafer.

  In the above, it is preferable that the optical sensor is a reflective line sensor in which image elements are arranged in a line.

  Furthermore, in the above, it is desirable that the light receiving angle is 0 ° to 4 °.

  Further, in the above, the wafer is a wafer that is bonded using at least one of glass, resin, and silicon, and the light receiving angle is 1 of an angle with respect to a horizontal plane of a slope portion of the wafer. / 10 or less is desirable.

  Further, in the above-described configuration, it is preferable that the light receiving angle is narrowed so that light is received with respect to a horizontal plane of the wafer and is not received on a sloped surface.

  Further, in the above, it is desirable that the light receiving angle is 0 ° to 2 °.

  Furthermore, in the above, it is preferable that a slit is disposed on the front surface in the light receiving direction of the optical sensor, and the light receiving angle is narrowed by the slit.

  Further, the present invention provides a chamfering apparatus for chamfering that grinds an end surface of a wafer, a measurement table that can be rotated while placing the wafer and holding the wafer, and the vicinity of the outer peripheral edge of the placed wafer And an optical sensor that receives the reflected light from the substantially disk-shaped surface of the wafer, and has a light-receiving angle that is inclined with respect to the horizontal surface of the wafer. Then, the center of the wafer is detected by detecting the outer peripheral edge of the wafer by the optical sensor narrowed so as to reduce the detection sensitivity.

  Furthermore, in the above, the wafer is a wafer that has been bonded using at least one of glass, silicon, and resin, and is a reflective line sensor in which image elements are arranged in a line. The optical sensor detects the edge position of the inner periphery of the silicon, determines the center position of the wafer from the detected edge position, and rotates the wafer table on which the wafer is placed during the chamfering process. It is desirable to place the shaft so that the center position matches.

  According to the present invention, an optical sensor that receives reflected light from a substantially disk-shaped surface of a wafer that is installed in the vicinity of the outer peripheral edge of the wafer with a predetermined distance from the measurement table is provided, and the light receiving angle of the optical sensor is Because the detection sensitivity is narrowed on the surface that is inclined with respect to the horizontal plane of the wafer, the edge portion is surely attached even to wafers that are bonded or molded with glass, resin, or silicon. A detectable wafer positioning apparatus and a chamfering apparatus using the same can be obtained.

The front view which shows the principal part of the chamfering apparatus which concerns on one Embodiment of this invention. The top view which shows the principal part of the chamfering apparatus in one Embodiment. Side view showing detection of edge inner periphery of wafer in one embodiment The top view which shows the structure of the chamfering process part which concerns on one Embodiment of this invention. Explanatory drawing which shows the detection of the outer periphery edge by the conventional reflection type line sensor Explanatory drawing which shows the measurement of the plane in one Embodiment Explanatory drawing which shows the measurement of the edge part (slope) in one Embodiment The graph which compares and shows the measurement result of the wafer W height in one Embodiment and the former

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front view showing a main part of a chamfering apparatus according to an embodiment of the present invention. The chamfering apparatus 10 includes a wafer feeding unit 20, a grindstone rotating unit 50, a wafer supply / storage unit (not shown), a wafer cleaning / drying unit, a wafer transfer unit, and a controller that controls operations of each part of the chamfering device.

  On the other hand, there is a strong demand for quality improvement of the wafer, and the processing state of the wafer end face (edge portion) is important. In order to prevent chipping due to handling, chamfering is performed by grinding the edge, and chamfering is performed by polishing. That is, in the manufacturing process, the quality improvement of the edge characteristics is an indispensable process from the wafer manufacturing to the device manufacturing.

  In order to perform the chamfering process, positional information of the wafer W is required, and the wafer W needs to be accurately arranged on the apparatus before the chamfering process. As a pre-stage process of the polishing process, the position of the center point of the wafer and the position of the OF of the wafer W must be accurately detected at predetermined positions and placed on the wafer table 34. Further, in normal grinding, the chamfered portion is ground in a state where the main surface of the wafer W is perpendicular to the rotation axis of the resin grindstone, but so-called helical grinding is performed in which the chamfered portion of the wafer W is ground by tilting the resin grindstone. It is known to do.

