JP2011009295A - Device and method for conveyance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for conveyance highly accurately conveying a conveying object to a destination.SOLUTION: A substrate tray conveyance device holds a substrate tray 17 mounting a substrate 3 by a conveyance arm 26 to convey the substrate tray to a mounting table 5. The conveyance arm 26 has a reflection type optical fiber sensor 25 at the end of the arm. The conveyance arm 26 is slowed down just before reaching an edge of the mounting table. Then, the sensor 25 detects the edge of the mounting table 5. Since the conveyance arm 26 has been slowed down, the sensor 25 stably detects the position of the edge. Based on a detection result of the position of the edge by the sensor 25, a control device 37 controls a first moving mechanism 28 so that the conveyance arm 26 is moved from the edge of the mounting table 5 by a distance obtained by adding a distance from the edge of the mounting table 5 to the center of the mounting table 5 and a distance from the substrate tray 17 to the sensor 25.

Description

  The present invention relates to a transport apparatus that holds a transported object and transports it to a target position and a transport method thereof.

  Conventionally, the use of compound semiconductors is expanding in various fields. Examples of frequently used compound semiconductors include semiconductor laser elements and LED (light emitting diode) elements. For manufacturing these elements, MOCVD (metal organic chemical vapor deposition) apparatus or MBE (molecular beam epitaxy) apparatus is widely used.

  The MOCVD apparatus is an apparatus that performs a film formation process by irradiating a heated substrate with a gas as a raw material. The MBE apparatus is an apparatus that performs a film forming process by irradiating a substrate with a material evaporated in a vacuum. Both apparatuses perform film formation processing using the principle of crystal growth. The MOCVD apparatus has better productivity and maintainability than the MBE apparatus. For this reason, when a compound semiconductor is mass-produced industrially, an MOCVD apparatus is generally used.

  A general MOCVD apparatus is shown in FIG. FIG. 8 is a view showing a cross section of the MOCVD apparatus.

  The MOCVD apparatus 1 includes a reaction chamber 2, a motor 9, and a gas supplier 15.

  In the reaction chamber 2, a plurality of mounting tables 5 are provided on the upper surface of the turntable 4. A substrate 3 is mounted on each mounting table 5. As a material of the substrate 3, Si, GaAs, GaN, sapphire glass or the like is used. The appropriate one is used depending on the compound semiconductor to be produced.

  Details of the turntable 4 are shown in FIG. FIG. 9 is a view showing the upper surface of the turntable 4.

  The turntable 4 is supported on the upper end of the rotary shaft 8. The rotary shaft 8 is rotated by a motor 9. The plurality of mounting tables 5 provided on the upper surface of the turntable 4 are each configured to rotate. Accordingly, the substrate 3 placed on the mounting table 5 is rotated and rotated by the rotation of the rotating table 4 and the rotation of the mounting table 5. This is for improving the uniformity of the crystal growth layer to be generated and generating a uniform film.

  As a mechanism for rotating the mounting table 5, Patent Document 1 discloses a method of rotating by using gear meshing. Each mounting table 5 is installed on a rotating gear 6, and a fixed gear 7 is installed on the outer periphery of the rotating table 4. Since the rotation gear 6 is installed on the turntable 4, the rotation gear 6 is synchronized with the rotation of the turntable 4, and rotates by meshing with a fixed gear 7 fixed to the outer periphery of the turntable 4.

  Further, Patent Document 2 discloses a method in which a rotation driving gas is supplied from below the mounting table 5 to float and rotate the mounting table 5.

  Further, a heater 10 is disposed below the turntable 4, and the substrate 3 is heated by the heater 10. A substantially parallel partition wall 11 is provided above the turntable 4 to separate the space inside the reaction chamber 2.

  A pipe 12 is connected to the upper part of the reaction chamber 2. A gas supplier 15 is connected to the pipe 12, and a raw material gas 14 that is a raw material for the film forming process is held therein. This source gas 14 is supplied along the surface of the turntable 4 from a gas outlet 13 at the tip of the pipe 12. At this time, when the source gas 14 reaches the substrate 3 heated by the heater 10, a chemical reaction occurs. As a result, crystal growth is performed and a film forming process is performed on the substrate 3. Excess source gas 14 passes through the substrate 3 and is exhausted from an exhaust path 16 provided on the outer periphery of the turntable 4.

  In the MOCVD apparatus 1, in order to perform the film forming process, the substrate 3 must be set on the mounting table 5 in the apparatus. This is usually done manually.

  An MOCVD apparatus 1 in which the reaction chamber 2 opens and closes is shown in FIG. FIG. 10 is a view showing a cross section of the MOCVD apparatus 1 in which the reaction chamber 2 is open.

  In general, the reaction chamber 2 is divided above and below the reaction chamber 2a and the reaction chamber 2b, and the reaction chamber 2b is often raised and opened. At that time, the partition 11 inside the reaction chamber 2 may be lifted together with the reaction chamber 2b, or may be removed by the operator each time.

