JP2000210890A - Position detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely detect the position slippage of a work to a hand, even when the work loaded on the hand of a work conveying robot, and an article other than the work, are conveyed in the approaching condition. SOLUTION: An allowable displacement setting part 13 sets beforehand the allowable displacement of a work W2 to the reference position of the work detected by a sensor group SS2 when the work W2 is loaded without the displacement to a hand 8b. A work detection deciding part 12 finds the difference between the reference position of the work W2 and the detecting positions when the sensor carries out a detecting operation, and calculates the minimum value of the difference, and when the minimum value is larger than the allowable displacement, it is decided that the sensor detects an article, for example an arm 56a, other than the work W2, and depending on the deciding result, a displacement calculator 14 finds the center position of the work from the edge detecting position of the work W2, and calculates the displacement of the work W2, and the correcting amount of the hand is calculated so as to convey the work in the regular position, by a hand position correcting part 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a positional deviation of a workpiece such as a wafer with respect to the hand when the workpiece such as a wafer is placed on a hand of a workpiece transport robot and transported along a predetermined transport path. To a position detecting device.

[0002]

2. Description of the Related Art Conventionally, a work such as a glass substrate or a wafer is taken out or stored from a plurality of chambers using a work transfer robot, and a predetermined processing is performed on the work in each chamber. And a series of machining processes are performed on the workpiece to perform efficient machining processes on a plurality of workpieces.

FIG. 13 is a schematic plan view of a multi-chamber type semiconductor manufacturing apparatus using a work transfer robot. The work transfer robot is arranged in a transfer chamber 1. Around the transfer chamber 1, a plurality of process chambers 2a to 2e and a transfer chamber 3 for transferring a work such as a wafer to the outside are provided. Also, transfer chamber 1
The inside is always kept in a vacuum state. Delivery chamber 3
Is taken out by a work transfer robot A1 shown in FIG. 14 which will be described later and is arranged in the transfer chamber 1, for example, in the process chamber 2c.
The workpieces are transported in the order of → 2d → 2e → 2a → 2b and processed by each process chamber, and the workpieces that have been subjected to a series of processing are transported to the other side of the transfer chamber 3. In order to efficiently perform the processing in each process chamber, the work transfer robot A1 performs the processing on the work in parallel in the processing in each process chamber by a control process such as a pipeline process. The unprocessed work is sequentially brought in from outside through one of the transfer chambers, and the processed work is sequentially taken out through the other of the transfer chambers.

[0004] The transfer chamber 1 has a structure as shown in FIG.
A gate 6 is provided so as to be pivotable, and is provided on a partition wall 5 which is a peripheral wall and faces each of the process chambers 2a to 2e and the transfer chamber 3 as a work entrance / exit to each of the process chambers 2a to 2e. This gate 6
Is opened and closed by a gate valve (not shown) provided inside the transfer chamber 1 so as to face each gate 6.

The work transfer robot A1 is a frog-leg type double-armed work transfer robot. FIG.
As shown in FIG.
, And arms 42a and 42b which are perpendicular to the shaft 41 and rotate along the turning surface. This arm 42
At the distal ends of a and 42b, there are driven arms 43a and 44a and driven arms 43b and 44b whose bases are connected to the arms 42a and 42b, respectively. Driven arm 43
A hand 45b is connected to the tips of the a and 43b, and a hand 45a is connected to the tips of the driven arms 44a and 44b. Therefore, the arms 42a and 42b are
5b, the hand 45b extends far away from the shaft 41, and the hand 45b
5a is dragged by it and approaches the shaft 41. On the other hand, by turning the arms 42a and 42b toward each other toward the hand 45a, the hand 45a extends far away from the shaft 41, and the hand 45b is dragged by the hand 45b and approaches the shaft 41.

An example of a specific transfer operation of the work transfer robot A1 will be described with reference to FIGS.

First, in FIG. 15A, one hand 4b is set in a state where the hand 45b faces the process chamber 2d.
A work W1 as a wafer is already placed on 5a.
Here, the work transfer robot A1 is in the process chamber 2
In order to take out the work W2 in e, the shaft 41 is turned to the right and the hand 45b is opposed to the process chamber 2e. Thereafter, the arms 45a and 42b are turned toward the hand 45b to insert the hand 45b into the process chamber 2e, and the work W2 is placed on the hand 45b. Thereafter, as shown in FIG.
make a turn to return a, 42b to the original initial state,
The work W2 placed on the hand 45b is removed from the process chamber 2e by contracting the hand 45b. Thereafter, as shown in FIG. 16A, the shaft 41 is turned 180 degrees to the right, and the hand 45a is opposed to the process chamber 2e. Thereafter, by inserting the hand 45a into the process chamber 2e, the hand 45a
The work W1 placed on the top is transported to a predetermined position in the process chamber 2e, and the work W1 is transferred to the process chamber 2e.
To perform the operation of retracting the hand 45a. Thus, the predetermined work W2 is taken out from the process chamber 2e, the unprocessed work W1 is placed in the process chamber 2e, and the processing on the work W1 is executed. That is, the work W1 and the work W2 are exchanged. Such processing is performed for each of the process chambers 2a to 2e.