  In FIG. 1, a wafer feed unit 20 includes an X-axis base 21, two X-axis guide rails 22, 22, four X-axis linear guides 23, 23,. And an X table 24 which is moved in the X direction in the figure by an X-axis drive mechanism 25 comprising a stepping motor.

  The X table 24 has two Y-axis guide rails 26, 26, four Y-axis linear guides 27, 27,..., And is moved in the Y direction in the figure by a Y-axis drive mechanism including a ball screw and a stepping motor (not shown). The Y table 28 to be used is incorporated.

  The Y table 28 is guided by two Z-axis guide rails 29 and 29 and four Z-axis linear guides (not shown), and is moved in the Z direction in the figure by a Z-axis drive mechanism 30 including a ball screw and a stepping motor. Z table 31 is incorporated.

  A motor 32 and a θ spindle 33 are incorporated in the Z table 31, and a wafer table 34 on which a wafer W (plate-like workpiece) is sucked and mounted is attached to the θ spindle 33. The wafer table 34 is rotated about the wafer table rotation axis CW in the θ direction in the figure.

  A truing grindstone 41 (hereinafter referred to as a truer 41) used for truing a grindstone for chamfering the periphery of the wafer W is attached to the lower portion of the wafer table 34 concentrically with the wafer table rotation axis CW.

  By this wafer feeding unit 20, the wafer W and the truer 41 are rotated in the θ direction in the figure and moved in the X, Y, and Z directions.

  The grindstone rotating unit 50 is provided with an outer peripheral rough grinding grindstone 52, an outer grindstone spindle 51 which is driven to rotate around an axis by an unillustrated outer grindstone motor, and an upper outer perimeter precision mounted on an upper turntable 53. A grinding spindle 54 and an upper and outer peripheral fine grinding motor 56 are provided. Similarly, a lower outer peripheral precision spindle 57 and a lower outer peripheral precision motor (not shown) are provided on the turntable 53 via a lower fixing frame 59 (not shown in FIG. 1).

The upper and lower outer peripheral spindles 54 and 57 are used for chamfering the outer periphery of the wafer W with the rotation axis inclined at 3 ° to 15 °, preferably 6 ° to 10 ° with respect to the rotation axis of the wafer W. Finish processing. Thereby, although helical grinding is performed and a weak grinding trace is generated in the chamfered portion of the wafer W in an oblique direction, an effect of improving the surface roughness of the chamfered portion as compared with normal grinding can be obtained.
The upper outer periphery precision grinding spindle 54 is equipped with an upper outer periphery precision grinding wheel (upper grinding wheel) that is a chamfering grind for grinding the outer periphery of the wafer W. Similarly, the lower outer periphery precision grinding spindle 57 is provided with a lower outer periphery precision grinding. The grindstone (lower grinding grindstone) is attached to the upper and outer peripheral fine grinding grindstones so that the rotating shaft is substantially concentric with a gap of about 0.1 to 1 mm smaller than the thickness of the wafer W.

  Further, the upper outer periphery precision grinding wheel and the lower outer periphery precision grinding wheel are driven by the upper outer periphery precision grinding spindle 54 and the lower outer periphery precision grinding spindle 57, respectively, so that the rotation directions are reverse, that is, reverse rotation. A grinding groove for processing the wafer W is formed by an upper and outer peripheral precision grinding wheel and a lower and outer peripheral precision grinding wheel.

  The wafer processing process is performed in the order of block cutting → orientation flat (OF) processing → slicing → chamfering → lapping → etching → donor killer → fine chamfering, and various cleanings are used to remove dirt between the processes. In block cutting, both ends (top and tail) of the ingot are cut and the outer periphery is ground, and the long one is cut at an appropriate length to form a cylindrical “block” having a predetermined diameter.