  The substrate 3 is made of a material that is easily damaged. For this reason, an operator who handles the substrate 3 is required to have a high level of skill and must work carefully. For this reason, the operation of placing the substrate 3 takes time. Therefore, the device which automates this work is performed.

  Patent Document 3 discloses an apparatus for transporting a substrate 3 by a robot hand. When the robot hand detects the mark provided on the mounting table 5, the positional relationship with the mounting table 5 is recognized. Based on the information, the robot hand places the substrate 3 on the placing table 5.

  Patent Document 4 discloses an apparatus that corrects an error between the center point of the mounting table 5, which is a target position for mounting the substrate 3, and the actual center point of the substrate 3. A reference index is provided on the substrate 3, and its center point is detected. An offset amount between the center point and the center point of the mounting table 5 is obtained, and the position where the substrate 3 is mounted is corrected.

Japanese Laid-Open Patent Publication No. 2002-17592 (published on June 21, 2002) Special table 2004-513243 public information (announced April 30, 2004) Japanese Laid-Open Patent Publication No. 8-71973 (published on March 19, 1996) JP 11-42579 public information (released February 16, 1999)

  The MOCVD apparatus 1 operates in a high temperature environment exceeding several hundred degrees Celsius to 1000 degrees Celsius. For this reason, in order to avoid the influence of thermal expansion, the tolerance of the fitting of the rotation gear 6 and the fixed gear 7 must be made large. As a result, the position of the mounting table 5 when the turntable 4 is stopped sometimes deviates by mm.

  The methods disclosed in Patent Document 3 and Patent Document 4 described above are aimed at automating the placement of the substrate 3 at the target position set when the apparatus is started up. Therefore, it cannot be applied to conveyance in which the position of the mounting table 5 as the target position changes every time during conveyance.

  As an extension technique of the method disclosed in Patent Document 3, it is conceivable to detect the positional relationship between the mark and the robot hand each time the substrate 3 is transported to the target position. However, the substrate 3 is not positioned before the transfer, and it is unclear how the robot hand holds the substrate 3. Therefore, it is difficult to appropriately transport the substrate 3 to the target position.

  As described above, the MOCVD apparatus 1 performs the film forming process in a high temperature environment. For this reason, the temperature of the mounting table 5 may not be lowered during the conveyance, and may be 100 ° C. or higher. In particular, when transport is performed before the temperature inside the apparatus drops to reduce the throughput of the apparatus, the temperature inside the apparatus exceeds 400 ° C. In addition, the temperature changes every moment during the conveyance. Under such circumstances, the methods disclosed in Patent Document 3 and Patent Document 4 cannot follow the change of the target position due to the temperature change during the conveyance and cannot be applied.

Further, when the substrate 3 moves from a room temperature of about 25 ° C. to a high temperature of about 400 ° C., the substrate 3 may be damaged by a sudden temperature change. In particular, a sapphire glass substrate having a relatively large linear expansion coefficient (linear expansion coefficient 7.7 × 10 ⁻⁶ / ° C.) or the like may be broken by thermal shock. Therefore, in that case, it is necessary to reduce the moving speed of the substrate 3 as much as possible so that the substrate 3 is not suddenly changed in temperature. This leads to a reduction in the throughput of the apparatus.

  In any of the methods disclosed in Patent Document 3 and Patent Document 4, a mark or a reference index must be provided on the mounting table 5. The MOCVD apparatus 1 is required to have a high temperature uniformity of the substrate 3 in order to perform a uniform film forming process. Therefore, providing a mark or a reference index on the mounting table 5 causes a non-uniform temperature of the substrate 3.

  In the reaction chamber 2 of the MOCVD apparatus 1, it is known that the product accumulates on the partition wall 11 after the film forming process and falls. Therefore, even if a mark or a reference index is provided at a position other than the mounting table 5, the product may fall on the mark or the reference index. In that case, the mark or the reference index cannot be detected correctly, and proper conveyance cannot be performed.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a transport apparatus that can automatically transport a transported object and place it with high accuracy, and a transport method therefor. It is in.

A transport device that transports an object to be transported arranged in a positioning mechanism installed in a first position to a mounting table installed in a second position,
A gripping unit that grips the object to be transported at a position at a certain distance from the sensor toward the first position, with a sensor at the tip near the second position;
A height direction moving mechanism capable of moving the grip portion up and down;
A first moving mechanism capable of moving the gripping portion between the first position and the second position;
A deceleration control unit for controlling the first moving mechanism so as to decelerate the gripping unit before reaching a predetermined position where the distance from the second position is determined;
A detection control unit for detecting the predetermined position based on an output from the sensor;
The first holding unit is moved from the predetermined position by a distance obtained by adding a distance from the detected predetermined position to the second position and a distance from the conveyed object to the sensor. And a movement control unit that controls the movement mechanism.

