JP4571477B2 - Board transfer mechanism - Google Patents

Description

  The present invention relates to a substrate transport mechanism having a substrate presence / absence detection mechanism.

  An example of a semiconductor pattern writing apparatus is an electron beam drawing apparatus. This apparatus irradiates a predetermined position on a drawing material such as a wafer or a mask placed on a stage by irradiating an electron beam. A predetermined pattern is drawn.

  On the other hand, the semiconductor pattern inspection apparatus includes, for example, an electron beam inspection apparatus. This apparatus scans a predetermined area on a sample to be inspected such as a patterned wafer or mask placed on a stage with an electron beam. Then, based on the secondary electron signal obtained from the scanning area, the predetermined area is observed and analyzed.

  In such a drawing apparatus or inspection apparatus, a substrate such as a drawing material or a sample to be inspected is exchanged between a processing chamber such as a drawing room or an inspection room and the outside. That is, the substrate transfer mechanism is used to transfer a substrate that has undergone predetermined processing in the processing chamber to the outside, and a new substrate stored outside is transferred to the processing chamber.

  For example, FIG. 1 shows an outline of a configuration in which the entire electron beam lithography apparatus for mask lithography is viewed from above.

  In the drawing, reference numeral 1 denotes a drawing chamber. A stage 2 that can move in the X and Y directions is provided at a substantially central portion of the drawing chamber, and a mask is placed on the stage. Above the drawing chamber is an electron optical system barrel equipped with an electron gun for generating an electron beam, a focusing lens for focusing the electron beam on the substrate, a deflector for scanning the substrate with the electron beam, and the like. (Not shown) is mounted. Further, the drawing chamber 1 and the lens barrel (not shown) are provided with an exhaust device (not shown) for evacuating each interior.

  In the figure, reference numeral 3 denotes a substrate storage container provided with a large number of shelves for placing a mask in parallel in the vertical direction, and is placed on an elevator (not shown). It can move up and down.

  In the figure, reference numeral 4 denotes an exchange chamber disposed between the drawing chamber 1 and the substrate storage container 3, which is connected to the drawing chamber 1 via a gate valve 5. It is connected through atmospheric space.

In the figure, reference numeral 7 denotes an alignment chamber directly connected to the exchange chamber 4 and includes an alignment mechanism (not shown) for adjusting the position and direction of the mask carried from the substrate storage container 3 to the exchange chamber 4.
Substrate transport mechanisms 8 and 9 are disposed in the exchange chamber 4 and between the gate valve 6 and the substrate storage container 3, respectively.

  FIG. 2 shows a schematic example of the substrate transport mechanism, which comprises a drive mechanism body 10, a control device 11, and a multistage arm 12, as shown in the figure.

  The drive mechanism main body 10 includes a rotation drive mechanism 13 and a vertical movement drive mechanism 14 inside. The drive mechanism 13 rotates the rotary shaft 15 by a drive signal from the control device 11 to move up and down. The drive mechanism 14 works to move the rotary drive mechanism 13 itself up and down through the shaft 16.

  The multi-stage arm 12 includes a first arm (first stage arm) 17 that is rotatably attached to the rotary shaft 15, a second arm 18 that is rotatably attached to the rotary shaft at the tip of the first arm, And a third arm 19 rotatably attached to the rotation shaft at the tip of the two arms. The third arm is referred to as a tip arm, and is configured such that Max is placed on the top surface of the tip arm. In the following description, each component of the substrate transport mechanism 9 is described with an A after the number, and each component of the substrate transport mechanism 8 is described with a B after the number.