By the way, in such a work transfer robot A1, since the work is merely placed on the hand, the work may be displaced with respect to the hand during the transfer of the work. When this displacement occurs, even if the hand is accurately conveyed, the position of the work is different, so that when the work passes through the gate 6, the work hits the edge of the gate 6, causing damage to the work. The transfer chamber 1 and the like are stained by the particles due to the damage, and other works are also stained. In addition, the degree of vacuum of the transfer chamber 1 and the like is deteriorated. The work is placed on the hand and transported because the transfer chamber 1 and the like are in a vacuum state.

Therefore, the work transfer robot detects such a positional deviation of the work with respect to the hand and performs a transfer operation based on the work. For example, a system and method for automatically positioning a substrate in a processing chamber described in Japanese Patent Application Laid-Open No. 6-224284 discloses a method of disposing a wafer and a hand on which the wafer is placed in a direction substantially transverse to the circular orbit. A relative position of the wafer with respect to the hand is detected by the sensor array, and the transfer of the hand is controlled using the detection result.

[0010]

By the way, the above-described work transfer robot A1 has to rotate the shaft 41 by 180 degrees during the work transfer operation due to its configuration, and the work exchange cycle time becomes longer. FIG.
The work transfer robot A2 shown in FIG. In this work transfer robot A2,
The turning angle of the shaft 41 at the time of replacing the workpiece can be set to about the arrangement angle of the adjacent process chamber.

The configuration of the work transfer robot A2 will be described with reference to FIGS. 17 and 18. The work transfer robot A2 is located at the center of the transfer chamber 1 and has first and second ring-shaped bosses 50a, 50a. 50
b are concentrically overlapped in order from the bottom and are rotatably supported individually via bearings (not shown). First and second arms 56a and 56b are provided on the side surface of the first ring-shaped boss 50a.
A third arm 56c is provided on a side surface of the second ring-shaped boss 50b, and a fourth arm 56c is provided on a top surface of the second ring-shaped boss 50b via a pillar 56e.
Are protruded in the radial direction, respectively.
The lower surface of the distal end of the fourth arm 56d is a rotation fulcrum, and the other arm has the upper surface of the distal end of each arm as a rotation fulcrum.

The radius of the rotation fulcrum of each of the arms 56a to 56d has the same size.
One ends of first to fourth links 57a to 57d having substantially the same length are rotatably connected to the rotation fulcrum 56d.
The distal end of the first link 57a connected to a rotation fulcrum provided on the top surface of the distal end of the first arm 56a is bent upward at the rotation fulcrum at the distal end so as to overhang outward. It has become.

The first link 57a and the fourth link 57d
The first hand 8a is connected to the distal end of the first hand 8 via a hand posture regulating mechanism, thereby forming a first robot link mechanism B1. At this time, the first ring 5
The U-shaped rising height of 7a is such that the hand 8a is located above the ring-shaped boss, and the hand 8b of the second robot link mechanism B2 and one arm 56
c and the link 57c are connected to the first arm 56a and the link 5
7a so as to be able to move. Further, the second hand 8b is connected to the distal ends of the second and third links 57b and 57c via a hand attitude regulating mechanism, and thus a second robot link mechanism B2 is configured. These two robot link mechanisms B1, B2
Of the hands 8a and 8b in the turning direction are α (for example, 60 degrees)
And is not shifted in the turning direction, and is located at the same position in the vertical direction.

The workpiece transfer robot A2 is provided with the second and third arms 56b, 5b of the second robot link mechanism B2.
6c is in a standby state when it becomes linear in the diameter direction. In this standby state, both hands 8a, 8
b is displaced in the turning direction, and (see FIG. 18) is in a standby state of the work transfer robot A2. From this standby state,
By rotating the ring-shaped bosses in directions opposite to each other, the hands 8a and 8b are moved in and out in the radial direction of the ring-shaped bosses, and the work transfer robot A2 is turned in the standby state. In addition, the position of the pillar 56e is on the middle bisector M of the deviation angle between the hands 8a and 8b, and is displaced from the axial center of the ring upper boss in a direction away from the hands 8a and 8b. .

In the work transfer robot A2, the links 57a to 57d of the first and second robot link mechanisms B1 and B2 are connected to the respective robot link mechanisms B1 and B2.
During the retreat operation, a pillar 56e provided on the top surface of the gate 6 of the transfer chamber 1 or the second ring-shaped boss 50b.
It is curved in the horizontal direction so as not to interfere. That is, the portions of the robot link mechanisms B1 and B2 near the connecting portions of the pair of links 57a, 57d and 57b, 57c with the arms are curved in the direction approaching each other, and the portions near the connecting portions with the hand. Are curved away from each other.

FIG. 19 shows a state in which the hand 8b of the second link mechanism B2 is inserted into the process chamber via the gate 6.