  According to said structure, in the conveying apparatus which concerns on this invention, a holding part hold | grips the to-be-conveyed object installed in the 1st position, and conveys it to the mounting base installed in the 2nd position.

  Specifically, the gripper grips the object to be transported and starts moving to the second position as it is by the first moving mechanism. A sensor is provided at the tip of the grip portion, and the sensor detects a predetermined position where the distance to the second position is fixed. Prior to reaching the predetermined position, the gripping portion is configured to decelerate. When the sensor detects the predetermined position, the gripper is moved from the predetermined position by a distance obtained by adding the distance from the predetermined position to the second position and the distance from the conveyed object to the sensor. As a result, the gripping part reaches the second position, and the object to be transported is placed on the placing table.

  Therefore, the conveying apparatus according to the present invention can stabilize the predetermined position detection process by the sensor by decelerating the gripping part before reaching the predetermined position. As a result, it becomes possible to more accurately convey the object to be conveyed. Further, even when the transport destination position is changed, it is possible to cope with the change of the transport destination by the sensor provided in the gripping unit, and it is possible to accurately transport the object to be transported. Therefore, the transport apparatus according to the present invention can transport the transported object to the second position with high accuracy regardless of whether or not the transport destination position has changed.

A plurality of the mounting tables are installed on the rotating table, and it is possible to select which mounting table is moved to the second position by rotating the rotating table,
The gripping unit includes a second moving mechanism that can move in a direction perpendicular to both the height direction moving mechanism and the first moving mechanism.

  According to said structure, it can be freely selected which mounting base is moved to a 2nd position among several mounting bases. Further, it is possible to correct an error of the turntable stop angle generated when the turntable is stopped.

  The turntable includes an angle sensor that detects a rotation angle, and the movement control unit obtains the amount of movement of the gripper by the second moving mechanism based on an output of the angle sensor.

  According to said structure, in order to correct | amend the error of the turntable stop angle produced at the time of a turntable stop, the quantity which a holding part should move can be calculated.

The grip portion includes at least two sensors at the tip portion, and they are arranged with a predetermined interval in the moving direction of the grip portion by the second moving mechanism,
The movement control unit obtains a movement amount of the gripping part by the second movement mechanism based on outputs of the at least two sensors.

  According to said structure, since the error of a turntable stop angle can be correct | amended based on the information of a some sensor, a 2nd position can be recognized more correctly.

  The transported object has a structure that covers the mounting table when transported.

  According to said structure, it can prevent that a foreign material accumulates on a mounting base.

  The predetermined position is an edge of the mounting table.

  According to said structure, the position of a mounting base can be recognized because a sensor detects the edge of a mounting base.

  The sensor is preferably a reflective optical fiber sensor.

  According to said structure, even if a conveyance destination position is under high temperature, a reflective optical fiber sensor which has heat resistance can detect a predetermined position without a problem.

The mounting table is composed of either graphite, silicon carbide, or graphite coated with silicon carbide,
It is preferable that either boron nitride or a compound of boron nitride and silicon nitride can be seen from the sensor closer to the first position than the edge of the mounting table.

  According to said structure, since the contrast of a mounting base and its outer side becomes large enough, it becomes easy to detect the edge of a mounting base.

A method of transporting an object to be transported arranged in a positioning mechanism installed in a first position to a mounting table installed in a second position,
A step of holding the transported object by a gripping unit that grips the transported object at a position at a certain distance from the sensor toward the first position, the sensor being provided at the tip near the second position. When,
Moving the gripping part in the height direction and lifting the conveyed object from a first position;
Moving the grip portion toward a second position;
A step of decelerating the movement of the gripping part when the gripping part reaches a position before the predetermined position where the distance to the second position is clear;
Detecting the predetermined position by the sensor;
The grip portion is moved from the predetermined position by a distance obtained by adding a distance from the detected predetermined position to the second position and a distance from the transferred object to the sensor, and the transferred object is moved to the second position. And a step of placing on the mounting table from the gripping part.

  According to said structure, the predetermined position detection process by a sensor can be stabilized by decelerating a holding | grip part before reaching | attaining a predetermined position, and more exact conveyance of a to-be-conveyed object is attained.

The conveyance device according to the present invention can stabilize the predetermined position detection process by the sensor by decelerating the gripping part before reaching the predetermined position. As a result, it becomes possible to more accurately convey the object to be conveyed. Further, even when the transport destination position is changed, it is possible to cope with the change of the transport destination by the sensor provided in the gripping unit, and it is possible to accurately transport the object to be transported. Therefore, the transport apparatus according to the present invention can transport the transported object to the second position with high accuracy regardless of whether or not the transport destination position has changed.