The control device 11 controls the tip arm 19 to move linearly by an arbitrary distance by controlling the rotation angle of the rotation shaft to which each arm is attached.
In the electron beam lithography apparatus for mask lithography having such a configuration, the substrate storage container 3 moves in the vertical direction so that an arbitrary shelf comes to a predetermined position by operating an elevator (not shown). At this time, the gate valve 5 is closed and the gate valve 6 is open.
In this state, the tip arm 19A of the substrate transport mechanism 9 moves in the direction of the substrate storage container 3 based on a command from the control device 11A, and the mask placed on the shelf at a predetermined position is moved to the tip arm 19A. Place it on the top surface and retract it. Next, the multistage arm 12 </ b> A rotates 180 degrees, and the distal arm 19 </ b> A moves in the direction of the gate valve 6. At this time, the front end arm 19B of the substrate transport mechanism 8 moves in the direction of the gate valve 6 based on a command from the control device 11B, and the front end of the substrate transport mechanism 9 is located in the exchange chamber near the position where the gate valve 6 is disposed. The mask is transferred from the arm 19A to the tip arm 19B of the substrate transfer mechanism 8. After this delivery, the tip arm 19A is retracted, the gate valve 6 is closed, and the exchange chamber 4 is evacuated. Note that the gate valve 5 is opened after the exchange chamber 4 is exhausted to a sufficiently low pressure.

Next, after the front end arm 19B of the substrate transport mechanism 8 is once retracted, the multi-stage arm 12B rotates 90 degrees counterclockwise, and the front end arm 19B moves in the direction of the alignment chamber 7.
In the alignment chamber 7, the mask placed on the upper surface of the tip arm 19B is once placed on a mask mounting table (not shown) of an alignment mechanism (not shown) and aligned there. The mask after the alignment is again placed on the upper surface of the tip arm 19B, and in this state, the tip arm 19B is temporarily retracted.

  Next, the multi-stage arm 12B rotates 90 degrees counterclockwise, the tip arm 19B moves in the direction of the drawing chamber 1, and the mask placed on the upper surface of the tip arm 19B is placed at a predetermined position on the stage 2. Thereafter, the tip arm 19B is temporarily retracted into the exchange chamber 4, and the gate valve 5 is closed.

In this state, a predetermined pattern is drawn on the mask by electron beam irradiation. When the predetermined pattern drawing is completed, the gate valve 5 is opened, the tip arm 19B is moved, the mask is placed on the upper surface, and once returned to the exchange chamber, the gate valve 5 is closed, and the gate valve 6 is opened. .
Next, the multistage arm 12B rotates 180 degrees, and the distal arm 19B moves in the direction of the gate valve 6. At this time, the tip arm 19A of the substrate transfer device 9A moves in the direction of the gate valve 6, and the tip arm 19B of the substrate transfer mechanism 8 to the tip arm of the substrate transfer mechanism 9 in the exchange chamber close to the arrangement position of the gate valve 6. The mask is transferred to 19A.

  Next, the tip arm 19A is once retracted, the multi-stage arm 12A is rotated 180 degrees, and the tip arm 19A moves toward the substrate storage container 3. At this time, the operation of the elevator (not shown) moves the substrate storage container 3 in the vertical direction so that an arbitrary empty shelf is at a predetermined position. Then, the mask placed on the upper surface of the tip arm 19A is returned to the empty shelf at a predetermined position.

  Next, when a pattern is drawn on a new mask, the same steps as described above are performed.

  In such an electron beam drawing apparatus for mask drawing, a detection sensor is attached to the inside of the drawing chamber, the alignment chamber, and the exchange chamber. The operation of each unit constituting the drawing electron beam drawing apparatus is performed in accordance with a predetermined program.

  However, since the presence / absence of the mask cannot be confirmed until the tip arm comes to the specific position, as a result, the throughput is hindered.

