JP2015074039A - Carrier device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply execute correction of a position correction parameter.SOLUTION: A carrier device is configured so as to execute a generation operation of a correction parameter consisting of: a second step of making a laser sensor 4 detect a wafer W, making a relative displacement calculation part 31 calculate relative displacement between the wafer and a reference position O on an end effector 21, and carrying the wafer by performing position correction of the end effector 21 based on the calculated relative displacement; a third step of lapping the reference position on the end effector to a target position, making the end effector receive the wafer, making the laser sensor detect the wafer, and making the relative displacement calculation part 31 calculate the relative displacement between the wafer and the reference position O on the end effector as relative displacement after correction; and a fourth step of generating a correction parameter for correcting a correction command so that the relative displacement after the correction becomes small, to correct the correction command to be obtained by a correction command generation part 32 based on the generated correction parameter, and to carry the wafer W toward the target position.

Description

  In the present invention, when a transported object placed on an end effector is transported to a target position, the position of the end effector is corrected based on the relative displacement between the transported object and the end effector, thereby accurately transporting the transported object. The present invention relates to a transport device that can transport an object.

  Widely and generally, a transport device that can move a transported object to a target position by receiving the transported object on the end effector by operating the end effector and further moving the end effector toward the target position. It is used.

  Such a transfer device can be used effectively in scenes where work is performed in a clean room or a vacuum chamber such as in the semiconductor field. For example, it can be used when a transferred object such as a semiconductor wafer is taken out from a container such as a FOUP (Front Opening Unified Pod) and transferred between a transfer chamber, a load lock chamber, and a semiconductor processing chamber.

  At that time, in particular, when precise processing is performed on such a transported object, it is necessary to precisely control the position of the end effector and transport the transported object with respect to the target position with high accuracy. .

  In addition, when receiving an object to be conveyed by the end effector, if there is a deviation between the object to be conveyed and the reference position set for the end effector, that is, a relative displacement occurs, Therefore, it is necessary to correct the position of the end effector by the amount of the relative displacement and transport the object to be transported.

  In order to meet these requirements, Patent Document 1 is provided with three sensors along an axis that crosses the moving path of a robot arm (end effector) on which a moving body (conveyed object) is placed, Based on the detection signals obtained by these sensors when operating the end effector, the relative displacement between the conveyed object and the end effector is derived, and the position of the end effector is corrected based on the relative displacement, thereby conveying the object. Has been disclosed that is configured to accurately convey the squeeze to the target position.

Japanese Patent Publication No. 7-27953

  However, even if the relative displacement between the transported object and the end effector is accurately detected and a correction command is given to the transport robot based on the detected relative displacement, mechanical errors in components such as a speed reducer and a timing belt are not detected. There is a problem that the position correction amount according to the correction command cannot be obtained due to the operation error of the transport robot as a cause, and the positional deviation at the time of mounting remains. In particular, since the position correction operation is a minute operation in units of 0.1 mm, for example, it does not operate according to the command value due to mechanical resistance, hysteresis, or the like that varies from individual to individual, which causes the position correction accuracy to deteriorate.

  In order to correct the deviation between the correction command value and the actual position correction amount due to the above problem and improve the position correction accuracy, it is conceivable to set a correction parameter for correcting the position correction amount for each individual. . In order to generate and appropriately set such correction parameters, by introducing an image processing apparatus using a CCD camera or the like, the deviation from the target position of the conveyed object after conveyance is measured, and this deviation is eliminated. It is conceivable to adjust the correction parameter as described above.

  However, if the image processing apparatus is incorporated as a means for obtaining the target position of the object to be conveyed in this way, the apparatus configuration becomes large due to the incorporation of equipment unnecessary for the original conveying operation, which significantly increases the cost. Incurs a large installation area. On the other hand, if the image processing apparatus is configured separately from the apparatus main body and used only for initial adjustment, it is difficult to adjust the correction parameters again because it cannot cope with changes in apparatus characteristics over time. . In addition, even if an image processing device is installed only during maintenance and adjustment parameters are to be adjusted, it requires a long time for maintenance because it requires complicated rework and adjustments in advance. As a result, running costs will increase.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide equipment necessary for the transport operation to generate correction parameters for correcting the position correction amount of the end effector and improving the position correction accuracy. It is an object of the present invention to provide a transport apparatus that can be simply executed without increasing costs.

  In order to achieve the object, the present invention takes the following means.

