JP6032888B2 - Stacked wafer tilt correction method and wafer stacking apparatus - Google Patents

Description

  The present invention relates to a method and an apparatus for correcting the tilt of the uppermost wafer in a stacking apparatus that takes out a large number of stacked wafers one by one from the top.

  In general, a wafer for solar cells (hereinafter simply referred to as “wafer”) is manufactured by slicing a silicon ingot with a wire saw device, and the sliced wafers are sent to an inspection process in a state of being stacked up and down after cleaning. It is done. For example, when inspecting a square having a plane dimension of about 125 to 156 mm and a thickness of 0.2 mm, 500 wafers are stacked and set in a magazine of a stacking apparatus of the wafer inspection apparatus.

As shown in FIG. 7, the magazine 100 of the stacking apparatus of the wafer inspection apparatus has a cubic shape in which an upper surface portion is opened and a slit 101 is provided at an intermediate position between the four side surfaces. A bottom plate 103 for placing the stacked wafers 102 is disposed. The bottom plate 103 can be moved up and down in the magazine 100 by a push-up unit 104 penetrating the bottom of the magazine 100. The stacked wafers 102 are picked up by a take-out device (not shown) one by one in order from the top. When taken out by the suction pad 105 of the head 107, the push-up unit 104 raises the bottom plate 103 by the thickness of one wafer 102 in accordance with the take-out operation.

As a conventional technique for taking out the stacked wafers one by one in this way, there is one disclosed in Patent Document 1, for example. In the technique disclosed in Patent Document 1, two peripheral portions of the uppermost wafer are vacuum-sucked by a suction pad, and then one suction pad is lifted and tilted by a small amount, and the wafer held by the suction pad is held. The peripheral edge of the wafer is bent, a gap is formed between the wafers, air is blown into the gap to eliminate the contact state of the wafers, and then both suction pads are raised to separate only the uppermost wafer. It is surely taken out.

  By the way, the wafer sliced by the wire saw has a variation in thickness in the portion. For example, as shown in FIG. 8, the thickness of the wafer 106 sliced by a specific wire saw device is gradually changed from a thin state to a thick state from one side of the wafer 106 to the opposite side. There is a difference in thickness of about 20 μm between one end and the other end. Further, this difference in thickness may occur in two directions on the plane of the wafer 106. It is empirically known that the same difference in thickness occurs in all the wafers included in the lot for the same lot.

Generally, it sliced wafer 106, since the stacked while maintaining the orientation when sliced, for example, when the wafer 106 stacking 500 sheets, as shown in FIG. 9, the difference of the thickness are accumulated, the bottom plate 103 Even when the wafer 106 is horizontal, there is a difference of as much as 10 mm between the height position of one end and the height position of the other end in the tilt direction, so that the wafer 106 on the top is It will be greatly inclined. If the uppermost wafer 106 is tilted, the conventional suction head 107 does not allow the plurality of suction pads 105 to contact the wafer 106 at the same time with a uniform force. 106 could not be adsorbed and lifted.

Although it is conceivable that the suction head 107 can follow the tilt of the wafer 106 with a swingable structure, in this case, the first suction pad 105 that contacts the wafer 106 is pressed against the wafer 106. A local force acts on 106 , causing a problem that the wafer 106 that is thin and easily broken is damaged, or a mark of the suction pad 105 remains on the surface of the wafer 106.

On the other hand, in a device that picks out workpieces one by one from stacked workpieces, there is, for example, one disclosed in Patent Document 2 as a conventional technique corresponding to the tilt of the workpiece to be taken out. In the technique of Patent Document 2, after positioning the height position of the card as the uppermost workpiece in the stacked state by the uppermost detection sensor, a pair of the cards arranged so as to sandwich the opposite sides of the uppermost card. The outputs of the optical sensors are monitored, and it is determined that the card is tilted when the outputs of the pair of optical sensors are different, and the cards are determined to be horizontal when the outputs of the pair of optical sensors are both off.