  In addition, when transport is stopped due to the absence of a mask at a specific position, the tip arm can be seen from the viewing window in the drawing chamber, alignment chamber, or exchange chamber to check for the presence of a mask on the tip arm. The multi-stage arm had to be moved manually to the position, and the operation was troublesome.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 10-175734, a reflection type optical sensor having a light emitting part and a light receiving part on the tip arm itself of the substrate transport mechanism disposed in the exchange chamber 4, and a reflection There has been considered a substrate transport mechanism that attaches a mirror and constantly detects the presence / absence of a substrate on the tip arm by the presence / absence of reflected light.
JP-A-10-175734 JP 2001-007181 A JP 2003-065711 A JP 2003-303754 A

  In such a substrate transport mechanism, the signal of the reflection type optical sensor attached to the tip arm is sent to a control device provided outside (outside a chamber such as an exchange chamber) through a signal line connected to the sensor. The control device determines the presence or absence of a substrate.

  However, since the linear movement distance of the tip arm is extremely large, an extremely long signal line is required, which is a heavy burden on the arm. Further, the tip arm needs to be rotated to change the direction by 90 degrees and 180 degrees, which may cause the signal line to get tangled, and the operation becomes troublesome.

  The present invention provides a novel substrate transport mechanism that solves such problems.

  The substrate transport mechanism of the present invention is configured to connect a plurality of arms in a manner that another arm is rotatably connected to the tip of the first-stage arm connected to the rotation shaft of the rotation driving means, and to place the substrate on the tip arm. In a substrate transport mechanism that is equipped with a multi-stage arm in the chamber and the tip arm moves linearly in an arbitrary direction by controlling the rotational position of each arm, each optical axis approaches the outside of the chamber. The light emitting means and the light receiving means are provided, an intermediate reflector that is rotatable in synchronization with the first stage arm is provided on the extension line of the rotation axis, and a substrate detection reflector is provided on the tip arm or the tip arm attached object. Light is directed toward the reflector for substrate detection through the intermediate reflector, and the arrival and non-arrival of light to the reflector for substrate detection corresponds to the placement and non-placement of the substrate on the tip arm. I will do it To form, reflected light from the substrate the reflecting body when the light arrives is characterized in that form to be received by the light receiving means.

  The substrate transport mechanism of the present invention is provided with a light emitting means and a light receiving means outside the chamber, a multistage arm body and an intermediate reflector are provided in the chamber, and the substrate detection reflector is attached to the tip arm of the multistage arm body or an object attached to the tip arm. With this configuration, it is possible to irradiate light from the light emitting means to the reflector for detecting the substrate and to receive light from the reflector for detecting the substrate of the light receiving means, so that the signal line connected to the tip arm in the chamber is unnecessary, The presence or absence of the substrate on the tip arm can always be detected. Therefore, even if the linear movement distance of the tip arm is extremely large, no burden is imposed on the arm based on the signal line. Further, even if the tip arm rotates to change the direction by 90 degrees and 180 degrees, there is no danger of tangling the signal line, and there is no operational problem.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 shows a schematic example of the substrate transport mechanism of the present invention. In the exchange chamber 20 and in the exchange chamber 20, the substrate is transferred between the drawing chamber (not shown) and the outside. A substrate transport mechanism performing transport is shown.

  As described above, the substrate transport mechanism includes the drive mechanism main body 21, the control device, and the multistage arm 22, but the control device is omitted in FIG. Since the drive mechanism main body 21 has the same configuration as described above, other internal components other than the rotating shaft 23 are omitted in FIG.

  As shown in FIG. 3, the substrate transport mechanism is disposed by vacuum-sealing and attaching the upper part of the drive mechanism body 21 to the bottom wall of the exchange chamber 20.

  Reflective mirror support bases 25 and 26 are fixed to the upper and lower surfaces of the first arm (first-stage arm) 24 constituting the multi-stage arm 22 with the end where the rotary shaft 23 is fitted, respectively.

  The reflection mirror support base 25 is formed in a column shape, for example, and an intermediate reflection mirror 27 is attached to the upper end portion thereof. On the other hand, the reflecting mirror support 26 is formed in a plate shape having an L-shaped cross section, and is formed at the tip of the plate that is perpendicular to one plate attached to the lower surface of the first arm 24. Two intermediate reflecting mirrors 28 are attached. The intermediate reflection mirror 27 is attached to the reflection mirror support 25 so that the rotation center of the rotation shaft 23 of the first arm 24 coincides with the center of the intermediate reflection mirror 27.

