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

Abstract

To stably teach a standby position of a lift pin.SOLUTION: In a lift pin standby position teaching method, a weight 42 is mounted to a mounting surface so as to block an open of a pin hole 22 that is opened to the mounting surface of a mounting stage 15, an accumulated pulse as an index corresponded to a difference of an ideal position on control of a tip end of a lift pin 23 and an actual position of the tip end of the lift pin 23 during the lift pin 23 is lifted in the internal part of the pin hole 22 is calculated, a threshold value for determining that the lift pin 23 is contacted to the weight 42 on the basis of the accumulated pulse is set, the actual position of the tip end of the lift pin 23 when the accumulated pulse is reached to the threshold value is detected as a reference position when the tip end of the lift pin 23 is matched to the mounting surface of the mounting stage 15, and the position of the tip end of the lift pin 23 when it is dropped by a third distance to be predetermined from a reference position is taught as a standby position, and the threshold value is calculated from the accumulated pulse before the lift pin 23 is contacted to the weight 42.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a lift pin standby position teaching method, a substrate processing apparatus, and a lift pin position calibration method.

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. This mounting table may also serve as a lower electrode. Then, when loading and unloading the substrate into and out of the processing container, the substrate is lifted by protruding a plurality of lift pins from the surface of the mounting table and separated from the mounting table.

[0003] When performing various processes on the substrate, each lift pin is accommodated 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 waits during processing. The position where the tip of the lift pin waits (hereinafter referred to as the "standby position") is a position that sinks by a predetermined distance from the surface of the mounting table according to the processing content. Therefore, in order to teach the standby position, first, the position of the lift pin when the tip of the lift pin coincides with the surface of the mounting table needs to be grasped, and then the lift pin needs to be lowered by a predetermined distance.

[0004] As a method for grasping the position of the tip of the lift pin when the tip of the lift pin coincides with the surface of the mounting table (hereinafter referred to as the "reference position"), a method using a weight has been conventionally used. Specifically, after placing the weight 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 weight is regarded as the reference position.

[0005] At this time, it is determined whether the tip of the lift pin has come into contact with the weight using the accumulated pulse, which is an index corresponding to the difference between the position of the tip of the lift pin in the ideal (computed) control and the actual position of the tip of the lift pin. Hereinafter, the position of the tip of the ideal lift pin in control is referred to as the "control ideal position" of the lift pin, and the actual position of the tip of the lift pin is referred to as the "actual position" of the lift pin.

[0006] After the tip of the lift pin comes into contact with the weight, while the weight does not lift, the control ideal position and the actual position of the lift pin deviate, and the absolute value of the accumulated pulse increases. Then, when the weight 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 accumulated pulse becomes smaller.

[0007] That is, after the tip of the lift pin comes into contact with the weight, the absolute value of the accumulated pulse changes from increasing to decreasing. Therefore, a threshold value is set between the point where the absolute value of the accumulated pulse starts to increase and the point where the absolute value of the accumulated pulse starts to decrease, and it is determined that the tip of the lift pin has come into contact with the weight when the accumulated pulse reaches the threshold value (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] The technology according to the present disclosure stably teaches the standby position of the lift pin.

Means for Solving the Problems

[0010] One aspect of the technology according to the present disclosure is a lift pin standby position teaching method for placing a lift pin, which is disposed in a pin hole opening on a placement surface of a placement table for placing a substrate and is provided so as to be able to protrude and retract with respect to the placement surface, in a standby position inside the pin hole. The lift pin is connected to a drive mechanism that raises and lowers the lift pin. The method includes the steps of: setting the position of the tip of the lift pin to an initial position that is lowered by a predetermined first distance from the placement surface inside the pin hole; placing an object to be abutted on the placement surface so as to close the opening of the pin hole; raising, by the drive mechanism, the lift pin whose tip position is set to the initial position by a predetermined second distance that is longer than the first distance; continuously calculating a drive difference index, which is an index corresponding to the difference between the ideal position in terms of control of the lift pin and the actual position of the lift pin while raising the lift pin; setting a threshold value for determining that the lift pin has abutted against the object to be abutted based on the drive difference index; detecting, as a reference position, the actual position of the lift pin when the drive difference index reaches the threshold value, at which time the tip of the lift pin coincides with the placement surface of the placement table; lowering the tip of the lift pin inside the pin hole by a predetermined third distance from the reference position; and teaching, as a standby position, the position of the tip of the lift pin that has been lowered by the predetermined third distance from the reference position. The threshold value is calculated from the drive difference index before the lift pin abuts against the object to be abutted.

Advantages of the Invention

[0011] According to the technology of the present disclosure, the standby position of the lift pin can be stably taught.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0013] Hereinafter, each embodiment of the technology according to the present disclosure will be described with reference to the drawings. First, the first embodiment will be described. FIG. 1 is a cross-sectional view schematically showing the configuration of a substrate processing apparatus according to the present embodiment.

[0014] The substrate processing apparatus 10 shown in FIG. 1 is, for example, a capacitively coupled parallel plate type plasma etching apparatus that performs an etching process using plasma on a rectangular glass substrate G for an FPD (Flat Panel Display). The substrate processing apparatus 10 includes a rectangular tube-shaped processing container 11 made of aluminum whose surface is anodized (aluminum anodizing 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 openable and closable 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 each side wall 13 are sealed by a seal member (not shown), and the inside of the processing container 11 is kept airtight.

[0015] 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 has, for example, 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. Further, a high-frequency power source for bias (both not shown) is connected to the base material 16 via a power supply line and a matcher, and the base material 16 also functions as a lower electrode. Furthermore, the mounting table 15 has an electrostatic chuck 17 made of a dielectric disposed on the base material 16. An electrode 18 is embedded in the electrostatic chuck 17, and by applying a DC voltage to the electrode 18 from a DC power supply 19 via a power supply line 20, the glass substrate G is electrostatically adsorbed to the mounting table 15 by, for example, Coulomb force.

[0016] 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 glass substrate G of the 10th generation 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 figure, and a drive unit 24 (drive mechanism) that is connected to the lift pin 23 and drives (raises and lowers) the lift pin 23 in the vertical direction.

[0017] Each lift pin 23 is disposed in each pin hole 22 by being inserted into the pin hole 22 formed corresponding to each lift pin 23 in the base material 16 of the mounting table 15. Each pin hole 22 opens to the mounting surface for mounting the glass substrate G on the mounting table 15, and each lift pin 23 is configured to be able to project and retract with respect to the mounting surface of the mounting table 15 by each drive unit 24.

[0018] In each lift pin device 21, when the lift pin 23 is driven upward by the drive unit 24, the tip thereof projects from the mounting surface of the mounting table 15, thereby lifting the glass substrate G and separating it from the mounting surface of the mounting table 15. In the present embodiment, the mounting surface of the mounting table 15 coincides with the surface of the electrostatic chuck 17.

[0019] Above the mounting table 15, a shower head 25 as an upper electrode is provided. The shower head 25 is attached to the 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 thereof. Further, a plurality of gas discharge holes 27 for discharging an etching gas as a processing gas are formed on the lower surface of the shower head 25. This shower head 25 is grounded and constitutes a pair of parallel plate electrodes together with the mounting table 15.