  However, in the technique of Patent Document 2, although the presence or absence of the tilt of the uppermost workpiece can be detected, the tilt amount cannot be detected. Therefore, until the outputs of the pair of optical sensors are both turned off, Ascending and adjusting the tilt amount of the base must be repeated, and it takes time to correct the tilt of the workpiece, and the workpiece pick-up speed decreases.

JP-A-6-321371 JP-A-11-11692

An object of the present invention, in the stacking device issuing the Ri preparative One not a one from the top wafer of the stacked state, can be prevented with traces of breakage or wafer surface of wafer upon retrieval of the U Fine stacked state, in particular there the reduction in the extraction speed of the wafer due to inclination correction operation of the top wafer suppressed Erareru, to provide a tilt compensation method and stacking apparatus of the wafer.

Based on the above problems, the present invention detects the tilt of the uppermost wafer, corrects the tilt of the uppermost wafer, and then takes out the uppermost wafer before taking out the second and subsequent wafers. Based on the inclination, the amount of inclination for the second and subsequent sheets is obtained in advance by proportional calculation and stored.

The wafer tilt correction method of the present invention is a wafer in which a number of wafers are stacked on a bottom plate in a magazine, and the bottom plate is lifted by a push-up unit, and the top wafer in a stacked state is picked up one by one with a suction pad. in the stacking apparatus, the first sheet of inclination of the wafer in the top in the initial stack state is detected by the sensor unit slope at the position of the two different points on the X and Y directions, by the controller, one detected It compares the reference posture of the eye wafer inclination and the wafer to obtain the first tilt amount from the difference, based on the first correction signal corresponding to the first tilt amount obtained above by the X-direction and the Y direction of the actuator By tilting the bottom plate, the tilt of the first wafer is corrected to the reference posture, and before the second and subsequent wafers are taken out, the control is performed. By using a roller, an inclination amount of each of the second and subsequent wafers in the first stacked state is obtained in advance from a proportional relationship between the initial inclination amount and the stacked amount of the wafers, and the obtained inclination amounts of the second and subsequent wafers are obtained. After the first wafer is taken out by the suction pad , the tilt amount of the second and subsequent wafers at the top is taken out in the process of taking out the second and subsequent wafers from the top. read, read by the X and Y directions of the actuator based on second and subsequent correction signal corresponding to the amount of inclination tilting the bottom plate, reference the inclination of the second and subsequent wafer to be uppermost position The correction is performed sequentially .

The wafer stacking apparatus of the present invention stacks a number of wafers on a bottom plate in a magazine, and stacks the wafers one by one with a suction pad while raising the bottom plate by a push-up unit. In the apparatus, an inclination sensor unit for detecting the inclination of the uppermost first wafer in the first stacked state at two different positions in the X direction and the Y direction, and a detecting means for detecting the amount of stacked wafers Then, the tilt of the first wafer from the tilt sensor unit and the stacking amount of the wafer from the detection means are input, the input tilt of the first wafer is compared with the reference posture of the wafer, and Obtain the first tilt amount and before the second and subsequent wafers are taken out, the second and subsequent wafers in the first stacked state. A controller for generating a correction signal corresponding to the tilt amount of each of the second and subsequent wafers, the bottom plate, and the push-up unit, by previously obtaining and storing the tilt amount from the proportional relationship between the first tilt amount and the wafer stack amount A gonio unit interposed between the unit and tilting the bottom plate by an actuator in the X direction and the Y direction with the correction signal as an input, and correcting the tilt of the uppermost wafer to a reference posture, When the controller takes out the first wafer, the controller tilts the bottom plate by the actuators in the X and Y directions based on the first correction signal corresponding to the first tilt amount, and uses the tilt of the first wafer as a reference. In addition to correcting the posture, in the process of taking out the second and subsequent wafers, the tilt amount of the second and subsequent wafers at the top is read, and the read second sheet Tilt the bottom plate by the X and Y directions of the actuator, sequentially corrects the inclination of the second and subsequent wafer to be top reference posture based on the modified signal corresponding to the inclination amount of descending of the wafer , it is characterized a call.