  A transparent body (for example, a glass plate) 29 is fitted on the upper wall of the exchange chamber 20 facing the front end surface of the reflection mirror support base 25 with a vacuum seal.

  On the opposite side of the intermediate reflecting mirror 27 across this transparent glass plate 29, that is, outside the exchange chamber, for example, a linear light regression photoelectric sensor 30 (provided with a light emitting part and a light receiving part in which the respective optical axes are close to each other) A linear light regression type laser sensor) is attached.

  In the intermediate reflection mirrors 27 and 28, the light beam from the light emitting portion of the photoelectric sensor 30 is incident on the substantially central portion of the intermediate reflection mirror 27, and the reflected light is incident on the substantially central portion of the second intermediate reflection mirror 28. The reflection support bases 25 and 26 are respectively attached with an inclination so that the reflected light is directed toward the center of the reflection mirror support base 25.

  A hole 31 through which the reflected light can pass is formed in the central portion of the reflecting mirror support base 25 from which the reflected light from the second intermediate reflecting mirror 28 is directed.

  As described above, the first arm 24 rotatably attached to the rotary shaft 23 has a second arm 32 rotatably attached to the rotary shaft at the tip, and the tip of the second arm is attached to the tip of the second arm. A third arm, i.e., a tip arm 33 is rotatably attached to the rotation shaft at the tip. A mask is placed on the upper surface of the tip arm 33. On the upper surface, strip-shaped mask mounting tables 34A and 34B extending in a direction perpendicular to the paper surface of FIG. 3 are attached.

  As shown in FIG. 4, these mask mounting tables 34A and 34B are arranged on a column-like mask mounting table support 35 so that the mask mounting surfaces are inclined inward, respectively, as viewed from above. They are attached integrally through 36A and 36B.

  An elastic body 37 such as a spring is provided at the center of the mask mounting table support 35.

  The mask mounting table support 35 having such a structure is placed on the upper surface of the first arm 24. The mounting portion of the mask mounting table support 35 of the first arm 24 has a mask mounting table support. A square hole 38 that is slightly larger than the mask mounting table support 35 is provided so that the body 35 can move up and down, and holes 39A and 39B that can guide the columns 36A and 36B in the vertical direction are provided at both ends. Are provided with holes 40 to which the elastic bodies 37 are attached.

  Now, a portion of the mask mounting table support 35 that is folded at a right angle with respect to the bottom surface is provided on the reflecting mirror support table 25 side, and a substrate detection reflecting mirror 41 is attached to that portion. When not mounted, the light beam that has passed through the hole 31 of the reflection mirror table 25 hits the substrate detection reflection mirror 41, and the mask is mounted. As a result, the elastic body 37 contracts and the mask table support 35 is lowered. The regressive reflection type photoelectric sensor 30, the intermediate reflection mirrors 27 and 28, and the hole 31 of the reflection mirror base are adjusted in position so that the light beam that has passed through the hole 31 does not hit the reflection mirror 41 for substrate detection. Yes.

In the substrate transport mechanism having such a configuration, the reflection mirror bases 25 and 26 are fixed to the first arm 24, and the first arm 24 is fixed to the rotating shaft 23. Therefore, the rotation of the rotating shaft 23 is exactly the same. In addition, the first arm 24, the reflection mirror bases 25 and 26, and the reflection mirrors 27 and 28 rotate. That is, the rotation of the rotary shaft 23 causes the tip arm 33 to face the substrate storage container side, to the alignment chamber side, to the drawing chamber side, or to somewhere in between. Regardless of the extent of extension in the direction in which the tip arm 33 faces, the photoelectric sensor 30, the intermediate reflection mirror 27, the second intermediate reflection mirror 28, and the light between the holes 31 of the reflection mirror support base The trajectory does not change. Therefore, no matter where the tip arm 33 is located, it is possible to always inspect the presence or absence of the mask on the tip arm as described below.