  That is, the transport apparatus according to the present invention includes an end effector on which a transported object is placed, control means for controlling the operation of the end effector to transport the transported object toward a target position, and a transport path of the end effector. And a detection unit that detects the object to be conveyed placed on the end effector, and the control means is configured to detect the object to be conveyed and the end effector on the basis of the output of the detection unit. The relative displacement calculation unit that calculates the relative displacement with respect to the reference position provided in the position, and the position of the end effector when the object to be conveyed is transported toward the target position based on the relative displacement obtained by the relative displacement calculation unit A correction command generation unit for generating a correction command for correcting the movement, wherein the control means transfers the object placed at the target position to the end effector in advance. A first step of causing the end effector to receive a state shifted by a predetermined shift amount; causing the detection unit to detect the object to be conveyed; and providing the relative displacement calculation unit on the object to be conveyed and the end effector. A second step of calculating a relative displacement with respect to the determined reference position, correcting the position of the end effector based on the correction command based on the relative displacement, and transporting the transported object toward the target position; The reference position on the end effector is overlapped with the target position, the end effector receives the object to be conveyed, the object to be conveyed is detected by the detection unit, and the object to be conveyed is detected by the relative displacement calculation unit. And a third step of calculating a relative displacement between the reference position provided on the end effector and the corrected relative displacement, and the corrected relative displacement is reduced. A correction command generated by the correction command generation unit based on the generated correction parameter by executing a correction parameter generation operation comprising: a fourth step of generating a correction parameter for correcting the correction command And is configured to convey the object to be conveyed toward a target position.

  If comprised in this way, since the conveying apparatus has a detection part and a relative displacement calculation part, the relative displacement of the said to-be-conveyed object and the reference position provided on the said end effector can be calculated, and correction | amendment By generating a correction command based on the relative displacement by the command generation unit and giving this correction command to the control means, it is possible to correct the deviation from the target position and transport the object to be conveyed with high positional accuracy.

  Further, by correcting the correction command based on the correction parameter, it is possible to compensate for the deviation between the amount that is to be corrected by the correction command and the actual operation amount, and further improve the position accuracy when transporting the object to be transported. It becomes possible to improve. Further, since the detection unit and the relative displacement calculation unit used for obtaining the correction command can also be used to generate correction parameters, it is necessary to separately provide an image processing device or the like in order to obtain the deviation amount of the conveyed object. In addition, it is possible to improve the position correction accuracy only with an apparatus necessary for the transport operation. In addition, since the correction parameters can be generated based on the data obtained by causing the end effector to perform an operation close to the actual transport operation, the transport position accuracy can be further improved. .

  In the present specification, “convey” refers to an operation until the object is transported to a predetermined position and transferred to the predetermined position.

  Further, in order to be able to give appropriate correction parameters to correction commands corresponding to any relative displacement, the correction parameters are obtained from the relationship between the shift amount and the corrected relative displacement. It is preferable to configure to be generated based on a function.

  In order to generate a correction parameter with higher accuracy from the relationship between each shift amount and the corresponding corrected relative displacement, the control means sequentially changes the shift amount and performs the first to third steps. It is effective that the correction parameter is generated repeatedly based on the value of each shift amount and the corrected relative displacement corresponding thereto in the fourth step.

  In order to generate the correction parameter with higher accuracy, the control unit repeats generation of the correction parameter executed by combining the first to fourth steps until the corrected relative displacement becomes a predetermined value or less. It is preferable to configure as described above.

  In order to make it possible to determine the relative displacement between the transported object and the reference position provided on the end effector with a simple apparatus configuration, assuming that the transported object is substantially circular and the radius is known. Is a photoelectric sensor in which the detection unit detects a transported object at the position and outputs a detection signal, and the relative displacement calculation unit detects a detection signal from the photoelectric sensor and an end effector when the detection signal is obtained. It is effective that the relative displacement between the transported object and the reference position provided on the end effector is calculated based on the position.

  In addition, the substantially perfect circle shape mentioned here includes a complete perfect circle shape, and almost the whole is a perfect circle shape, and a non-circular portion such as a notch or a straight line portion is formed in part. It also includes things. However, it is preferable that the non-circular portion is away from the place where the sensor detects.

  In order to enable the relative displacement between the transported object and a reference position provided on the end effector to be appropriately calculated even when the transported object is thermally expanded to increase the radius, the photoelectric sensor Are mounted so as to cross the conveyance path of the object to be conveyed in the width direction, and the relative displacement calculation unit calculates the relative displacement using detection signals from at least two photoelectric sensors. Is preferred.

  According to the present invention described above, since it is not necessary to provide a special device separately, an increase in equipment cost can be suppressed, and correction parameters can be generated easily and with high accuracy only by a device necessary for the transport operation. It is possible to provide a transport device that can transport the object to be transported with high positional accuracy by correcting the correction command with this correction parameter.

The figure which shows the block diagram of the conveying apparatus which concerns on embodiment of this invention. The flowchart which shows the procedure at the time of conveying a wafer in normal mode. The top view which shows typically the semiconductor wafer processing apparatus with which the conveying apparatus which concerns on embodiment of this invention was integrated. The flowchart which shows the procedure when producing | generating a correction parameter. The figure which shows the geometrical relationship at the time of deriving | leading-out a center position by a photoelectric sensor detecting a semiconductor wafer. The figure which shows the table which defines the shift amount of the end effector with respect to a semiconductor wafer. The figure which shows the example of the approximate straight line calculated | required from the amount of shift of the R-axis direction, and the relative displacement of the reference | standard position provided on the end effector with respect to a wafer. The figure which shows the example of the approximate straight line calculated | required from the displacement amount of a T-axis direction, and the relative displacement of the reference position provided on the end effector with respect to a wafer.