[0020] A gas inlet 28 is provided near the upper center of the shower head 25. A gas supply pipe 29 for supplying a processing gas is connected to the gas inlet 28, and the gas supply pipe 29 connects, for example, a gas supply source 30 for supplying an etching gas as a processing gas to the gas inlet 28.

[0021] Exhaust openings 31 as through openings are formed at a plurality of positions on the bottom wall 12 near the four corners inside the processing container 11. 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 the etching process.

[0022] In addition, a carry-in / carry-out port 34 is provided in 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. The glass substrate G is carried into and out of the inside of the processing container 11 through the carry-in / carry-out port 34.

[0023] 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.

[0024] FIG. 2 is a block diagram showing the configuration of the 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 as a motor driver, and an encoder 40. A deviation counter 41 is provided in the servo amplifier 39.

[0025] The pulse generation unit 37 is, for example, a programmable logic controller (PLC). The pulse generation unit 37 generates command pulses according to the speed (hereinafter, “set speed”) for moving the lift pin 23 set by the control unit 36, and inputs the command pulses to the servo amplifier 39.

[0026] The servo amplifier 39 outputs a command signal for driving the motor 38 according to the command pulses to the motor 38, receives a feedback signal generated by the driving of the motor 38, and controls 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).

[0027] The motor 38 is connected to the lift pin 23, rotates and drives at a rotational speed and torque corresponding to the command signal from the servo amplifier 39, and drives the lift pin 23 in the vertical direction. The encoder 40 generates feedback pulses proportional to the actual rotation speed of the motor 38, and feeds back the feedback pulses to the servo amplifier 39.

[0028] In the drive unit 24, command pulses generated according to the set speed are integrated by the deviation counter 41 of the servo amplifier 39. Then, the integrated value of these command pulses is converted into a DC analog voltage by the servo amplifier 39 and the motor 38 is rotated to drive the lift pin 23 in the vertical direction. At this time, when the motor 38 rotates, a feedback pulse proportional to the rotation speed of the motor 38 is generated by the encoder 40. This feedback pulse is fed back to the servo amplifier 39, and the feedback pulse is subtracted from the integrated value of the command pulses of the deviation counter 41.

[0029] While moving the lift pin 23 at the set speed, the command pulses continue to be generated. Therefore, the integrated value of the command pulses corresponds to the position of the tip of the lift pin 23 in the control ideal (computational) sense (corresponding to the "control ideal position" described above), which is obtained by multiplying the set speed by the driving time of the motor 38. Also, since the feedback pulse is proportional to the actual number of rotations of the motor 38, it is the actual moving distance of the lift pin 23 by the motor 38 and corresponds to the actual position of the tip of the lift pin 23 (corresponding to the "actual position" described above).

[0030] Therefore, the pulse obtained by subtracting the feedback pulse from the integrated value of the command pulses of the deviation counter 41 becomes an index corresponding to the difference between the control ideal position and the actual position (the driving difference of the lift pin 23). In this embodiment, this index is defined as the "accumulated pulse". For example, when the movement of the lift pin 23 is obstructed by an obstacle, the actual position deviates from the control ideal position and the difference between the control ideal position and the actual position increases, so the absolute value of the accumulated pulse increases. Note that the accumulated pulse is an example of a driving difference index.

[0031] The drive unit 24 calculates the accumulated pulses as needed and outputs them to the control unit 36. At the same time, when the accumulated pulses are calculated, the drive unit 24 also outputs to the control unit 36 the time at which the accumulated pulses are calculated, the torque of the motor 38, and the actual position of the lift pin 23. Since the accumulated pulses are calculated as needed as described above, the accumulated pulses are discrete values. Also, since the accumulated pulses are obtained by subtracting the feedback pulses from the integrated value of the command pulses, the unit of the accumulated pulses is the number of pulses.

[0032] Next, a general teaching method for the standby position of the lift pin 23 will be described. FIG. 3 is a process diagram showing a general teaching method for the standby position of the lift pin 23. This teaching method is periodically executed in all the lift pin devices 21 provided in the mounting table 15 in the substrate processing apparatus 10.

[0033] First, the drive unit 24 lowers the tip of the lift pin 23 inside the pin hole 22. At this time, using a dial gauge, the position of the tip of the lift pin 23 is set to an initial position that has been lowered by a predetermined first distance, for example, 0.5 mm, from the mounting surface of the mounting table 15 (FIG. 3(A)). Also, a weight 42 (contact object) is placed on the mounting surface of the mounting table 15 so as to block the opening of the pin hole 22. The weight 42 is, for example, a columnar member having a weight of 2 kgf and a diameter of, for example, 50 mm.

[0034] Thereafter, the control unit 36 sends an instruction to the drive unit 24 of the lift pin device 21 to raise the lift pin 23 by a predetermined second distance that is longer than the first distance, 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 lift pin 23 upward (FIG. 3(B)). While the lift pin 23 is being driven upward, the drive unit 24 continues to output to the control unit 36 the accumulated pulses, the time at which the accumulated pulses are calculated, the torque of the motor 38, and the actual position of the lift pin 23 as a data set.

[0035] Thereafter, the control unit 36 detects the actual tip position of the lift pin 23 (hereinafter referred to as the "weight detection position") when the tip of the lift pin 23 abuts against the weight 42, taking the reference position when the tip of the lift pin 23 coincides with the mounting surface of the mounting table 15 as a reference (Fig. 3(C)).

[0036] Furthermore, the control unit 36 moves the tip of the lift pin 23 by the driving unit 24 to a position that has descended by a predetermined third distance (x μm in the figure) within, for example, 200 μm from the detected reference position (Fig. 3(D)). Then, the control unit 36 teaches itself the actual tip position of the lift pin 23 after the movement as the standby position where the lift pin 23 waits.

[0037] In this embodiment, the predetermined third distance is set within 200 μm. However, the predetermined third distance is 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.

[0038] In the method of teaching 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 tip of the lift pin 23 abuts against the weight 42. Therefore, the actual position is less likely to deviate from the ideal control position of the lift pin 23. Accordingly, during this period, the absolute value of the accumulated pulse transitions to near approximately 0.

[0039] Thereafter, although the tip of the lift pin 23 abuts against the weight 42, while the weight 42 does not lift, the command pulse continues to be generated but the lift pin 23 does not move and the feedback pulse does not change. Therefore, during this period, the deviation of the actual position of the lift pin 23 from the ideal control position increases with the passage of time, and the absolute value of the accumulated pulse increases with the passage of time.

[0040] Then, when the weight 42 starts to be lifted by the lift pin 23, the movement of the lift pin 23 resumes and the return pulse increases, so the deviation between the actual position and the control ideal position of the lift pin 23 starts to decrease. Therefore, after the weight 42 starts to be lifted, the absolute value of the accumulated pulse decreases with the passage of time.

[0041] That is, after the tip of the lift pin 23 abuts against the weight 42, the absolute value of the accumulated pulse, which has been almost transitioning near 0 until then, suddenly increases, 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 accumulated pulse turns to increase and the point where it turns to decrease, and the actual position of the lift pin 23 when the accumulated pulse reaches the threshold value is determined as the weight detection position (reference position).