As shown in FIG. 4A, when the mask M is not placed on the upper surface of the tip arm 33, that is, the mask placing tables 34A and 34B of the mask placing table support 35 do not place the mask M. In this case, since the load based on the weight of the mask M is not applied to the mask mounting table support 35, the elastic body 37 remains sufficiently stretched.

  Therefore, the light beam from the photoelectric sensor 30 is reflected by the intermediate reflection mirror 27, the reflected light beam from the intermediate reflection mirror 27 is reflected by the second intermediate reflection mirror 28, and this reflected light beam is reflected on the reflection mirror support base 25. It passes through the hole 31 and hits the substrate detection reflection mirror 41 attached to the side surface of the mask mounting table support 35.

The light beam reflected by the substrate-detecting reflection mirror 41 is opposite to the path of the light beam, and the photoelectric sensor passes through the hole 31 of the reflection mirror support base 25, the intermediate reflection mirror 28, and the second intermediate reflection mirror 27. 30 receives light. The light reception signal of the photoelectric sensor 30 is sent to a control device (not shown), where it is detected that the mask M is not placed on the upper surface of the tip arm 33.

On the other hand, as shown in FIG. 4B, when the mask M is placed on the upper surface of the tip arm 33, that is, the mask placement tables 34A and 34B of the mask placement table support 35 place the mask M. In this case, since the load based on the weight of the mask M is applied to the mask mounting table support 35, the elastic body 37 is contracted downward (in the direction of gravity). Therefore, the side surface of the mask mounting table support 35 to which the substrate detection reflecting mirror 41 is attached falls below the passing line of the light beam passing through the hole 31 of the reflecting mirror support 25.

  Then, the light beam from the photoelectric sensor 30 is reflected by the intermediate reflecting mirror 27, the reflected light beam from the reflecting mirror 27 is reflected by the second intermediate reflecting mirror 28, and this reflected light beam is reflected in the hole of the reflecting mirror support base 25. 31, but does not hit the reflection mirror 41 for detecting a substrate attached to the side surface of the mask mounting table support 35.

  Therefore, the photoelectric sensor 30 does not receive the light beam, and the control device (not shown) detects that the mask M is not placed on the upper surface of the distal arm 23.

  The examples shown in FIGS. 3 and 4 are merely examples, and various modifications are possible.

  For example, in the above example, the reflection mirror support bases 25 and 26 having the intermediate reflection mirrors 27 and 28 are attached to the upper surface and the lower surface of the first arm 24, respectively, and the light beam from the photoelectric sensor 30 is transmitted to the two intermediate reflection mirrors. 27, 28 and the hole 31 of the reflection mirror support base 25 are directed toward the distal arm 33, but as shown in FIG. 6, a reflection having an intermediate reflection mirror 50 only on the upper surface of the first arm 24. A mirror support 51 may be provided so that the light beam from the photoelectric sensor 30 is directed toward the distal arm 33 via the intermediate reflection mirror 50. In FIG. 6, the same reference numerals as those used in FIG. 3 denote the same components. The intermediate reflection mirror 50 is attached to the reflection mirror support 51 so that the center thereof coincides with the rotation center of the rotation shaft 23 of the first arm 24.