However, when using this work transfer robot A2 to detect the displacement of the work placed on the hands 8a, 8b, the work placed on the hands 8a, 8b, the arms 56a, 56b, and the link 57a. , 57b
Is very narrow and the turning operation is performed in a close state, so whether the sensor group SS detects the work,
It is not determined whether an arm or link other than the work is detected, and if an object other than the work, for example, an adjacent arm or link is detected, the position of the work relative to the hand is actually shifted. Even in the case where there is almost no work, it is recognized that the work is greatly displaced with respect to the hand, and in this case, the transfer path of the hand is largely incorrectly corrected, the work collides with the gate, and the work is hit. There has been a problem that the workpiece may be damaged and the particles may affect the workpiece being processed.

The sensor group SS is provided in the transfer chamber 1 between the process chambers 2a and 2b. As described in JP-A-6-224284, similarly, the adjacent process chambers 2a to 2b 2
e, a plurality of similar sensor groups SS are provided in the transfer chamber 1 between the transfer chamber 3 and detect the position of the work during the transfer of the work. The reason for detecting the displacement in units of the plurality of sensor groups SS is that if all the sensors in the plurality of sensor groups SS are independently detected, the number of input / output ports of the sensors becomes considerably large. In addition, the sensor group SS
This is because the order in which each of the sensors detects the work is determined.

Therefore, the work transfer robot draws a selected one of the plurality of transfer paths and transfers the work through the sensor group SS, or draws an arbitrary transfer path to the sensor group. When the workpiece is conveyed through the SS, the detection order of each sensor in the sensor group SS may be different, and it is not possible to recognize which sensor in the sensor group SS is the detected signal, There is a problem that the sensor group SS that can reduce the number of input / output ports cannot be used as it is.

On the other hand, even if the position of the workpiece with respect to the hand can be detected, if the sensor has a hysteresis characteristic to prevent chattering of ON / OFF of the sensor, depending on the approach direction of the end face of the workpiece with respect to the sensor. Since the work detection positions are different, the position of the work may not be detected with high accuracy.

Therefore, the present invention eliminates such a problem, and even when a workpiece placed on the hand and an object other than the workpiece are conveyed in a state of being close to each other, the work is misaligned with respect to the hand. It is an object of the present invention to provide a position detecting device and a method thereof that can surely detect the position.

Another object of the present invention is to provide a position detecting device capable of detecting a positional deviation with high accuracy even when detecting a positional deviation of a work with respect to a hand using a sensor having hysteresis characteristics.

[0023]

According to a first aspect of the present invention, there is provided a position detecting apparatus having a plurality of transport path patterns, wherein the position is detected in accordance with any one of the plurality of transport path patterns. In the position detecting device for detecting the position of the work placed on the hand of the work transfer robot relative to the hand, the work transfer robot is provided at a transfer path position common to the plurality of transfer path patterns, and is mounted on the hand. A plurality of detection sensors for detecting a workpiece at a plurality of points, a determination unit for determining the order of detection of the plurality of points by the plurality of detection sensors corresponding to a currently used transport path pattern, and sequentially from the plurality of detection sensors Recognizing the read detection information as the detection information of the plurality of points read in the detection order determined by the determination unit,
Calculating means for calculating the position of the work with respect to the hand based on the detection information.

According to the first aspect of the present invention, the work previously placed on the hand of the work transfer robot has a plurality of transfer path patterns, and the work placed on the hand of the work transfer robot is one of the plurality of transfer path patterns. Conveyed along. The plurality of detection sensors are provided at a transport path position common to the plurality of transport path patterns, and detect a plurality of points when the work crosses the transport path position. The detection order of a plurality of points corresponding to is determined, and the calculation unit recognizes the detection information sequentially read from the plurality of detection sensors as the detection information of the plurality of points read in the detection order determined by the determination unit,
Since the position of the work with respect to the hand is calculated based on this detection information, the position of the work can be easily and efficiently detected with a minimum number of detection sensors even when the work is conveyed through multiple conveyance paths. In particular, by detecting the position of the work with respect to the hand, the position shift of the work can be reliably detected, and thus the hand movement control corresponding to the position shift of the work can be appropriately performed.

A position detecting device according to a second aspect of the present invention uses a plurality of detection sensors provided at predetermined positions on a transfer path of a work placed on a hand of a work transfer robot to detect the position of the work relative to the hand. In a position detecting device for detecting a positional deviation, an allowable positional deviation amount of the workpiece with respect to a reference position of the workpiece detected by the plurality of detection sensors when the workpiece is placed on the hand without positional deviation is determined Setting means for setting in advance, and calculating a minimum value of the difference between a reference position of the workpiece and each of the detection positions of the plurality of detection sensors when any of the plurality of detection sensors performs a detection operation. Calculating means, and when the minimum value calculated by the calculating means is larger than the allowable positional deviation amount of the work, the plurality of detection sensors detect an object other than the work. Characterized by comprising a determination means for determining that issued.