It is a figure which shows the cross section of the MOCVD apparatus and substrate tray conveying apparatus which concern on one Embodiment of this invention. It is a figure which shows the cross section of the board | substrate tray conveying apparatus which concerns on one Embodiment of this invention. It is a figure which shows the cross section of the board | substrate tray which concerns on one Embodiment of this invention. It is a figure which shows the cross section of the substrate tray conveyance apparatus and the MOCVD apparatus in the initial stage of conveyance of the substrate tray which concerns on one Embodiment of this invention. It is a figure which shows the cross section of the state which the reflection type optical fiber sensor which concerns on one Embodiment of this invention detects the edge of a mounting base. It is a figure which shows the cross section of the state which is making the board | substrate tray which concerns on one Embodiment of this invention fit in the mounting base. It is a figure which shows the upper surface of the board | substrate tray conveying apparatus provided with the some reflective optical fiber sensor which concerns on one Embodiment of this invention. It is a figure which shows the cross section of the conventional MOCVD apparatus. It is a figure which shows the upper surface of a turntable. It is a figure which shows the cross section of the conventional MOCVD apparatus with which the reaction chamber is open.

  Embodiments according to the present invention will be described below in detail with reference to the drawings.

  In all the drawings for explaining the present embodiment, those having the same function are denoted by the same reference numerals, and the repeated explanation thereof is omitted.

[First embodiment]
(Outline of MOCVD apparatus 1 and substrate tray transfer apparatus 19)
The outline | summary of the MOCVD apparatus 1 and the substrate tray conveyance apparatus 19 which concern on embodiment of this invention is demonstrated with reference to FIG. FIG. 1 is a view showing a cross section of the MOCVD apparatus 1 and the substrate tray transfer apparatus 19 according to the present embodiment.

  As shown in FIG. 1, a positioning mechanism 18 for a substrate tray 17 and a substrate tray transfer device 19 are arranged outside the MOCVD apparatus 1 according to the present embodiment.

  As an outline of the present invention, a substrate tray 17 placed on a positioning mechanism 18 placed on a first position is held by a substrate tray transfer device 19 and placed on a second position inside the MOCVD apparatus 1. Transport to. A film forming process is performed in the MOCVD apparatus 1, and the substrate tray 17 is again gripped and carried out by the substrate tray transfer apparatus 19 after the film forming process is completed.

(Configuration of MOCVD apparatus 1)
A configuration of the MOCVD apparatus 1 according to the present embodiment will be described.

  As shown in FIG. 1, the MOCVD apparatus 1 includes a reaction chamber 2, a motor 9, a gas supplier 15, and an encoder 30.

  Similar to the conventional MOCVD apparatus 100, the MOCVD apparatus 1 is provided with a plurality of substantially disk-shaped mounting tables 5 on the upper surface of the turntable 4 in the reaction chamber 2. In the present embodiment, a total of eight mounting tables 5 are installed on the rotating table 4. A substrate tray 17 is placed on each mounting table 5, and a substrate 3 is placed on each substrate tray 17.

  The turntable 4 is supported on the upper end of the rotary shaft 8. Since the rotating shaft 8 is rotated by the motor 9, the rotating base 4 is rotated. The plurality of mounting tables 5 provided on the upper surface of the turntable 4 are each configured to rotate. As a mechanism for the mounting table 5 to rotate, a method using gear meshing is employed. Each mounting table 5 is installed on a rotating gear 6, and a fixed gear 7 is installed on the outer periphery of the rotating table 4. The rotation gear 6 is synchronized with the rotation of the turntable 4 and rotates by engaging with a fixed gear 7 fixed to the outer periphery of the turntable 4. Accordingly, the substrate 3 placed on the mounting table 5 is rotated and rotated by the rotation of the rotating table 4 and the rotation of the mounting table 5.

  Since the mounting table 5 is required to have high thermal conductivity and high durability, graphite, SiC (silicon carbide) or SiC-coated graphite is used. The rotation gear 6 uses BN (boron nitride) or SBN (compound of boron nitride and silicon nitride) as a material. The reason for using these is also to facilitate detection of the edge of the mounting table 5 by a sensor. This will be described in detail later.

  As shown in FIG. 1, a heater 10 is disposed below the turntable 4 to heat the substrate 3. An encoder 30 is attached to the rotary shaft 8 and outputs the rotation angle of the turntable 4.

(Configuration of Substrate Tray Transfer Device 19)
The configuration of the substrate tray transfer device 19 will be described with reference to FIG. FIG. 2 is a view showing a cross section of the substrate tray transfer device 19.

  As shown in FIG. 2, the substrate tray transfer device 19 includes a suction head 22, a transfer arm 26, a height direction moving mechanism 27, a first moving mechanism 28, and a second moving mechanism 29.