  In orientation flat (OF) processing, the crystal orientation is measured, and an orientation flat (OF) or “notch” is cut into a predetermined position so that the orientation can be determined in a later step. In slicing, a wafer is cut out from the block with a dicing saw, a wire saw, or an inner peripheral blade. A block having a diameter of 300 mm is usually cut up to 200 at a time by a multi-wire saw.

  In the chamfering, if the end surface of the wafer remains sharp during slicing, the wafer is easily cracked or chipped during handling such as conveyance and alignment in subsequent processing steps, and the fragments damage or contaminate the wafer surface. In order to prevent this, the end face of the cut wafer is chamfered with a grinding wheel coated with diamond.

  The chamfering process may be performed after the lapping process. At this time, the diameter of the outer periphery with variations is matched, the length of the width of the orientation flat (OF) is matched, and the dimension of a small notch called a notch is also matched.

  FIG. 2 is a plan view showing the main part of the entire chamfering apparatus 10. The supply / recovery unit supplies the wafer W to be chamfered from the wafer cassette 70 and collects the chamfered wafer in the wafer cassette 70. This operation is performed by the supply / recovery robot 40. The wafer cassette 70 is set on a cassette table 71 and contains a number of wafers W to be chamfered. The supply / recovery robot 40 takes out the wafers W one by one from the wafer cassette 70 and stores the chamfered wafers W in the wafer cassette 70.

  The supply / recovery robot 40 includes a triaxial rotary arm 80, and the arm 80 includes a suction pad (not shown) on the upper surface thereof. The arm 80 holds the wafer W by vacuum suction of the back surface of the wafer with a suction pad. That is, the arm 80 of the supply / recovery robot 40 can move up and down, move up and down and swivel while holding the wafer W, and transfers the wafer W by combining these operations.

  The chamfering device 10 is disposed in the front portion, and performs all processes for chamfering the outer periphery of the wafer W, that is, from roughing to finishing. The chamfering device 10 includes a wafer feeding unit 20 and a grindstone rotating unit 50.

  The transfer arm 63 enables transfer between the measurement table 66 and the wafer table 34 via the transfer rail 60 while maintaining the posture of the wafer W during transfer. For this reason, the transfer arm 63 can suck and fix the wafer W and release the suction.

  The transfer arm 63 lifts up the wafer W from the table in each process, and lifts down (places) the wafer W onto the table. The center of the wafer W placed on the measurement table 66 is slightly decentered from the rotation center of the measurement table 66 as long as the outer peripheral edge of the wafer W is in a position range that can be measured by the reflective line sensor 1. Good.

  The transfer rail 60 is a laying rail for moving the transfer arm 63 in order to transfer the wafer W to a predetermined table between processes, for example, between a measurement process and a chamfering process. The wafer table 34 is a table for placing the wafer W during the chamfering process. The wafer table 34 firmly holds the wafer W so that the mounted wafer W can be polished. For this purpose, the wafer table 34 sucks and fixes the wafer W.

  Further, since the wafer table 34 is movable in the X direction and the Y direction on the two-dimensional plane, the eccentric amount and the eccentric direction of the wafer W are adjusted, and the wafer W is placed when the wafer W is placed. The center position can be aligned with the rotation center of the wafer table 34. Thereby, the wafer table 34 is adjusted based on the adjustment data including at least the eccentric amount and the eccentric direction of the wafer W detected when the wafer W transferred from the measurement table 66 is placed. The position can be adjusted to the rotation center of the wafer table 34.

  In the chamfering step, by aligning the center of the wafer W with the rotation center (rotation axis center) of the wafer table 34, the amount of polishing on the wafer W can be reduced during chamfering. Thereby, it can also lead to reduction of the cycle time in a chamfering process.