According to the second aspect of the present invention, the work placed on the hand is conveyed along an arbitrary conveyance path,
When detecting the positional deviation of the work with respect to the hand during the transportation by the plurality of detection sensors provided at predetermined positions on the arbitrary transportation path, the setting unit detects that the workpiece is placed without positional deviation with respect to the hand. In this case, the allowable displacement of the work relative to the reference position of the work detected by the plurality of detection sensors is set in advance, and the calculating means calculates the reference position of the work when any of the plurality of detection sensors performs the detecting operation. And a difference between each detection position of the plurality of sensors and a minimum value of the difference is calculated.If the minimum value calculated by the calculation unit is larger than the allowable displacement of the workpiece, Since the detection sensor is configured to determine that an object other than the work has been detected, during the process of transporting the work placed on the hand, an object close to the work, for example, driving of the hand When there is an arm for supporting and controlling, it is possible to reliably distinguish whether multiple detection sensors have detected a workpiece or an object in proximity to the workpiece. In this way, it is possible to detect the positional deviation of a work with a high level, and thus it is possible to appropriately perform hand movement control corresponding to the positional deviation of the work.

A position detecting device according to a third aspect of the present invention has a detection sensor having a predetermined hysteresis characteristic with respect to an ON operation indicating detection of an object and an OFF operation indicating non-detection of an object. In a position detection device that corrects a detection position of the object detected by a sensor, a correction hysteresis movement amount in a movement direction of the object based on a movement direction of the object at the time of detection and a detection edge angle of the object with respect to the movement direction. A calculating means for calculating, and a position correcting means for increasing or decreasing the correction hysteresis movement amount in a moving direction component of a detection position of the object in accordance with an on / off operation of the detection sensor.

According to the third aspect of the present invention, the calculating means detects when an object is detected by a detection sensor having a predetermined hysteresis characteristic with respect to an ON operation indicating object detection and an OFF operation indicating non-object detection. The correction hysteresis movement amount in the object moving direction is calculated based on the moving direction of the object and the detected edge angle of the object with respect to the moving direction, and the position correcting means detects the position of the object corresponding to the on / off operation of the detection sensor. The correction hysteresis movement amount is increased or decreased in the movement direction component of the above. This correction hysteresis movement amount is
For example, the movement amount is a half of the hysteresis movement amount of the object between the ON operation and the OFF operation, and when the detection sensor performs the ON operation, the position correction means reverses the movement direction from the detection position of the object. When the detection sensor performs the OFF operation in the direction, the half movement amount is subtracted from the detection position of the object in the direction opposite to the movement direction. Therefore, distortion of the detection position of the object due to a change in the detection edge angle of the object is eliminated, and the position of the object can be detected with high accuracy. If the object is a workpiece placed on the hand, the hand Can be detected with higher accuracy.

According to a fourth aspect of the present invention, there is provided a position detecting device having a plurality of transport path patterns, and a position detecting device mounted on a hand of a workpiece transport robot which is transported according to any one of the plurality of transport path patterns. In a position detection device for detecting a position of a placed work with respect to the hand, the position detection device is provided at a common conveyance path position for the plurality of conveyance path patterns, and indicates an ON operation indicating the detection of the work and a non-detection of the work. A plurality of detection sensors each having a predetermined hysteresis characteristic with respect to an off operation and detecting the work at a plurality of points; and detecting the work in the work transfer direction and the work in the transfer direction when the plurality of detection sensors detect the work. Correction amount calculation means for calculating a correction hysteresis movement amount in the transfer direction of the workpiece based on the edge angle; Position correction means for increasing or decreasing the correction hysteresis movement amount in the transport direction component of the detection position of the work in response to the on / off operation of the sensor; and when the work is placed on the hand without displacement. Setting means for presetting an allowable displacement of the work relative to a reference position of the work detected by the plurality of detection sensors; and a reference position of the work when any of the plurality of detection sensors performs a detection operation. And a difference between each detection position of the plurality of detection sensors, and a minimum value calculating means for calculating a minimum value of the difference, and the minimum value calculated by the minimum value calculating means is compared with the allowable displacement of the workpiece. When the plurality of sensors are large, the plurality of detection sensors determine that the object other than the workpiece has been detected, and the determination unit determines that the workpiece is detected. Characterized in that a positional deviation amount calculating means for calculating a positional deviation amount of the workpiece relative to the hand on the basis of the detection information from the serial plurality of detection sensors.

According to the fourth aspect of the present invention, the plurality of detection sensors are provided at a common transport path position for the plurality of transport path patterns, and each of the plurality of detection sensors performs an ON operation indicating detection of a work and an OFF operation indicating non-detection of a work. And has a predetermined hysteresis characteristic, and detects the work at a plurality of points. At this time, the correction amount calculating means calculates a correction hysteresis movement amount in the work transfer direction based on the work transfer direction and the detected edge angle of the work with respect to the work direction at the time of detection by the plurality of detection sensors, The position correction means performs a detection position correction for increasing or decreasing the correction hysteresis movement amount in the transport direction component of the detection position of the work in response to the on / off operation of the detection sensor. On the other hand, by the setting means, when the work is placed on the hand without displacement, an allowable displacement of the work relative to a reference position of the work detected by the plurality of detection sensors is set in advance, The minimum value calculating means obtains a difference between a reference position of the work and each detection position of the plurality of detection sensors when any of the plurality of detection sensors performs a detection operation, and calculates a minimum value of the difference. When the minimum value is larger than the allowable displacement of the work, the determining means determines that the plurality of detection sensors have detected an object other than the work, and the minimum value is equal to the allowable displacement of the work. If not, the plurality of sensors determine that the work has been detected. The positional deviation amount calculating means is configured to calculate the positional deviation amount of the work with respect to the hand based on the detection information determined to be the detection of the work by the determining means.