  Hereinafter, a transport device according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 3, the transfer apparatus of the present embodiment is disposed at the center of the semiconductor wafer processing apparatus M, and between the load lock chamber 5 and the process unit 6 disposed around the semiconductor wafer W (hereinafter referred to as wafer W). Are conveyed as a substantially circular object to be conveyed.

  In addition, a substantially perfect circle shape includes a perfect circle shape, and a substantially entirely round shape with a non-circular portion such as a notch or a straight portion formed in part. Is also included. That is, like a general semiconductor wafer, a notch-like notch or a linear orientation flat may be formed on a part of the outer periphery, and the non-circular part only needs to be away from the location where the sensor detects. .

  As shown in FIGS. 1 and 3, the transport device 1 is configured as a horizontal articulated robot having two sets of arm mechanisms 2 and 2, and controls for operating the arm mechanisms 2 and 2. Means 3 are provided.

  Since the two sets of arm mechanisms 2 and 2 have the same configuration, the specific configuration will be described below by taking one arm mechanism 2 as an example.

  As shown in FIG. 1, the arm mechanism 2 is connected to a plate-like end effector 21 on which the wafer W is placed at the distal end portion 21a, and a proximal end portion 21b of the end effector 21 at the distal end portion 22a. A first arm 22 that is pivotally supported by the second arm 23, a second arm 23 that is connected to the base end portion 22b of the first arm 22 at the distal end portion 23a, and is pivotally supported in a horizontal plane, and a second arm And a base 20 that rotatably supports a base end portion 23b of the base plate 23 in a horizontal plane.

  Motors (not shown) are provided at the joint portions 24, 25, 26 formed between the end effector 21 and the first arm 22, the first arm 22 and the second arm 23, and the second arm 23 and the base 20. Each of these motors is incorporated, and these motors are individually controlled by the control means 3 described above, so that the angles among the end effector 21, the first arm 22, the second arm 23, and the base 20 can be changed. ing. In this way, the end effector 21 can be moved to a desired position by the control means 3 and the wafer W can be transferred.

  Further, an elevating mechanism (not shown) for elevating and lowering the arm mechanism 2 is incorporated in the base 20, and the end effector 21, the first arm 22, and the second arm 23 are turned by rotation. It is possible to receive the wafer W by the end effector 21 and transfer the wafer W from the end effector 21 to the target position by moving the effector 21 and raising and lowering the end effector 21 by the lifting mechanism.

  The control unit 3 targets the wafer W based on the relative displacement calculation unit 31 that calculates the relative displacement of the reference position O provided on the end effector 21 with respect to the wafer W, and the relative displacement obtained by the relative displacement calculation unit 31. A correction command generation unit 32 that generates a correction command for correcting the position of the end effector 21 when transporting toward the position, and a correction command for correcting the correction command so that the positional deviation after the correction operation by the correction command is reduced. And a parameter storage unit 33 for storing correction parameters, and the end effector 21 and the arms 22 and 23 are operated by outputting a control signal to the motor. The correction parameter is generated when the normal mode in which the normal conveyance is performed is switched to the parameter generation mode in which the correction parameter is generated.

  As shown in FIG. 3, a photoelectric sensor as a detection unit for detecting the wafer W is provided at the entrances of the load lock chamber 5 and the process unit 6 as the transfer destination, and more specifically, two laser sensors 4 and 4. Each of the laser sensors 4 and 4 detects the wafer W when the wafer W placed on the end effector 21 enters the load lock chamber 5 or the process unit 6, and the wafer W exists at that location. The ON signal is output to the relative displacement calculator 31 as a detection signal. The relative displacement calculator 31 calculates the relative displacement of the reference position O provided on the end effector 21 with respect to the center position X of the wafer W based on the input detection signal.

  Here, a method in which the relative displacement calculation unit 31 derives the relative displacement of the reference position O provided on the end effector 21 with respect to the center position X of the wafer W based on the output signals of the two laser sensors 4 and 4 is shown in FIG. 5 will be described.

  As shown by arrows in FIGS. 5A to 5D, the end effector 21 and the wafer W on the end effector 21 cross the two laser sensors 4L and 4R by the extension of the arm mechanism 2 (see FIG. 3). A straight traveling operation is performed in a direction intersecting with a straight line connecting the two laser sensors 4L and 4R. The straight direction at this time is the R-axis direction, and the direction perpendicular to the R-axis direction in the horizontal plane is the T-axis direction. The coordinates of the end effector 21 can be derived from an encoder (not shown) of a motor that rotates the end effector 21 and the arms 22 and 23.