  FIG. 3 is a diagram illustrating detection of the inner peripheral edge of the bonded wafer. The position of the center of the wafer W in which the lower silicon is bonded to the upper glass substrate is aligned with the rotation center of the wafer table 34. The measurement table 66 is formed in a thin disk shape, and the outer diameter of the disk shape is smaller than the outer diameter of the wafer W.

  The measurement table 66 can be freely controlled. The measurement table 66 rotates with the wafer W mounted thereon. The measurement table 66 can measure the rotation angle, detects the position of the outer peripheral edge reaching the entire circumference of the wafer W by the reflection type line sensor 1, and obtains the distance between the outer peripheral edge and the rotation center. In the reflective line sensor 1, the image elements are arranged in a line in the radial direction of the wafer W in a line from the outermost periphery to the inner periphery.

  In FIG. 3, the reflective line sensor 1 is installed near the outer peripheral edge of the wafer W and irradiated with light as indicated by an arrow in a direction substantially perpendicular to the substantially disk-shaped surface of the wafer W. The reflected light of the light is received and the outer peripheral edge of the wafer W is detected. When the outer edge is detected, the distance from the center of the measurement table 66 is calculated. In the calculation, measurement data for each rotation angle can be obtained over the entire circumference of the wafer W by rotating the wafer W. In addition to this, the measurement data may include a measurement date and time, an identification number that can specify the wafer W to be measured, a measurement result in the measurement table 66 (measurement impossible or the number of re-measurements), and the like. Based on the measurement data, the center position and radius of the wafer W, and the amount and direction of eccentricity of the measurement table 66 from the center of rotation of the measurement table 66 with respect to the center of the wafer W are obtained.

  FIG. 4 is a plan view showing the configuration of the processing portion. In the standby state before the start of processing, the wafer W held on the wafer table 34 is placed so that the center position of the wafer W obtained from the measurement data coincides with the rotation axis of the wafer table 34. At this time, the OF portion of the wafer W is arranged to face a predetermined direction.

  The outer peripheral rough grinding wheel 52 and the outer peripheral fine grinding wheel 55 are located at a predetermined distance from the wafer W, respectively. Specifically, the rotation center of the outer peripheral rough grinding wheel 52 is disposed at a position separated from the rotation center of the wafer W by a predetermined distance in the Y-axis direction, and the rotation center is in the X-axis direction with respect to the wafer W. It is arranged at a position separated by a predetermined distance.

  First, an alignment operation is performed. In this alignment operation, the relative positional relationship between the wafer W held on the wafer table 34, the outer peripheral rough grinding wheel 52, and the outer peripheral fine grinding wheel 55 in the vertical direction (Z-axis direction) is adjusted.

  When the alignment operation is completed, the outer peripheral grinding wheel spindle 51 is driven. Next, grinding (rough machining) by the outer periphery rough grinding wheel 52 is started. Specifically, a Y-axis motor (not shown) is driven, and the outer peripheral grinding wheel spindle 51 is sent toward the wafer table 34 along the Y-axis direction.

  When the outer peripheral grinding wheel spindle 51 is fed toward the wafer table 34, the outer periphery of the wafer W comes into contact with the outer peripheral rough grinding grinding groove formed in the outer peripheral rough grinding wheel 52, and the outer periphery of the wafer W is the outer peripheral rough grinding wheel. After being ground by 52, rough machining of the outer peripheral chamfering of the wafer W is started.

  After the rough machining by the outer peripheral rough grinding wheel 52 is started, the wafer W held on the wafer table 34 starts to rotate in the arrow direction at a constant speed. When the rotation angle, that is, the OF portion where the processing point is a linear portion, the outer grindstone spindle 51 is increased in the Y direction and the feed amount toward the wafer table 34 is increased, and the outer grindstone spindle 51 is linearly moved in the X direction to obtain a straight line. Machining part. Thereafter, when the processing of the straight portion is finished, the plate-like wafer W held on the wafer table 34 is rotated again in the direction of the arrow at a constant speed, the remaining circular portion is ground, and rough processing by the outer peripheral rough grinding wheel 52 is performed. Exit.