[0042] FIG. 4 is a diagram for explaining a method of setting a threshold value for detecting a conventional weight detection position. In FIG. 4, a graph is shown with the horizontal axis representing the actual position of the lift pin 23 output by the encoder 40 and the vertical axis representing the accumulated pulse (an example of a drive difference index). In this graph, a data series of the accumulated pulse that changes according to the actual position of the lift pin 23 is indicated by a broken line. Note that 0 μm on the horizontal axis corresponds to the position of the mounting surface of the mounting table 15 when setting the position of the tip of the lift pin 23 to a position 0.5 mm lower from the mounting surface of the mounting table 15 using a dial gauge. Also, in the present disclosure, since the actual position of the lift pin 23 increases with the passage of time, in the following description, "time" and "actual position" may be described equivalently. The same applies to any of the embodiments described later. Further, ideally, there should be no movement of the lift pin 23 from the time it contacts the weight 42 until it starts to lift the weight 42. Specifically, the actual position of the lift pin 23 should not change until the absolute value of the accumulated pulse, which had been transitioning near 0, suddenly increases and then turns to decrease. However, in FIG. 4, the actual position of the lift pin 23 changes slightly. This is because the inclination and vibration of the lift pin 23 caused by various factors such as the mounting method and rigidity of the lift pin 23 are measured and detected as the amount of change in the actual position of the lift pin 23. However, since this amount of change is a small value, it has no substantial impact on the setting of the threshold value and the like in the present disclosure.

[0043] As shown in FIG. 4, in the conventional threshold setting method, first, in the data series of the accumulated pulse, an extraction target range for extracting the lower limit value of the accumulated pulse used for setting the threshold value is set. For a while after the tip of the lift pin 23 starts to be driven upward, the output of the accumulated pulse is not stable. Therefore, the starting point of the extraction target range is set to the actual position of the lift pin 23 corresponding to the timing when a predetermined time, for example, 5 seconds, has elapsed after the tip of the lift pin 23 set at the position 0.5 mm lower starts to be driven upward.

[0044] Further, the end point of the extraction target range is set to the actual position of the lift pin 23 traced back from the maximum value of the accumulated pulse (hereinafter referred to as the "accumulated pulse peak") corresponding to the timing when the weight 42 starts to be lifted, which corresponds to a predetermined period. The accumulated pulse peak is the maximum value of the accumulated pulse after the start point of the extraction target range. The predetermined period here is indicated by a black arrow in the graph. More specifically, the predetermined period is set so that the actual position of the lift pin 23 (the "rising position" in the graph) at which the lift pin 23 starts to contact the weight 42 and the absolute value of the accumulated pulse begins to increase is not included in the extraction target range. That is, the lower limit value is extracted from the accumulated pulse before the tip of the lift pin 23 contacts the weight 42. Then, the maximum value of the accumulated pulse in the extraction target range, that is, the second maximum value of the accumulated pulse following the accumulated pulse peak, is extracted as the lower limit value of the accumulated pulse.

[0045] Furthermore, the accumulated pulse peak, which is the point at which the weight 42 starts to be lifted and the absolute value of the accumulated pulse begins to decrease, is extracted as the upper limit value of the accumulated pulse used for setting the threshold value. Then, the intermediate value (average value) between the upper limit value and the lower limit value of the accumulated pulse is set as the threshold value.

[0046] In the teaching method of the standby position of the lift pin 23, the weight 42 is placed on the placement surface of the placement table 15 so that its center coincides with the central axis of the corresponding pin hole 22. However, after the weight 42 is placed on the placement surface of the placement table 15, the center of the weight 42 may deviate from the central axis of the pin hole 22.

[0047] FIG. 5 is a process diagram for explaining the phenomenon in which 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 lift pin 23, prior to the detection of the weight detection position, the weight 42 is placed so as to block the corresponding pin hole 22. At this time, a jig or the like is used to approximately align the center of the weight 42 with the central axis of the pin hole 22.

[0048] Here, since the operator manually arranges the weight 42, in the substrate processing apparatus 10, with the lid 14 open and the inside of the processing container 11 open to the atmosphere, the weight 42 is placed on the placement surface of the placement table 15 (FIG. 5(A)). At this time, air may be trapped in the pin hole 22.

[0049] And, since the instruction 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, when detecting the weight detection position, the inside of the processing container 11 is evacuated to a reduced pressure atmosphere. At this time, the air trapped in the pin hole 22 is discharged from the pin hole 22 toward the inside of the processing container 11, and the discharged air (see the white arrow in the figure) may lift the weight 42 (FIG. 5(B)).

[0050] When the trapped air has finished being discharged from the pin hole 22, the weight 42 lands on the placement surface of the placement table 15 again, but when the weight 42 is lifted or when the weight 42 lands, the weight 42 may move in the lateral direction (horizontal direction). In this case, the center of the weight 42 is displaced with respect to the central axis of the pin hole 22 (FIG. 5(C)).

[0051] FIG. 6 is a diagram for explaining the influence when the center of the weight 42 is displaced with respect to the central axis of the pin hole 22, and FIG. 7 is a diagram showing the change in the accumulated pulse peak when the center of the weight 42 is displaced with respect to the central axis of the pin hole 22.

[0052] When the center of the weight 42 is not displaced with respect to the central axis of the pin hole 22 (FIG. 6(A)), when the lift pin 23 is driven upward and the tip of the lift pin 23 is brought into contact with the weight 42, a rotational moment (see the black arrow) centered on one end of the weight 42 occurs (FIG. 6(B)).

[0053] When the lift pin 23 lifts the weight 42, the entire weight 42 does not separate from the placement surface of the placement table 15, and the weight 42 rotates with one end of the weight 42 as a fulcrum. That is, since the weight 42 partially lifts with one end of the weight 42 as a fulcrum, the above-described rotational moment is considered to be the driving force for lifting the weight 42. And this rotational moment corresponds to the product of the upward driving force of the lift pin 23 and the distance L from the tip of the lift pin 23 to one end of the weight 42. When the weight 42 is exactly on the central axis of the pin hole 22, it is also considered that the weight 42 ideally rises straight without tilting in either direction. However, in reality, since it is unstable, the weight 42 tilts in either direction in response to a very slight deviation with respect to the central axis of the pin hole 22 of the weight 42, and the weight 42 lifts with one end in the tilted direction as a fulcrum. However, this very slight deviation is much smaller than the deviation in FIG. 6(C) below and is treated as having substantially no deviation.

[0054] Here, when the center of the weight 42 is deviated with respect to the central axis of the pin hole 22 (FIG. 6(C)), since the distance L from the tip of the lift pin 23 to one end of the weight 42 changes (FIG. 6(D)), the upward driving force of the lift pin 23 required for the rotational moment to lift the weight 42 also changes. For example, in the case shown in FIG. 6(C), since the distance L becomes longer, the upward driving force of the lift pin 23 required for the rotational moment to lift the weight 42 can be smaller than in the case shown in FIG. 6(A).

[0055] And since the upward driving force of the lift pin 23 is proportional to the integrated value of the command pulses, when the center of the weight 42 is deviated with respect to the central axis of the pin hole 22, the weight 42 will lift before the absolute value of the accumulated pulses becomes that large. That is, the greater the deviation of the center of the weight 42 with respect to the central axis of the pin hole 22, the smaller the upward driving force required to lift the weight 42, so the maximum value (accumulated pulse peak) of the accumulated pulses when the weight 42 is lifted becomes smaller (see the white arrow in FIG. 7).