  As shown in FIG. 3, a suction head 22 is provided at the tip of the substrate tray transfer device 19. The suction head 22 has four suction pads 23. A vacuum pipe 24 is connected to the suction pad 23, and the inside of the vacuum pipe 24 can be changed from an atmospheric pressure state to a vacuum state. When the inside of the vacuum pipe 24 is in a vacuum state, the substrate tray 17 can be sucked and held from above and transported. The suction pad 23 is set so as to suck the upper surface of the substrate tray 17 so as not to accidentally suck the substrate 3. At this time, the upper surface of the substrate tray 17 is sucked, but the lower surface or the side surface may be sucked and held. In addition to the method of attracting the substrate tray 17 by the vacuum pipe 24, a method using an electrostatic chuck or the like may be employed. In the present embodiment, the substrate 3 is transported using the substrate tray 17, but other in-furnace members may be used.

  The configuration of the substrate tray 17 according to the present embodiment will be described with reference to FIG. FIG. 3 is a view showing a cross section of the substrate tray 17 according to the present embodiment.

  The substrate tray 17 is a substantially disk-shaped quartz plate. As shown in FIG. 3, the substrate tray 17 has a concave portion 20 on the upper surface and a convex portion 21 on the lower surface. The recess 20 is a part for placing the substrate 3 thereon. The convex portion 21 is a part to be fitted with the mounting table 5, and the dimension of the convex portion 21 is set according to the outer periphery of the mounting table 5.

(Detection mechanism of the reflective optical fiber sensor 25)
A reflective optical fiber sensor 25 is attached to the tip of the suction head 22 placed at a fixed distance from the suction pad 23 toward the second position. The reflective optical fiber sensor 25 is mounted with its sensor tip facing downward, and emits light therefrom. Usually, the reflective optical fiber sensor 25 detects the presence or absence of an object by measuring a change in the amount of reflected light from the object with respect to emitted light. In the present embodiment, as described above, graphite, SiC, or SiC-coated graphite is used for the mounting table 5, and BN or SBN is used for the rotating gear 6. That is, from the first position rather than the edge of the mounting table 5, either boron nitride or a compound of boron nitride and silicon nitride can be seen from the reflective optical fiber sensor 25.

  Since the reflectivity of graphite, SiC or SiC-coated graphite is very small compared to BN or SBN, the contrast of the mounting table 5 and the rotating gear 6 is sufficiently large. Therefore, in this embodiment, the edge of the mounting table 5 can be detected by detecting the contrast between the mounting table 5 and the rotation gear 6. Further, the reflection type optical fiber sensor 25 is connected to a detection control unit of the control device 37, and a signal when the sensor detects an edge can be transmitted to the detection control unit. The reason why the edge of the mounting table 5 is detected by the reflective optical fiber sensor 25 is to detect a predetermined position where the distance to the mounting table 5 as the second position is fixed.

  In the present embodiment, as the reflective optical fiber sensor 25, GXH500J series of Takenaka Electronics Co., Ltd. having heat resistance is used. Since the reflective optical fiber sensor 25 is relatively inexpensive and has many variations, it is widely used industrially for the purpose of detecting the presence or absence of an object. As the position detection, an image processing method using a video camera is more widely used than the reflective optical fiber sensor 25 because of its accuracy and versatility. However, since an image processing apparatus using a video camera is expensive, large, and inferior in heat resistance, it is difficult to apply to this embodiment. In the present embodiment, the reflection type optical fiber sensor 25 is used, but a capacitance type sensor or an eddy current detection type sensor is also applicable. Basically, a non-contact type is desirable, but a mechanical switch type using a cantilever or the like can also be configured.

(Movement mechanism of the substrate tray transfer device 19)
A moving mechanism of the substrate tray transfer device 19 will be described.

  As shown in FIG. 2, the suction head 22 is connected to the transport arm 26. The transfer arm 26 is fixed to a height direction moving mechanism 27, and the height direction moving mechanism 27 is fixed to a first moving mechanism 28. The height direction moving mechanism 27 can move up and down, and the first moving mechanism 28 can move in the same direction as the direction in which the transfer arm 26 extends. Further, a second moving mechanism 29 that moves in a direction perpendicular to the moving direction of either the height direction moving mechanism 27 or the first moving mechanism 28 is disposed. The first moving mechanism 28 is fixed to the second moving mechanism 29. Therefore, when the second moving mechanism 29 moves, both the height direction moving mechanism 27 and the first moving mechanism 28 move.

  The height direction moving mechanism 27, the first moving mechanism 28, and the second moving mechanism 29 are each connected to a movement control unit of a control device 37, and this movement control unit controls each mechanism.

(Conveying procedure of substrate tray 17)
A specific conveyance procedure of the substrate tray 17 will be described with reference to FIGS. 4, 5, and 6.

  For transporting the substrate tray 17 to the MOCVD apparatus 1, a specific one of the plurality of mounting tables 5 on the turntable 4 is a transport destination.

  First, the film forming process on the substrate 3 is completed in the MOCVD apparatus 1, and the substrate 3 subjected to the film forming process and other objects to be transported are already carried out. FIG. 4 is a view showing a cross section of the substrate tray transfer device 19 and the MOCVD apparatus 1 in the initial stage of transfer of the substrate tray 17. As shown in FIG. 4, the reaction chamber 2 of the MOCVD apparatus 1 is in an open state.