  First, when the wafer W is not detected by the laser sensor 4 and the linear movement operation is started, when there is a relative displacement in the T-axis direction between the wafer W and the end effector 21, one laser is used as shown in FIG. The sensor 4L first detects the wafer W and outputs an ON signal to the relative displacement calculator 31. When the other laser sensor 4R detects the wafer W as shown in FIG. 5B by continuing the straight traveling operation, the laser sensor 4R starts outputting an ON signal. Thereafter, when the laser sensor 4R finishes detecting the wafer W first as shown in FIG. 5C, the laser sensor 4R outputs an OFF signal, and finally, as shown in FIG. 5D, any of the laser sensors 4L. , 4R, the laser sensor 4L also outputs an OFF signal by proceeding to a position where the wafer W is not detected.

  In the above-described operation process, the output from the laser sensors 4L and 4R changes from the OFF signal to the ON signal, and further from the ON signal to the OFF signal, and the end effector detected from the motor encoder at these timings. 21 and the angles of the arms 22 and 23, the lengths L1 and L2 of the chords B1 and B2 of the wafer W that have passed over the laser sensors 4L and 4R shown in FIGS. Based on this, the positional relationship between the strings B1 and B2 and the end effector 21 can be obtained. When the positional relationship between the two strings B1 and B2 and the end effector 21 is determined, the center position X of the wafer W can be determined even when the radius of the wafer W is unknown. The relative displacement of the reference position O provided on the end effector 21 with respect to X can be calculated.

  In the present embodiment, the above calculation method using the two laser sensors 4L and 4R is applied on the assumption that the radius of the substantially circular wafer W is unknown. However, if the radius of the wafer W is known, If there is one laser sensor 4, the relative displacement can be calculated. That is, if either of the chords B1 and B2 in FIG. 5C or FIG. 5D can be determined with respect to the end effector 21, the reference provided on the end effector 21 with respect to the center position X of the wafer W is similarly applied. The relative displacement at the position O can be calculated.

  Next, the operation of the transport apparatus 1 of the present embodiment configured as described above will be described.

  First, until the end effector 21 acquires the wafer W during the operation in the normal mode and places it on the target position, the control means 3 sequentially executes the steps shown in the flowchart of FIG. Yes.

  Hereinafter, the description will be made with reference to FIG.

  The control means 3 opens the gate valve of the load lock chamber 5 or the process unit 6 (see FIG. 3), which is the transfer destination, so that the port on which the wafer W is placed can be accessed, and then executes the following processing. To do.

  First, in step S1, the control means 3 is positioned below the wafer W that is the object to be transported by the end effector 21, and the reference position O of the end effector 21 is at a position where it overlaps with the center position X of the wafer W. Then, the end effector 21 is moved. Next, in step S2, the end effector 21 is raised and the wafer W is acquired. In step S3, the end effector 21 on which the wafer W is mounted is moved toward the set position set as the destination corresponding to the target position for transporting the wafer W so as to pass straight toward the laser sensor 4. Let it begin. In step S4, the detection value from the encoder at the timing when the detection signal of the wafer W from the laser sensor 4 is switched from the OFF signal to the ON signal and from the ON signal to the OFF signal is acquired. In step S5, the relative displacement calculation unit 31 determines the position on the end effector 21 with respect to the wafer W based on the angles of the end effector 21 and the joints 24, 25, and 26 of the arms 22 and 23 when the ON signal is output. The relative displacement (t, r) of the reference position O provided at is calculated. In step S6, the process does not proceed to the next step until it is determined that the end effector 21 has reached the set position based on the encoder output. The conveyance operation is temporarily stopped. In step S8, the correction command generator 32 is caused to output a position correction command based on the relative displacement (t, r). In step S9, the position correction command is corrected by multiplying or adding the correction parameter stored in the correction parameter storage unit 33 to the position correction command generated in step S8.

In the present embodiment, the correction parameters are “Ra” and “Rb” for correcting the position correction amount in the R-axis direction according to the correction command, and “Ta” and “Tb” for correcting the position correction amount in the T-axis direction. Represents one parameter. Of these, Ra and Ta are parameters for correcting the magnification of the actual position correction amount with respect to the correction command for the R-axis and T-axis directions, and by adjusting this, the entire variation in the R-axis and T-axis directions is respectively compressed. can do. On the other hand, Rb and Tb are parameters for correcting deviations in the entire actual position correction amount with respect to the correction commands for the R-axis and T-axis directions, and by adjusting this, the entire variation in the R-axis and T-axis directions is adjusted. It can be offset. Note that the arm movement amount in the T-axis direction is defined by an angle [deg] with respect to the T-axis turning center, but since the correction operation is minute, Δθ = tan ⁻¹ Δt / R _s (t is a coordinate in the T-axis direction) , R _s is approximated by the distance [mm] from the turning center to the center of the end effector 21).