In the wafer stacking apparatus according to the present invention, the tilt sensor unit includes a light projector and a light receiver, and the light projector and the light receiver are provided at the same height position, and the top 1 to set the height of th wafer at a predetermined height position, the lowest height position of the first wafer on the stacked state different on two points and the Y-direction different on the X-direction 2 as well as measured at the point, in order to determine the amount of tilting of the first wafer at the top, the top first wafer from the difference in height measured at two different locations on the X-direction The tilt in the X direction is detected, and the tilt in the Y direction of the top first wafer is detected from the difference in height measured at two different positions in the Y direction.

Further, according to the present invention, in the wafer stacking apparatus described above, the projector and the light receiver of the tilt sensor unit are provided in two opposed positions in the X direction and two different positions in the Y direction, respectively. ing.

Further, according to the present invention, in the wafer stacking apparatus described above, the projector and the light receiver of the tilt sensor unit are provided in a pair of opposing states in the X direction and the Y direction, and they are arranged in the X direction or the Y direction. The wafer can be moved, and the tilt of the wafer is detected at two different positions .

According to the stacked wafer tilt correction method and the wafer stacking apparatus of the present invention , the first wafer , and the second and subsequent wafers after the first wafer are kept parallel to the suction pad in a plane. Therefore, a plurality of suction pads can be brought into contact with the top wafer with a uniform force and sucked, so that the wafer can be removed without breaking the wafer or leaving a mark on the wafer surface. It can be lifted gently from the magazine, and the suction head does not need to follow the tilt of the wafer, so that the structure of the suction head can be simplified, and the wafer is planar with respect to the suction pad. Since it is possible to increase the arrangement interval of the plurality of suction pads, the plurality of suction pads can be brought into contact with the wafer with a uniform force over a wide range. Rukoto can, wafer can be prevented from acting local forces, along with damage to the wafer can be prevented, can be realized stable handling, there are effects such as.

In particular, according to the stacked wafer tilt correction method and the wafer stacking apparatus of the present invention, after correcting the tilt amount of the first wafer taken out first, the tilt amounts of the second and subsequent wafers are proportionally related. Therefore, it is not necessary to detect the tilt of the wafer every time the second and subsequent top wafers are taken out. can be suppressed to decrease the extraction speed, yet before removal of the second and subsequent wafers, previously determined amount of inclination of the second and subsequent sheets, for storing their inclination amount, the second and subsequent wafers A unique effect is obtained that the speed of the removal of the wafer and the correction of the tilt of the wafer can be further increased .

Then, the stacking device of the wafer, lever to detect the tilt in each direction at the position of the two different points on the position and the Y direction of the two different places on the X-direction, good measurement accuracy for each direction, their The inclination in the composition direction can also be detected.

Further, in the wafer stacking apparatus, if the projector and the light receiver of the tilt sensor unit are provided at two different positions in the X direction and two different positions in the Y direction so as to face each other, the tilt in the X direction and the Y direction It is possible to reliably detect not only the inclination of the angle but also the inclination of the synthesis direction in a stable state.

Further, in the wafer stacking apparatus, if a projector and a light receiver of the tilt sensor unit are provided in pairs in the X direction and the Y direction so that they can be moved in the X direction or the Y direction, The tilt in the X direction and the Y direction can be detected with one sensor unit, whereby the tilt of the wafer can be detected with a small number of sensors in each direction.

It is a perspective view which shows the outline of the stacking apparatus of the wafer of this invention. It is a top view of the stacking apparatus of the wafer of the present invention. It is an AA cross-sectional arrow view in FIG. 2, and shows the state before inclination correction. It is a block diagram which shows the structure of the stacking apparatus of the wafer of this invention. It is an AA cross-sectional arrow view in FIG. 2, and shows the state after inclination correction. It is the stacking apparatus of the other Example of this invention, (a) is the top view, (b) is the partial side surface sectional drawing. It is a perspective view which shows the outline of the stacking apparatus of the prior art wafer. It is sectional drawing of a wafer. FIG. 3 is a side sectional view of a conventional wafer stacking apparatus.