[0056] Here, as described above, in the conventional method for teaching the standby position of the lift pin 23, since the accumulated pulse peak is used for setting the threshold value, when the weight 42 is displaced and the accumulated pulse peak changes, the threshold value changes. As a result, the detection of the weight detection position becomes unstable, and thus the variation from the ideal position of the standby position to be taught becomes large, making it difficult to stably teach the standby position of the lift pin 23. In the present embodiment, in response to this, the threshold value is set without using the accumulated pulse peak.

[0057] Note that even if the center of the weight 42 is displaced with respect to the central axis of the pin hole 22, the actual position of the lift pin 23 when the tip of the lift pin 23 starts to contact the weight 42 does not change. Therefore, as shown in FIG. 7, the point at which the absolute value of the accumulated pulse turns to an increase (the "rising position" in the graph) hardly changes even if the center of the weight 42 is displaced with respect to the central axis of the pin hole 22.

[0058] FIG. 8 is a diagram for explaining a method of setting a threshold value for detecting the weight detection position in the present embodiment. In FIG. 8, similar to FIG. 4, a graph is shown with the horizontal axis representing the actual position of the lift pin 23 output by the encoder 40 and the vertical axis representing the accumulated pulse (an example of a drive difference index). In this graph, a data series of the accumulated pulse that changes according to the actual position of the lift pin 23 is indicated by a broken line. Note that 0 μm on the horizontal axis corresponds to the position of the mounting surface of the mounting table 15 when setting the position of the tip of the lift pin 23 to a position 0.5 mm lower from the mounting surface of the mounting table 15 using a dial gauge, similar to FIG. 4.

[0059] As shown in FIG. 8, also in the method of setting the threshold value in the present embodiment, an extraction target range for extracting the accumulated pulse used for setting the threshold value is set. The starting point of the extraction target range is set to the actual position of the lift pin 23 corresponding to the timing when, for example, 5 seconds have elapsed after the tip of the lift pin 23 starts to be driven upward, similar to the conventional method of setting the threshold value, in order to exclude the range where the output of the accumulated pulse is unstable.

[0060] Also, the end point of the extraction target range is set to the actual position of the lift pin 23 shifted back by a position corresponding to a predetermined period from the accumulated pulse peak (corresponding to the timing when the weight starts to be lifted) (see the black arrow in the graph). This predetermined period is set so that the rising position of the accumulated pulse is not included in the extraction target range, similar to the predetermined period in the conventional threshold setting method. However, in this embodiment, different from the conventional threshold setting method, the threshold is set using only the accumulated pulse before the tip of the lift pin 23 contacts the weight 42 (the object to be contacted). In other words, the threshold is calculated from the value of the accumulated pulse before the lift pin 23 contacts the weight 42, i.e., the object to be contacted. Note that when the rising speed of the lift pin 23, the weight of the weight 42, or the waveform of the DC analog voltage of the servo amplifier 39 changes, the rising position may change. Therefore, the above-mentioned predetermined period is obtained again through prior experiments or the like each time these parameters change.

[0061] Then, as shown in the following formula (1), the average value P of the accumulated pulses in the extraction target range ave plus three times the standard deviation P of the accumulated pulses in the extraction target range σ is set as the threshold. In this embodiment, since the average value P of the accumulated pulses ave is a positive value, three times the standard deviation P of the accumulated pulses σ is added to the average value P of the accumulated pulses ave . However, when the average value P of the accumulated pulses ave is a negative value, three times the standard deviation P of the accumulated pulses σ is subtracted from the average value P of the accumulated pulses ave . That is, three times the standard deviation P of the accumulated pulses σ is added or subtracted in terms of absolute value. The same applies to each of the embodiments described below.

[0062] Threshold = P ave + 3P σ … (1)

[0063] Also, in the method for teaching the standby position of the lift pin 23 according to the present embodiment, as in FIG. 3, first, the lift pin 23 is lowered by the drive unit 24, and the position of the tip of the lift pin 23 is set to a position 0.5 mm lower than the placement surface of the placement table 15. Then, the weight 42 is placed on the placement surface of the placement table 15 so as to close the pin hole 22.

[0064] Then, the lift pin 23 is driven upward at a rising speed of, for example, 0.05 mm / second, and the tip of the lift pin 23 is raised by 1 mm. During this period, the tip of the lift pin 23 abuts against the weight 42 and does not move while the weight 42 does not rise. When the weight 42 starts to rise, it moves upward again. While driving the lift pin 23 upward, the drive unit 24 of the lift pin device 21 continuously outputs the accumulated pulses, the time when the accumulated pulses are calculated, the torque of the motor 38, and the actual position of the lift pin 23 to the control unit 36 as a data set.

[0065] After that, the control unit 36 sets a threshold value according to the threshold value setting method in FIG. 8, traces back in time from the accumulated pulse peak (see the dashed arrow in the figure), and detects the actual position of the lift pin 23 corresponding to the accumulated pulse that first reaches the threshold value as the reference position (weight detection position). In other words, when there are a plurality of accumulated pulses that reach the threshold value (hereinafter referred to as "threshold value reach pulses"), the actual position of the lift pin 23 corresponding to the threshold value reach pulse closest to the accumulated pulse peak is detected as the reference position.

[0066] Next, the control unit 36 moves the tip of the lift pin 23 to a predetermined lower position within 200 μm from the detected reference position. Then, the control unit 36 teaches itself the actual tip position of the lift pin 23 after the movement as the standby position for the tip of the lift pin 23 to wait.

[0067] According to this embodiment, a threshold value for detecting a reference position (weight detection position) is set based on the average value and standard deviation of the accumulated pulses in the extraction target range. That is, without using the accumulated pulse peak, the threshold value is calculated from the accumulated pulses (drive difference index) before the lift pin 23 contacts the weight 42 (contact target object). As a result, in the teaching method of the standby position of the lift pin 23, even if the center of the weight 42 is displaced with respect to the central axis of the pin hole 22 and the accumulated pulse peak changes, the threshold value is not affected and the threshold value is stabilized. As a result, the detection of the reference position is stabilized, and the variation in the standby position to be taught can be suppressed, so that the standby position of the lift pin 23 can be taught stably.

[0068] Also, in this embodiment, since the extraction target range does not include a range where the output of the accumulated pulses is unstable or the rising position of the accumulated pulses, the accumulated pulses extracted from this extraction target range are relatively stable. Therefore, the threshold value set using the accumulated pulses extracted from this extraction target range can be made more stable.

[0069] Furthermore, in this embodiment, among the plurality of threshold arrival pulses, the actual position of the lift pin 23 corresponding to the threshold arrival pulse closest to the accumulated pulse peak is detected as the reference position. This threshold arrival pulse corresponds to the accumulated pulse that first exceeds the threshold value after the actual position of the lift pin 23 reaches the rising position. And, as described above, the rising position hardly changes even if the center of the weight 42 is displaced with respect to the central axis of the pin hole 22. Therefore, after the actual position of the lift pin 23 reaches the rising position, the actual position of the lift pin 23 at which the corresponding accumulated pulse first exceeds the threshold value is also stabilized. From this point as well, the detection of the weight detection position can be stabilized.

[0070] The applicant obtained the respective threshold values when the center of the weight 42 was not displaced with respect to the central axis of the pin hole 22 and when the center of the weight 42 was displaced by about 25 mm with respect to the central axis of the pin hole 22, using the conventional threshold setting method. Then, the reference positions of the former and the latter were detected using these threshold values. At this time, the displacement between the two detected reference positions was 3.7 μm.