  Next, in step S10, the end effector 21 is corrected toward the target position based on the position correction command after correction by the correction parameter. In step S11, the end effector 21 is lowered, the wafer W on the end effector is transferred to the target position, and the transfer operation is completed.

  Of these series of operations, the correction operation of the position of the end effector 21 executed in step S10 is a minute operation in units of 0.1 mm, for example. For this reason, mechanical characteristics such as mechanical resistance and hysteresis may change over time, and a deviation may occur between the command value and the actual movement amount.

  Therefore, unlike the normal transport operation, the control unit 3 in the transport apparatus 1 of the present embodiment can perform an operation in the parameter generation mode in which a new correction parameter is generated by adjusting the correction parameter described above. It is possible. The transition to the parameter generation mode is performed when an instruction is given by an operator via an input unit (not shown). However, the parameter generation mode is automatically performed at a predetermined timing within the program. It may be.

  In the parameter generation mode, the control means 3 adjusts the correction parameter and generates a new correction parameter according to the procedure shown in the flowchart of FIG. Hereinafter, the operation in the parameter generation mode will be described based on FIG. 2 with reference to FIG.

First, in step S101, the control means 3 prepares the wafer W at a port on which the wafer W is placed in the load lock chamber 5 or the process unit 6 (see FIG. 3), which is a transfer destination for position correction, and opens the gate valve. To make the port accessible. In step S102, the end effector 21 is caused to receive the wafer W at a normal position (a position where the reference position O and the target position on the end effector are substantially overlapped). In step S103, by passing the end effector 21 through the laser sensor 4, the relative displacement calculation unit 31 is provided on the end effector 21 with respect to the wafer W from the output of the laser sensor 4, similarly to the position correction operation during normal conveyance. The relative displacement of the reference position O is calculated, and the relative displacement is acquired. In step S104, the position correction command is output to the correction command generation unit 32 based on the acquired relative displacement, the position correction command is corrected by the correction parameter stored in the correction parameter storage unit 33, and the position is corrected to correct the wafer. W is transported toward the target position. At this time, the wafer W is transferred to at least the vicinity of the target position, although the center position X does not always match the target position. In step S105, a shift amount (xt _n , xr _n ) is set based on a predetermined table shown in FIG. Here, the shift amounts (xt _n , xr _n ) refer to amounts by which the reference position O on the end effector 21 is shifted from the normal position when the wafer W is received. In the present embodiment, the shift amounts (xt _n , xr _n ) are determined in advance based on the table shown in FIG. 7, and specifically correspond to locations (−4, −4), ..., data of 32 points (4, 4) are stored. Returning to FIG. 4, in step S106, the wafer W is received in a state in which the position of the end effector 21 is forcibly shifted from the normal position by the shift amount (xt _n , xr _n ) set in step S105. Thus, the wafer W is offset with respect to the end effector 21.

  Next, in step S107, the wafer W is passed through the laser sensor 4 in an offset state, and the relative displacement of the reference position O provided on the end effector 21 with respect to the wafer W is changed in the same manner as the position correction operation during normal transfer. get. In step S108, the correction command generation unit 32 outputs a position correction command based on the acquired relative displacement, and the position correction command is corrected by the correction parameter held in the parameter storage unit 33, and then the position correction is performed. The wafer W is transferred toward the target position.

Thereafter, in step S109, the wafer W is received at the aforementioned normal position without shifting the end effector 21. In step S110, by passing the end effector 21 through the laser sensor 4, the relative displacement calculation unit 31 calculates the relative displacement of the reference position O provided on the end effector 21 with respect to the wafer W from the output of the laser sensor 4. The corrected relative displacement (yt _n , yr _n ) is acquired.

  In step S111, the correction command generation unit 32 outputs a position correction command based on the acquired relative displacement, and the position correction command is corrected by the correction parameter held in the parameter storage unit 33, and then the position correction is performed. The wafer W is transferred toward the target position.

In step S112, it is determined whether or not the relative displacement (corrected relative displacement (yt _n , yr _n )) has been acquired for all the shift amounts (xt _n , xr _n ) set in the table described above. If it is determined that all data has not been obtained (in the case of determination no), the process returns to step S105, and the corrected relative displacement (yt) with respect to all the shift amounts (xt _n , xr _n ) determined in advance in the table Steps S105 to S112 are repeated until _{( n} , yr _n ) is acquired. If it is determined in step S112 that corrected relative displacements (yt _n , yr _n ) have been obtained for all the shift amounts (xt _n , xr _n ) (in the case of determination yes), the process proceeds to the next step S113. .

In step S113, an approximate expression representing the relationship between each shift amount (xt _n , xr _n ) set in the table and the corrected relative displacement (yt _n , yr _n ) obtained in step S110 is created. As shown in FIGS. 8 and 9, the approximate expression plots a set (xt _n , yt _n ) and (xr _n , yr _n ) of the shift amount and the corrected relative displacement for each of the R axis and the T axis, and R It is derived by approximating a linear equation by the least square method for each of the axis and the T axis. If an approximate expression can be derived, a method other than the method of least squares may be adopted.