As a result, the distortion of the detection position of the object due to the change of the detection edge angle of the object is eliminated, and the detection accuracy of the detection sensor, which can detect the position of the object with high accuracy, can be improved. Since it is determined whether a work is detected or an object other than a work is detected, there is an object that is in proximity to the work, for example, an arm that supports and controls the driving of the hand in the process of transporting the work placed on the hand. In this case, it is possible to reliably distinguish whether a plurality of detection sensors have detected a work or an object in proximity to the work. The detection can be performed, and the movement control of the hand corresponding to the positional deviation amount of the work can be appropriately performed.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a semiconductor manufacturing apparatus including a position detecting device according to a first embodiment of the present invention.

In FIG. 1, the work transfer robot A2 is the one shown in FIGS. 17 to 20, is located at the center of the transfer chamber 1, and the work transfer robot A2 performs the corresponding processing process.
Workpieces W1 and W2 that are circular disc-shaped wafers for 2e
Is carried out through the gate 6.

The hands 8a, 8 of the work transfer robot A2
b, hands 8a and 8b of workpieces W1 and W2 placed on
A plurality of sensor groups SS1 and SS2 are provided in the transfer chamber 1 in order to detect a positional shift with respect to. The sensor group is arranged along a transfer path for transferring the work in the transfer chamber 1 by the work transfer robot A2. For example, as shown in FIG.
When the turning operation is performed while b is in the standby state, the work W1,
W2 is radially arranged with respect to the axis 41 so as to cross the sensor groups SS1 and SS2. Although only the sensor groups SS1 and SS2 are shown in FIG. 1, a sensor group similar to the sensor groups SS1 and SS2 is provided between each adjacent process chamber.

The detector 11 detects the detection signals of the sensors constituting the sensor groups SS1 and SS2, and sends the detection result to the workpiece detection determiner 12. Sensor group SS1, S
Each sensor constituting S2 includes, for example, a transmitting unit that transmits laser light and a receiving unit that receives laser light from the transmitting unit. The work blocks laser light between the pair of transmitting unit and receiving unit. This is an on / off sensor that is turned on when the work is interrupted and is turned off when the work is not interrupted. Of course, other sensors may be used as long as they can detect the end face of the work.

The work detection judging section 12 has an allowable position shift amount setting section 13. The allowable position deviation amount setting unit 13 includes:
An allowable displacement amount, which will be described later, used to determine whether the sensor has detected a work or an object other than the work is set in advance. The allowable position deviation amount is an amount determined by the configuration of the work transfer robot, for example, the position of the arm or the like and the position of the work. Work detection determination unit 1
2 determines which of the sensors in the sensor groups SS1 and SS2 is the detection signal from the current position information of the hands 8a and 8b, and determines whether the sensor has detected a work or an object other than the work. Judge whether it was detected,
Only the detection information when the work is detected based on this determination result is sent to the position shift calculating unit 14. The process of the work detection determination unit 12 will be described later.

The position shift calculating section 14 obtains the center position of the work based on the detection information sent from the work detection determining section 12. Assuming that the workpiece is circular, the center position of the workpiece can be determined by determining at least three points on the end face of the workpiece. For example, at the center of the circle of the work, if there are three detection points, at least two straight lines connecting the two detection points can be obtained, and an intersection position on a vertical bisector of these two straight lines is obtained. Thus, the center of the circle can be obtained. The sensor group has three sensors, and the detection unit 11 obtains a total of six points, that is, the point in time when one workpiece starts to cross the sensor group and the point in time when one workpiece crosses the sensor group, and calculates the average of the center position of the workpiece from the six points. It is calculated. The displacement calculator 14 calculates the workpieces W1, W
Hand 2 corresponding to the center position of the workpieces W1 and W2 when the workpiece 2 is normally placed on the hands 8a and 8b without displacement.
a, 8b, the center position of the hand 8a, 8b
The distance between the center position 8b and the calculated center positions of the workpieces W1 and W2 is calculated as a positional deviation amount, and the calculation result is sent to the hand position correcting unit 15.

The hand position correction unit 15 calculates a correction amount of the hand position based on the calculation result, and sends the correction amount to the controller C.

The controller C is a work transfer robot A
2 is performed. At this time, based on the correction amount sent from the hand position correction unit 15, the controller C performs correction so that the center position of the work becomes the center position of the hand, and drives and controls the work transfer robot A2. Thereby, even if the work placed on the hand is displaced, the work itself is transferred to the regular transfer path, and the work is transferred to the process chambers 2a to 2e without colliding with the gate 6. be able to. Further, as described above, the controller C sends the current position information of the hands 8a and 8b to the work detection determination unit 12.

Next, a description will be given, with reference to the flowchart of FIG.