  The operation is performed from the operation in which the substrate tray 17 on which the substrate 3 is placed is transported to the positioning mechanism 18 by a transport device (not shown). The substrate tray 17 is positioned at a predetermined position by the positioning mechanism 18 and then held by the suction head 22.

At this time, the current stop angle θ of the turntable 4 is output from the encoder 30 provided on the rotary shaft 8. The control device 37 obtains a stop angle error Δθ that is a difference between the current stop angle θ of the turntable 4 and the stop angle θ0 that should originally stop the turntable 4. From there, the movement amount Ly to which the second movement mechanism 29 should move is calculated. Specifically, it is obtained by the following equation (1) from the revolution radius R of the plurality of mounting tables 5 and the stop angle error Δθ.
Ly = R × sin Δθ (1)
The second moving mechanism 29 moves by the calculated Ly.

  At the same time, the first moving mechanism 28 moves to start moving the substrate tray 17 held by the suction head 22 toward the mounting table 5 that is the transfer destination. At this time, the moving speed of the first moving mechanism 28 is set to 200 mm / sec. Note that a position that is sufficiently in front of the edge of the mounting table 5 is input to the control device 37 in advance. The position sufficiently before the edge of the mounting table 5 is a section approximately 2 mm to 4 mm before the edge of the mounting table 5. An example in which approximately 2 mm before the edge of the mounting table 5 is input as the position sufficiently before the edge of the mounting table 5 is shown below.

  When the reflection type optical fiber sensor 25 passes through a previously input position, the first moving mechanism 28 is decelerated to 2 mm / sec by the deceleration control unit of the control device 37. Therefore, the first moving mechanism 28 decelerates approximately 2 mm before passing over the edge of the mounting table 5 and moves approximately 4 mm in the decelerated state. By doing so, the reflective optical fiber sensor 25 passes over the edge of the mounting table 5 at a relatively low speed.

(Detection by reflection type optical fiber sensor 25)
FIG. 5 is a view showing a cross section in a state where the reflection type optical fiber sensor 25 detects the edge of the mounting table 5. As shown in FIG. 5, the reflective optical fiber sensor 25 emits projection light 31 from the sensor tip while moving toward the mounting table 5. As described above, the mounting table 5 is made of graphite coated with SiC, and the rotating gear 6 is made of SBN as a material. The reflectance of SiC coated graphite is very small compared to that of SBN. Therefore, the reflection type optical fiber sensor 25 moves from a state where the amount of the reflected light 32 with respect to the projection light 31 is large to a state where it is small.

  The first moving mechanism 28 always detects its own coordinate and outputs it to the control device 37 at all times. On the other hand, the reflective optical fiber sensor 25 is set to output a signal to the control device 37 at the moment when the detected light quantity exceeds (or falls below) a predetermined threshold.

  When the reflection type optical fiber sensor 25 senses a change in the intensity of the reflected light, that is, when a change across the threshold value is sensed, a signal is issued to the control device 37 triggered by this sense. At the time when the signal is received, the control device 37 detects the coordinate input from the first moving mechanism 28 to the control device 37 as the edge position of the mounting table 5.

  During the detection process, the reflection type optical fiber sensor 25 moves at a low speed, so that the reflection type optical fiber sensor 25 can accurately detect the timing of the change in the amount of the reflected light 32 with respect to the projection light 31. Note that the control device 37 is set so as not to sense (i.e., ignore) the output from the reflective optical fiber sensor 25 at a position before the previously input position. Accordingly, the control device 37 senses the output from the reflection type optical fiber sensor 25 from the time when the reflection type optical fiber sensor 25 passes the position input in advance. As a result, since the region where the contrast does not change other than the edge of the mounting table 5 is substantially scanned, it is possible to prevent the reflective optical fiber sensor 25 from erroneously detecting the non-edge portion as the edge. it can.

  During the film forming process, since the mounting table 5 is covered with the substrate tray 17, the possibility that the product is deposited is low. Therefore, there is no problem that an error occurs in the detection of the edge of the mounting table 5 by depositing the product on the mounting table 5. Further, by detecting the edge of the mounting table 5, it is possible to prevent the temperature of the substrate 3 from becoming uneven by newly providing a mark or a reference index on the mounting table 5.

  Note that the temperature inside the MOCVD apparatus 1 immediately after unloading the film-formed substrate 3 is about 400 ° C., and gradually decreases from there. Accordingly, when the substrate 3 at room temperature is transferred into the high temperature MOCVD apparatus 1, a problem such as destruction may occur due to a rapid temperature rise. In the present embodiment, the first moving mechanism 28 moves at a low speed in the vicinity of the edge of the mounting table. For this reason, the temperature of the substrate 3 is gradually increased, and the occurrence of destruction or the like can be suppressed.