[0071] On the other hand, the applicant also obtained the respective threshold values when the center of the weight 42 was not displaced with respect to the central axis of the pin hole 22 and when the center of the weight 42 was displaced by about 25 mm with respect to the central axis of the pin hole 22, using the setting method of the present embodiment. Then, the reference positions of the former and the latter were detected using these threshold values. At this time, the displacement between the two detected reference positions decreased to 0.5 μm. Therefore, 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.

[0072] Next, a second embodiment will be described. The second embodiment is basically the same as the first embodiment described above in terms of its configuration and operation, and is different from the first embodiment only in that torque is used instead of the accumulated pulses for detecting the reference position. Therefore, the description of the configuration and operation overlapping with those of the first embodiment will be omitted, and the following will describe the different configuration and operation.

[0073] FIG. 9 is a diagram for explaining a method of setting a threshold value for detecting the weight detection position in the present embodiment. FIG. 9 shows a graph with the horizontal axis being the actual position of the lift pin 23 output by the encoder 40 and the vertical axis being the torque of the motor 38. In this graph, a data series of torque that changes according to the actual position of the lift pin 23 is indicated by a broken line. Note that since the torque is defined to be a negative value when generating an upward lifting force, in the graph of FIG. 9, the larger the torque value, the more it shifts downward, that is, in the negative direction.

[0074] When the torque of the motor 38 is such that the lift pin 23 moves smoothly in response to the rotation of the rotor so that the lift pin 23 can move without being obstructed by an obstacle, the absolute value thereof does not increase significantly. On the other hand, when the lift pin 23 is obstructed by an obstacle and has difficulty moving even when the rotor tries to rotate, the absolute value thereof increases. Therefore, the torque, like the accumulation pulse, is an index of the driving difference of the lift pin 23. Note that the torque is also an example of the driving difference index.

[0075] Incidentally, when the lift pin 23 is driven upward in the pin hole 22, until the tip of the lift pin 23 abuts against the weight 42, the lift pin 23 moves smoothly, so the absolute value of the torque does not increase significantly.

[0076] After that, even though the tip of the lift pin 23 abuts against the weight 42, while the weight 42 does not lift, the lift pin 23 does not move even when the rotor of the motor 38 tries to rotate, so the absolute value of the torque increases. In particular, since the rotor of the motor 38 continues to try to rotate, the absolute value of the torque increases with the passage of time.

[0077] Then, when the weight 42 starts to be lifted by the lift pin 23, the movement of the lift pin 23 resumes, so the lift pin 23 moves along with the rotation of the rotor of the motor 38, and the absolute value of the torque does not change so as to increase with the passage of time, but shows a substantially stable value.

[0078] That is, after the tip of the lift pin 23 abuts against the weight 42, the absolute value of the torque, which has been stably transitioning until then, turns to an abrupt increase and then stabilizes again. In this embodiment, since the torque is output as a negative value, in FIG. 9, after the tip of the lift pin 23 abuts against the weight 42, the torque once drops and then stabilizes again. Also, 0 μm on the horizontal axis of the graph in FIG. 9 corresponds to the position of the mounting surface of the mounting table 15 when setting the position of the tip of the lift pin 23 to a position 0.5 mm lower from the mounting surface of the mounting table 15 using a dial gauge, similar to FIG. 8.

[0079] As shown in FIG. 9, in the threshold setting method according to the present embodiment, an extraction target range for extracting the torque used for setting the threshold is set. For a while after the start of the movement of the lift pin 23, the torque is not stable, just like the accumulated pulse. Therefore, in order to exclude the range where the torque output is not stable, the starting point of the extraction target range is, as in the first embodiment, the actual position of the lift pin 23 corresponding to the timing when 5 seconds have elapsed, for example, after the tip of the lift pin 23 starts to be driven upward.

[0080] Also, the end point of the extraction target range is the actual position of the lift pin 23 corresponding to the timing when the weight 42 starts to be lifted, that is, the actual position of the lift pin 23 corresponding to the accumulated pulse peak (indicated as "position corresponding to the accumulated pulse peak" in the graph), minus the position corresponding to a predetermined period (see the black arrow in the graph). In FIG. 9, the position where the absolute value of the torque increases (decreases in the figure) with time and then turns stable is the position corresponding to the accumulated pulse peak.

[0081] This predetermined period is set so that the falling position of the torque is not included in the extraction target range. That is, in the present embodiment, the threshold is set using the torque before the tip of the lift pin 23 contacts the weight 42. Note that when the rising speed of the lift pin 23, the weight of the weight 42, or the waveform of the DC analog voltage of the servo amplifier 39 changes, the falling position may change. Therefore, the above-mentioned predetermined period is obtained again through prior experiments or the like each time these parameters change.

[0082] Then, as shown in the following formula (2), the average value T of the torque in the extraction target range ave minus three times the standard deviation T of the torque in the extraction target range σ is set as the threshold. Note that in the present embodiment, since the average value T of the torque ave is a negative value, three times the standard deviation T of the torque is subtracted from the average value T of the torque ave σ . ​

[0083] Threshold = T ave - 3T σ … (2)

[0084] Also, in the method for teaching the standby position of the lift pin 23 according to the present embodiment, as in FIG. 3, first, the lift pin 23 is lowered by the drive unit 24, and the position of the tip of the lift pin 23 is set to a position 0.5 mm lower than the placement surface of the placement table 15. Then, the weight 42 is placed on the placement surface of the placement table 15 so as to close the pin hole 22.

[0085] Then, the lift pin 23 is driven upward at a rising speed of, for example, 0.05 mm / second, and the tip of the lift pin 23 is raised by 1 mm. During this period, the tip of the lift pin 23 abuts against the weight 42 and does not move while the weight 42 does not rise. When the weight 42 starts to rise, it moves upward again. While driving the lift pin 23 upward, the drive unit 24 of the lift pin device 21 continuously outputs the torque, the time when the torque is calculated, the torque of the motor 38, and the actual position of the lift pin 23 to the control unit 36 as a data set.

[0086] Thereafter, the control unit 36 sets the threshold according to the threshold setting method of FIG. 9, and traces back in time from the accumulated pulse peak corresponding position (corresponding to the timing when the object to be abutted starts to be lifted) (see the dashed arrow in the figure), and detects the actual position of the lift pin 23 corresponding to the torque that first reaches the threshold as the reference position (weight detection position). In other words, when there are a plurality of torques that reach the threshold (hereinafter referred to as "threshold reach torques"), the actual position of the lift pin 23 corresponding to the threshold reach torque closest to the accumulated pulse peak corresponding position is detected as the reference position.

[0087] Next, the control unit 36 moves the tip of the lift pin 23 to a predetermined lower position within 200 μm from the detected reference position. Then, the control unit 36 teaches itself the actual tip position of the lift pin 23 after the movement as the standby position for the tip of the lift pin 23 to wait.

[0088] According to the present embodiment, a threshold value for detecting a reference position (weight detection position) is set based on the average value and the standard deviation of the torque in the extraction target range. That is, the threshold value is calculated from the torque (drive difference index) before the lift pin 23 contacts the weight 42 (contact object) without using the torque corresponding to the accumulated pulse peak. As a result, in the method of teaching the standby position of the lift pin 23, even if the center of the weight 42 is displaced with respect to the central axis of the pin hole 22 and the accumulated pulse peak changes and the corresponding torque changes, the threshold value is not affected and the threshold value is stabilized. As a result, the detection of the reference position is stabilized, and the variation in the standby position to be taught can be suppressed, so that the standby position of the lift pin 23 can be taught stably.