First, the work detection judging section 12 judges which sensor in the sensor group has detected based on the position information of the hands 8a and 8b sent from the controller C, and furthermore, the determined sensor A work detection determination process is performed to determine whether or not an object has been detected (step 10).
1). Thereafter, the displacement calculator 14 calculates the center position of the work relative to the hand based on the detection information sent from the work detection determiner 12 (step 102), and the work is placed on the hand without displacement. The positional deviation information from the reference center position of the work in the tilted state to the calculated center position of the work is calculated (step 103). After that, the hand position correction unit 15 calculates hand position correction information based on the calculated position shift information (step 10).
4), end this processing.

Next, referring to the flowchart of FIG. 3 and FIG. 4, the processing procedure of the work detection determination processing in step 101 will be described in detail.

In FIG. 3, the work detection determining section 12
First, it is determined whether or not there is a detection output from the detection unit 11 (step 201). Whether or not there is this detection output,
It is to determine whether the sensor has changed from the on state to the off state or from the off state to the on state.

When there is a detection output (step 201,
YES), as shown in FIG. 4, the absolute value ΔL1 of the difference between the distance L1 from the reference center position P1 of the hand 8b to the sensor S1 and the radius R of the work W2, and the absolute value ΔL1 of the difference from the reference center position P1 of the hand 8b to the sensor S2. The absolute value ΔL2 of the difference between the distance L2 and the radius R of the workpiece W2 and the absolute value ΔL3 of the difference between the reference center position P1 of the hand 8b and the distance L3 from the sensor S3 are obtained (step 202). Sensors S1 to S3
Is known in advance, and the reference center position P1 of the hand 8b can be known by the controller C.

Thereafter, the minimum value among the absolute values ΔL1 to ΔL3 is obtained (step 203). Then, the work detection determination unit 12 determines a sensor candidate that has detected the edge of the work as a sensor having the minimum value obtained in step 203 (step 204).

Thereafter, it is determined whether or not the minimum value obtained in step 203 is smaller than the permissible displacement set by the permissible displacement setting unit 13 (step 20).
5). The allowable positional deviation amount refers to the distance amount β of the position WW that is not considered to approach the arm 56a due to the extreme positional deviation in consideration of the fact that the positional deviation amount of the work is originally small. .

If it is determined in step 205 that the minimum value is smaller than the allowable displacement (step 205,
In YES, the candidate sensor determined in step 204 is determined to have detected the edge of the work (step 206), and the detection information of the determined sensor is output to the displacement calculator 14 (step 207). ). That is,
The sensor determines that the workpiece has been detected, and outputs detection information including information such as a number indicating the detected sensor and information that has been turned on or off to the displacement calculator 14.

On the other hand, if it is determined in step 205 that the minimum value is not smaller than the allowable displacement (step 205, NO), the candidate sensor detects an edge other than the work, for example, the arm 56a. It is determined that it has been detected, and the information detected by the sensor is not sent to the displacement calculator 14 (step 208).

According to the work detection determination process, it is possible to determine which of the sensors S1 to S3 has detected the current state and whether or not the edge of the work has been detected. Even when 56a or the like exists, by appropriately setting the allowable positional deviation amount,
The edge of the work can be reliably detected.

In the first embodiment described above, the sensor groups SS1 and SS2 are arranged at positions where the workpieces W1 and W2 cross the sensor groups SS1 and SS2, and traverse the sensor groups SS1 and SS2. The above-described position detection processing can be performed even when the workpiece is transported along an arbitrary transport path. However, in the actual work transfer processing, the work is generally transferred along a set transfer path. For example, FIG.
As shown in (a), first, only the hand is shrunk to perform a standby state, and thereafter, the transport control is performed to rotate only the shaft 41. On the other hand, as shown in FIG. 5B, in order to shorten the transport time, a so-called short pass, in which the workpiece is transported with a shortest transport distance from the gate, may be performed. This short path controls the turning of the shaft 41 at the same time as expanding and contracting the work. Such a transport control can be selected by the controller C and can be determined in advance.

In this case, the order of work detection by the arranged sensors S1 to S3 is determined in advance by the transport path. For example, when drawing the transport path shown in FIG. 5A, the sensors S2 → S1 → S3 → S3 → S1 →
The edges of the workpieces are detected in the order of S2. When the transport path shown in FIG. 5B is drawn, the edges of the workpieces are detected in the order of the sensors S2 → S3 → S1 → S3 → S1 → S2. Will be detected.

Therefore, in the second embodiment shown in FIG. 6, a transport path pattern determining section 16 for selecting the predetermined transport path is provided, and the transport path determined by the transport path pattern determining section 16 is selected. For example, the position of a work is detected based on a transport path as shown in FIG. 5A or 5B. The transport route pattern determination unit 16 sends information on the determined transport route to the controller C
And the detection order of each sensor in the sensor group corresponding to the determined transport path is determined by the workpiece detection determination unit 12.
To send to. Other configurations are the same as those shown in FIG.

Next, the position detecting operation according to the second embodiment will be described with reference to the flowchart of FIG.

In FIG. 7, the controller C obtains the transport route determined by the transport route pattern determining unit 16 (step 301), and controls the drive of the work transport robot A2 according to the determined transport route. on the other hand,
The transport path pattern determination unit 16 sets the detection order of each sensor in the sensor group corresponding to the determined transport path (Step 302), and determines this detection order by the work detection determination unit 12
To send to.

