Lift pin standby position teaching method, substrate processing apparatus, and lift pin position correction method

Abstract

The invention provides a lifting pin standby position teaching method, a substrate processing apparatus, and a lifting pin position correction method, which can stably teach the standby position of a lifting pin. In the teaching method, a weight is placed on a placement surface of a placement table so as to block an opening of a pin hole having an opening in the placement surface, and a retention pulse, which is an index corresponding to a difference between a controlled ideal position of a tip of the lift pin and an actual position of the tip of the lift pin, is calculated while the lift pin is being lifted. A threshold value for determining that the lift pin is in contact with the weight is set on the basis of the retention pulse, and the actual position of the tip of the lift pin when the retention pulse reaches the threshold value is detected as a reference position when the tip of the lift pin coincides with the placement surface. The position of the tip of the lift pin when lowered from the reference position by a predetermined third distance is taught as a standby position, and a threshold value is calculated on the basis of the remaining pulse before the lift pin comes into contact with the weight.

Description

Technical Field

[0001] The present disclosure relates to a method for teaching a standby position of a lift pin, a substrate processing apparatus, and a method for correcting the position of a lift pin. Background Art

[0002] In a substrate processing apparatus, when performing various processes on a substrate such as a wafer or a glass substrate, the substrate is placed on a mounting table inside a processing container. The mounting table sometimes also serves as a lower electrode. Further, when loading and unloading the substrate into and out of the inside of the processing container, a plurality of lift pins protrude from the surface of the mounting table to lift the substrate so that the substrate is separated from the mounting table.

[0003] When performing various processes on the substrate, each lift pin is housed in a pin hole formed in the mounting table. Since the position of the tip of the lift pin affects the processing result, it is necessary to teach in advance the position where the tip of the lift pin is to wait during the process. The position where the tip of the lift pin waits (hereinafter referred to as the "standby position") is a position that is sunk by a distance preset according to the processing content from the surface of the mounting table. Therefore, in order to teach the standby position, it is necessary to first grasp the position of the lift pin when the tip of the lift pin coincides with the surface of the mounting table, and then lower the lift pin by a preset distance.

[0004] As a method for grasping the position of the tip of the lift pin (hereinafter referred to as the "reference position") when the tip of the lift pin coincides with the surface of the mounting table, a method using a heavy object has been used. Specifically, after placing a heavy object on the surface of the mounting table so as to block the pin hole, the lift pin is raised, and the position when the tip of the lift pin abuts against the heavy object is regarded as the reference position.

[0005] At this time, a hold pulse is used to determine whether the tip of the lift pin has abutted against the heavy object. The hold pulse is an index corresponding to the difference between the ideal (computed) position of the tip of the lift pin in terms of control and the actual position of the tip of the lift pin. Further, hereinafter, the ideal position of the tip of the lift pin in terms of control will be referred to as the "control ideal position" of the lift pin, and the actual position of the tip of the lift pin will be referred to as the "actual position" of the lift pin.

[0006] After the tip of the lift pin abuts against the heavy object and before the heavy object is lifted, the control ideal position and the actual position of the lift pin deviate from each other, and the absolute value of the hold pulse gradually increases. Then, when the heavy object starts to be lifted by the lift pin, the deviation between the control ideal position and the actual position decreases, and the absolute value of the hold pulse decreases.

[0007] That is, after the front end of the lifting pin comes into contact with the heavy object, the absolute value of the remaining pulse increases and then decreases. Therefore, a threshold value is set between the point where the absolute value of the remaining pulse starts to increase and the point where the absolute value of the remaining pulse starts to decrease, and when the remaining pulse reaches the threshold value, it is determined that the front end of the lifting pin has come into contact with the heavy object (for example, refer to Patent Document 1).

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-50534 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] The technology according to the present disclosure teaches the standby position of the lifting pin stably.

[0013] Solutions to the Problems

[0014] One aspect of the technology according to the present disclosure is a method for teaching the standby position of a lifting pin, which is used to make a lifting pin disposed in a pin hole having an opening on a mounting surface of a mounting table and provided so as to be able to protrude and retract relative to the mounting surface wait at a standby position inside the pin hole. In the method for teaching the standby position of the lifting pin, the lifting pin is connected to a drive mechanism that raises and lowers the lifting pin. The method for teaching the standby position of the lifting pin includes the following steps: setting the position of the front end of the lifting pin inside the pin hole and at an initial position that has descended a predetermined first distance from the mounting surface; placing an abutting object on the mounting surface so as to block the opening of the pin hole; raising the lifting pin whose front end position is set at the initial position by a predetermined second distance that is longer than the first distance through the drive mechanism; continuously calculating a drive differential index during the raising of the lifting pin, the drive differential index being an index corresponding to the difference between the ideal position in the control of the lifting pin and the actual position of the lifting pin; setting a threshold value for determining that the lifting pin has come into contact with the abutting object based on the drive differential index; detecting the actual position of the lifting pin when the drive differential index reaches the threshold value as a reference position when the front end of the lifting pin coincides with the mounting surface of the mounting table; lowering the front end of the lifting pin inside the pin hole from the reference position by a predetermined third distance; and teaching the position of the front end of the lifting pin that has descended a predetermined third distance from the reference position as the standby position, wherein the threshold value is calculated based on the drive differential index before the lifting pin comes into contact with the abutting object.

[0015] Effects of the Invention

[0016] According to the technology related to the present disclosure, it is possible to stably teach the standby position of the lifting pin. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. is a cross-sectional view schematically showing the structure of a substrate processing apparatus according to a first embodiment of the technology related to the present disclosure.

[0018] Figure 2 shows Figure 1 the structure of the drive unit of the lifting pin device.

[0019] Figure 3 FIG. is a process chart showing a general teaching method for the standby position of the lifting pin.

[0020] Figure 4 FIG. is a diagram for explaining a conventional method for setting a threshold value for detecting a heavy object detection position.

[0021] Figure 5 FIG. is a process chart for explaining the phenomenon that the center of the heavy object deviates from the central axis of the pin hole.

[0022] Figure 6 FIG. is a diagram for explaining the influence when the center of the heavy object deviates from the central axis of the pin hole.

[0023] Figure 7 FIG. is a diagram showing the change in the peak value of the remaining pulse when the center of the heavy object deviates from the central axis of the pin hole.

[0024] Figure 8 FIG. is a diagram for explaining a method for setting a threshold value for detecting a heavy object detection position in the first embodiment.

[0025] Figure 9 FIG. is a diagram for explaining a method for setting a threshold value for detecting a heavy object detection position in the second embodiment.

[0026] Figure 10 FIG. is a diagram for explaining a method for setting a threshold value for detecting a heavy object detection position in the third embodiment.

[0027] Figure 11 FIG. is a diagram for explaining a method for setting a threshold value for detecting a heavy object detection position in the fourth embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] Next, each embodiment of the technology related to the present disclosure will be described with reference to the drawings. First, the first embodiment will be described. Figure 1 FIG. is a cross-sectional view schematically showing the structure of a substrate processing apparatus according to the present embodiment.

[0029] Figure 1 The substrate processing apparatus 10 shown, for example, is a capacitively coupled parallel plate type plasma etching apparatus that performs an etching process on a rectangular glass substrate G for an FPD (Flat Panel Display) using plasma. The substrate processing apparatus 10 includes a processing container 11 having a square tube shape made of aluminum and whose surface has been anodized (anodic oxidation treatment). The processing container 11 is composed of a bottom wall 12 and four side walls 13, and a lid 14 is joined to the upper part of the processing container 11. The lid 14 is configured to be opened and closed by an opening and closing mechanism (not shown). In a state where the lid 14 is closed, the joint portions of the lid 14 and the respective side walls 13 are sealed by a sealing member (not shown), and the inside of the processing container 11 is kept airtight.

[0030] Below the inside of the processing container 11, a mounting table 15 for mounting the rectangular glass substrate G is provided. The mounting table 15, for example, has a base material 16 made of a conductive material such as aluminum or stainless steel (SUS), and an insulating member (not shown) covering the base material 16. In addition, the base material 16 is connected to a high-frequency power source for bias (both not shown) via a power supply line and a matcher, and the base material 16 also functions as a lower electrode. Further, the mounting table 15 has a dielectric electrostatic chuck 17 disposed on the base material 16. Electrodes 18 are embedded in the electrostatic chuck 17, and a DC voltage is applied to the electrodes 18 from a DC power supply 19 via a power supply line 20, whereby the glass substrate G is electrostatically adsorbed to the mounting table 15 by, for example, Coulomb force.