In step S114, a new correction parameter is generated based on the approximate expression created in step S112. Specifically, based on the coefficients a and b obtained from the approximate expression y = ax + b derived from the graph in the R-axis direction in FIG. 8, “−b” is added to the correction parameter Rb, and “−a” is It adds to the correction parameter Ra. Similarly, “tan ⁻¹ (−b / R _s )” is added to Tb with respect to the approximate expression y = ax + b derived from the graph in the T-axis direction in FIG. 9, and “tan ⁻¹ (−ax / R). _s ) "is added to Ta. At this time, on the basis of the coefficients a and b obtained by the approximate expression, an addition correction by multiplication or addition is performed on the previous correction parameter used so far, but it depends on the previous correction parameter. It is also possible to configure to generate completely new correction parameters without doing so. In step S115, the correction parameters obtained as described above are stored in the correction parameter storage unit 33.

  The control means 3 can obtain a new correction parameter by sequentially executing the above steps. By doing this, it is possible to obtain the latest correction parameters, perform position correction with higher accuracy, and transport the wafer W with higher position accuracy.

In the case where only the more characteristic part is extracted by rearranging the above steps again, in this parameter generation mode, the control means 3 moves the wafer W placed at the target position to the shift amount (the end effector 21 set in advance) xt _n , xr _n ) The first step SS1 that is received by the end effector 21 in a state shifted by xt _n , xr _n ), and the wafer W is detected by the laser sensor 4, and the relative displacement calculation unit 31 is provided on the end effector 21 with respect to the wafer W. And calculating the relative displacement of the reference position O, correcting the position of the end effector 21 based on the correction command based on this, and transferring the wafer W toward the target position. The reference position O is superimposed on the target position, the end effector 21 receives the wafer W, and the wafer W is A third step SS3 that causes the sensor sensor 4 to detect and calculate the relative displacement of the reference position O provided on the end effector 21 with respect to the wafer W as a corrected relative displacement (yt _n , yr _n ) with respect to the wafer W; And a fourth step SS4 for generating a correction parameter for correcting the correction command so that the corrected relative displacement (yt _n , yr _n ) is reduced, and a correction parameter generating operation is executed. Can do.

  Here, the first step SS1 is the above-described steps S105 and S106, the second step SS2 is the above-described steps S107 and S108, the third step SS3 is the above-described steps S109 and S110, The above-mentioned steps S113 and S114 correspond to step SS4.

  When the correction amount is obtained by changing the shift amount to obtain the corrected relative displacement and calculating the approximate expression from a plurality of data, after repeatedly executing the first to third steps SS1 to SS3, The fourth step SS4 will be executed.

In addition, when the adjustment of the correction parameter in the parameter generation mode is insufficient once, it is possible to repeatedly execute the above-described processing a plurality of times, and to automatically execute this by a program. . Specifically, using the obtained correction parameters, the steps shown in FIG. 4 are repeatedly executed until all the corrected relative displacements (yt _n , yr _n ) are within a predetermined range, and appropriate correction is performed. What is necessary is just to obtain a parameter. In the case of such a configuration, the entire process including the first to fourth steps SS1 to SS4 is repeatedly executed.

As described above, the transfer apparatus 1 according to the present embodiment transfers the wafer W toward the target position by controlling the operation of the end effector 21 on which the wafer W that is the transfer object is placed, and the end effector 21. A control unit 3; and a laser sensor 4 as a photoelectric sensor which is provided on the transport path of the end effector 21 and detects a wafer W placed on the end effector 21, and the control unit 3 includes Based on the output of the laser sensor 4, the relative displacement calculator 31 that calculates the relative displacement between the wafer W and the reference position O provided on the end effector 21, and the relative displacement obtained by the relative displacement calculator 31. A correction command generation unit 32 that generates a correction command for correcting the position of the end effector 21 when the wafer W is transferred toward the target position. In location 1, the first step of the control unit 3 causes receive wafers W placed in the target position, the amount of shift is set to the end effector 21 previously (xt n, _{xr n)} to the end effector 21 min shifting state SS1 and the wafer W are detected by the laser sensor 4, and the relative displacement calculator 31 calculates the relative displacement between the wafer W and the reference position O provided on the end effector 21, and based on this, based on the correction command. Then, the position of the end effector 21 is corrected, and the second step SS2 for transporting the wafer W toward the target position and the reference position O on the end effector 21 are overlapped to the target position, and the end effector 21 receives the wafer W. The wafer W is detected by the laser sensor 4, and the relative displacement calculator 31 is provided on the wafer W and the end effector 21. Reference position O and the corrected relative displacement _{(yt n,} yr n) a relative displacement between the third step SS3 to be calculated as the corrected relative displacement _{(yt n,} yr n) a correction command to decrease A correction parameter generation operation including a fourth step SS4 for generating a correction parameter for correction is executed, and the correction command obtained by the correction command generation unit 32 is corrected based on the generated correction parameter. In this configuration, W is transported toward the target position.