  A semiconductor substrate that has been bonded or molded using at least one of glass, resin, and silicon is a transparent wafer. For this reason, even if alignment is performed based on the silicon standard, normal line-type sensors, such as roundness due to sagging of the outer edge, undulation, dust, how to overlap the laminate, bubbles on the glass surface, dirt, and variations due to illumination, etc. It was very difficult to identify the outer edge due to the influence.

  FIG. 5 is an explanatory diagram showing detection of an outer peripheral edge by the conventional reflective line sensor 1, FIG. 6 is an explanatory diagram showing measurement of a plane according to one embodiment, and FIG. 7 is an edge portion (slope) according to one embodiment. FIG. 8 is a graph showing a comparison of measurement results of the respective wafer W heights. In the figure, arrows 1-1 and 1-2 represent one of the image elements in the reflective line sensor 1 as a representative. An arrow 1-1 indicates that the surface of the wafer W is irradiated with light, and light reflected by the surface of the wafer W is received at a relatively wide light receiving angle as indicated by an arrow 1-2. Irradiation may not be performed by the reflective line sensor 1 but may be illumination at a measurement location.

  Although the inner peripheral part of the silicon surface W-2 of the wafer W is substantially horizontal, it becomes a slope as it goes to the outer periphery, and its corner is sagging and rounded. Further, it is difficult to specify the edge due to the overlapping method of bonding, bubbles on the glass surface, dirt, and the like, and the measurement result is, for example, a dotted line in FIG. In FIG. 8, the vertical axis indicates the height in the thickness direction of the wafer W measured by the reflective line sensor 1, and the horizontal axis indicates the position of the wafer W in the radial direction.

  The horizontal line at the right end of FIG. 8 is the height of the horizontal surface of the silicon surface W-2, and the horizontal line at the left end is the height of the glass surface W-1. The dotted line portion is a boundary portion between the silicon surface W-2 and the glass surface W-1, and the shape of the slope portion of the silicon surface W-2 is reflected as it is. And it becomes irregular under the influence of garbage and how it overlaps, and the boundary becomes unclear.

  In this state, in order to specify the edge of the silicon surface W-2 that is the boundary, it cannot be determined unless a height threshold value is defined in the dotted line portion. However, since it is a transparent wafer, the value of height data in the figure is extremely unstable due to the large influence of irradiation light or illumination variations.

  6 and 7 show an improved example with respect to the above, in which the margin angle that the reflective line sensor 1 can receive light, that is, the light receiving angle φ is narrowed by the slit 1-3 arranged in front of the light receiving direction. It is. FIG. 6 shows a case where the measurement surface is horizontal, and the light receiving angle φ is small, but the measurement is performed without any difference from the state of FIG. FIG. 7 shows the measurement at the slope, and the reflected light is blocked by the slit 1-3 as shown by the arrow 1-2. That is, the reflected light from the inclined surface exceeding the margin angle that can be received with respect to the horizontal plane of the wafer W is not detected or is narrowed so that the detection sensitivity becomes small. Alternatively, the light receiving angle φ may be narrowed so that reflected light from the horizontal plane is received but reflected light from the inclined surface is not received.

  As a result, only the substantially horizontal portion of the wafer W, that is, the surface width can be detected. The light receiving angle φ is determined based on the actual state of the wafer W bonded or molded with glass, resin, or silicon, for example, the angle of the edge of the boundary between the silicon surface W-2 and the glass surface W-1, the roundness, or the like. . As a result of various experiments and the like, good results were obtained when the light receiving angle φ was 0 ° to 4 °, preferably 0 ° to 2 °.