  The wafer stacking apparatus 1 of the present invention is mainly provided in a solar cell wafer inspection apparatus. As shown in FIG. 1, the wafer stacking apparatus 1 stacks square wafers 3 as an example on a bottom plate 4 in a magazine 2, and pushes the bottom plate 4 up by a push-up unit 5, and moves the top wafer 3 in a stacked state. It is used when taking out one sheet at a time by the suction pad 7.

State magazine 2 of the wafer stacking device 1 has an upper surface portion is opened, has a standing side body shape slit 28 in the middle position of the four side surfaces is provided, inside the magazine 2, stacked A bottom plate 4 on which the wafer 3 is placed is disposed. The bottom plate 4 is supported by a push-up unit 5 penetrating the bottom of the magazine 2 so that the inside of the magazine 2 can be moved up and down. The stacked wafers 3 are taken out one by one from the top by the suction pads 7 of the suction head 6. In accordance with the operation performed, the push-up unit 5 raises the bottom plate 4 by the thickness of one wafer 3 and maintains the uppermost wafer 3 at a constant height.

The upper opening of the magazine 2 is provided with tilt sensor units 8, 9, 10, 11 for detecting the tilt of the top, that is, the first wafer 3 in the first stacked state. 3 is provided at the same height position in order to detect the amount of inclination relative to the horizontal as the reference posture. These tilt sensor units 8, 9, 10, and 11 are transmissive (light emitting / receiving) type area sensors. If the direction of one side perpendicular to the wafer 3 is the X direction and the direction of the other side is the Y direction, And two different positions in the Y direction are provided facing each other so as to sandwich the first wafer 3 in a stacked state while forming detection areas in the height direction. In this manner, the tilt amount of the wafer 3 is detected for each of the X direction and the Y direction at two different heights on the tilt direction of the wafer 3.

  As shown in FIG. 2, the light projectors 8a and 9a and the light receivers 8b and 9b of the inclination sensor units 8 and 9 are provided so that the optical axis is orthogonal to the X direction, and these are the first wafer. 3 is used to determine the amount of inclination in the X direction. The light projectors 10a and 11a and the light receivers 10b and 11b of the inclination sensor units 10 and 11 are provided so that the optical axis is orthogonal to the Y direction, and these are the Y direction of the first first wafer 3. It is used to determine the amount of inclination of.

  As described above, since the tilt sensor units 8, 9, 10, and 11 are provided at the same height position, the received light amounts of the tilt sensor units 8 and 9 are the same, and the tilt sensor units 10 and 11 If the amount of received light is the same, the first wafer 3 can be said to have zero inclination, that is, horizontal in the X and Y directions. Thus, the same height of the tilt sensor units 8, 9, 10, and 11 corresponds to the horizontal as the reference posture.

  In FIG. 3, the push-up unit 5 includes push-up drive means 27, a goniometer unit 12 that tilts the bottom plate 4 in the X direction, and a goniometer unit 13 that tilts the bottom plate 4 in the Y direction in order to push up the bottom plate 4. The push-up drive means 27 is configured by an elevator mechanism such as a worm gear mechanism or a toothed belt in addition to the rack and pinion mechanism.

The gonio units 12 and 13 are interposed between the bottom plate 4 and the push-up drive means 27, and are driven by motors 15 and 16 as actuators that rotate by receiving a correction signal from the controller 14 described later. A built-in worm gear mechanism or the like that is not rotated is rotated to incline the bottom plate 4 in the X or Y direction. In the illustrated example, drive transmission from the motors 15 and 16 to the gonio units 12 and 13 is performed by pulleys 17, 19, 20, and 22 and belts 18 and 21, but the motors 15 and 16 are gonio units. You may connect directly to input parts, such as a 12 and 13 worm gear mechanism.