[0031] In addition, the mounting table 15 has a plurality of lift pin devices 21. For example, the substrate processing apparatus 10 that performs an etching process on a tenth-generation glass substrate G has 30 lift pin devices 21. Each lift pin device 21 has a lift pin 23 that is movable in the vertical direction in the drawing, and a drive unit 24 (drive mechanism) connected to the lift pin 23 and driving (lifting) the lift pin 23 in the vertical direction.

[0032] Each lift pin 23 is disposed in each pin hole 22 by being inserted into the pin hole 22 formed in the base material 16 of the mounting table 15 corresponding to each lift pin 23. Each pin hole 22 is configured such that an opening is provided on the mounting surface of the mounting table 15 for mounting the glass substrate G, and each lift pin 23 can be made to protrude from and retract into the mounting surface of the mounting table 15 by each drive unit 24.

[0033] In each lift pin device 21, when the lift pin 23 is driven upward by the drive unit 24, the front end of the lift pin 23 protrudes from the mounting surface of the mounting table 15, thereby lifting the glass substrate G away from the mounting surface of the mounting table 15. In addition, in the present embodiment, the mounting surface of the mounting table 15 coincides with the surface of the electrostatic chuck 17.

[0034] Above the mounting table 15, a shower head 25 serving as an upper electrode is provided. The shower head 25 is attached to a lid 14 at the upper part of the processing container 11. The shower head 25 is a hollow plate-like member, and a gas diffusion space 26 is provided inside the shower head 25. Further, a plurality of gas ejection holes 27 for ejecting an etching gas as a processing gas are formed on the lower surface of the shower head 25. The shower head 25 is grounded and forms a pair of parallel plate electrodes together with the mounting table 15.

[0035] Near the center of the upper part of the shower head 25, a gas introduction port 28 is provided. A gas supply pipe 29 for supplying a processing gas is connected to the gas introduction port 28. The gas supply pipe 29 is used, for example, to connect a gas supply source 30 that supplies an etching gas as a processing gas to the gas introduction port 28.

[0036] At positions on the bottom wall 12 near the four corners inside the processing container 11, a plurality of exhaust openings 31 serving as through openings are formed. An exhaust pipe 32 is connected to each exhaust opening 31, and an exhaust device 33 equipped with a vacuum pump such as a turbo molecular pump is connected to the exhaust pipe 32. The exhaust device 33 evacuates the inside of the processing container 11 to a reduced-pressure atmosphere required for performing an etching process.

[0037] Further, a carry-in / carry-out port 34 is provided on the side wall 13 of the processing container 11, and the carry-in / carry-out port 34 is opened and closed by a gate valve 35. A glass substrate G is carried into and out of the inside of the processing container 11 through the carry-in / carry-out port 34.

[0038] The substrate processing apparatus 10 has a control unit 36. Each component of the substrate processing apparatus 10 is connected to the control unit 36. The control unit 36 is, for example, a Module Controller, and controls the operations of the respective components by transmitting and receiving control signals to and from the respective components.

[0039] Figure 2 It is a block diagram showing the structure of a drive unit 24 of the lift pin device 21. The drive unit 24 is a servo motor having a pulse generation unit 37, a motor 38, a servo amplifier 39 serving as a motor driver, and an encoder 40. Further, a deviation counter 41 is provided in the servo amplifier 39.

[0040] The pulse generation unit 37 is, for example, a Programmable Logic Controller (PLC). The pulse generation unit 37 generates command pulses according to a speed (hereinafter referred to as "set speed") for moving the lift pin 23 set by the control unit 36, and inputs the command pulses to the servo amplifier 39.

[0041] The servo amplifier 39 outputs an instruction for driving the motor 38 to the motor 38 according to the command pulse, and receives the feedback signal generated by the driving of the motor 38 to control the torque, rotational speed, position, etc. of the motor 38. In addition, the servo amplifier 39 outputs various parameters based on the command signal and the feedback signal to the control unit 36. The servo amplifier 39 has a deviation counter 41 and a D / A conversion unit (not shown).

[0042] The motor 38 is connected to the lifting pin 23 and is rotationally driven at a rotational speed and torque corresponding to the command signal from the servo amplifier 39, thereby driving the lifting pin 23 in the vertical direction. The encoder 40 generates a feedback pulse proportional to the actual rotational speed of the motor 38 and feeds back the feedback pulse to the servo amplifier 39.

[0043] In the drive unit 24, the command pulses generated according to the set speed are accumulated by the deviation counter 41 of the servo amplifier 39. Moreover, the accumulated value of the command pulses is converted into a DC analog voltage by the servo amplifier 39 to rotate the motor 38, thereby driving the lifting pin 23 in the vertical direction. At this time, when the motor 38 rotates, a feedback pulse proportional to the rotational speed of the motor 38 is generated by the encoder 40. The feedback pulse is fed back to the servo amplifier 39, and the feedback pulse is subtracted from the accumulated value of the command pulses of the deviation counter 41.

[0044] Since the command pulses are continuously generated during the period when the lifting pin 23 moves at the set speed, the accumulated value of the command pulses corresponds to the ideal (computed) position (equivalent to the above-mentioned "control ideal position") of the front end of the lifting pin 23 obtained by multiplying the driving time of the motor 38 by the set speed. In addition, since the feedback pulse is actually proportional to the rotational speed of the motor 38 rotating, it is the moving distance of the actual movement of the lifting pin 23 by the motor 38 and corresponds to the actual position (equivalent to the above-mentioned "actual position") of the front end of the lifting pin 23.

[0045] Therefore, the pulse obtained by subtracting the feedback pulse from the accumulated value of the command pulses of the deviation counter 41 is an index corresponding to the difference between the control ideal position and the actual position (the driving difference of the lifting pin 23). In the present embodiment, this index is defined as the "remaining pulse". For example, when the movement of the lifting pin 23 is blocked by an obstacle, the actual position deviates from the control ideal position, and the difference between the control ideal position and the actual position becomes larger, so the absolute value of the remaining pulse becomes larger. In addition, the remaining pulse is an example of a driving difference index.

[0046] The driving unit 24 calculates the remaining pulses at any time and outputs them to the control unit 36. At the same time, it also outputs the time when the remaining pulses are calculated, the torque of the motor 38, and the actual position of the lifting pin 23 to the control unit 36. As described above, the remaining pulses are calculated at any time, so the remaining pulses are discrete values. In addition, the remaining pulses are obtained by subtracting the feedback pulses from the cumulative value of the command pulses, so the unit of the remaining pulses is the number of pulses.

[0047] Next, a general teaching method for the standby position of the lifting pin 23 will be described. Figure 3 It is a process diagram showing a general teaching method for the standby position of the lifting pin 23. In the substrate processing apparatus 10, this teaching method is periodically executed in all the lifting pin devices 21 provided on the mounting table 15.

[0048] First, the driving unit 24 is used to lower the front end of the lifting pin 23 inside the pin hole 22. At this time, a micrometer is used to set the position of the front end of the lifting pin 23 to an initial position ( Figure 3 of (A)) that is lowered by a predetermined first distance, for example, 0.5 mm, from the mounting surface of the mounting table 15. In addition, a heavy object 42 (abutting object) is placed on the mounting surface of the mounting table 15 so as to block the opening of the pin hole 22. The heavy object 42 is a cylindrical member having a weight of, for example, 2 kgf and a diameter of, for example, 50 mm.

[0049] After that, the control unit 36 sends an instruction to the driving unit 24 of the lifting pin device 21 to raise the lifting pin 23 by a second distance that is longer than the first distance by a predetermined amount, for example, about 1 mm. The servo amplifier 39 outputs a command signal corresponding to this instruction to the motor 38. Then, the motor 38 drives the lifting pin 23 upward ( Figure 3 of (B)). During the upward driving of the lifting pin 23, the driving unit 24 continuously outputs the remaining pulses, the time when the remaining pulses are calculated, the torque of the motor 38, and the actual position of the lifting pin 23 to the control unit 36 as a data set.

