JP2022186971A - 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

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a positioning device for wafers bonded or molded with glass, resin, or silicon, and a chamfering device using the device.

In recent years, wafers bonded or molded with glass, resin, or silicon have been proposed. For example, due to the insulation and transparency of the substrate, various applications such as projectors, high-frequency devices, and MEMS application products are expected. ing. In addition, a notch called an orientation flat (OF) or a notch is provided at a predetermined position on the outer peripheral edge of the wafer as a mark for recognizing the crystal orientation in a later process. there is

Therefore, when a wafer having such a configuration is put into various devices such as a chamfering device for further processing and an inspection device for inspection, it is necessary to position the wafer with reference to the orientation flat. In particular, due to the demand for improved quality of wafers, the processing state of the wafer end face (edge portion) is emphasized, and in order to prevent chipping due to handling, chamfering is performed by grinding the edge portion.

As a technique for positioning a wafer, a positioning reference portion such as an orientation flat or a notch provided on the outer peripheral edge of a disk-shaped wafer is optically detected, and the wafer is positioned using this positioning reference portion as a reference. , after centering the wafer, optically measuring the outer peripheral edge of the wafer with a line sensor while rotating the wafer is known, and is described in Patent Document 1.

When aligning vertically stacked semiconductor wafers, an imaging means such as an infrared camera may image an alignment mark formed on the surface of the semiconductor wafer placed on the front side of the imaging means. is known and described in US Pat.

JP 2011-181849 A JP 2015-188042 A

However, in the conventional technology described above, 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 bonding surface. Especially in optical detection, the finite depth of field causes areas other than the focal point to be out of focus, the spread of the light source blurs the boundaries of shadows, and the rounded corners of the object create shadows. Edges obtained from actual images are far from ideal edges due to distortions caused by local reflections near the edges, making stable measurements difficult.

In particular, when aligning a glass-silicon bonded wafer with the silicon as a reference, problems such as the transparency of the glass part, dust, overlapping patterns, air bubbles, undulations, dirt, etc., can occur in the image with a normal line-type sensor. Positioning was extremely difficult.

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

The configuration of the present invention for achieving the above object is as follows.
[1] Wafer for detecting the center of the wafer by detecting the outer peripheral edge of the small diameter wafer, which is the smaller one of the stacked wafers in which two wafers, a large diameter wafer and a small diameter wafer, are bonded together. In the positioning apparatus of (1), a measuring table on which the laminated wafer is placed and which is rotatable while holding the laminated wafer, and the measuring table near the outer peripheral edge of the small-diameter wafer among the mounted laminated wafers. and an optical sensor for receiving reflected light from the small-diameter wafer and the substantially disk-shaped surface of the large-diameter wafer. A wafer positioning device characterized in that it is designed not to receive reflected light from a surface that is inclined with respect to a horizontal surface of the wafer.
[2] The positioning device according to [1], wherein the light-receiving angle is determined by the edge shape of the boundary portion of the two wafers.
[3] The positioning device according to [1] or [2], wherein only the surface width of the laminated wafer is detected by the reflected light.
[4] Wafer for detecting the center of the wafer by detecting the outer peripheral edge of the small diameter wafer, which is the smaller one of the stacked wafers in which two wafers of different sizes, a large diameter wafer and a small diameter wafer, are bonded together. In the positioning apparatus of (1), a measuring table on which the laminated wafer is placed and which is rotatable while holding the laminated wafer, and the measuring table near the outer peripheral edge of the small-diameter wafer among the mounted laminated wafers. and an optical sensor for receiving reflected light from the small-diameter wafer and the substantially disk-shaped surface of the large-diameter wafer, the light-receiving angle of the optical sensor being set at a predetermined distance from the small-diameter wafer. The surface that is inclined with respect to the horizontal surface is narrowed so that the detection sensitivity is small, and the optical sensor measures from the horizontal surface of the small-diameter wafer to the outer peripheral edge and the horizontal surface of the large-diameter wafer, and the laminated wafer is made of glass. , resin, or silicon, wherein the light-receiving angle is 1/10 or less of the angle of the inclined surface of the small-diameter wafer with respect to the horizontal plane. Wafer positioning device.
[5] In a chamfering device for grinding and chamfering the end face of a laminated wafer in which two wafers of different sizes, a large-diameter wafer and a small-diameter wafer, are bonded together, the laminated wafer is placed and held while holding the laminated wafer. A rotatable measurement table is placed near the outer peripheral edge of the mounted laminated wafer while maintaining a predetermined distance from the measurement table, and receives reflected light from the substantially disk-shaped surface of the laminated wafer. and an optical sensor, wherein the light receiving angle of the optical sensor is narrowed so as not to receive the reflected light from the surface that is inclined with respect to the horizontal surface of the small-diameter wafer.
[6] The chamfering apparatus according to [5], wherein the light-receiving angle is determined by the edge shape of the boundary portion of the two wafers.
[7] The surface and selling device according to [5] or [6], wherein only the surface width of the laminated wafer is detected from the reflected light.