  As shown in FIG. 4, the tilt sensor units 8, 9, 10, and 11 are connected to a controller 14 that drives motors 15 and 16. The detecting means 26 is also connected to the controller 14. The detection means 26 is provided for detecting the stacking amount of the wafers 3, that is, the stacking height or the number of stacked sheets. The stacking height of the wafers 3 corresponds to the upper surface of the uppermost wafer 3 from the bottom plate 4 and is detected directly by the height sensor or the rotation of the driving unit for detecting the rising amount of the push-up unit 5. It is detected indirectly by a quantity sensor. Further, the number of stacked sheets can be obtained by calculation from the stacked height of the wafers 3 and the thickness per sheet, or can be determined from the number of stacked first wafers 3 and the count of the counter for the number of removed sheets.

The controller 14 determines the tilt of the first wafer 3 in the initial stack state from the tilt sensor units 8, 9, 10, and 11, and the stack height of the wafer 3 or the wafer 3 as the stack amount of the wafer 3 from the detection means 26. In order to correct the initial tilt of the first wafer 3, the input tilt of the first wafer 3 is compared with the reference posture of the wafer 3, and the initial tilt amount is calculated based on the difference. Is generated , and before the second and subsequent wafers 3 in the first stacked state are taken out, the inclination amount of each of the second and subsequent wafers 3 in the first stacked state is determined as the first inclination signal. The amount of inclination of each of the second and subsequent wafers 3 is stored in advance from the proportional relationship between the amount of the wafers 3 and the amount of stacked wafers 3. Therefore, the inclination amounts of the second and subsequent wafers 3 are read out, and correction signals for the second and subsequent wafers corresponding to the inclination amounts of the second and subsequent wafers corresponding to the uppermost wafer 3 are read based on the read inclination amount. Occur.

Next, with reference to FIGS. 3 to 5, the operation of the stacking apparatus 1, that is, the operation of correcting the tilt of the wafer 3 will be described. As described above, the tilt correction operation detects the tilt of only the first wafer 3 in the first stacked state, and corrects the tilt of the first wafer 3 by comparing the detected tilt with the reference posture. However, the inclination of the second and subsequent wafers 3 is not detected, and the proportional relationship between the inclination amount of the first wafer 3 and the stacking height of the second and subsequent wafers 3 or the stacking number of the second and subsequent wafers 3 from calculating the amount of tilting of the second and subsequent wafers 3, based on the calculated inclination amount you correct the inclination of the second and subsequent wafers 3.

First, the push-up unit 5 raises a predetermined number of, for example, 500 stacked wafers 3 from below the detection area of the tilt sensor units 8, 9, 10, 11, and the tilt sensor units 8, 9, 10, 11 When all the received light amounts change, the ascent of the wafer 3 is stopped (FIG. 3). At this time, the top, that is, the first wafer 3 in the first stacked state is set at a predetermined height position. In this way, the tilt sensor units 8, 9, 10, and 11 are stopped while the stacked wafers 3 are raised, and the height of the uppermost first wafer 3 is set to a predetermined height position. Therefore, in order to measure the height of the uppermost first wafer 3 and detect the tilt amount of the uppermost first wafer 3 when the stacked wafers 3 are stopped, X From the difference in height measured at two different locations in the direction, the X direction inclination of the uppermost first wafer 3 is detected, and from the difference in height measured at two different locations in the Y direction. The inclination of the uppermost first wafer 3 in the Y direction is detected.

Now, consider correcting the tilt of the wafer 3 in the X direction. The tilt sensor units 8 and 9 detect the height position of the first wafer 3 in the first stacked state in the X direction, and output an output signal corresponding to the amount of received light to the controller 14. As shown in FIG. 3, if the first wafer 3 is tilted, there is a difference in the amount of light received by the tilt sensor units 8, 9, so the controller 14 outputs two outputs from the tilt sensor units 8, 9. The signals are compared, the difference in height at the position of the tilt sensor unit 8 , 9 of the first wafer 3 is obtained from the difference in the amount of received light, and the tilt amount in the X direction of the first wafer 3 is based on this difference. That is, the first inclination amount in the X direction is obtained, and the first correction signal corresponding to the obtained inclination amount is output to the motor 15. The motor 15 receives the first correction signal as input , and tilts the bottom plate 4 by the gonio unit 12 to correct the tilt of the first wafer 3 in the X direction (FIG. 5). After the correction, it is confirmed whether the received light amounts of the inclination sensor units 8 and 9 are the same. If the received light amounts are different, the inclination correction may be performed again.