(Fitting of the substrate tray 17)
FIG. 6 is a view showing a cross section in a state where the substrate tray 17 is fitted to the mounting table 5. The diameter of the mounting table 5 in this embodiment is 115 mm. The distance from the center of the substrate tray 17 to the reflective optical fiber sensor 25 in the state of being held by the suction head 22 is 80 mm. Therefore, when the first moving mechanism 28 is moved in the direction of the mounting table 5 by 115/2 + 80 = 137.5 mm from the edge of the mounting table 5, the suction head 22 reaches the mounting table 5. After that, as shown in FIG. 6, when the suction head 22 is brought close to the mounting table 5 by the height direction moving mechanism 27, the substrate tray 17 is accurately fitted with the mounting table 5.

  When the substrate tray 17 is transported to the mounting table 5 and the fitting is completed, the suction head 22 moves to the position of the positioning mechanism 18 again. Next, when the substrate tray 17 to be transported is transported to the positioning mechanism 18 by a transport device (not shown), the suction head 22 holds and transports it again. At that time, by rotating the turntable 4 and moving the new mounting table 5 to the second position, a new transport destination can be obtained. In this way, it is possible to select which mounting table 5 is moved to the second position.

  In the present embodiment, when the substrate tray 17 is transported to all eight mounting tables 5, the MOCVD apparatus 1 closes the reaction chamber 2 and starts a film forming process. When the film forming process is completed, the transfer operation is performed in the reverse direction, and the unloading operation is performed. At this time, since precise fitting between the mounting table 5 and the substrate tray 17 is not necessary, the edge of the mounting table 5 is not detected by the reflective optical fiber sensor 25.

  In the present embodiment, an apparatus that conveys one substrate tray 17 by one conveyance is shown, but an apparatus that conveys a plurality of substrate trays 17 by one conveyance may be adopted.

(Effect of this embodiment)
As described above, in this embodiment, the conveyance of the substrate tray 17 is all automated. Even if an error occurs in the angle at which the turntable 4 is stopped, the encoder 30 detects the error. Correction can be made by moving the substrate tray transfer device 19 based on the information. Further, the reflection type optical fiber sensor 25 attached to the tip of the substrate tray transfer device 19 detects the mounting table 5, so that the substrate tray 17 can be mounted on the mounting table 5 with high accuracy. At the same time, since the substrate tray 17 is transported at a low speed into the high-temperature MOCVD apparatus 1, it is possible to prevent the substrate 3 from being destroyed due to a sudden temperature rise.

  Therefore, the MOCVD apparatus 1 and the substrate tray transfer device 19 according to the present embodiment can automatically transfer the substrate tray 17 to the mounting table 5 in a stable and highly accurate manner.

[Second Embodiment]
(Outline of substrate tray transfer device 19 having a plurality of sensors)
A substrate tray transfer device 19 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a view showing the upper surface of the substrate tray transfer device 19 provided with a plurality of reflective optical fiber sensors 25.

  In the above-described embodiment, correction is performed based on the output of the encoder 30, but correction may be performed using a plurality of reflective optical fiber sensors 25. By providing a plurality of reflective optical fiber sensors 25, the center of the mounting table 5 on which the substrate tray 17 is to be mounted can be obtained. As an example, a case where two reflective optical fiber sensors 25 are provided will be described below.

In this case, as shown in FIG. 7, the two reflective optical fiber sensors 25 detect the coordinates (x ₁ , y ₁ ) 33 and the coordinates (x ₂ , y ₂ ) 34. The coordinates (x _r , y _r ) of the center of the mounting table 5 can be obtained from these coordinates and the radius r35 of the mounting table 5. Specifically, it is obtained from the following equations (2) and (3).

That is, if y ₁ = 0 and x ₁ = −x ₂ , the center coordinates (x _r , y _r ) of the mounting table 5 are A = −4 × x ₁ ² / y ₂ ² +1, B = √ {− 4 × (x ₁ ² + y ₂ ² / 4−r ² ) × (−A)},
x _r = B / (2 × A) (2)
y _r = y ₂ / 2-2 × (x ₁ / y ₂ ) × x _r (3)
Is established.

  In this case, the installation of the encoder 30 can be omitted, but there is a problem that the suction head 22 becomes large by mounting a plurality of reflective optical fiber sensors 25.

  When the function of controlling the rotation of the turntable 4 is sufficiently high, there is almost no error in the stop angle of the turntable 4 described above. The same applies to the case where the stop angle error can be sufficiently reduced by reducing the moment of inertia of the turntable 4. In these cases, the installation of the second moving mechanism 29, the encoder 30, and the plurality of reflective optical fiber sensors 25 can be omitted. Since the above-described embodiment is an apparatus intended for mass production, the apparatus is increased in size, and the inertia moment of the turntable 4 is large, and the stop angle error is large. Therefore, the second moving mechanism 29 and the encoder 30 are mounted.