  Note that the light receiving angle φ = 0 ° indicates that the center of light reflected by the reflective line sensor 1 coincides with the reflected light from the horizontal surface of the wafer W facing the reflective line sensor 1 (state of FIG. 6). I mean. Further, since the height of the slope portion of the bonded wafer W decreases from the inner periphery to the outer periphery, the light receiving angle of the horizontal portion from 0 ° to 4 ° in the inclined direction, that is, the light receiving angle φ = It may be 0 ° to 4 °, preferably 0 ° to 2 °. Alternatively, the light receiving angle φ in the horizontal portion may be given a margin of −1 ° to 4 °, preferably −1 ° to 2 °, and may be determined from the actually obtained output, image, etc. Good.

  From the actual state that the angle of the slope portion on the outer periphery of the bonded wafer is 20 ° to 30 ° with respect to the horizontal plane, in this case, the light receiving angle φ is set to 2 ° so that it becomes 1/10 or less of the angle of the slope portion. The measurement result when narrowed below is shown by the solid line in FIG. The horizontal line at the right end of FIG. 8 is the height of the horizontal plane of the silicon surface W-2, and the horizontal line at the left end is the height of the glass plane W-1. The light receiving angle φ of the reflective line sensor 1 is narrowed so that the detection sensitivity is reduced on a surface that is inclined with respect to the horizontal plane of the wafer W.

  The boundary portion between the silicon surface W-2 and the glass surface W-1 has an extremely small detection sensitivity when the light receiving angle φ is 2 ° or less, and hardly outputs. That is, only the surface width that is a horizontal and flat surface of the wafer W is output. Thus, when the wafer W is aligned on the basis of silicon, the edge position may be detected as the outer peripheral edge of the wafer W within the range where the silicon surface W-2 is output.

  When the outer peripheral edge of the wafer W is detected, the distance from the center of the measurement table 66 is obtained, and the wafer W is rotated to obtain measurement data for each rotation angle over the entire circumference of the wafer W. Furthermore, based on the measurement data, the center position of the wafer W is not affected by roundness, undulation, dust, how to overlap the bonding due to sagging of the outer peripheral edge, bubbles on the glass surface, dirt, variations due to illumination, etc. The edge position of the inner periphery of the can be obtained.

  As a result of the experiment, it is possible to reduce the alignment accuracy to ± 0.1 mm or less by setting the light receiving angle φ to 0 ° to 4 °, preferably 0 ° to 2 °, and there is no practical problem. Confirmed. In addition, optical detection is stable without being affected by defocusing of parts other than the focal position, blurring of boundaries due to the spread of the light source, shadows at rounded corners, and distortions due to local reflection near the edges. Edge detection is possible.

  Although the detection of the outer peripheral edge has been described as the reflective line sensor 1 in which the image elements are arranged in a line, the area sensor or the reflective laser sensor in which the image elements are arranged in the vertical and horizontal directions and arranged two-dimensionally. If the light receiving angle φ of an optical sensor such as a photoelectric sensor is narrowed, detection can be performed only in a limited region of the optical axis, and similarly stable edge detection is possible.

  The radius of the wafer W is obtained from the edge position of the inner peripheral portion of silicon, and it is determined whether or not the difference in the measurement data for each rotation angle over the entire circumference is within a predetermined threshold value. Then, measurement data determined to be within a predetermined threshold is extracted as an effective data group.

  Next, when the center position of the wafer W is obtained from the effective data group, extra errors caused by irregular elements such as foreign matter and chips attached to the outer peripheral edge of the wafer W, bubbles in the glass portion, undulation, and dirt are excluded. be able to. Then, the center of the wafer can be obtained more accurately from the measurement data with respect to the outer peripheral edge of the wafer W.