[0050] Then, the control unit 36 detects the actual position of the front end of the lifting pin 23 when it abuts against the heavy object 42 (hereinafter referred to as the "heavy object detection position") as the reference position when the front end of the lifting pin 23 coincides with the mounting surface of the mounting table 15 ( Figure 3 of (C)).

[0051] And, the control unit 36 moves the front end of the lifting pin 23 from the detected reference position to a position that is lowered by a predetermined third distance (x μm in the figure) within, for example, 200 μm, through the driving unit 24. Figure 3(D)). Then, the control unit 36 teaches itself by using the actual position of the front end of the lift pin 23 after the movement as the standby position where the front end of the lift pin 23 waits.

[0052] In addition, in the present embodiment, the preset third distance is set to be within 200 μm, but the preset third distance can be changed according to the specifications of the substrate processing apparatus 10, the material of the glass substrate G, and the content of the processing performed on the glass substrate G.

[0053] In the teaching method of the standby position of the lift pin 23, when the lift pin 23 is driven upward in the pin hole 22, the lift pin 23 moves smoothly until the front end of the lift pin 23 abuts against the heavy object 42. Therefore, it is difficult for the actual position of the lift pin 23 to deviate from the control ideal position. Thus, during this period, the absolute value of the retained pulse migrates approximately near 0.

[0054] After that, during the period when the front end of the lift pin 23 abuts against the heavy object 42 but the heavy object 42 does not lift, although the command pulse continues to be generated, the lift pin 23 does not move and the feedback pulse does not change. Thus, during this period, the deviation of the actual position of the lift pin 23 from the control ideal position increases with time, and the absolute value of the retained pulse increases with time.

[0055] Then, when the heavy object 42 starts to be lifted by the lift pin 23, the lift pin 23 starts to move again and the feedback pulse increases. Therefore, the deviation of the actual position of the lift pin 23 from the control ideal position starts to decrease. Thus, after the heavy object 42 starts to be lifted, the absolute value of the retained pulse decreases with time.

[0056] That is, after the front end of the lift pin 23 abuts against the heavy object 42, the absolute value of the retained pulse that has been migrating approximately near 0 suddenly turns to increase and then turns to decrease. Therefore, in the conventional teaching method of the standby position of the lift pin 23, a threshold value is set between the point where the absolute value of the retained pulse turns to increase and the point where it turns to decrease, and the actual position of the lift pin 23 when the retained pulse reaches the threshold value is determined as the heavy object detection position (reference position).

[0057] Figure 4 is a diagram for explaining the conventional method of setting the threshold value for detecting the heavy object detection position. In Figure 4A graph is shown in which the horizontal axis represents the actual position of the lifting pin 23 output by the encoder 40, and the vertical axis represents the retained pulse (an example of a driving differential index). In this graph, the data column of the retained pulse that changes according to the actual position of the lifting pin 23 is represented by a dashed line. In addition, 0 μm on the horizontal axis corresponds to the position of the mounting surface of the mounting table 15 when the position of the front end of the lifting pin 23 is set to a position 0.5 mm lower than the mounting surface of the mounting table 15 using a dial gauge. Also, in the present disclosure, the actual position of the lifting pin 23 increases with the passage of time. Therefore, in the following description, "time" and "actual position" may sometimes be regarded as equivalent for explanation. The same applies to all the embodiments described later. And ideally, there should be no movement of the lifting pin 23 during the period from when the lifting pin 23 abuts against the heavy object 42 to when the heavy object 42 starts to be lifted. Specifically, when the absolute value of the retained pulse that migrates near 0 suddenly starts to increase and before it starts to decrease, the actual position of the lifting pin 23 should not change. However, in Figure 4 there is a slight change in the actual position of the lifting pin 23. This is because the inclination and vibration of the lifting pin 23 caused by various reasons such as the mounting method and rigidity of the lifting pin 23 are actually measured and detected as the change amount of the actual position of the lifting pin 23. However, the value of this change amount is small, so it has no substantial influence on the setting of the threshold value in the present disclosure.

[0058] As Figure 4 shown, in the conventional method of setting the threshold value, first, an extraction target range for extracting the lower limit value of the retained pulse used in the threshold value setting is set in the data column of the retained pulse. In a period after the front end of the lifting pin 23 starts to be driven upward, the output of the retained pulse is unstable. Therefore, the starting point of the extraction target range is set to the actual position of the lifting pin 23 corresponding to the timing when a predetermined time, for example, 5 seconds, has elapsed since the front end of the lifting pin 23 set at a position 0.5 mm lower starts to be driven upward.

[0059] In addition, the end point of the extraction object range is set to the actual position of the lift pin 23 obtained by tracing back from the maximum value of the retention pulse corresponding to the timing when the weight 42 starts to be lifted (hereinafter referred to as the "retention pulse peak value") to a position corresponding to a predetermined period. In addition, the retention pulse peak value is the maximum value of the retention pulse after the starting point of the extraction object range. The predetermined period here is represented by a black arrow in the graph. More specifically, the predetermined period is set in such a way that the actual position of the lift pin 23 (the "rising position" in the graph) at which the lift pin 23 begins to abut against the weight 42 and the absolute value of the retention pulse turns to increase is not included in the extraction object range. That is, the lower limit value is extracted from the retention pulse before the front end of the lift pin 23 abuts against the weight 42. Then, the second largest maximum value of the retention pulse in the extraction object range, which is second only to the maximum value of the retention pulse, that is, the retention pulse peak value, is extracted as the lower limit value of the retention pulse.

[0060] The peak value of the retention pulse, which is the point at which the absolute value of the retention pulse decreases when the weight 42 is lifted, is extracted as the upper limit of the retention pulse for setting the threshold. Then, the middle value (average value) of the upper limit and lower limit of the retention pulse is set as the threshold.

[0061] In the teaching method of the standby position of the lifting pin 23, the weight 42 is placed on the loading surface of the loading platform 15 in such a manner that its center is aligned with the central axis of the corresponding pin hole 22. However, sometimes, after the weight 42 is placed on the loading surface of the loading platform 15, the center of the weight 42 deviates from the central axis of the pin hole 22.

[0062] Figure 5 This is a process diagram for explaining the phenomenon that the center of the weight 42 deviates from the central axis of the pin hole 22. In the teaching method of the standby position of the lifting pin 23, before detecting the weight detection position, the weight 42 is placed in a manner to block the corresponding pin hole 22. At this time, a jig or the like is used to make the center of the weight 42 roughly coincide with the central axis of the pin hole 22.

[0063] Here, the operator manually arranges the weight 42, and thus in the substrate processing apparatus 10, the operator places the weight 42 on the placing surface ( Figure 5 At this time, air may be sealed in the pin hole 22.

[0064] Moreover, the teaching of the standby position of the lift pin 23 needs to be performed in the same environment as the environment where the actual etching process is executed. Therefore, when detecting the heavy object detection position, the inside of the processing container 11 is evacuated to a reduced pressure atmosphere. At this time, the air sealed in the pin hole 22 sometimes discharges from the pin hole 22 to the inside of the processing container 11, and the discharged air (refer to the hollow arrow in the figure) lifts the heavy object 42 ( Figure 5 of (B)).

[0065] When the discharge of the sealed air from the pin hole 22 ends, the heavy object 42 lands on the placement surface of the placement table 15 again. However, when lifting the heavy object 42 or when the heavy object 42 lands, the heavy object 42 sometimes moves laterally (horizontally). In this case, the center of the heavy object 42 deviates from the central axis of the pin hole 22 ( Figure 5 of (C)).

[0066] Figure 6 FIG. is a diagram for explaining the influence when the center of the heavy object 42 deviates from the central axis of the pin hole 22, Figure 7 is a diagram showing the change in the peak value of the remaining pulse when the center of the heavy object 42 deviates from the central axis of the pin hole 22.

[0067] In the case where the center of the heavy object 42 does not deviate from the central axis of the pin hole 22 ( Figure 6 of (A)), when the lift pin 23 is driven upward so that the front end of the lift pin 23 abuts against the heavy object 42, a rotational moment centered on one end of the heavy object 42 is generated (refer to the black arrow) ( Figure 6 of (B)).