  Since it is configured in this way, the relative displacement calculation unit 31 can calculate the relative displacement between the wafer W and the reference position O provided on the end effector 21 based on the signal from the laser sensor 4. The correction command generation unit 32 generates a correction command based on the relative displacement, and gives the correction command to the control unit 3, thereby correcting the deviation from the target position when the wafer W is transferred. .

  Furthermore, by correcting the correction command based on the correction parameter, it is possible to compensate for the deviation between the amount that was corrected by the correction command and the actual operation amount, and further improve the positional accuracy when the wafer W is transferred. Is possible. Further, since the laser sensor 4 and the relative displacement calculation unit 31 used for obtaining the correction command are also used for correcting the correction command, an image processing device for measuring the amount of deviation of the wafer W is provided separately. There is no need, and it is possible to improve the position correction accuracy only with an apparatus necessary for the transport operation. Further, since the processing related to the correction command correction can be executed based on the data obtained by causing the end effector 21 to perform an operation close to the actual transport operation, the transport position accuracy can be further improved. Is possible.

Since the correction parameter is configured to be generated based on a function obtained from the relationship between the shift amount (xt _n , xr _n ) and the corrected relative displacement (yt _n , yr _n ), any correction command It is also possible to give a correction parameter to.

Further, the control unit 3 sequentially changes the shift amount and repeatedly executes the first to third steps SS1 to SS3. In the fourth step SS4, each shift amount (xt _n , xr _n ) corresponds to this. Since the correction parameter is generated based on the value of the corrected relative displacement (yt _n , yr _n ), each shift amount (xt _n , xr _n ) and the corresponding corrected relative displacement and Therefore, it is possible to generate a correction parameter with higher accuracy.

In addition, the control unit 3 repeats the generation of the correction parameter executed by combining the first to fourth steps SS1 to SS4 until the corrected relative displacement (yt _n , yr _n ) becomes a predetermined value or less. Therefore, it is possible to generate the correction parameter with higher accuracy.

  Further, the wafer W that is the object to be transferred has a substantially circular shape, the laser sensor 4 detects the wafer W at the position and outputs a detection signal, and the relative displacement calculation unit 31 detects by the laser sensor 4. Since the relative displacement between the wafer W and the reference position O provided on the end effector 21 is calculated based on the signal and the position of the end effector 21 when this detection signal is obtained, the laser is configured. It is possible to easily determine the relative displacement between the wafer W and the end effector 21 based on the detection signal from the sensor 4.

  A plurality of laser sensors 4 are attached so as to cross the conveyance path of the wafer W in the width direction, and the relative displacement calculation unit 31 calculates the relative displacement using detection signals from at least two laser sensors 4L and 4R. Therefore, even when the wafer W expands and the radius changes, the relative displacement of the wafer W can be calculated appropriately.

  The specific configuration of each unit is not limited to the above-described embodiment.

For example, in the above-described embodiment, the shift amount (xt _n , xr _n ) and the corrected relative displacement (yt _n , yr _n ) corresponding to the shift amount are the normal position when the wafer W is received or the center position of the wafer W. The relative position of the reference position O of the end effector 21 when X is used as a reference is set, but these relations are reversed, that is, the relative position when the reference position O of the end effector is used as a reference. Is also possible.

Further, an approximate expression is obtained from the relationship between a plurality of shift amounts (xt _n , xr _n ) set in the table and the corresponding corrected relative displacements (yt _n , yr _n ), and correction is made based on this. Although the parameters are generated, a representative shift amount (xt _n , xr _n ) is extracted only for one point, and only a corrected relative displacement (yt _n , yr _n ) corresponding to this is obtained. It is also possible to generate a correction parameter. By doing so, although the accuracy of correction is slightly reduced, the operation time in the parameter generation mode can be greatly shortened.

In the above-described embodiment, an approximate expression indicating the relationship between the shift amount (xt _n , xr _n ) and the corrected relative displacement (yt _n , yr _n ) corresponding thereto is obtained, and the correction is performed based on the approximate expression. Although the parameters are adjusted, the relative displacement calculated based on the detection value by the laser sensor 4 immediately before the wafer W is mounted after the position correction and the corrected relative displacement (yt _n , yr _n ) It is also possible to obtain an approximate expression indicating the relationship and adjust the correction parameter based on the approximate expression.

  Furthermore, in the above-described embodiment, when the wafer W is transferred by the normal operation, the end effector 21 is temporarily stopped at the set position, and then a correction command based on the relative displacement is given to the end effector 21 to perform the position correction operation. However, it is also possible to configure to perform these operations continuously.