In order to correct the tilt in the Y direction, the controller 14 receives an output signal corresponding to the amount of light received from the tilt sensor units 10 and 11 and obtains the initial tilt amount in the Y direction of the first wafer 3. The tilt in the Y direction of the first wafer 3 is corrected in the same manner as in the X direction. By such inclination correction in the X direction and the Y direction , the first wafer 3 is set horizontally as a reference posture before the start of the wafer 3 take-out operation. However, it cannot be said that the second and subsequent wafers 3 are still horizontal.

  In general, the plurality of wafers 3 stacked in the magazine 2 are usually the same lot, and it is empirically found that the individual wafers 3 included in the same lot have the same thickness error direction and the same amount tendency. Are known. For example, if the cross-sectional shape of an arbitrary wafer 3 included in a specific lot is a shape as shown in FIG. 8, it is determined that the cross-sectional shapes of other wafers 3 included in that lot are also the shape shown in FIG. There is no problem. Moreover, generally, the sliced wafers 3 are stacked while maintaining the orientation when sliced.

Therefore, the controller 14, the second sheet prior to removal for subsequent wafer 3, for inclination correction of the second or subsequent wafer 3, The first first wafer 3 in the initial stack state previously determined the inclination of, and calculates the inclination amount of each wafer 3 proportional relationship to these second and subsequent the stacking amount of the wafer 3, the calculated inclination amount external storage device 25 or built-in storage device of each wafer 3 And the second wafer corresponding to the uppermost wafer 3 in the process of removing the second uppermost wafer 3 after the uppermost first wafer 3 is taken out. Subsequent correction signals corresponding to the tilt amount of the wafer 3 are read out, and the X direction motor 15 or the Y direction motor 16 or both motors 15, based on the read correction signals after the second sheet , It is ready to be output to 16

The above proportional relationship specifically refers to the following proportional calculation relationship. Now, assuming that the number of wafers 3 is initially stacked N, and the initial inclination amount α of the uppermost first wafer 3 in the initial stacked state at that time is n, the nth sheet from the top. The inclination amount αn of the wafer 3 taken out is obtained by αn = [α × (N + 1−n)] / N.

The controller 14 stores the first tilt amount of the first wafer 3 in the external storage device 25 or the built-in storage device for calculation of the above formula, and before the second and subsequent wafers 3 are taken out. , for example, before starting the extraction operation of the first wafer 3, at the time of obtaining the initial slope of the first wafer 3, reads out the first tilt amount in advance also the inclination of the second and subsequent sheets The inclination amount after the second sheet obtained by the calculation of the above formula is stored in the external storage device 25 or the built-in storage device, and the second and subsequent sheets corresponding to the inclination amount after the second sheet are stored . by the correction signal provided to the drive of it makes the chromophore at the distal end over data 15, 16.

The inclination amount of the second and subsequent wafers 3 gradually decreases as the number of stacked sheets decreases, and when the remaining one wafer 3 is reached, the inclination amount of one wafer 3 is obtained. Therefore, when the last sheet is taken out, that is, when the bottom plate 4 is at the uppermost position, the inclination of the bottom plate 4 is almost horizontal in both the X direction and the Y direction.

When the second and subsequent wafers 3 are taken out, the controller 14 stores the tilt amount of the second and subsequent wafers 3 positioned at the top in the process of taking out the second and subsequent wafers 3. read from the device 25, rotates the X direction and the Y direction of the motor 15, 16 on the basis of the second and subsequent correction signal corresponding to the amount of the read gradient, and driving each direction of the goniometer unit 12, the bottom plate 4 is tilted to correct the X- and Y-direction tilts of the uppermost wafer 3, that is, the second and subsequent wafers 3 positioned at the top to be taken out.