Another configuration of the present invention is to detect the outer edge of the small-diameter wafer, which is the smaller one of the stacked wafers in which two wafers of different sizes, a large-diameter wafer and a small-diameter wafer, are bonded together. In a wafer positioning apparatus for detecting a center, a measurement table on which the laminated wafer is placed and which is rotatable while holding the laminated wafer, and the vicinity of the outer peripheral edge of the small-diameter wafer among the mounted laminated wafers. and an optical sensor installed at a predetermined distance from the measurement table to receive reflected light from the substantially disk-shaped surfaces of the small-diameter wafer and the large-diameter wafer, wherein the light-receiving angle of the optical sensor is The optical sensor is used to measure from the horizontal surface of the small-diameter wafer to the outer peripheral edge and to the horizontal surface of the large-diameter wafer. be.

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

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

Further, in the above, it is desirable that the light receiving angle is narrowed so that the light is received with respect to the horizontal surface of the small diameter wafer and is not received at the inclined surface.

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

Further, the present invention provides a chamfering apparatus for grinding and chamfering an end surface of a laminated wafer in which two wafers of different sizes, a large diameter wafer and a small diameter wafer are bonded together, wherein the laminated wafer is placed and the laminated wafer is cut. A measurement table that can be rotated while being held, and a measuring table that is placed in the vicinity of the outer peripheral edge of the mounted laminated wafer while maintaining a predetermined distance from the measurement table, and the reflection from the substantially disk-shaped surface of the laminated wafer. an optical sensor that receives light;
, the light receiving angle of the optical sensor is narrowed so that the detection sensitivity is small on the surface that is inclined with respect to the horizontal surface of the small diameter wafer, and from the horizontal surface of the small diameter wafer to the outer peripheral edge, and to the large diameter wafer By measuring up to the horizontal plane with the optical sensor, the peripheral edge of the small-diameter wafer is detected to detect the center of the small-diameter wafer.

Further, in the above, the laminated wafer is a wafer bonded using silicon and at least one of glass and resin, and a reflective line sensor in which image elements are arranged in a row. The edge position of the inner peripheral portion of the silicon is detected by the optical sensor, the center position of the laminated wafer is obtained from the detected edge position, and the wafer on which the laminated wafer is placed during the chamfering process. It is desirable to place the table so that the rotation axis of the table and the center position coincide.

According to the present invention, it is possible to obtain a wafer positioning device and a chamfering device using the same that can reliably detect the edge of a wafer that has been bonded or molded with glass, resin, or silicon. .

1 is a front view showing the main parts of a chamfering device according to one embodiment of the present invention; A plan view showing the main part of the chamfering device in one embodiment FIG. 4 is a side view showing detection of the edge inner perimeter of a wafer in one embodiment; FIG. 2 is a plan view showing the configuration of a chamfered portion according to one embodiment of the present invention; Explanatory drawing showing detection of outer peripheral edge by conventional reflective line sensor Explanatory diagram showing measurement of a plane in one embodiment Explanatory drawing showing measurement of an edge portion (slope) in one embodiment Graph showing a comparison of the measurement results of the wafer W height in one embodiment and the conventional one

BEST MODE FOR CARRYING OUT THE INVENTION Below, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing the main part of a chamfering device according to one embodiment of the present invention. The chamfering device 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 means, a controller for controlling the operations of each part of the chamfering device, and the like.