  Therefore, an appropriate device may be selected depending on the environment when designing the device or the environment when using the device.

  Although the invention made by the present inventor has been specifically described based on the embodiment, the invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  For example, the transfer apparatus 19 of the present invention is not limited to film forming apparatuses such as MOCVD apparatus and MBE apparatus, but can be used for transferring an object to be transferred into an apparatus where there is no rapid temperature rise.

  Further, the predetermined position detected by the reflective optical fiber sensor 25 is not limited to the edge of the mounting table 5. Any position other than the edge may be used as long as the MOCVD apparatus 1 has a certain contrast and the distance from the center (second position) of the mounting table 5 is fixed. As a position satisfying such a condition, for example, there is an edge of the rotation gear 6.

  The transfer apparatus of the film forming apparatus according to the present invention can be used as a transfer apparatus for transferring a substrate to a mounting table in an MOCVD apparatus that performs a film forming process, for example.

1 MOCVD equipment 2 Reaction chamber 3 Substrate (conveyed object)
DESCRIPTION OF SYMBOLS 4 Rotating base 5 Mounting base 6 Rotating gear 7 Fixed gear 8 Rotating shaft 9 Motor 10 Heater 11 Partition 12 Pipe 13 Gas outlet 14 Raw material gas 15 Gas supply 16 Exhaust path 17 Substrate tray 18 Positioning mechanism 19 Substrate tray conveyance device (conveyance) apparatus)
20 Concave part 21 Convex part 22 Suction head 23 Suction pad 24 Vacuum piping 25 Reflective optical fiber sensor (sensor)
26 Transfer arm (gripping part)
27 Height direction moving mechanism 28 First moving mechanism 29 Second moving mechanism 30 Encoder 31 Projected light 32 Reflected light 33, 34 Coordinate 35 Radius 36 of mount 5 Distance between reflective optical fiber sensors 37 Control device (deceleration control) Part, detection control part, movement control part)
100 Conventional MOCVD equipment

Claims (9)

A transport device that transports an object to be transported arranged in a positioning mechanism installed in a first position to a mounting table installed in a second position,
A gripping unit that grips the object to be transported at a position at a certain distance from the sensor toward the first position, with a sensor at the tip near the second position;
A height direction moving mechanism capable of moving the grip portion up and down;
A first moving mechanism capable of moving the gripping portion between the first position and the second position;
A deceleration control unit for controlling the first moving mechanism so as to decelerate the gripping unit before reaching a predetermined position where the distance from the second position is determined;
A detection control unit for detecting the predetermined position based on an output from the sensor;
The first holding unit is moved from the predetermined position by a distance obtained by adding a distance from the detected predetermined position to the second position and a distance from the conveyed object to the sensor. And a movement control unit that controls the movement mechanism. A plurality of the mounting tables are installed on the rotating table, and it is possible to select which mounting table is moved to the second position by rotating the rotating table,
2. The second movement mechanism capable of moving the grip portion in a direction perpendicular to both the height direction movement mechanism and the first movement mechanism. Transport device.   The rotary table includes an angle sensor that detects a rotation angle, and the movement control unit obtains a movement amount of the gripping unit by the second movement mechanism based on an output of the angle sensor. Item 3. The transfer device according to Item 2. The grip portion includes at least two sensors at the tip portion, and they are arranged with a predetermined interval in the moving direction of the grip portion by the second moving mechanism,
The transport apparatus according to claim 2, wherein the movement control unit obtains a movement amount of the grip part by the second movement mechanism based on outputs of the at least two sensors.   The transport apparatus according to claim 1, wherein the transported object has a structure that covers the mounting table when transported.   The transport apparatus according to claim 1, wherein the predetermined position is an edge of the mounting table.   The transport device according to claim 1, wherein the sensor is a reflective optical fiber sensor. The mounting table is composed of either graphite, silicon carbide, or graphite coated with silicon carbide,
The transport apparatus according to claim 7, wherein either boron nitride or a compound of boron nitride and silicon nitride can be seen from the sensor closer to the first position than the edge of the mounting table. A method of transporting an object to be transported arranged in a positioning mechanism installed in a first position to a mounting table installed in a second position,
A step of holding the transported object by a gripping unit that grips the transported object at a position at a certain distance from the sensor toward the first position, the sensor being provided at the tip near the second position. When,
Moving the gripping part in the height direction and lifting the conveyed object from a first position;
Moving the grip portion toward a second position;
A step of decelerating the movement of the gripping part when the gripping part reaches a position before the predetermined position where the distance to the second position is clear;
Detecting the predetermined position by the sensor;
The grip portion is moved from the predetermined position by a distance obtained by adding a distance from the detected predetermined position to the second position and a distance from the transferred object to the sensor, and the transferred object is moved to the second position. And a step of placing on the mounting table from the gripping part.

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