[0068] When the lift pin 23 lifts the heavy object 42, the heavy object 42 does not entirely leave the placement surface of the placement table 15, and the heavy object 42 rotates with one end of the heavy object 42 as a fulcrum. That is, since the heavy object 42 is locally lifted with one end of the heavy object 42 as a fulcrum, it is considered that the above-mentioned rotational moment is the driving force for lifting the heavy object 42. Moreover, this rotational moment is equivalent to the product of the upward driving force of the lift pin 23 and the distance L from the front end of the lift pin 23 to one end of the heavy object 42. In addition, it can be considered that in the case where the heavy object 42 is strictly located on the central axis of the pin hole 22, ideally the heavy object 42 rises straight without tilting in any direction. However, in reality, the heavy object 42 is not stable. Therefore, the heavy object 42 tilts in a certain direction according to a very small deviation of the heavy object 42 with respect to the central axis of the pin hole 22, and the heavy object 42 is lifted with one end in the tilting direction as a fulcrum. However, this very small deviation is much smaller than the deviation in Figure 6 of (C), and is a deviation that is substantially regarded as not having occurred for processing.

[0069] Here, when the center of the heavy object 42 is deviated from the central axis of the pin hole 22 ( Figure 6 in (C)), the distance L from the front end of the lifting pin 23 to one end of the heavy object 42 changes ( Figure 6 in (D)), and thus the upward driving force of the lifting pin 23 required for the rotational moment to lift the heavy object 42 also changes. For example, in the case shown in Figure 6 (C), the distance L becomes longer, and thus the upward driving force of the lifting pin 23 required for the rotational moment to lift the heavy object 42 can be smaller than the driving force in the case shown in Figure 6 (A).

[0070] Moreover, since the upward driving force of the lifting pin 23 is proportional to the cumulative value of the command pulses, when the center of the heavy object 42 is deviated from the central axis of the pin hole 22, the heavy object 42 will be lifted before the absolute value of the remaining pulses becomes not so large. That is, the greater the deviation of the center of the heavy object 42 from the central axis of the pin hole 22, the smaller the upward driving force required to lift the heavy object 42 can be, and thus the maximum value (remaining pulse peak value) of the remaining pulses when the heavy object 42 is lifted becomes smaller (refer to the white arrow in Figure 7 ).

[0071] Here, as described above, in the conventional teaching method of the standby position of the lifting pin 23, the remaining pulse peak value is used for setting the threshold value. Therefore, when the heavy object 42 is deviated and the remaining pulse peak value changes, the threshold value changes. As a result, the detection of the heavy object detection position becomes unstable, and furthermore, the deviation from the ideal position of the standby position to be taught becomes larger, and it becomes difficult to stably teach the standby position of the lifting pin 23. In the present embodiment, in response to this situation, the threshold value is set without using the remaining pulse peak value.

[0072] In addition, even if the center of the heavy object 42 is deviated from the central axis of the pin hole 22, the actual position of the lifting pin 23 when the front end of the lifting pin 23 starts to contact the heavy object 42 does not change. Thus, as shown in Figure 7 , even if the center of the heavy object 42 is deviated from the central axis of the pin hole 22, the point at which the absolute value of the remaining pulses starts to increase (the "rising position" in the graph) hardly changes.

[0073] Figure 8 is a diagram for explaining the method of setting the threshold value for detecting the heavy object detection position in the present embodiment. In Figure 8 , similar to Figure 4 , a graph is shown in which the horizontal axis is the actual position of the lifting pin 23 output by the encoder 40 and the vertical axis is the remaining pulses (an example of the drive difference index). In this graph, the data series of the remaining pulses that change according to the actual position of the lifting pin 23 is indicated by a dotted line. In addition, similar toFigure 4 Similarly, 0 μm on the horizontal axis corresponds to the position of the mounting surface of the mounting table 15 when the position of the front end of the lifting pin 23 is set to a position 0.5 mm lower than the mounting surface of the mounting table 15 using a dial indicator.

[0074] As Figure 8 shown, in the method for setting the threshold value in the present embodiment, a range for extracting the remaining pulses used in the setting of the threshold value is also set. In order to remove the range where the output of the remaining pulses is unstable, the starting point of the extraction range is set to the actual position of the lifting pin 23 corresponding to the timing, for example, 5 seconds after starting to drive the front end of the lifting pin 23 upward, in the same manner as in the conventional method for setting the threshold value.

[0075] In addition, the end point of the extraction range is also set to the actual position of the lifting pin 23 obtained by tracing back from the peak value of the remaining pulse (corresponding to the timing when the heavy object starts to be lifted) to a position corresponding to a predetermined period (refer to the black arrow in the figure). Similar to the predetermined period in the conventional method for setting the threshold value, the predetermined period is set such that the rising position of the remaining pulse is not included in the extraction range. However, in the present embodiment, different from the conventional method for setting the threshold value, only the remaining pulses before the front end of the lifting pin 23 abuts against the heavy object 42 (the object to be abutted) are used to set the threshold value. In other words, the threshold value is calculated based on the value of the remaining pulse before the lifting pin 23 abuts against the heavy object 42, that is, the object to be abutted. In addition, when the rising speed of the lifting pin 23, the weight of the heavy object 42, and the waveform of the DC analog voltage of the servo amplifier 39 change, the rising position sometimes changes. Therefore, whenever these parameters change, the above-mentioned predetermined period is re-acquired in advance through experiments or the like.

[0076] Then, as shown in the following formula (1), the value obtained by adding three times the standard deviation P of the remaining pulses within the extraction range to the average value P of the remaining pulses within the extraction range is set as the threshold value. In addition, in the present embodiment, the average value P of the remaining pulses is a positive value. Therefore, three times the standard deviation P of the remaining pulses is added to the average value P of the remaining pulses. However, when the average value P of the remaining pulses is a negative value, three times the standard deviation P of the remaining pulses is subtracted from the average value P of the remaining pulses. That is, the addition or subtraction of three times the standard deviation P of the remaining pulses is performed in such a way that it is an addition operation when taking the absolute value. The same applies to each of the embodiments described later. ave plus the standard deviation P of the remaining pulses within the extraction range σ and the value obtained by multiplying by 3 is set as the threshold value. In addition, in the present embodiment, the average value P of the remaining pulses ave is a positive value. Therefore, the standard deviation P of the remaining pulses is added to the average value P of the remaining pulses ave multiplied by 3. However, when the average value P of the remaining pulses σ is a negative value, the standard deviation P of the remaining pulses is subtracted from the average value P of the remaining pulses ave multiplied by 3. That is, the addition or subtraction of three times the standard deviation P of the remaining pulses is performed in such a way that it is an addition operation when taking the absolute value. The same applies to each of the embodiments described later. ave subtracted by 3 times the standard deviation P of the remaining pulses σ That is, the addition or subtraction of three times the standard deviation P of the remaining pulses is performed in such a way that it is an addition operation when taking the absolute value. The same applies to each of the embodiments described later. σ is added or subtracted. The same applies to each of the embodiments described later.

[0077] Threshold = P ave + 3P σ … (1)

[0078] In addition, in the teaching method of the standby position of the lifting pin 23 involved in the present embodiment, similar to Figure 3 Similarly, first, the driving unit 24 is used to lower the lifting pin 23 so that the position of the front end of the lifting pin 23 is set at a position 0.5 mm lower than the placement surface of the placement table 15. After that, the heavy object 42 is placed on the placement surface of the placement table 15 so as to block the pin hole 22.

[0079] Then, for example, the lifting pin 23 is driven upward at a rising speed of 0.05 mm / second to raise the front end of the lifting pin 23 by 1 mm. During this period, the front end of the lifting pin 23 abuts against the heavy object 42. During the period when the heavy object 42 is not lifted, the front end of the lifting pin 23 does not move. When the heavy object 42 starts to be lifted, the front end of the lifting pin 23 moves upward again. During the period when the driving unit 24 of the lifting pin device 21 drives the lifting pin 23 upward, the remaining pulse, the time when the remaining pulse is calculated, the torque of the motor 38, and the actual position of the lifting pin 23 are continuously output to the control unit 36 as a data set.