On the other hand, there is a strong demand for improving the quality of wafers, and the processed state of the wafer end surface (edge portion) is important. In order to prevent chipping due to handling, chamfering is performed by grinding the edges, and chamfering is performed by polishing. In other words, in the manufacturing process, from wafer manufacturing to device manufacturing, quality improvement of edge characteristics is an essential process.

Positional information of the wafer W is required for the chamfering process, and the wafer W must be accurately arranged on the apparatus before the chamfering process. As a pre-stage process of the polishing process, the center point position of the wafer and the OF position of the wafer W must be accurately detected at predetermined positions and placed on the wafer table 34 . Furthermore, in normal grinding, the chamfered portion of the wafer W is ground in a state in which the main surface of the wafer W is perpendicular to the rotation axis of the resin grindstone. known to do.

In FIG. 1, the wafer feed unit 20 includes an X-axis base 21 mounted on a main body base 11, two X-axis guide rails 22, 22, four X-axis linear guides 23, 23, . and an X-table 24 that is moved in the X-direction in the figure by an X-axis drive mechanism 25 consisting of a stepping motor.

The X table 24 has two Y-axis guide rails 26, 26, four Y-axis linear guides 27, 27, . Y table 28 is incorporated.

The Y table 28 is guided by two Z-axis guide rails 29, 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 consisting of a ball screw and a stepping motor. A Z table 31 is incorporated.

A motor 32 and a .theta. spindle 33 are incorporated in the Z table 31, and a wafer table 34 is attached to the .theta. Then, the wafer table 34 is rotated in the .theta. direction around the wafer table rotation axis CW.

Under the wafer table 34, a truing grindstone 41 (hereinafter referred to as a truer 41) used for truing the grindstone for finishing chamfering the peripheral edge of the wafer W is mounted concentrically with the wafer table rotation axis CW.

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

The grindstone rotating unit 50 has an outer circumference rough grinding grindstone 52 mounted thereon, an outer circumference grindstone spindle 51 driven to rotate about its axis by an outer circumference grindstone motor (not shown), and an upper circumference fine grinding wheel attached to a turntable 53 disposed above. It has a grinding spindle 54 and an upper peripheral precision grinding motor 56 . Similarly, the turntable 53 is provided with a lower outer peripheral fine-grinding spindle 57 and a lower outer peripheral fine-grinding motor (not shown) via a lower fixed frame 59 (in FIG. 1, a part of which is cut away).

The upper and lower peripheral precision grinding spindles 54 and 57 are used to chamfer the outer periphery of the wafer W in a state in which the rotation axis is inclined 3° to 15°, preferably 6° to 10°, with respect to the rotation axis of the wafer W. Carry out finishing. As a result, helical grinding is performed, and although weak grinding marks are generated in the oblique direction on the chamfered portion of the wafer W, the effect of improving the surface roughness of the chamfered portion compared to normal grinding is obtained.
An upper periphery precision grinding wheel (upper grinding wheel), which is a grindstone for chamfering the outer periphery of the wafer W, is attached to the upper periphery precision grinding spindle 54. Similarly, the lower periphery precision grinding spindle 57 is mounted with a lower periphery precision grinding wheel. A grindstone (lower grinding grindstone) is attached to the upper and outer circumference fine grinding grindstone with a gap of about 0.1 to 1 mm smaller than the thickness of the wafer W so that the rotating shaft is substantially concentric.

In addition, the upper and lower outer periphery precision grinding wheels are driven by the upper and lower outer periphery precision grinding spindles 54 and 57, respectively, so that their rotational directions are reverse rotations, ie, opposite rotations. A grinding groove for processing the wafer W is formed by an upper peripheral fine grinding wheel and a lower peripheral fine grinding wheel.