  In the above-described embodiment, the laser sensor 4 using a laser as a light source is used as a photoelectric sensor serving as a detection unit. However, a photoelectric sensor using a light source other than a laser such as infrared light may be used. Furthermore, as long as the presence of the wafer W at a specific position can be detected, in addition to the photoelectric sensor, other commonly used sensors such as a magnetic sensor and an ultrasonic sensor may be used as the detection unit. Is possible.

  Moreover, although the conveyance apparatus 1 of the above-mentioned embodiment was comprised as a horizontal articulated robot which combined the rotation element which consists of the end effector 21 and the arms 22 and 23, the end effector 21 can be moved linearly. If it is a thing, it is not restricted to this form. For example, the same effect as described above can be obtained even when configured as a transport device that combines a linear motion mechanism that operates in the R-axis direction and the T-axis direction, or a transport device that combines a rotating arm and a linear motion mechanism. It is possible to obtain. Furthermore, the number of elements to be combined is not limited to that described above, and even when configured as a horizontal articulated robot, the present invention can be applied to those in which the joint portions 24, 25, and 26 are further increased to perform more complicated operations.

  Further, in the above-described embodiment, the end effector 21 is configured to receive the wafer W by the lifting / lowering operation of the arm mechanism 2, but instead of causing the arm mechanism 2 to perform the lifting / lowering operation, the wafer W is transferred. An elevating mechanism may be provided on the process unit or the load lock side, and wafers may be exchanged with the end effector 21 using this elevating mechanism.

  In the above-described embodiment, an example is shown in which the transfer apparatus 1 is configured to transfer the wafer W as the transfer object. However, the transfer object is not limited to the wafer W, and various objects can be transferred. In particular, it can be suitably used in applications for transporting objects to be transported that require precise positioning.

  Other configurations can be variously modified without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Conveyance apparatus 3 ... Control means 4, 4L, 4R ... Laser sensor (a photoelectric sensor, a detection part)
DESCRIPTION OF SYMBOLS 21 ... End effector 31 ... Relative displacement calculation part 32 ... Correction command generation part O ... Reference position W ... Semiconductor wafer (conveyed object)
SS1 ... first step SS2 ... second step SS3 ... third step SS4 ... fourth step

Claims (6)

An end effector for placing the object to be transported; control means for controlling the operation of the end effector to transport the object to be transported toward a target position; and a transport path of the end effector. A detector that detects the object to be transported, and
The control means is obtained by a relative displacement calculation unit that calculates a relative displacement between the transported object and a reference position provided on the end effector based on an output of the detection unit, and the relative displacement calculation unit. In a transport apparatus comprising: a correction command generation unit that generates a correction command for correcting the position of the end effector when transporting the transported object toward the target position based on the relative displacement.
The control means is
A first step of receiving the object to be transported placed at the target position while the end effector is shifted by a preset shift amount;
The detection unit is caused to detect the object to be conveyed, and the relative displacement calculation unit is configured to calculate a relative displacement between the object to be conveyed and a reference position provided on the end effector. A second step of correcting the position of the end effector based on the position and transporting the object to be transported toward the target position;
The reference position on the end effector is overlapped with the target position, the end effector receives the object to be conveyed, the object to be conveyed is detected by the detection unit, and the object to be conveyed is detected by the relative displacement calculation unit. And a third step of calculating a relative displacement between the reference position provided on the end effector and the corrected relative displacement;
A fourth step of generating a correction parameter for correcting the correction command so that the corrected relative displacement becomes small;
The correction command generation operation is executed, the correction command obtained by the correction command generation unit is corrected based on the generated correction parameter, and the object to be conveyed is transported toward the target position. A conveying device characterized by that.   The transport apparatus according to claim 1, wherein the correction parameter is generated based on a function obtained from a relationship between the shift amount and the corrected relative displacement.   The control means sequentially changes the shift amount and repeatedly executes the first to third steps, and based on the value of each shift amount and the corrected relative displacement corresponding thereto in the fourth step. The transport apparatus according to claim 1, wherein the correction parameter is generated.   4. The control unit according to claim 1, wherein the control unit repeats generation of a correction parameter executed by combining the first to fourth steps until the corrected relative displacement becomes a predetermined value or less. Crab transport device.   The object to be transported is a substantially circular shape, the detection unit is a photoelectric sensor that detects the object to be transported at the position and outputs a detection signal, and the relative displacement calculation unit is a detection signal from the photoelectric sensor and the detection signal The relative displacement between the transported object and a reference position provided on the end effector is calculated based on the position of the end effector when the detection signal is obtained. Crab transport device.   A plurality of the photoelectric sensors are attached so as to cross the conveyance path of the object to be conveyed in the width direction, and the relative displacement calculation unit calculates the relative displacement using detection signals from at least two photoelectric sensors. The conveyance device according to claim 5, wherein the conveyance device is configured.

Images