[0080] After that, the control unit 36 sets the threshold according to Figure 8 the threshold setting method, performs a time backtracking from the peak of the remaining pulse (refer to the dotted arrow in the figure), and detects the actual position of the lifting pin 23 corresponding to the remaining pulse that first reaches the threshold as the reference position (heavy object detection position). In other words, in the case where there are multiple remaining pulses that reach the threshold (hereinafter referred to as "threshold arrival pulses"), the actual position of the lifting pin 23 corresponding to the threshold arrival pulse closest to the peak of the remaining pulse is detected as the reference position.

[0081] Next, the control unit 36 moves the front end of the lifting pin 23 from the detected reference position to a position 200 μm or less below a predetermined position. Then, the control unit 36 uses the actual front end position of the moved lifting pin 23 as the standby position for the front end of the lifting pin 23 to teach itself.

[0082] According to the present embodiment, a threshold value for detecting a reference position (heavy object detection position) is set based on the average value and standard deviation of the remaining pulses within the extraction object range. That is, the threshold value is calculated based on the remaining pulses (drive differential index) before the lifting pin 23 abuts against the heavy object 42 (abutment object), without using the peak value of the remaining pulses. Thus, in the teaching method of the standby position of the lifting pin 23, even if the center of the heavy object 42 deviates from the central axis of the pin hole 22 and the peak value of the remaining pulses changes, the threshold value is not affected and the threshold value is stable. As a result, the detection of the reference position is stable, the deviation of the standby position to be taught can be suppressed, and thus the standby position of the lifting pin 23 can be taught stably.

[0083] In addition, in the present embodiment, the extraction object range does not include the range where the output of the remaining pulses is unstable and the rising position of the remaining pulses. Therefore, the remaining pulses extracted from this extraction object range are relatively stable. Thus, the threshold value set using the remaining pulses extracted from this extraction object range can be made more stable.

[0084] Moreover, in the present embodiment, the actual position of the lifting pin 23 corresponding to the threshold arrival pulse closest to the peak value of the remaining pulses among the multiple threshold arrival pulses is detected as the reference position. This threshold arrival pulse corresponds to the remaining pulse that first exceeds the threshold value after the actual position of the lifting pin 23 reaches the rising position. And as described above, even if the center of the heavy object 42 deviates from the central axis of the pin hole 22, the rising position hardly changes. Thus, the actual position of the lifting pin 23 when the corresponding remaining pulse first exceeds the threshold value after the actual position of the lifting pin 23 reaches the rising position is also stable. From this point of view, the detection of the heavy object detection position can also be made stable.

[0085] In addition, the applicant obtained the respective threshold values in the case where the center of the heavy object 42 did not deviate from the central axis of the pin hole 22 and in the case where the center of the heavy object 42 deviated from the central axis of the pin hole 22 by about 25 mm using the conventional threshold setting method. Then, the reference positions in the former and latter cases were detected using these threshold values. At this time, the deviation between the two detected reference positions was as much as 3.7 μm.

[0086] On the other hand, the applicant also obtained the respective threshold values in the case where the center of the heavy object 42 did not deviate from the central axis of the pin hole 22 and in the case where the center of the heavy object 42 deviated from the central axis of the pin hole 22 by about 25 mm using the setting method of the present embodiment. Then, the reference positions in the former and latter cases were detected using these threshold values. At this time, the deviation between the two detected reference positions was reduced to 0.5 μm. Thus, it was confirmed that when using the setting method of the present embodiment, the threshold value is stable and the detection of the reference position is stable.

[0087] Next, a second embodiment will be described. The structure and function of the second embodiment are basically the same as those of the first embodiment described above. The only difference from the first embodiment is that torque is used instead of retained pulses in the detection of the reference position. Therefore, the description of the structure and function that duplicates the first embodiment is omitted. Below, the different structure and function will be described.

[0088] Figure 9 is a diagram for explaining a method of setting a threshold value for detecting a heavy object detection position in the present embodiment. In Figure 9 a graph is shown in which the horizontal axis represents the actual position of the lifting pin 23 output by the encoder 40 and the vertical axis represents the torque of the motor 38. In this graph, a data series of torque that changes according to the actual position of the lifting pin 23 is represented by a dashed line. In addition, torque is defined as a negative value when a force to lift upward is generated. Therefore, in Figure 9 the graph, the lower, that is, the more negative the direction, the greater the value of the torque.

[0089] When the lifting pin 23 moves naturally according to the rotation of the rotor without being obstructed by an obstacle, the absolute value of the torque of the motor 38 does not become large. On the other hand, when the rotor of the motor 38 wants to rotate but the lifting pin 23 is difficult to move as the lifting pin 23 is obstructed by an obstacle, the absolute value of the torque of the motor 38 becomes large. Therefore, torque is also an index of the driving difference of the lifting pin 23 in the same way as the retained pulse. In addition, torque is also an example of an index of the driving difference.

[0090] In addition, when the lifting pin 23 is driven upward in the pin hole 22, the lifting pin 23 moves smoothly until the front end of the lifting pin 23 abuts against the heavy object 42. Therefore, the absolute value of the torque does not become very large.

[0091] After that, during the period when the front end of the lifting pin 23 abuts against the heavy object 42 but the heavy object 42 is not lifted, even if the rotor of the motor 38 wants to rotate, the lifting pin 23 does not move. Therefore, the absolute value of the torque becomes large. In particular, since the rotor of the motor 38 wants to continue rotating, the absolute value of the torque increases with the passage of time.

[0092] Then, when the heavy object 42 starts to be lifted by the lifting pin 23, the lifting pin 23 starts to move again. Therefore, the lifting pin 23 moves as the rotor of the motor 38 rotates, and the absolute value of the torque shows a substantially stable value without changing as it increases with the passage of time.

[0093] That is, after the front end of the lifting pin 23 abuts against the heavy object 42, the absolute value of the torque that has been migrating stably before suddenly turns to increase and then becomes stable again. In addition, in the present embodiment, torque is output as a negative value. Therefore, inFigure 9 In this case, after the front end of the lifting pin 23 abuts against the heavy object 42, the torque temporarily decreases and then becomes stable again. In addition, similar to Figure 8 similarly, Figure 9 0 μm on the horizontal axis of the graph of [] corresponds to the position of the placement surface of the placement table 15 when the position of the front end of the lifting pin 23 is set to a position 0.5 mm lower than the placement surface of the placement table 15 using a dial indicator.

[0094] As Figure 9 shown, in the method for setting the threshold value in the present embodiment, an extraction target range for the torque used in setting the threshold value is set. For a period after the lifting pin 23 starts to move, similar to the retention pulse, the torque is also unstable. Therefore, in order to remove the range where the output of the torque is unstable, similar to the first embodiment, the starting point of the extraction target range is set to the actual position of the lifting pin 23 corresponding to the timing after, for example, 5 seconds have elapsed since the front end of the lifting pin 23 started to be driven upward.

[0095] In addition, the end point of the extraction target range is set to the actual position of the lifting pin 23 obtained by tracing back from the actual position of the lifting pin 23 corresponding to the timing when the heavy object 42 starts to be lifted, that is, the actual position of the lifting pin 23 corresponding to the peak of the retention pulse (indicated as "position corresponding to the peak of the retention pulse" in the graph) by a position corresponding to a predetermined period (refer to the black arrow in the graph). In Figure 9 this case, the position where the absolute value of the torque increases (decreases in the figure) over time and then becomes stable becomes the position corresponding to the peak of the retention pulse.

[0096] The predetermined period is set so that the decreasing position of the torque is not included in the extraction target range. That is, in the present embodiment, the torque before the front end of the lifting pin 23 abuts against the heavy object 42 is used to set the threshold value. In addition, when the rising speed of the lifting pin 23, the weight of the heavy object 42, and the waveform of the DC analog voltage of the servo amplifier 39 change, the decreasing position may change. Therefore, whenever these parameters change, the above-mentioned predetermined period is re-acquired in advance through experiments, etc.

[0097] Then, as shown in the following formula (2), the value obtained by subtracting three times the standard deviation T of the torque within the extraction target range from the average value T of the torque within the extraction target range is set as the threshold value. In addition, in the present embodiment, the average value T of the torque is a negative value, so three times the standard deviation T of the torque is subtracted from the average value T of the torque. ave minus the standard deviation T of the torque within the extraction target range σ of the torque within the extraction target range ave is a negative value, so three times the standard deviation T of the torque is subtracted from the average value T of the torque. ave minus the standard deviation T of the torque σ of the torque within the extraction target range.