The wafer processing process is performed in the order of block cutting→orientation flat (OF) processing→slicing→chamfering→lapping→etching→donor killer→precise chamfering, and various types of cleaning are used between steps to remove dirt. In block cutting, both ends (top and tail) of the ingot are cut and the outer circumference is ground, and the long one is cut to an appropriate length to create a cylindrical "block" with a predetermined diameter.

In orientation flat (OF) processing, the crystal orientation is measured and an orientation flat (OF) or "notch" is carved at a predetermined position so that the orientation can be determined in a later step. For slicing, wafers are cut from the block with a dicing saw, wire saw, or inner diameter blade. Blocks with a diameter of 300mm are usually cut up to 200 pieces at a time with a multi-wire saw.

In chamfering, if the edge face of the wafer remains sharp at the time of slicing, it is easily broken or chipped during handling such as transportation and alignment in subsequent processing steps, and the fragments damage or contaminate the wafer surface. To prevent this, the end face of the cut wafer is chamfered with a diamond-coated grinding wheel.

The chamfering process may also be performed after the lapping process. At this time, it also includes adjusting the diameter of the outer circumference, which varies, adjusting the width of the orientation flat (OF), and adjusting the dimensions of minute cutouts called notches.

FIG. 2 is a plan view showing the main parts of the chamfering apparatus 10 as a whole. This operation is performed by the supply/collection robot 40 . A wafer cassette 70 is set on a cassette table 71 and contains a large 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 into the wafer cassette 70 .

The supply/recovery robot 40 has a three-axis rotating arm 80, and the arm 80 has a suction pad (not shown) on its upper surface. The arm 80 holds the wafer W by vacuum-sucking the rear surface of the wafer with a suction pad. That is, the arm 80 of the supply/recovery robot 40 can move back and forth, move up and down, and turn while holding the wafer W, and the wafer W is transported by combining these movements.

The chamfering device 10 is arranged in the front part and performs all the processing of chamfering the outer periphery of the wafer W, that is, from rough processing to finishing processing. The chamfering device 10 is composed of a wafer feeding unit 20 and a grindstone rotating unit 50 .

The transfer arm 63 can transfer the wafer W between the measurement table 66 and the wafer table 34 via the transfer rail 60 while holding the attitude of the wafer W during transfer. For this reason, the transfer arm 63 can hold and release the wafer W by suction.

The transfer arm 63 lifts up the wafer W from the table of each process, and lifts down (places) the wafer W onto the table. Note that the center of the wafer W placed on the measurement table 66 may be slightly off-center from the rotation center of the measurement table 66 as long as the outer peripheral edge of the wafer W is within a position range measurable by the reflective line sensor 1. good.

The transport rail 60 is a laying rail for moving the transport arm 63 to transport the wafer W to a predetermined table between each process, for example, between the measurement process and the chamfering process. The wafer table 34 is a table on which the wafer W is placed during the chamfering process. The wafer table 34 firmly holds the wafer W so that the mounted wafer W can be polished. For this reason, the wafer table 34 holds the wafer W by suction.

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

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

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

The measurement table 66 is rotatably controllable. The measurement table 66 rotates with the wafer W placed thereon. The measurement table 66 is capable of measuring the rotation angle, and detects the position of the outer peripheral edge of the wafer W along the entire circumference by the reflective line sensor 1 to obtain the distance between the outer peripheral edge and the center of rotation. In the reflective line sensor 1, image elements are arranged in a row in the radial direction of the wafer W from the outermost circumference to the inner circumference.

In FIG. 3, the reflective line sensor 1 is installed in the vicinity of the outer peripheral edge of the wafer W, and is irradiated with light in a direction substantially perpendicular to the substantially disk-shaped surface of the wafer W as indicated by an arrow. The outer peripheral edge of the wafer W is detected by receiving the reflected light. When the outer edge is detected, the distance from the center of the measurement table 66 is calculated. By rotating the wafer W in the calculation, measurement data for each rotation angle can be obtained over the entire circumference of the wafer W. FIG. The measurement data may also include the date and time of measurement, an identification number that can identify the wafer W to be measured, the measurement result (impossibility of measurement, number of remeasurements) in the measurement table 66, and the like. Based on the measurement data, the center position and radius of the wafer W, and the amount and direction of eccentricity 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 section. In a standby state before starting 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 so as to face a predetermined direction.