[0089] Further, in the present embodiment, since the extraction target range does not include a range where the output of the torque is unstable or the torque fall position, the torque extracted from this extraction target range is relatively stable. Therefore, the threshold value set using the torque extracted from this extraction target range can be made more stable.

[0090] Next, a third embodiment will be described. The third embodiment is basically the same as the first embodiment described above in terms of its configuration and operation, and is different from the first embodiment only in that the slope of the accumulated pulse instead of the accumulated pulse is used for detecting the reference position. Therefore, the description of the configuration and operation overlapping with those of the first embodiment will be omitted, and the following description will be made on the different configuration and operation.

[0091] The slope of the accumulated pulse in the present embodiment is the degree of change per second of the accumulated pulse, which is calculated based on the accumulated pulse output by the drive unit 24 and the time, and the unit is "number of pulses / second". Specifically, the control unit 36 obtains, for example, a regression line of 10 consecutive times and 10 accumulated pulses in terms of time based on the data set output from the drive unit 24, and calculates the slope of the regression line as the slope of the accumulated pulse. This slope of the accumulated pulse is also an example of the drive difference index.

[0092] FIG. 10 is a diagram for explaining a method of setting a threshold value for detecting the weight detection position in the present embodiment. FIG. 10 shows a graph with the horizontal axis representing the actual position of the lift pin 23 output by the encoder 40 and the vertical axis representing the slope of the accumulated pulses. In this graph, a data series of the slope of the accumulated pulses that changes according to the actual position of the lift pin 23 is indicated by a broken line.

[0093] Incidentally, when the lift pin 23 is driven upward in the pin hole 22, until the tip of the lift pin 23 abuts against the weight 42, the lift pin 23 moves smoothly, so the accumulated pulses hardly change, and the slope of the accumulated pulses transitions near approximately 0.

[0094] After that, although the tip of the lift pin 23 abuts against the weight 42, while the weight 42 does not lift, the absolute value of the accumulated pulses changes so as to increase with the passage of time, so the slope of the accumulated pulses becomes a positive value. And after the weight 42 starts to be lifted by the lift pin 23, the absolute value of the accumulated pulses changes so as to decrease with the passage of time, so the slope of the accumulated pulses becomes a negative value. Therefore, at the accumulated pulse peak corresponding to the timing when the weight 42 starts to be lifted, the slope of the accumulated pulses becomes 0.

[0095] That is, after the tip of the lift pin 23 abuts against the weight 42, the slope of the accumulated pulses, which had been transitioning near approximately 0 until then, rises to a positive value, then passes through 0 and becomes a negative value.

[0096] Note that the 0 μm on the horizontal axis of the graph in FIG. 10 also corresponds to the position of the mounting surface of the mounting table 15 when setting the position of the tip of the lift pin 23 to a position 0.5 mm lower from the mounting surface of the mounting table 15 using a dial gauge, similar to FIG. 8.

[0097] As shown in FIG. 10, in the threshold setting method according to the present embodiment, an extraction target range for extracting the slope of the accumulated pulse used for setting the threshold is set. The starting point of the extraction target range is the actual position of the lift pin 23 corresponding to the timing when, for example, 5 seconds have elapsed since the tip of the lift pin 23 began to be driven upward in order to exclude the range where the output of the accumulated pulse is unstable, similar to the first embodiment.

[0098] Further, the end point of the extraction target range is set to the actual position of the lift pin 23 that has regressed by a position corresponding to a predetermined period from the position corresponding to the accumulated pulse peak (see the black arrow in the graph). This predetermined period is set so that the actual position of the lift pin 23 corresponding to the rise of the accumulated pulse (indicated as the "rise corresponding position" in the graph) is not included in the extraction target range. That is, in the present embodiment, the threshold is set using the slope of the accumulated pulse before the tip of the lift pin 23 contacts the weight 42.

[0099] Then, as shown in the following formula (3), the average value ΔP of the slope of the accumulated pulse in the extraction target range ave and three times the standard deviation ΔP of the slope of the accumulated pulse in the extraction target range σ are added together and set as the threshold.

[0100] Threshold = ΔP ave + 3ΔP σ … (3)

[0101] Also, in the teaching method of the standby position of the lift pin 23 according to the present embodiment, as in FIG. 3, first, the lift pin 23 is lowered by the drive unit 24, and the position of the tip of the lift pin 23 is set to a position 0.5 mm lower than the placement surface of the placement table 15. Then, the weight 42 is placed on the placement surface of the placement table 15 so as to close the pin hole 22.

[0102] Then, the lift pin 23 is driven upward at a rising speed of, for example, 0.05 mm / second, and the tip of the lift pin 23 is lifted by 1 mm. During this period, the tip of the lift pin 23 abuts against the weight 42 and does not move while the weight 42 does not lift. When the weight 42 starts to lift, it moves upward again. The drive unit 24 of the lift pin device 21 continuously outputs, as a data set, the accumulated pulse, the time when the accumulated pulse is calculated, the torque of the motor 38, and the actual position of the lift pin 23 to the control unit 36 while driving the lift pin 23 upward.

[0103] Thereafter, the control unit 36 sets a threshold value according to the threshold value setting method shown in FIG. 10 and traces back in time from the upper limit value of the slope of the accumulated pulse (see the dashed arrow in the figure). Then, the actual position of the lift pin 23 corresponding to the slope of the accumulated pulse that first reaches the threshold value is detected as the reference position (weight detection position). In other words, when there are a plurality of slopes of the accumulated pulse that reach the threshold value (hereinafter referred to as "threshold value reach pulse slopes"), the actual position of the lift pin 23 corresponding to the threshold value reach pulse slope that is closest to the upper limit value of the slope of the accumulated pulse is detected as the reference position.

[0104] Next, the control unit 36 moves the tip of the lift pin 23 to a predetermined lower position within 200 μm from the detected reference position. Then, the control unit 36 teaches itself the actual tip position of the lift pin 23 after the movement as the standby position where the tip of the lift pin 23 waits.

[0105] According to this embodiment, a threshold value for detecting a reference position (weight detection position) is set based on the average value and standard deviation of the slope of the accumulated pulses in the extraction target range. That is, without using the slope of the accumulated pulses corresponding to the accumulated pulse peaks, the threshold value is calculated from the torque (drive difference index) before the lift pin 23 contacts the weight 42 (contact target object). As a result, in the method of teaching the standby position of the lift pin 23, even if the center of the weight 42 is displaced with respect to the central axis of the pin hole 22 and the accumulated pulse peak changes and the slope of the corresponding accumulated pulse changes, the threshold value is not affected and the threshold value is stabilized. As a result, the detection of the reference position is stabilized, and the variation in the standby position to be taught can be suppressed, so that the standby position of the lift pin 23 can be taught stably.

[0106] Further, in this embodiment, since the extraction target range does not include the range where the output of the accumulated pulses is unstable or the rising position of the accumulated pulses, the slope of the accumulated pulses extracted from this extraction target range is relatively stable. Therefore, the threshold value set using the slope of the accumulated pulses extracted from this extraction target range can be made more stable.