[0098] Threshold value = T ave - 3Tσ … (2)

[0099] In addition, in the teaching method of the standby position of the lifting pin 23 involved in the present embodiment, similar to Figure 3 Similarly, first, the driving unit 24 is used to lower the lifting pin 23 so that the position of the front end of the lifting pin 23 is set at a position 0.5 mm lower than the placement surface of the placement table 15. Then, the heavy object 42 is placed on the placement surface of the placement table 15 so as to block the pin hole 22.

[0100] Then, for example, the lifting pin 23 is driven upward at a rising speed of 0.05 mm / second to raise the front end of the lifting pin 23 by 1 mm. During this period, the front end of the lifting pin 23 abuts against the heavy object 42. During the period when the heavy object 42 is not lifted, the front end of the lifting pin 23 does not move. When the heavy object 42 starts to be lifted, the front end of the lifting pin 23 moves upward again. During the period when the driving unit 24 of the lifting pin device 21 drives the lifting pin 23 upward, the torque, the time when the torque is calculated, the torque of the motor 38, and the actual position of the lifting pin 23 are continuously output to the control unit 36 as a data set.

[0101] After that, the control unit 36 sets the threshold according to Figure 9 the threshold setting method, performs a time backtracking from the retention pulse peak corresponding position (corresponding to the timing of starting to lift the abutting object) (refer to the dotted arrow in the figure), and detects the actual position of the lifting pin 23 corresponding to the torque that first reaches the threshold as the reference position (heavy object detection position). In other words, in the case where there are multiple torques that reach the threshold (hereinafter referred to as "threshold arrival torques"), the actual position of the lifting pin 23 corresponding to the threshold arrival torque closest to the retention pulse peak corresponding position is detected as the reference position.

[0102] Next, the control unit 36 moves the front end of the lifting pin 23 from the detected reference position to a position 200 μm or less below a predetermined position. Then, the control unit 36 uses the actual front end position of the moved lifting pin 23 as the standby position for the front end of the lifting pin 23 to teach itself.

[0103] According to this embodiment, a threshold value for detecting a reference position (heavy object detection position) is set based on the average value and standard deviation of the torque within the extraction object range. That is, the threshold value is calculated based on the torque (driving differential index) before the lifting pin 23 abuts against the heavy object 42 (abutting object), without using the torque corresponding to the peak of the remaining pulse. Thus, in the teaching method of the standby position of the lifting pin 23, even if the center of the heavy object 42 deviates from the central axis of the pin hole 22, the peak of the remaining pulse changes, and the corresponding torque changes, the threshold value is not affected, and the threshold value is stable. As a result, the detection of the reference position is stable, the deviation of the standby position to be taught can be suppressed, and thus the standby position of the lifting pin 23 can be taught stably.

[0104] In addition, in this embodiment, the extraction object range does not include the range where the output of the torque is unstable and the falling position of the torque. Therefore, the torque extracted from this extraction object range is relatively stable. Thus, the threshold value set using the torque extracted from this extraction object range can be made more stable.

[0105] Next, a third embodiment will be described. The structure and function of the third embodiment are basically the same as those of the above-described first embodiment. The difference from the first embodiment is only that the slope of the remaining pulse is used instead of the remaining pulse in the detection of the reference position. Therefore, the description of the structure and function that repeats the first embodiment is omitted. Below, the different structure and function will be described.

[0106] The slope of the remaining pulse in this embodiment is the degree of change per second of the remaining pulse, which is calculated based on the remaining pulse and time output by the drive unit 24, and the unit is "pulses / second". Specifically, the control unit 36 obtains, for example, the regression line of 10 consecutive times and 10 remaining pulses in time based on the data set output from the drive unit 24, and calculates the slope of this regression line as the slope of the remaining pulse. The slope of this remaining pulse is also an example of a driving differential index.

[0107] Figure 10 It is a diagram for explaining the method of setting the threshold value for detecting the heavy object detection position in this embodiment. In Figure 10 a graph is shown with the actual position of the lifting pin 23 output by the encoder 40 on the horizontal axis and the slope of the remaining pulse on the vertical axis. In this graph, the data series of the slope of the remaining pulse that changes according to the actual position of the lifting pin 23 is represented by a dotted line.

[0108] In addition, when the lifting pin 23 is driven upward in the pin hole 22, the lifting pin 23 moves smoothly until the front end of the lifting pin 23 abuts against the heavy object 42. Therefore, the remaining pulse changes little, and the slope of the remaining pulse migrates approximately near 0.

[0109] Thereafter, during the period when the front end of the lifting pin 23 abuts against the heavy object 42 but the heavy object 42 is not lifted, the absolute value of the remaining pulse changes in a manner that increases with the passage of time, so the slope of the remaining pulse becomes a positive value. Then, after the heavy object 42 starts to be lifted by the lifting pin 23, the absolute value of the remaining pulse changes in a manner that decreases with the passage of time, so the slope of the remaining pulse becomes a negative value. Therefore, at the peak of the remaining pulse corresponding to the timing when the heavy object 42 starts to be lifted, the slope of the remaining pulse is 0.

[0110] That is, after the front end of the lifting pin 23 abuts against the heavy object 42, the slope of the remaining pulse that has been migrating approximately near 0 before then rises to become a positive value, and then passes through 0 and becomes a negative value.

[0111] In addition, similar to Figure 8 similarly, Figure 10 the 0 μm on the horizontal axis of the graph of

[0112] also corresponds to the position of the placement surface of the placement table 15 when the position of the front end of the lifting pin 23 is set to a position 0.5 mm lower than the placement surface of the placement table 15 using a dial gauge. Figure 10 As

[0113] shown, in the method for setting the threshold value in the present embodiment, a range of extraction objects for extracting the slope of the remaining pulse used in the setting of the threshold value is set. In order to remove the range where the output of the remaining pulse is unstable, similar to the first embodiment, the starting point of the extraction object range is set to the actual position of the lifting pin 23 corresponding to the timing when, for example, 5 seconds have passed since the front end of the lifting pin 23 starts to be driven upward.

[0114] Then, as shown in the following formula (3), the average value ΔP of the slope of the remaining pulse within the extraction object range ave is added to three times the standard deviation ΔP of the slope of the remaining pulse within the extraction object range σ and the resulting value is set as the threshold value.

[0115] Threshold value = ΔP ave + 3ΔP σ … (3)

[0116] In addition, in the teaching method for the standby position of the lifting pin 23 according to the present embodiment, similar to Figure 3 First, the driving unit 24 is used to lower the lifting pin 23 so that the position of the front end of the lifting pin 23 is set at a position 0.5 mm lower than the placement surface of the placement table 15. After that, the heavy object 42 is placed on the placement surface of the placement table 15 so as to block the pin hole 22.

[0117] Then, for example, the lifting pin 23 is driven upward at a rising speed of 0.05 mm / second to raise the front end of the lifting pin 23 by 1 mm. During this period, the front end of the lifting pin 23 abuts against the heavy object 42. During the period when the heavy object 42 is not lifted, the front end of the lifting pin 23 does not move. When the heavy object 42 starts to be lifted, the front end of the lifting pin 23 moves upward again. During the period when the driving unit 24 of the lifting pin device 21 drives the lifting pin 23 upward, the remaining pulse, the time when the remaining pulse is calculated, the torque of the motor 38, and the actual position of the lifting pin 23 are continuously output to the control unit 36 as a data set.

[0118] After that, the control unit 36 sets the threshold value according to Figure 10 the threshold setting method, and traces back in time from the upper limit value of the slope of the remaining pulse (refer to the dotted arrow in the figure). Moreover, the actual position of the lifting pin 23 corresponding to the slope of the remaining pulse that first reaches the threshold value is detected as the reference position (heavy object detection position). In other words, in the case where there are multiple slopes of the remaining pulses that reach the threshold value (hereinafter referred to as "threshold arrival pulse slopes"), the actual position of the lifting pin 23 corresponding to the threshold arrival pulse slope closest to the upper limit value of the slope of the remaining pulse is detected as the reference position.