In the example of FIG. 4, the substrate detection reflecting mirror 41 is attached to the side surface of the mask mounting table support 35, and the light beam from the photoelectric sensor 30 is reflected when the mask M is not mounted. However, when the mask M is mounted on the side surface of the mask support base 34B closer to the reflection mirror support base 25, the light beam from the photoelectric sensor 30 is transmitted. It may be configured to hit the reflection mirror for substrate detection.
Further, in the above example, the mask mounting table support 35 is provided on the upper surface of the tip arm 33, and the substrate detection reflecting mirror 41 is attached to the side surface of the mask mounting table support 35. However, as shown in FIG. In addition, without providing the mask mounting table support 35 and the like, the mask mounting tables 42A and 42B are directly provided on the tip arm 33, and the side wall 43 is provided at the tip of the tip arm 33, and the reflection mirror support table is provided there. The substrate detection reflection mirror 44 may be attached at a position where the reflected light beam that has passed through the 25 holes 31 hits. With such a configuration, as shown in FIG. 5A, when the mask M is not placed on the upper surface of the distal arm 33, that is, when the mask placement tables 42A and 42B do not place the mask M. The reflected light beam from the second intermediate reflecting mirror 28 that has passed through the hole 31 of the reflecting mirror support base 25 hits the reflecting mirror 44 for substrate detection attached to the side wall 43 at the tip of the tip arm 33 and is based on the reflected light. Thus, it is detected that the mask M is not placed on the upper surface of the tip arm 33.

  On the other hand, as shown in FIG. 5B, when the mask M is placed on the upper surface of the distal arm 33, that is, when the mask placing tables 42A and 42B are placing the mask M, the reflecting mirror support 25 is provided. The reflected light beam from the second intermediate reflecting mirror 28 that has passed through the hole 31 hits the side surface of the mask M and does not hit the reflecting mirror 44 for substrate detection attached to the side wall 43 at the tip of the tip arm 33, so that the mask M It is detected that the robot is placed on the upper surface of the distal arm 33.

In the above example, the reflecting mirror support base 25 (51) is directly mounted on the first arm 24 so as to be positioned on a line connecting the rotating shaft 23 and the photoelectric sensor 30. The attachment in this way is based on the premise that the movement range of the second arm 32 and the tip arm 33 is in a range where it does not collide with the reflection mirror support base 25. However, when the movement range of the second arm 32 and the tip arm 33 is in a range where the second arm 32 and the tip arm 33 collide with the reflecting mirror support base 25 (51), as shown in FIG. As described above, the reflecting mirror support base 25 ′ is placed on the end portion of the support plate 60 and the other end portion of the support plate 60 is mounted on the first arm 24. In this case, the intermediate reflection mirror attached to the reflection support base 25 ′ is in a strip shape parallel to the support plate 60 so that a part thereof is on the extension line of the rotation center axis of the rotation shaft 23 as shown in 27 ′. To form. In such a case, a hole for allowing the light beam to pass through is not necessary in the reflecting mirror support base 25 '.

  In addition, although the inside of the exchange chamber 20 and the inside of the exchange chamber 20 were relayed, it demonstrated taking the case of the board | substrate conveyance mechanism which has conveyed the board | substrate between the drawing chamber (not shown) and the exterior etc. as an example, It goes without saying that the present invention can also be applied to a substrate transport mechanism provided in another chamber (such as a drawing room).