The outer circumference rough grinding wheel 52 and the outer circumference fine grinding wheel 55 are located at positions separated from the wafer W by a predetermined distance. Specifically, the center of rotation of the outer circumference rough grinding grindstone 52 is located at a predetermined distance in the Y-axis direction from the center of rotation of the wafer W, and the center of rotation is located in the X-axis direction with respect to the wafer W. They are arranged at positions 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 and the outer circumference rough grinding wheel 52 and the outer circumference fine grinding wheel 55 is adjusted in the vertical direction (Z-axis direction).

After completing the alignment operation, the outer peripheral grindstone spindle 51 is driven. Next, grinding (rough processing) by the outer peripheral rough grinding wheel 52 is started. Specifically, a Y-axis motor (not shown) is driven to feed the outer peripheral grindstone spindle 51 toward the wafer table 34 along the Y-axis direction.

When the outer circumference grindstone spindle 51 is sent toward the wafer table 34, the outer circumference of the wafer W comes into contact with the grinding groove for outer circumference rough grinding formed in the outer circumference rough grinding grindstone 52, and the outer circumference of the wafer W contacts the outer circumference rough grinding stone. After grinding by 52, the rough processing of chamfering the outer periphery of the wafer W is started.

After the rough processing by the outer circumference rough grinding wheel 52 is started, the wafer W held on the wafer table 34 starts rotating at a constant speed in the direction of the arrow. When this rotation angle, that is, the processing point reaches the OF portion, which is a linear portion, the feed amount of the outer peripheral grindstone spindle 51 toward the wafer table 34 in the Y direction is increased, and the outer peripheral grindstone spindle 51 is linearly moved in the X direction. process the part. After that, when the processing of the straight portion is completed, the plate-shaped wafer W held on the wafer table 34 is again rotated at a constant speed in the direction of the arrow, and the remaining circular portion is ground and rough-processed by the outer circumference rough grinding wheel 52. exit.

A semiconductor substrate bonded or molded using at least one of glass, resin, and silicon is a transparent wafer. Therefore, even if you try to perform alignment based on the silicon standard, the image from a normal line-type sensor will have roundness due to sagging of the outer edge, undulation, dust, overlap of pasting, air bubbles on the glass surface, dirt, variations due to lighting, etc. It was extremely 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 an embodiment, and FIG. 7 is an edge portion (slope) according to an embodiment. , and FIG. 8 is a graph showing the measurement results of the heights of the wafers W in comparison. In the figure, arrows 1-1 and 1-2 represent one image element in the reflective line sensor 1. FIG. An arrow 1-1 indicates that the surface of the wafer W is irradiated with light, and light reflected from the surface of the wafer W is received at a relatively wide light receiving angle as indicated by an arrow 1-2. It should be noted that the irradiation may be performed not by the reflective line sensor 1 but by illumination at the measurement location.

The inner peripheral portion of the silicon surface W-2 of the wafer W is substantially horizontal, but it slopes toward the outer periphery, and its corners are sagging and rounded. In addition, it is difficult to identify the edge due to the overlapping manner of bonding, air bubbles on the glass surface, stains, etc., resulting in measurement results such as the dotted line in FIG. 8, for example. In FIG. 8, the vertical axis indicates the height of the wafer W measured by the reflective line sensor 1 in the thickness direction, and the horizontal axis indicates the position of the wafer W in the radial direction.

The rightmost horizontal line in FIG. 8 is the height of the silicon surface W-2, and the leftmost horizontal line is the height of the glass surface W-1. A 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. Then, it becomes irregular under the influence of dust and the way it overlaps, and the boundary becomes unclear.

In this state, the edge of the silicon surface W-2, which is the boundary, cannot be identified unless a height threshold value is determined by the dotted line. However, since it is a transparent wafer, it is greatly affected by variations in light or illumination, and the values of the height data in the figure are extremely unstable.