Thereafter, based on the detection order sent from the transport path pattern determination unit 16, the work detection determination unit 12 determines whether the detection signal sent from the detection unit 11 determines the edge of the work by which sensor in the sensor group. It is determined whether or not it has been detected (step 303). In this case, since the transport path is determined in advance, it is not necessary to determine whether the target detected by the sensor is a work or an object other than a work, and based on the position information of the hand sent from the controller C. It is said that the edge position of the workpiece was immediately detected. The determined detection information of each sensor and the position information of the hand are sent to the position shift calculating unit 14.

Thereafter, the displacement calculator 14 calculates the center position of the work with respect to the hand based on the detection information of each sensor sent from the work detection determiner 12 (step 304). Is calculated from the reference center position of the work in a state where the work is placed on the hand without any positional deviation to the center position of the work calculated in step 304 (step 305). Thereafter, the hand position correction unit 15 calculates correction information of the hand position based on the calculated positional deviation information (Step 306), and ends the processing.

According to the second embodiment, the displacement can be detected by a simpler process than the position detection process of the first embodiment.

Next, a position detecting device according to the third embodiment will be described. In the third embodiment,
In addition to the configuration of the first embodiment, a hysteresis movement amount correction unit 17 and a work detection determination unit 12 and a displacement calculation unit 14
The hysteresis movement amount correction unit 17 corrects a detection error based on the hysteresis characteristic of the sensor. Other configurations are the same as those of the first embodiment.

The hysteresis characteristic is such that, as shown in FIG. 9, when the work W enters or exits the detection area of the sensor S and the sensor S is turned on / off, the position where the work W is turned on / off is made different. , Work W is on /
This prevents chattering and the like in the case where it is located at a critical position where it is turned off.

However, as shown in FIG. 10, when a workpiece such as a wafer enters or exits the detection area of the sensor S, the edge angle of the workpiece with respect to the sensor S is different, so that the detection position of the edge of the workpiece is different. Different cases may occur depending on the sensor. That is, as shown in FIG. 10 (a), when the edge angle of the workpiece with respect to the sensor S enters / exits perpendicularly, a hysteresis movement amount of the distance ΔL is exhibited. Sensor S
When the edge angle of the workpiece enters / exits obliquely with respect to the distance ΔL, the distance ΔLL of the moving amount is larger than the distance ΔL. Therefore, the sensors are arranged side by side like the sensors S1 to S3, and the disc-shaped work is formed by these sensors S1 to S3.
, The detection position of each sensor causes an error corresponding to the hysteresis movement amount.

Therefore, the hysteresis moving amount correcting section 17
Performs the correction of the hysteresis movement amount. This correction processing will be described with reference to FIG.

In FIG. 11, the amount of hysteresis movement when the edge of the conveyed work is perpendicular to the sensor is d (corresponding to the distance ΔL in FIG. 10). Further, in the hand coordinate system with the reference center position P1 as a zero point, the traveling direction angle of the conveyed work is set to θv. Further, in the hand coordinate system, the direction angle of the edge position of the work that crosses the sensor is defined as θp.

Assuming that the hysteresis movement amount at which the workpiece is conveyed and the edge of the workpiece turns on / off the sensor is Δ,
In the hand coordinate system, the hysteresis movement amount Δ becomes Δ = d / | cos (θv−θp) |. Δsinθv.

Therefore, in order to determine that the workpiece is detected at the same position regardless of the entry / exit angle of the edge position of the workpiece, a correction is made such that Δx ′ = Δx / 2 Δy ′ = Δy / 2. Thus, regardless of the entry / exit angle of the edge position of the work, each sensor has the same position,
That is, the edge of the work can be detected on the broken line LA, so that the detection accuracy of the edge position of the work can be significantly improved.

By providing the hysteresis movement amount correction section 17 for performing such hysteresis movement amount correction processing between the work detection determination section 12 and the position shift calculation section 14, a position detection device with higher detection accuracy can be provided. Is achieved.

That is, the hysteresis movement amount correction unit 17
The present invention calculates the current position and moving direction of the hand based on the position information of the hand, obtains the hysteresis movement amount, and corrects the detection information.

Similarly, in the fourth embodiment shown in FIG. 12, a hysteresis movement amount correcting section 17 is provided between the work detection determining section 12 and the displacement calculating section 14 in the second embodiment. With the configuration, the same operation and effect as those of the third embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a semiconductor manufacturing apparatus including a position detection device according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating a position detection processing procedure according to the first embodiment of the present invention.

FIG. 3 is a detailed flowchart showing a work detection determination procedure in step 101 of FIG. 2;

FIG. 4 is an explanatory diagram showing a specific state associated with a work detection determination process.

FIG. 5 is a diagram illustrating a specific example of a transport path pattern.

FIG. 6 is a diagram illustrating a schematic configuration of a semiconductor manufacturing apparatus including a position detecting device according to a second embodiment of the present invention.

FIG. 7 is a flowchart illustrating a position detection processing procedure according to the second embodiment of the present invention.

FIG. 8 is a diagram illustrating a schematic configuration of a semiconductor manufacturing apparatus including a position detecting device according to a third embodiment of the present invention.