  W ... wafer, W-1 ... glass surface, W-2 ... silicon surface, 1 ... reflection line sensor, 1-1, 1-2 ... arrow, 1-3 ... slit, 10 ... chamfering device, 11 ... base body , 20 ... Wafer feeding unit, 21 ... X-axis base, 22 ... X-axis guide rail, 23 ... X-axis linear guide, 24 ... X-table, 25 ... X-axis drive mechanism, 26 ... Y-axis guide rail, 27 ... Y-axis Linear guide, 28 ... Y table, 29 ... Z axis guide rail, 30 ... Z axis drive mechanism, 31 ... Z table, 32 ... motor, 33 ... spindle, 34 ... wafer table, 40 ... feed / recovery robot, 41 ... truer, DESCRIPTION OF SYMBOLS 50 ... Grinding wheel rotation unit, 51 ... Outer periphery grindstone spindle, 52 ... Outer periphery rough grinding grindstone, 53 ... Turntable, 54 ... Upper outer periphery fine grinding spindle, 55 ... Outer periphery fine grinding wheel, 55-1 ... Upper and lower Fine grinding wheel (upper grinding wheel), 55-2 ... Lower outer circumference fine grinding wheel (lower grinding wheel), 56 ... Upper outer circumference fine grinding motor, 57 ... Lower outer circumference fine grinding spindle, 59 ... Lower fixed frame, 60 ... Conveying rail , 63 ... Transfer arm, 66 ... Measurement table, 70 ... Wafer cassette, 71 ... Cassette table, 80 ... Arm

Claims (9)

In the wafer positioning device that detects the outer edge and detects the center of the wafer,
A measurement table placed on the wafer and made rotatable while holding the wafer;
An optical sensor that is installed in the vicinity of the outer peripheral edge of the mounted wafer while maintaining a predetermined distance from the measurement table, and receives reflected light from a substantially disk-shaped surface of the wafer;
With
The wafer positioning apparatus, wherein the light receiving angle of the optical sensor is narrowed so that the detection sensitivity is reduced on a surface that is inclined with respect to a horizontal plane of the wafer.   2. The wafer positioning apparatus according to claim 1, wherein the optical sensor is a reflective line sensor in which image elements are arranged in a line.   The wafer positioning apparatus according to claim 1, wherein the light receiving angle is set to 0 ° to 4 °.   The wafer is a wafer that is bonded using at least one of glass, resin, and silicon, and the light receiving angle is set to 1/10 or less of an angle of the inclined portion of the wafer with respect to a horizontal plane. The wafer positioning apparatus according to claim 1, wherein   5. The wafer positioning apparatus according to claim 1, wherein the light receiving angle is narrowed so that light is received with respect to a horizontal plane of the wafer and is not received on a sloped surface. 6.   5. The wafer positioning apparatus according to claim 1, wherein the light receiving angle is 0 [deg.] To 2 [deg.].   7. The wafer positioning apparatus according to claim 1, wherein a slit is disposed on a front surface in a light receiving direction of the optical sensor, and the light receiving angle is narrowed by the slit. 8. In chamfering equipment for chamfering to grind the wafer edge,
A measurement table placed on the wafer and made rotatable while holding the wafer;
An optical sensor that is installed in the vicinity of the outer peripheral edge of the mounted wafer while maintaining a predetermined distance from the measurement table, and receives reflected light from a substantially disk-shaped surface of the wafer;
Prepared,
The chamfering is characterized in that the center of the wafer is detected by detecting the outer peripheral edge of the wafer by the optical sensor which is narrowed so that the detection sensitivity is reduced on the surface where the light receiving angle is inclined with respect to the horizontal plane of the wafer. apparatus. The wafer is a wafer that has been bonded using at least one of glass, silicon, and resin,
The optical sensor, which is a reflective line sensor in which image elements are arranged in a row, detects the edge position of the inner periphery of the silicon,
Find the center position of the wafer from the detected edge position,
9. The chamfering apparatus according to claim 8, wherein the chamfering device is mounted so that a rotation axis of the wafer table on which the wafer is mounted and the center position coincide with each other.