[0107] Next, a fourth embodiment will be described. The fourth embodiment is basically the same as the first embodiment described above in terms of its configuration and operation, and is different from the first embodiment only in that the slope of the torque instead of the accumulated pulses is used for detecting the reference position. Therefore, the description of the configuration and operation overlapping with those of the first embodiment will be omitted, and the following description will be made about the different configuration and operation.

[0108] The slope of the torque in this embodiment is the degree of change per second of the torque of the motor 38, which is calculated based on the torque output by the drive unit 24 and the time, and the unit is “‰ / second”. Specifically, the control unit 36 obtains, based on the data set output from the drive unit 24, for example, the regression line of ten consecutive torques of the motor 38 in terms of time and the time when these torques of the motor 38 are measured, and calculates the slope of the regression line as the slope of the torque. This slope of the torque is also an example of the drive difference index.

[0109] FIG. 11 is a diagram for explaining a method of setting a threshold value for detecting the weight detection position in the present embodiment. FIG. 11 shows a graph with the horizontal axis representing the actual position of the lift pin 23 output by the encoder 40 and the vertical axis representing the torque inclination. In this graph, a data series of the torque inclination that changes according to the actual position of the lift pin 23 is indicated by a broken line.

[0110] Incidentally, when the lift pin 23 is driven upward in the pin hole 22, until the tip of the lift pin 23 contacts the weight 42, the lift pin 23 moves smoothly, so the torque hardly changes, and the torque inclination transitions to near approximately 0.

[0111] After that, although the tip of the lift pin 23 contacts the weight 42, while the weight 42 does not lift, the absolute value of the torque changes to increase, but since the torque is output as a negative value, the torque inclination becomes a negative value. And after the weight 42 starts to be lifted by the lift pin 23, since the absolute value of the torque no longer changes, the torque inclination transitions to near approximately 0 again. Therefore, at the accumulated pulse peak corresponding to the timing when the weight 42 starts to be lifted, the torque inclination becomes approximately 0.

[0112] That is, after the tip of the lift pin 23 contacts the weight 42, the torque inclination, which has been transitioning to near approximately 0 until then, drops to a negative value and then transitions to near approximately 0 again.

[0113] Note that the 0 μm on the horizontal axis of the graph in FIG. 11 also corresponds to the position of the mounting surface of the mounting table 15 when setting the position of the tip of the lift pin 23 to a position 0.5 mm lower from the mounting surface of the mounting table 15 using a dial gauge, similar to FIG. 8.

[0114] As shown in FIG. 11, in the threshold setting method according to the present embodiment, an extraction target range for extracting the slope of the torque used for setting the threshold is set. The starting point of the extraction target range is the actual position of the lift pin 23 corresponding to the timing when, for example, 5 seconds have elapsed since the tip of the lift pin 23 began to be driven upward in order to exclude the range where the torque output is unstable, similar to the second embodiment.

[0115] Further, the end point of the extraction target range is set to the actual position of the lift pin 23 retrogressed by a position corresponding to a predetermined period from the position corresponding to the accumulated pulse peak (see the black arrow in the graph). This predetermined period is set so that the actual position of the lift pin 23 corresponding to the torque fall position (indicated as "fall corresponding position" in the graph) is not included in the extraction target range. That is, in the present embodiment, the threshold is set using the slope of the torque before the tip of the lift pin 23 contacts the weight 42.

[0116] Then, as shown in the following formula (4), the average value ΔT of the torque slope in the extraction target range ave minus three times the standard deviation ΔT of the torque slope in the extraction target range σ is set as the threshold.

[0117] Threshold = ΔT ave - 3ΔT σ … (4)

[0118] Also, in the teaching method of the standby position of the lift pin 23 according to the present embodiment, as in FIG. 3, first, the lift pin 23 is lowered by the drive unit 24, and the position of the tip of the lift pin 23 is set to a position 0.5 mm lower from the placement surface of the placement table 15. Then, the weight 42 is placed on the placement surface of the placement table 15 so as to close the pin hole 22.

[0119] Then, the lift pin 23 is driven upward at a rising speed of, for example, 0.05 mm / second, and the tip of the lift pin 23 is lifted by 1 mm. During this period, the tip of the lift pin 23 abuts against the weight 42 and does not move while the weight 42 does not lift. When the weight 42 starts to lift, it moves upward again. The drive unit 24 of the lift pin device 21 continuously outputs the accumulated pulses, the time when the accumulated pulses are calculated, the torque of the motor 38, and the actual position of the lift pin 23 as a data set to the control unit 36 while driving the lift pin 23 upward.

[0120] Thereafter, the control unit 36 sets a threshold value according to the threshold value setting method in FIG. 11, traces back in time from the lower limit value of the torque inclination (see the dashed arrow in the figure), and detects the actual position of the lift pin 23 corresponding to the torque inclination that first reaches the threshold value as the reference position (weight detection position). In other words, when there are a plurality of torque inclinations that reach the threshold value (hereinafter referred to as "threshold value reaching torque inclinations"), the actual position of the lift pin 23 corresponding to the threshold value reaching torque inclination that is closest to the lower limit value of the torque inclination is detected as the reference position.

[0121] Next, the control unit 36 moves the tip of the lift pin 23 to a predetermined lower position within 200 μm from the detected reference position. Then, the control unit 36 teaches itself the actual tip position of the lift pin 23 after the movement as the standby position where the tip of the lift pin 23 waits.

[0122] According to this embodiment, a threshold value for detecting a reference position (weight detection position) is set based on the average value and standard deviation of the torque slope in the extraction target range. That is, without using the slope of the torque corresponding to the accumulated pulse peak, the threshold value is calculated from the slope of the torque (drive difference index) before the lift pin 23 contacts the weight 42 (contact object). As a result, in the teaching method of the standby position of the lift pin 23, even if the center of the weight 42 is displaced with respect to the central axis of the pin hole 22, the accumulated pulse peak changes, and the corresponding torque slope changes, the threshold value is not affected and the threshold value is stabilized. As a result, the detection of the reference position is stabilized, and the variation in the standby position to be taught can be suppressed, so that the standby position of the lift pin 23 can be taught stably.

[0123] Further, in this embodiment, since the extraction target range does not include a range where the torque output is unstable or a position corresponding to the torque fall, the slope of the torque extracted from this extraction target range is relatively stable. Therefore, the threshold value set using the slope of the torque extracted from this extraction target range can be made more stable.

[0124] As described above, the preferred embodiments of the present disclosure have been described. However, the present disclosure is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist thereof.

[0125] For example, in each of the above-described embodiments, the control unit 36 of the substrate processing apparatus 10 executes the teaching method of the standby position of the lift pin 23. However, the drive unit 24 of each lift pin device 21 may transmit a data set to a server different from the substrate processing apparatus 10, and the server may execute the teaching method of the standby position of the lift pin 23.

[0126] Further, in each of the above-described embodiments, the standby position of the lift pin 23 is taught. However, calibration of the reference position when the tip of the lift pin 23 coincides with the mounting surface of the mounting table 15 may be performed using the actual position of the lift pin 23 when the accumulated pulse, torque, slope of the accumulated pulse, or slope of the torque reaches the threshold value.