FIG. 6 and FIG. 7 show examples of improvements to the above, in which the leeway angle at which 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 in the light-receiving direction. is. FIG. 6 shows a case in which the measurement surface is horizontal, and although the light receiving angle φ is small, measurement is performed in the same manner as in FIG. FIG. 7 shows the measurement at the oblique portion, the reflected light is blocked by the slit 1-3 as indicated by the arrow 1-2. In other words, the reflected light from the slope that exceeds the marginal angle at which light can be received with respect to the horizontal plane of the wafer W is not detected, or is narrowed so that the detection sensitivity is reduced. Alternatively, the light-receiving angle φ may be narrowed so that the reflected light from the horizontal plane is received but the reflected light from the slope 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 from the actual state of the wafer W bonded or molded with glass, resin, or silicon, such as the edge angle and roundness of the boundary portion between the silicon surface W-2 and the glass surface W-1. . As a result of various experiments, good results were obtained when the light receiving angle φ is set to 0° to 4°, preferably 0° to 2°.

The light-receiving angle φ=0° means that the reflected light from the horizontal surface of the wafer W faces the reflective line sensor 1, and the center of the light received by the reflective line sensor 1 coincides (state in FIG. 6). means. In addition, since the height of the sloped portion of the bonded wafer W decreases from the inner periphery to the outer periphery, the light-receiving angle of 0° in the horizontal portion is 4° in the direction of the slope, that is, the light-receiving angle φ= 0° to 4°, preferably 0° to 2°. Alternatively, the light-receiving angle φ of the horizontal portion may be given a margin of -1° to 4°, preferably -1° to 2°. good.

From the fact that the angle of the sloped portion on the outer periphery of the bonded wafer is 20° to 30° with respect to the horizontal plane, in that case, the light receiving angle φ is set to 2° so that the angle of the sloped portion is 1/10 or less. A solid line in FIG. The rightmost horizontal line in FIG. 8 is the height of the silicon surface W-2, and the leftmost horizontal line is the height of the glass surface W-1. The light-receiving angle φ of the reflective line sensor 1 is narrowed so that the detection sensitivity decreases on the surface of the wafer W that is inclined with respect to the horizontal surface.

At the boundary portion between the silicon surface W-2 and the glass surface W-1, the detection sensitivity is extremely low when the light receiving angle φ is 2° or less, and almost no light is output. That is, only the surface width of the horizontal and flat surface of the wafer W is output. Accordingly, when aligning the wafer W on the basis of silicon, it is sufficient to detect the edge position as the outer peripheral edge of the wafer W within the output range of the silicon surface W-2.

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, undulations, dust, overlapping of bonding, air bubbles on the glass surface, dirt, variations due to lighting, etc. due to sagging of the outer peripheral edge. can be obtained.

Experimental results show that it is possible to achieve an alignment accuracy of ±0.1 mm or less by setting the light receiving angle φ to 0° to 4°, preferably 0° to 2°, and that there is no practical problem. I have confirmed. In addition, even though it is optical detection, it is stable without being affected by blurring of areas other than the focus position, blurring of boundaries due to the spread of the light source, shadows at rounded corners, and distortion due to local reflection near edges. edge detection is possible.

Although detection of the outer peripheral edge has been described as a reflective line sensor 1 in which image elements are arranged in a row, an area sensor in which image elements are arranged in the vertical and horizontal directions and arranged two-dimensionally, or a reflective laser sensor can be used. Similarly, stable edge detection is possible by using an optical sensor such as a photoelectric sensor with a narrow light-receiving angle φ so as to detect only a limited area of the optical axis.

The radius of the wafer W is obtained from the edge position of the inner peripheral portion of the 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. Then, the measured data determined to be within the predetermined threshold are extracted as the effective data group.

Next, if the center position of the wafer W is obtained from the effective data group, extra errors due to irregular factors such as foreign matter and chipping attached to the outer peripheral edge of the wafer W, air bubbles in the glass portion, undulation, dirt, etc. are eliminated. be able to. Then, the center of the wafer W can be obtained with higher accuracy from the measurement data for the outer peripheral edge of the wafer W. FIG.