The inclination correction of the second and subsequent wafers 3 may be performed every time one is taken out or every time a plurality of wafers are taken out as long as the picking pad 7 does not adversely affect the taking-out operation.

In the example shown in FIGS. 1 to 5 above, the projectors 23a, 24a and the light receivers 23b, 24b of the inclination sensor units 8, 9, 10, 11 are located at two different positions in the X direction and in the Y direction. As shown in FIG. 6 , the projectors 23a and 23b and the light receivers 24a and 24b of the inclination sensor units 23 and 24 are provided so as to be opposed to each other in the X direction and the Y direction, respectively. They may be configured to be movable in the X direction or the Y direction during measurement.

6, a pair of projectors 23a and light receiver 23b of the tilt sensor unit 23, linear actuator, not shown, guide rods or Ri by the combining means such as a guide rod and the feed screw, horizontally movable in the X direction, Is provided. Similarly, the pair of light projectors 24a and light receivers 24b of the tilt sensor unit 24 are also provided so as to be horizontally movable in the Y direction. The configuration other than the tilt sensor units 23 and 24 is the same as the configuration shown in FIGS.

  In FIG. 6, for example, when detecting the tilt in the X direction of the uppermost wafer 3 in the stacked state, the tilt sensor unit 23 first detects the uppermost wafer 3 in the stacked state at an arbitrary position in the X direction. The height position is detected, an output signal is output to the controller 14 (not shown), and the controller 14 stores the output level at that position. Next, the tilt sensor unit 23 is moved in the X direction by a predetermined distance by a linear actuator or the like (not shown), detects the height position of the uppermost wafer 3 at the moved position, and outputs an output signal to the controller. 14 and store the output level at that position. After such two measurements before and after the movement, the controller 14 obtains the difference in height of the uppermost wafer 3 at the position before and after the movement from the difference in output level before and after the movement. The amount of inclination of the upper wafer 3 in the X direction is obtained. Similarly, the controller 14 also obtains the amount of tilt of the wafer 3 in the Y direction, and based on the amount of tilt, the bottom plate 4 is tilted by the gonio units 12 and 13 and the first wafer 3 is Correct the tilt.

As described above, according to the present invention, only the first first wafer 3 is detected by the tilt sensor units 8, 9, 10, 11, 23, 24 to correct the tilt of the bottom plate 4. For the first and subsequent wafers 3, without using the tilt sensor units 8, 9, 10, 11, 23, 24, the initial tilt amount and the tilt amount of the wafer 3 are determined from the tendency of the thickness error of the wafer 3. The inclination is obtained by a proportional relationship, that is, proportional calculation, so that the inclination of the second and subsequent wafers 3 can be corrected quickly.

  The present invention can be applied not only to wafers for solar cells but also to wafers for other purposes.

1 Wafer Stacking Device 2 Magazine 3 Wafer 4 Bottom Plate 5 Push-up Unit 6 Suction Head 7 Suction Pad 8 Tilt Sensor Unit 8a Light Emitter 8b Light Receiver 9 Tilt Sensor Unit 9a Light Emitter 9b Light Receiver 10 Tilt Sensor Unit 10a Light Emitter 10b Light Receiver 11 Tilt Sensor 11 Unit 11a Projector 11b Receiver 12 Goniometer unit 13 Goniometer unit 14 Controller 15 Motor 16 Motor 17 Pulley 18 Belt 19 Pulley 20 Pulley 21 Belt 22 Pulley 23 Tilt sensor unit 23a Emitter 23b Light receiver 24 Tilt sensor unit 24a Emitter 24b Light receiver 25 Memory Device 26 Detection means 27 Push-up drive means 28 Slit 100 Magazine 101 Slit 102 Wafer 103 Bottom plate 104 Push-up unit 105 Wear pads 106 wafer 107 suction head

Claims (5)