1 schematically shows the configuration of an electron beam lithography apparatus for a mask lithography apparatus as viewed from above. An example of a board | substrate conveyance mechanism is shown. 1 shows a schematic example of a substrate transport mechanism according to the present invention. 1 shows a schematic example of a main part of a substrate transport mechanism of the present invention. The other schematic example of the principal part of the board | substrate conveyance mechanism of this invention is shown. The other schematic example of the principal part of the board | substrate conveyance mechanism of this invention is shown. The other schematic example of the principal part of the board | substrate conveyance mechanism of this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drawing chamber 2 ... Stage 3 ... Substrate storage container 4 ... Exchange chamber 5 ... Gate valve 6 ... Gate valve 7 ... Alignment chamber 8 ... Substrate conveyance mechanism 9 ... Substrate conveyance mechanism 10 ... Drive mechanism main body 11 ... Controller 12 ... Multistage Arm 13 ... Rotation drive mechanism 14 ... Vertical drive mechanism 15 ... Rotating shaft 16 ... Shaft 17 ... First arm 18 ... Second arm 19 ... Third arm 20 ... Exchange chamber 21 ... Drive mechanism body 22 ... Multi-stage arm 23 ... Rotating shaft 24 ... first arm 25,25 '... reflecting mirror support 26 ... reflecting mirror support 27,27' ... reflecting mirror 28 ... reflecting mirror 29 ... transparent glass plate 30 ... regressive reflection type photoelectric sensor
31 ... Hole 32 ... Second arm 33 ... Third arm (tip arm)
34A, 34B ... Mask mounting table 35 ... Mask mounting table support 36A, 36B ... Strut 37 ... Elastic body 38 ... Hole 39A, 39B ... Hole 40 ... Hole 41 ... Reflection mirror M ... Mask 42A, 42B ... Mask mounting table 43 ... Side wall 44 ... Reflection mirror 50 ... Reflection mirror 51 ... Reflection mirror support base 60 ... Support plate

Claims (10)

  The chamber is equipped with a multi-stage arm body in which a plurality of arms are connected to the tip of the first-stage arm connected to the rotation shaft of the rotation driving means in a manner that the other arm can be rotated and a substrate is placed on the tip arm. In the substrate transport mechanism configured to linearly move the tip arm in an arbitrary direction by controlling the rotation position of each arm, a light emitting unit and a light receiving unit in which the respective optical axes are close to each other are provided outside the chamber. An intermediate reflector that can rotate in synchronization with the first stage arm is provided on the extension line of the rotating shaft, a substrate detection reflector is provided on the tip arm or an object attached to the tip arm, and the light from the light emitting means is passed through the intermediate reflector. So that the arrival and non-arrival of the light to the substrate detection reflector correspond to the placement and non-mounting of the substrate on the tip arm. When it arrives Substrate transfer mechanism reflected light from the substrate the reflecting body has form as received by the light receiving means.   2. The substrate transport mechanism according to claim 1, wherein the light emitting means and the light receiving means are an integrated linear light regression laser sensor.   The substrate transport mechanism according to claim 1, wherein the intermediate reflector is indirectly integrated with the first stage arm on an extension line of the central axis of the rotation axis.   The substrate transfer mechanism according to claim 1, wherein a reflector support is attached on the first stage arm, and an intermediate reflector is attached to the reflector support.   2. The substrate transport mechanism according to claim 1, wherein a second intermediate reflector configured to reflect the reflected light from the intermediate reflector again to be directed toward the substrate detection reflector is indirectly integrated with the first stage arm.   The substrate transport mechanism according to claim 4, wherein a hole through which light from the second intermediate reflector passes is formed in the reflector support base.   5. The substrate transport mechanism according to claim 4, wherein the reflective support base is provided at a position where there is no interference with each arm, and the reflective support base is mounted on the first stage arm via a support plate.   2. The substrate detection reflector according to claim 1, wherein the substrate detection reflector is attached to a tip of the tip arm at a position where the light from the intermediate reflector reaches when the substrate is not placed and does not reach when the substrate is placed. Substrate transport mechanism.   A substrate support for mounting the substrate is separately mounted on the tip arm, and an elastic body is provided on the bottom surface of the substrate support, and the side close to the rotation axis of the substrate support 2. A substrate transport according to claim 1, wherein a substrate detection reflector is attached to a side of the substrate at a position where the light from the intermediate reflector reaches when the substrate is not placed and does not reach when the substrate is placed. mechanism. A substrate support for placing the substrate is separately placed on the tip arm, and an elastic body is provided on the bottom surface of the substrate support, on the side close to the rotation axis of the substrate support. 2. The substrate transport mechanism according to claim 1, wherein a substrate detection reflector is attached to a side portion where light from the intermediate reflector reaches when the substrate is placed and does not reach when the substrate is not placed. .

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