[0119] Next, the control unit 36 moves the front end of the lifting pin 23 from the detected reference position to a position 200 μm or less below a predetermined position. Then, the control unit 36 uses the actual front end position of the moved lifting pin 23 as the standby position for the front end of the lifting pin 23 to teach itself.

[0120] According to the present embodiment, a threshold for detecting a reference position (heavy object detection position) is set based on the average value and standard deviation of the slopes of the remaining pulses within the extraction object range. That is, the threshold is calculated based on the torque (driving differential index) before the lifting pin 23 contacts the heavy object 42 (contact object), without using the slope of the remaining pulse corresponding to the peak of the remaining pulse. Thus, in the teaching method of the standby position of the lifting pin 23, even if the center of the heavy object 42 deviates from the central axis of the pin hole 22, the peak of the remaining pulse changes, and the slope of the corresponding remaining pulse changes, the threshold is not affected, and the threshold is stable. As a result, the detection of the reference position is stable, the deviation of the standby position to be taught can be suppressed, and thus the standby position of the lifting pin 23 can be taught stably.

[0121] In addition, in the present embodiment, the extraction object range does not include the range where the output of the remaining pulse is unstable and the rising position of the remaining pulse. Therefore, the slope of the remaining pulse extracted from this extraction object range is relatively stable. Thus, the threshold set using the slope of the remaining pulse extracted from this extraction object range can be made more stable.

[0122] Next, a fourth embodiment will be described. The structure and function of the fourth embodiment are basically the same as those of the above-described first embodiment. The difference from the first embodiment is only that the slope of the torque is used instead of the remaining pulse in the detection of the reference position. Therefore, the description of the structure and function that repeats the first embodiment is omitted. Below, the different structures and functions will be described.

[0123] The slope of the torque in the present embodiment is the degree of change per second of the torque of the motor 38, which is calculated based on the torque and time output by the drive unit 24, and the unit is "‰ / second". Specifically, the control unit 36 obtains, for example, the regression line of the torques of 10 motors 38 that are continuous in time and the times when these torques of the motors 38 are measured based on the data set output from the drive unit 24, and calculates the slope of this regression line as the slope of the torque. The slope of this torque is also an example of a driving differential index.

[0124] Figure 11 It is a diagram for explaining the method of setting the threshold for detecting the heavy object detection position in the present embodiment. In Figure 11 a graph is shown with the actual position of the lifting pin 23 output by the encoder 40 on the horizontal axis and the slope of the torque on the vertical axis. In this graph, the data series of the slope of the torque that changes according to the actual position of the lifting pin 23 is represented by a dashed line.

[0125] In addition, when the lifting pin 23 is driven upward in the pin hole 22, the lifting pin 23 moves smoothly until the front end of the lifting pin 23 contacts the heavy object 42. Therefore, the torque change is small, and the slope of the torque migrates substantially near 0.

[0126] After that, during the period when the front end of the lifting pin 23 abuts against the heavy object 42 but the heavy object 42 does not lift, the absolute value of the torque changes in an increasing manner, but the torque is output as a negative value, so the slope of the torque becomes a negative value. Then, after the heavy object 42 starts to be lifted by the lifting pin 23, the absolute value of the torque no longer changes, so the slope of the torque migrates again approximately near 0. Therefore, at the peak of the remaining pulse corresponding to the timing when the heavy object 42 starts to be lifted, the slope of the torque is approximately 0.

[0127] That is, after the front end of the lifting pin 23 abuts against the heavy object 42, the slope of the torque that has been migrating approximately near 0 before decreases to become a negative value, and then migrates again approximately near 0.

[0128] In addition, similar to Figure 8 similarly, Figure 11 the 0 μm on the horizontal axis of the graph of

[0129] is also equivalent to the position of the mounting surface of the mounting table 15 when the position of the front end of the lifting pin 23 is set to a position 0.5 mm lower than the mounting surface of the mounting table 15 using a dial indicator. Figure 11 As shown in

[0130] In the method for setting the threshold value in the present embodiment, a range of extraction objects for extracting the slope of the torque used in setting the threshold value is set. In order to remove the range where the output of the torque is unstable, similar to the second embodiment, the starting point of the extraction object range is set to the actual position of the lifting pin 23 corresponding to the timing after, for example, 5 seconds have elapsed since the front end of the lifting pin 23 starts to be driven upward.

[0131] Then, the end point of the extraction object range is set to the actual position of the lifting pin 23 obtained by tracing back a position corresponding to a predetermined period from the position corresponding to the peak of the remaining pulse (refer to the black arrow in the graph). The predetermined period is set such that the actual position of the lifting pin 23 corresponding to the falling position of the torque (indicated by "falling corresponding position" in the graph) is not included in the extraction object range. That is, in the present embodiment, the slope of the torque before the front end of the lifting pin 23 abuts against the heavy object 42 is used to set the threshold value. ave σ ave σ

[0132] Threshold = ΔT ave - 3ΔT σ … (4)

[0133] In addition, in the teaching method for the standby position of the lifting pin 23 according to the present embodiment, similar to Figure 3 First, the lifting pin 23 is lowered by the driving unit 24 so that the position of the front end of the lifting pin 23 is set at a position 0.5 mm lower than the mounting surface of the mounting table 15. After that, the heavy object 42 is placed on the mounting surface of the mounting table 15 so as to block the pin hole 22.

[0134] Then, for example, the lifting pin 23 is driven upward at a rising speed of 0.05 mm / second to raise the front end of the lifting pin 23 by 1 mm. During this period, the front end of the lifting pin 23 abuts against the heavy object 42. During the period when the heavy object 42 is not lifted, the front end of the lifting pin 23 does not move. When the heavy object 42 starts to be lifted, the front end of the lifting pin 23 moves upward again. During the period when the driving unit 24 of the lifting pin device 21 drives the lifting pin 23 upward, the remaining pulse, the time when the remaining pulse is calculated, the torque of the motor 38, and the actual position of the lifting pin 23 are continuously output to the control unit 36 as a data set.

[0135] After that, the control unit 36 sets the threshold value according to Figure 11 the threshold setting method, traces back in time from the lower limit value of the slope of the torque (refer to the dotted arrow in the figure), and detects the actual position of the lifting pin 23 corresponding to the slope of the torque that first reaches the threshold value as the reference position (heavy object detection position). In other words, in the case where there are multiple slopes of the torque that reach the threshold value (hereinafter referred to as "threshold reaching torque slopes"), the actual position of the lifting pin 23 corresponding to the threshold reaching torque slope closest to the lower limit value of the slope of the torque is detected as the reference position.

[0136] Next, the control unit 36 moves the front end of the lifting pin 23 from the detected reference position to a position 200 μm or less below the predetermined position. Then, the control unit 36 uses the actual front end position of the moved lifting pin 23 as the standby position for the front end of the lifting pin 23 to teach itself.

[0137] According to the present embodiment, a threshold for detecting a reference position (heavy object detection position) is set based on the average value and standard deviation of the slopes of the torques within the extraction object range. That is, the threshold is calculated based on the slope of the torque (drive differential index) before the lifting pin 23 comes into contact with the heavy object 42 (contact object), without using the slope of the torque corresponding to the retained pulse peak. Thus, in the teaching method of the standby position of the lifting pin 23, even if the center of the heavy object 42 deviates from the central axis of the pin hole 22 and the retained pulse peak changes and the corresponding slope of the torque changes, the threshold is not affected and the threshold is stable. As a result, the detection of the reference position is stable, the deviation of the standby position to be taught can be suppressed, and thus the standby position of the lifting pin 23 can be taught stably.

[0138] In addition, in the present embodiment, the extraction object range does not include the range where the output of the torque is unstable and the position corresponding to the decrease in the torque. Therefore, the slope of the torque extracted from this extraction object range is relatively stable. Thus, the threshold set using the slope of the torque extracted from this extraction object range can be made more stable.

[0139] The preferred embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above embodiments, and various modifications and changes can be made within the scope of its gist.

[0140] For example, in the above embodiments, the teaching method of the standby position of the lifting pin 23 is executed by the control unit 36 of the substrate processing apparatus 10. However, it may also be that the drive unit 24 of each lifting pin device 21 sends a data set to a server separate from the substrate processing apparatus 10, and the server executes the teaching method of the standby position of the lifting pin 23.