FIG. 9 is an explanatory diagram showing hysteresis characteristics of a sensor.

FIG. 10 is a diagram illustrating a specific example of a hysteresis movement amount that changes depending on the angle of entry of a workpiece edge.

FIG. 11 is an explanatory diagram for explaining a hysteresis movement amount correction process.

FIG. 12 is a diagram illustrating a schematic configuration of a semiconductor manufacturing apparatus including a position detection device according to a fourth embodiment of the present invention.

FIG. 13 is a diagram showing a schematic configuration of a conventional semiconductor manufacturing apparatus.

FIG. 14 is an exploded perspective view illustrating a positional relationship between the work transfer robot and the semiconductor manufacturing apparatus.

FIG. 15 is an explanatory diagram illustrating an example of a transfer operation of a conventional work transfer robot.

FIG. 16 is an explanatory diagram showing an example of a transfer operation of a conventional work transfer robot.

FIG. 17 is a front view of a work transfer robot used in the present invention.

FIG. 18 is a plan view of a work transfer robot used in the present invention.

FIG. 19 is a perspective view showing a projecting / retracting operation state of the work transfer robot used in the present invention.

FIG. 20 is an explanatory diagram showing a positional relationship between a work transfer robot used in the present invention and a work placed on a hand.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transfer chamber 2a-2e ... Process chamber 3 ... Transfer chamber 6 ... Gate 8a, 8b ... Hand 11 ... Detection part 12 ... Work detection judgment part 13 ... Permissible position deviation setting part 14 ... Position deviation calculation part 15 ... Hand position correction Unit 16: Transport path pattern determination unit 17: Hysteresis movement amount correction unit 56a: Arms S1 to S3: Sensor A2: Work transfer robot W1, W2: Work

Claims (4)

[Claims] A position of a work placed on a hand of a work transfer robot that has a plurality of transfer path patterns and is transferred according to any one of the plurality of transfer path patterns with respect to the hand. A plurality of detection sensors provided at a common transport path position for the plurality of transport path patterns and detecting a work placed on the hand at a plurality of points; Determining means for determining the order of detection of the plurality of points by the plurality of detection sensors in accordance with the path pattern; detection information sequentially read from the plurality of detection sensors is read in the detection order determined by the determination means Calculating means for recognizing the detection information of the plurality of points and calculating the position of the work with respect to the hand based on the detection information. A position detecting device characterized by the following. 2. A position detecting device for detecting a positional shift of a work relative to a hand of a work mounted on the hand using a plurality of detection sensors provided at predetermined positions on a transfer path of the work mounted on the hand of the work transfer robot. Setting means for presetting an allowable displacement of the work relative to a reference position of the work detected by the plurality of detection sensors when the work is placed on the hand without displacement, and A calculating unit that calculates a difference between a reference position of the workpiece and each of the detection positions of the plurality of detection sensors when any one of the detection sensors performs a detection operation, and calculates a minimum value of the difference; A determination unit configured to determine that the plurality of detection sensors have detected an object other than the work when the minimum value obtained is larger than the allowable displacement amount of the work. A position detecting device characterized by the above-mentioned. 3. A detection sensor having a predetermined hysteresis characteristic with respect to an ON operation indicating detection of an object and an OFF operation indicating non-detection of an object, and a detection position of the object detected by the detection sensor. Calculating means for calculating a correction hysteresis movement amount in the moving direction of the object based on the moving direction of the object at the time of detection and a detected edge angle of the object with respect to the moving direction; A position detecting device, comprising: a position correcting means for increasing / decreasing the correction hysteresis moving amount in a moving direction component of a detection position of the object in response to an on / off operation. 4. A position of a work placed on a hand of a work transfer robot that has a plurality of transfer path patterns and is transferred according to any one of the plurality of transfer path patterns with respect to the hand. A plurality of transport path patterns provided at a common transport path position, wherein a predetermined hysteresis characteristic is provided for an ON operation indicating detection of the work and an OFF operation indicating non-detection of the work. A plurality of detection sensors for detecting the work at a plurality of points, each of which includes: a plurality of detection sensors for transferring the work based on a work conveyance direction and a detection edge angle of the work with respect to the conveyance direction at the time of detection by the plurality of detection sensors. Correction amount calculating means for calculating a correction hysteresis movement amount for the direction, and corresponding to an on / off operation of the detection sensor. Position correction means for increasing or decreasing the correction hysteresis movement amount in the transport direction component of the detection position of the work, wherein the plurality of detection sensors detect when the work is placed on the hand without displacement. Setting means for presetting an allowable positional deviation amount of the work with respect to a reference position of the work; and a reference position of the work and respective detection positions of the plurality of detection sensors when any of the plurality of detection sensors performs a detection operation. And a minimum value calculating means for calculating a minimum value of the difference, and when the minimum value calculated by the minimum value calculating means is larger than the allowable positional deviation amount of the work, the plurality of detection sensors are Judging means for judging that an object other than the work has been detected; and detecting information from the plurality of detection sensors judged by the judging means to be detection of the work. A position shift calculating means for obtaining a position shift amount of the work with respect to the hand based on a report.