[0127] Furthermore, in each of the above-described embodiments, the case where the etching process is performed on the rectangular glass substrate G by a parallel plate type plasma etching apparatus has been described. However, the types of the apparatus and the substrate are not limited to these. For example, the substrate is not limited to a glass substrate and may be a resin substrate. Also, the shape of the substrate may be circular such as a wafer. Furthermore, the material and shape of the substrate may be other materials and shapes. Also, the apparatus for processing the substrate is not limited to an etching apparatus and may be other processing apparatuses such as a film forming apparatus or an ashing apparatus. Also, the plasma generation method is not limited to parallel plate plasma and may be other plasma generation methods such as inductively coupled plasma or microwave plasma.

Description of Reference Numerals

[0128] G Glass substrate 10 Substrate processing apparatus 15 Mounting table 21 Lift pin device 22 Pin hole 23 Lift pin 24 Driving unit 36 Control unit 42 Weight

Claims

1. A lift pin standby position teaching method for waiting a lift pin disposed in a pin hole opening on a placement surface of a placement table for placing a substrate and provided so as to be able to project and retract with respect to the placement surface in a standby position inside the pin hole, comprising: The lift pin is connected to a drive mechanism for raising and lowering the lift pin; setting a step of setting the position of the tip of the lift pin to an initial position lowered by a predetermined first distance from the placement surface inside the pin hole; a step of placing an object to be contacted on the placement surface so as to close the opening of the pin hole; a step of raising the lift pin, the tip position of which is set to the initial position, by a predetermined second distance longer than the first distance by the drive mechanism; a step of continuously calculating a drive difference index, which is an index corresponding to a difference between an ideal position in control of the lift pin and an actual position of the lift pin while raising the lift pin; a step of setting a threshold value for determining that the lift pin has contacted the object to be contacted based on the drive difference index; a step of detecting, as a reference position, an actual position of the lift pin when the drive difference index reaches the threshold value, at which the tip of the lift pin coincides with the placement surface of the placement table; a step of lowering the tip of the lift pin by a predetermined third distance from the reference position inside the pin hole; a step of teaching, as a standby position, the position of the tip of the lift pin lowered by a predetermined third distance from the reference position, and A lift pin standby position teaching method for calculating the threshold value from the drive difference index before the lift pin contacts the object to be contacted.

2. In the data series of the drive difference index that changes according to the actual position of the lift pin, a step of setting an extraction target range for setting the threshold value; a step of setting the threshold value using an average value of all the drive difference indexes in the extraction target range and a standard deviation of all the drive difference indexes in the extraction target range, and The extraction target range does not include the drive difference index in the range from when the lift pin starts to rise until the drive difference index stabilizes and the drive difference index at the timing when the lift pin starts to contact the object to be contacted. The lift pin standby position teaching method according to claim 1.

3. The threshold value is obtained by adding three times the standard deviation of all the drive difference indicators to the average value of all the drive difference indicators when the average value is a positive value, or subtracting the same when the average value is a negative value. The lift pin standby position teaching method according to claim 2.

4. The end point of the extraction target range is the actual position of the lift pin traced back from the actual position of the lift pin corresponding to a predetermined period from the drive difference indicator at the timing when the lift pin starts to lift the contact object. The lift pin standby position teaching method according to claim 2.

5. Tracing back in time from the drive difference indicator at the timing when the lift pin starts to lift the contact object, the actual position of the lift pin corresponding to the drive difference indicator that first reaches the threshold value is determined as the position where the lift pin contacts the contact object. The lift pin standby position teaching method according to claim 1.

6. Among the plurality of drive difference indicators that reach the threshold value, the actual position of the lift pin corresponding to the drive difference indicator closest to the drive difference indicator at the timing when the lift pin starts to lift the contact object is determined as the position where the lift pin contacts the contact object. The lift pin standby position teaching method according to claim 1.

7. The drive mechanism has a motor, The drive difference indicator is an accumulated pulse obtained by subtracting a feedback pulse proportional to the actual rotation speed of the motor from the integrated value of command pulses generated according to the set speed for moving the lift pin, The accumulated pulse is obtained as a discrete value. The lift pin standby position teaching method according to claim 1.

8. The drive mechanism has a motor, The drive difference indicator is the torque of the motor. The lift pin standby position teaching method according to claim 1.

9. The drive mechanism has a motor, The drive difference indicator is the slope of the accumulated pulse obtained by subtracting a feedback pulse proportional to the actual rotation speed of the motor from the integrated value of command pulses generated according to the set speed, The slope of the accumulated pulse is the slope of the regression line between a plurality of the accumulated pulses that are continuous in time and the time when the plurality of accumulated pulses are calculated. The lift pin standby position teaching method according to claim 1.

10. The drive mechanism has a motor, The drive difference indicator is the slope of the torque of the motor, The lift pin standby position teaching method according to claim 1, wherein the inclination of the torque of the motor is the inclination of the regression line between the torques of the plurality of motors that are continuous in time and the time when the torques of the plurality of motors are measured.

11. A mounting table for mounting a substrate, A lift pin disposed in a pin hole that opens on the mounting surface of the mounting table and provided so as to be able to project and retract with respect to the mounting surface, A drive mechanism connected to the lift pin to raise and lower the lift pin, A control unit, and The control unit, A step of setting the position of the tip of the lift pin to an initial position that has descended by a predetermined first distance from the mounting surface inside the pin hole, A step of placing an object to be abutted on the mounting surface so as to close the opening of the pin hole, A step of raising the lift pin, whose tip position is set to the initial position, by a predetermined second distance that is longer than the first distance by the drive mechanism, A step of continuously calculating a drive difference index, which is an index corresponding to the difference between the ideal position in terms of control of the lift pin and the actual position of the lift pin while raising the lift pin, A step of setting a threshold value for determining that the lift pin has abutted against the object to be abutted based on the drive difference index, A step of detecting the actual position of the lift pin when the drive difference index reaches the threshold value as a reference position when the tip of the lift pin coincides with the mounting surface of the mounting table, A step of lowering the tip of the lift pin by a predetermined third distance from the reference position inside the pin hole, A step of teaching the position of the tip of the lift pin, which has been lowered by a predetermined third distance from the reference position, as a standby position, and The control unit calculates the threshold value from the drive difference index before the lift pin abuts against the object to be abutted, a substrate processing apparatus.

12. A method for calibrating the position of a lift pin disposed in a pin hole that opens on the mounting surface of a mounting table for mounting a substrate and provided so as to be able to project and retract with respect to the mounting surface, The lift pin is connected to a drive mechanism that raises and lowers the lift pin, A step of setting the position of the tip of the lift pin to an initial position that has descended by a predetermined first distance from the mounting surface inside the pin hole, A step of placing an object to be abutted on the mounting surface so as to close the opening of the pin hole, A step of raising, by the drive mechanism, the lift pin whose tip position is set to the initial position by a predetermined second distance longer than the first distance; A step of continuously calculating a drive difference index, which is an index corresponding to the difference between the control ideal position and the actual position of the lift pin while the lift pin is being raised; A step of setting a threshold value for determining that the lift pin has come into contact with the contact object based on the drive difference index; A step of calibrating a reference position when the tip of the lift pin coincides with the placement surface of the placement table using the actual position of the lift pin when the drive difference index reaches the threshold value; and A method for calibrating the position of a lift pin, wherein the threshold value is calculated from the drive difference index before the lift pin comes into contact with the contact object.

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