[0141] In addition, in the above embodiments, the standby position of the lifting pin 23 has been taught. However, it is also possible to correct the reference position when the front end of the lifting pin 23 coincides with the placement surface of the placement table 15 by using the actual position of the lifting pin 23 when the retained pulse, torque, slope of the retained pulse, or slope of the torque reaches the threshold.

[0142] Further, in each of the above-described embodiments, the case where a rectangular glass substrate G is etched using a parallel plate type plasma etching apparatus has been described. However, the types of the apparatus and the substrate are not limited thereto. For example, the substrate is not limited to a glass substrate and may be a resin substrate. Further, the shape of the substrate may be circular such as a wafer, and the material and shape of the substrate may also be other materials and shapes. Further, the apparatus for processing the substrate is not limited to an etching apparatus and may be a processing apparatus for performing other processes such as a film forming apparatus and an ashing apparatus. Further, the method of generating plasma is not limited to parallel plate plasma and may be other methods of generating plasma such as inductively coupled plasma and microwave plasma.

[0143] Description of Reference Numerals

[0144] G: glass substrate; 10: substrate processing apparatus; 15: mounting table; 21: lift pin device; 22: pin hole; 23: lift pin; 24: drive unit; 36: control unit; 42: weight.

Claims

1. A method for teaching a standby position of a lift pin, wherein a lift pin disposed on a mounting surface of a mounting table for mounting a substrate and having an open pin hole and arranged so as to be able to protrude and retract relative to the mounting surface, is made to wait at a standby position inside the pin hole, wherein: The lifting pin is connected to a driving mechanism that causes the lifting pin to move up and down. The lifting pin standby position teaching method comprises the following steps: Setting the position of the front end of the lifting pin to an initial position inside the pin hole and lowered from the mounting surface by a predetermined first distance; placing the abutment object on the placement surface in a manner that blocks the opening of the pin hole; The driving mechanism causes the lifting pin whose front end is set at the initial position to rise by a predetermined second distance longer than the first distance; During the period when the lift pin is lifted, a driving difference index is continuously calculated, wherein the driving difference index is an index corresponding to a difference between an ideal position of the lift pin under control and an actual position of the lift pin; setting a threshold value for determining that the lift pin is in contact with the contact object based on the drive difference index; detecting the actual position of the lift pin when the drive differential index reaches the threshold value, as a reference position when the front end of the lift pin is aligned with the mounting surface of the mounting table; Lowering the front end of the lifting pin from the reference position within the pin hole by a predetermined third distance; as well as The position of the tip of the lift pin which is lowered by a predetermined third distance from the reference position is taught as a standby position, The threshold value is calculated based on the drive difference index before the lift pin comes into contact with the contact object.

2. The method for teaching the standby position of the lifting pin according to claim 1, further comprising the following steps: setting an extraction target range for setting the threshold value in the data sequence of the drive difference index that changes according to the actual position of the lift pin; and The threshold is set using an average value of all the drive difference indicators within the extraction target range and a standard deviation of all the drive difference indicators within the extraction target range, in, The extraction target range does not include the drive differential index in a range from when the lift pin starts to rise to when the drive differential index stabilizes and the drive differential index at a timing when the lift pin starts to come into contact with the contact object.

3. The method for teaching the lifting pin standby position according to claim 2, wherein: The threshold is a threshold value obtained by adding three times the standard deviation of all the drive differential indicators to the average value when the average value of all the drive differential indicators within the extraction object range is a positive value, or a threshold value obtained by subtracting three times the standard deviation of all the drive differential indicators from the average value when the average value is a negative value.

4. The method for teaching the lifting pin standby position according to claim 2, wherein: The end point of the extraction target range is an actual position of the lift pin obtained by tracing back a position corresponding to a predetermined period from the drive difference index at the timing when the lift pin starts to lift the contact object.

5. The method for teaching the lifting pin standby position according to claim 1, wherein: The actual position of the lift pin corresponding to the drive differential index that first reaches the threshold is determined as the position at which the lift pin abuts against the contact object by tracing back in time from the drive differential index at the timing when the lift pin starts to lift the contact object.

6. The method for teaching the lifting pin standby position according to claim 1, wherein: The actual position of the lift pin corresponding to the drive differential index closest to the timing at which the lift pin starts lifting the contact object among the plurality of drive differential indexes reaching the threshold is determined as the position at which the lift pin abuts against the contact object.

7. The method for teaching the lifting pin standby position according to claim 1, wherein: The driving mechanism comprises a motor, The drive differential index is a retained pulse obtained by subtracting a feedback pulse proportional to the actual rotation speed of the motor from an integrated value of command pulses generated according to a set speed for moving the lift pin. The retention pulse is acquired in the form of discrete values.

8. The method for teaching the lifting pin standby position according to claim 1, wherein: The driving mechanism comprises a motor, The drive differential indicator is the torque of the motor.

9. The method for teaching the lifting pin standby position according to claim 1, wherein: The driving mechanism comprises a motor, The drive differential index is the slope of the retained pulse obtained by subtracting the feedback pulse proportional to the actual rotation speed of the motor from the accumulated value of the command pulse generated according to the set speed. The slope of the retention pulse is the slope of a regression line between a plurality of the retention pulses that are continuous in time and the time when the plurality of the retention pulses are calculated.

10. The lift pin standby position teaching method according to claim 1, wherein: The driving mechanism comprises a motor, The drive differential index is the slope of the motor torque, The slope of the torque of the motor is the slope of a regression line between a plurality of torques of the motor that are continuous in time and the times when the torques of the plurality of motors are measured.

11. A substrate processing device comprising: A mounting table for mounting a substrate; A lifting pin is arranged in a pin hole having an opening on the mounting surface of the mounting table and is provided in a manner capable of protruding and sinking relative to the mounting surface; a driving mechanism connected to the lifting pin and used to lift the lifting pin; and Control Department, in, The control unit performs the following steps: Setting the position of the front end of the lifting pin to an initial position inside the pin hole and lowered from the mounting surface by a predetermined first distance; placing the abutment object on the placement surface in a manner that blocks the opening of the pin hole; The driving mechanism causes the lifting pin whose front end is set at the initial position to rise by a predetermined second distance longer than the first distance; During the period when the lift pin is lifted, a driving difference index is continuously calculated, wherein the driving difference index is an index corresponding to a difference between an ideal position of the lift pin under control and an actual position of the lift pin; setting a threshold value for determining that the lift pin is in contact with the contact object based on the drive difference index; detecting the actual position of the lift pin when the drive differential index reaches the threshold value, as a reference position when the front end of the lift pin is aligned with the mounting surface of the mounting table; Lowering the front end of the lifting pin from the reference position within the pin hole by a predetermined third distance; as well as The position of the tip of the lift pin which is lowered by a predetermined third distance from the reference position is taught as a standby position, The control unit calculates the threshold value based on the drive difference index before the lift pin comes into contact with the contact object.

12. A method for correcting the position of a lift pin, wherein the lift pin is arranged in a pin hole having an opening on a mounting surface of a mounting table for mounting a substrate and is arranged in a manner that it can protrude and retract relative to the mounting surface, wherein: The lifting pin is connected to a driving mechanism that causes the lifting pin to move up and down. The position correction method of the lifting pin comprises the following steps: Setting the position of the front end of the lifting pin to an initial position inside the pin hole and lowered from the mounting surface by a predetermined first distance; placing the abutment object on the placement surface in a manner that blocks the opening of the pin hole; The driving mechanism causes the lifting pin whose front end is set at the initial position to rise by a predetermined second distance longer than the first distance; During the period when the lift pin is lifted, a driving difference index is continuously calculated, wherein the driving difference index is an index corresponding to a difference between an ideal position of the lift pin under control and an actual position of the lift pin; setting a threshold value for determining that the lift pin is in contact with the contact object based on the drive difference index; as well as using the actual position of the lift pin when the drive differential index reaches the threshold value to correct a reference position when the tip of the lift pin coincides with the mounting surface of the mounting table, The threshold value is calculated based on the drive difference index before the lift pin comes into contact with the contact object.

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