In a wafer stacking apparatus in which a large number of wafers are stacked on a bottom plate in a magazine, and the bottom plate is lifted by a lifting unit, and the top wafer in a stacked state is picked up one by one with a suction pad.
The top of the first sheet of the inclination of the wafer is detected by the sensor unit slope at the position of the two different points on the X and Y directions, by the controller, the inclination of the first wafer has been detected in the initial stack state and compared with the reference posture of the wafer to obtain the first tilt amount from the difference, the first based on the first correction signal corresponding to the inclination amount in the X direction and the Y-direction actuator calculated by tilting the bottom plate, It is corrected to the reference orientation of the inclination of the first wafer, before removal of the second and subsequent wafers, by the controller, the initial slope of the inclination amount of each wafer in the second and subsequent sheets in the first stack state The amount of inclination of each of the second and subsequent wafers is stored in advance from the proportional relationship between the amount and the stacked amount of wafers, and the first wafer is removed by the suction pad. In the process of taking out the second and subsequent wafers from the top , the tilt amount of the second and subsequent wafers from the top is read out, and the second and subsequent wafers corresponding to the read tilt amount are read out. tilt the bottom plate by the X and Y directions of the actuator based on the modified signal, sequentially correct the inclination of the top and consisting of two subsequent wafer to the reference position, the stacked state, characterized in that Wafer tilt correction method. In a wafer stacking apparatus in which a large number of wafers are stacked on a bottom plate in a magazine, and the bottom plate is lifted by a lifting unit, and the top wafer in a stacked state is picked up one by one with a suction pad.
A tilt sensor unit that detects the tilt of the first wafer in the first stacking state at two different height positions in the tilt direction, a detection unit that detects the stacking amount of the wafer, and the tilt Input the tilt of the first wafer from the sensor unit and the stacking amount of the wafer from the detection means, compare the input tilt of the first wafer with the reference orientation of the wafer, and calculate the first tilt from the difference. In addition, the amount of inclination of each of the second and subsequent wafers in the first stacked state is obtained in advance from the proportional relationship between the amount of initial inclination and the amount of stacked wafers before the second and subsequent wafers are taken out. And a controller that generates a correction signal corresponding to the tilt amount of each of the second and subsequent wafers, and is interposed between the bottom plate and the push-up unit, and receives the correction signal as an input. Tilt the bottom plate by the direction and the Y direction of the actuator, and a goniometer unit for correcting the reference posture the inclination of the top and comprising a wafer,
When removing the first wafer, the controller tilts the bottom plate by the actuators in the X and Y directions based on the first correction signal corresponding to the first tilt amount, thereby tilting the first wafer. In addition to correcting to the reference posture, in the process of taking out the second and subsequent wafers, the tilt amount of the second and subsequent wafers as the top is read, and corresponds to the read tilt amount of the second and subsequent wafers. tilt the bottom plate by the X and Y directions of the actuator based on the modified signal, the second and subsequent wafer to be uppermost tilt sequentially corrects the reference attitude, the wafer characterized by the this Stacking device. The tilt sensor unit includes a projector and a light receiver. The projector and the light receiver are provided at the same height position, and the height of the uppermost first wafer is set to a predetermined height position. to set, with measured at the top first sheet height position the two positions different on two points and the Y-direction different on the X-direction of the wafer stacked state, one top to determine the amount of tilting of the eyes of the wafer, it detects the first sheet in the X direction of inclination of the wafer on the top from the difference in height measured at two different locations on the X-direction, different on Y direction 2 you detecting the inclination in the Y direction of the first wafer on the top from the difference in height measured at the position of the point, the wafer stacking apparatus according to claim 2, characterized in that.
The emitter and receiver tilt sensor unit according to claim 3 which is provided in each of opposite state to the position of the two different points on the position and the Y direction of the two different places on the X-direction, it is characterized in the wafer Stacking device. The projector and light receiver of the tilt sensor unit are provided in a pair facing each other in the X direction and the Y direction, and can be moved in the X direction or the Y direction so that the wafer tilts at two different positions. 4. The wafer stacking apparatus according to claim 3 , wherein the wafer stacking apparatus detects the wafer.

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