W... Wafer, W-1... Glass surface, W-2... Silicon surface, 1... Reflective line sensor, 1-1, 1-2... Arrow, 1-3... Slit, 10... Chamfering device, 11... Main body base , 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 Supply and recovery robot 41 Truer 50... Grindstone rotation unit 51... Periphery grinding wheel spindle 52... Periphery rough grinding wheel 53... Turntable 54... Upper periphery fine grinding spindle 55... Periphery fine grinding wheel 55-1... Upper periphery fine grinding wheel (upper Grinding wheel), 55-2... Lower periphery precision grinding wheel (lower grinding wheel), 56... Upper periphery precision grinding motor, 57... Lower periphery precision grinding spindle, 59... Lower fixed frame, 60... Transport rail, 63... Transport arm , 66... Measurement table, 70... Wafer cassette, 71... Cassette table, 80... Arm

Claims (7)

A wafer positioning device for detecting the center of the wafer by detecting the outer peripheral edge of the small-diameter wafer, which is the smaller one of the stacked wafers in which two wafers of different sizes, a large-diameter wafer and a small-diameter wafer, are bonded together. in
a measurement table on which the laminated wafer is placed and which is rotatable while holding the laminated wafer;
It is installed near the outer edge of the small-diameter wafer among the stacked wafers while maintaining a predetermined distance from the measurement table, and reflects light from the substantially disk-shaped surfaces of the small-diameter wafer and the large-diameter wafer. an optical sensor for receiving light;
with
A wafer positioning apparatus, wherein the light receiving angle of the optical sensor is narrowed so as not to receive reflected light from a surface that is an incline with respect to the horizontal surface of the small-diameter wafer. 2. The positioning device according to claim 1, wherein said light receiving angle is determined by the edge shape of the boundary portion of said two wafers. 3. The positioning device according to claim 1, wherein only the surface width of said laminated wafer is detected by said reflected light. A wafer positioning device that detects the center of the wafer by detecting the outer peripheral edge of the small diameter wafer, which is the smaller one of the stacked wafers in which two wafers, a large diameter wafer and a small diameter wafer, are bonded together. in
a measurement table on which the laminated wafer is placed and which is rotatable while holding the laminated wafer;
It is installed near the outer edge of the small-diameter wafer among the stacked wafers while maintaining a predetermined distance from the measurement table, and reflects light from the substantially disk-shaped surfaces of the small-diameter wafer and the large-diameter wafer. an optical sensor for receiving light;
with
The light-receiving angle of the optical sensor is narrowed so that the detection sensitivity is small on the surface that is inclined with respect to the horizontal surface of the small-diameter wafer, and from the horizontal surface of the small-diameter wafer to the outer peripheral edge, to the horizontal surface of the large-diameter wafer. measured with an optical sensor,
The laminated wafer is a wafer bonded using at least one of glass, resin, and silicon, and the light-receiving angle is 1/10 or less of the angle of the inclined surface of the small-diameter wafer with respect to the horizontal plane. A wafer positioning device characterized by: A chamfering device that grinds and chamfers an end surface of a laminated wafer in which two wafers of different sizes, a large diameter wafer and a small diameter wafer are bonded together,
a measurement table on which the laminated wafer is placed and which is rotatable while holding the laminated wafer;
an optical sensor installed near the outer peripheral edge of the mounted laminated wafer while maintaining a predetermined distance from the measurement table and receiving reflected light from the substantially disk-shaped surface of the laminated wafer;
with
A chamfering device in which the light-receiving angle of the optical sensor is narrowed so as not to receive the reflected light from the surface that is inclined with respect to the horizontal surface of the small-diameter wafer. 6. The chamfering apparatus according to claim 5, wherein said light receiving angle is determined by the edge shape of the boundary portion of said two wafers. 7. The chamfering apparatus according to claim 5, wherein only the surface width of said laminated wafer is detected from said reflected light.

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