Substrate transport device, substrate transport method, and storage medium

Abstract

To transport a substrate to a desired mounting position with high precision.SOLUTION: A substrate transport device includes: a first substrate holding unit having a first suction hole for sucking and holding a substrate; a suction force changing unit for switching a suction force by the first suction hole between a first state and a second state lower than the first state; a detection unit for detecting a state of the suction force; and a moving mechanism for moving the first substrate holding unit such that the substrate is transported from the first substrate holding unit to a mounting unit by decelerating the first substrate holding unit for holding the substrate in the first state in the middle of lowering the first substrate holding unit from a first height to a second height above the mounting unit and then lowering the first substrate holding unit from the second height to a third height below an upper end of the mounting unit after the change to the second state is detected.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a substrate transport apparatus, a substrate transport method, and a storage medium. [Background technology]

[0002] In the manufacturing process of semiconductor devices, various processes are performed by transporting a semiconductor wafer (hereinafter, referred to as a wafer) as a substrate within a system using a substrate transport device. Patent Document 1 shows a substrate transport device equipped with a suction port for suctioning the wafer, and detects an abnormality in suction by detecting the pressure in an exhaust path connected to the suction port. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-183704 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can transport a substrate to a desired placement position with high precision. [Means for solving the problem]

[0005] The substrate processing apparatus of the present disclosure includes a first substrate holding unit having a first suction hole for holding a substrate by suction; a suction force changing unit for switching a suction force by the first suction hole between a first state and a second state lower than the first state; A detection unit for detecting a state of the suction force; a moving mechanism that moves the first substrate holding unit, which holds the substrate in the first state, by decelerating the first substrate holding unit during descent from a first height to a second height above the mounting unit, and then, after a change to the second state is detected, by descent from the second height to a third height below an upper end of the mounting unit, so that the substrate is transported from the first substrate holding unit to the mounting unit; Equipped with. Effect of the Invention

[0006] The present disclosure makes it possible to transport a substrate to a desired placement position with high precision. [Brief description of the drawings]

[0007] [Figure 1] 1 is a plan view of a substrate processing system to which a substrate transport device is applied; [Diagram 2] FIG. 2 is a vertical sectional front view of the substrate processing system. [Diagram 3] 2 is a perspective view of a wafer transfer device provided in the substrate processing system. FIG. [Figure 4] FIG. 2 is a plan view of the wafer transport device. [Diagram 5] 11 is an operation diagram of the comparative example of the wafer transfer device. [Figure 6] 11 is an operation diagram of the comparative example of the wafer transfer device. [Figure 7] 11 is an operation diagram of the comparative example of the wafer transfer device. [Figure 8] 11 is an operation diagram of the comparative example of the wafer transfer device. [Figure 9] 11 is an operation diagram of the comparative example of the wafer transfer device. [Figure 10] 11 is an operation diagram of the comparative example of the wafer transfer device. [Figure 11] 11 is an operation diagram of the comparative example of the wafer transfer device. [Figure 12] 11 is an operation diagram of the comparative example of the wafer transfer device. [Figure 13] 4 is an operational diagram of the first embodiment of the wafer transfer device. FIG. [Figure 14] 4 is an operational diagram of the first embodiment of the wafer transfer device. FIG. [Figure 15] 4 is an operational diagram of the first embodiment of the wafer transfer device. FIG. [Figure 16] 4 is a flowchart showing the operation of the first embodiment of the wafer transfer device. [Figure 17] 11A to 11C are operation diagrams for providing a supplementary explanation of the operation of the wafer transfer device. [Figure 18] 11A to 11C are operation diagrams for providing a supplementary explanation of the operation of the wafer transfer device. [Figure 19] 11A to 11C are operation diagrams for providing a supplementary explanation of the operation of the wafer transfer device. [Figure 20] 11A to 11C are operation diagrams for providing a supplementary explanation of the operation of the wafer transfer device. [Figure 21] 6 is an operational diagram of the second embodiment of the wafer transfer device. FIG. [Figure 22] 6 is an operational diagram of the second embodiment of the wafer transfer device. FIG. [Diagram 23] 6 is an operational diagram of the second embodiment of the wafer transfer device. FIG. [Figure 24] 13 is a flowchart showing the operation of the third embodiment of the wafer transfer device. [Diagram 25] FIG. 13 is a flowchart showing the operation of the fourth embodiment of the wafer transfer device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, a wafer processing system as a substrate processing apparatus according to the present embodiment will be described with reference to the drawings. In this specification, elements having substantially the same functional configurations are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0009] <Wafer Processing System> First, the configuration of the wafer processing system according to this embodiment will be described. Figures 1 and 2 are a plan view and a front view, respectively, that show a schematic outline of the configuration of the wafer processing system 1. In this embodiment, the wafer processing system 1 will be described as an example of a photolithography processing system that performs a resist film forming process and a developing process on a wafer W, which is a circular substrate.

[0010] 1, the wafer processing system 1 has a cassette station 2 where a cassette C containing a plurality of wafers W is loaded and unloaded, and a processing station 3 equipped with a plurality of various processing devices that perform predetermined processing on the wafers W. The wafer processing system 1 has a configuration in which the cassette station 2 and an interface station 4 that transfers the wafers W between the processing station 3 and an exposure device (not shown) adjacent to the opposite side of the processing station 3 are integrally connected. Note that, although two processing stations 3 are installed between the cassette station 2 and the interface station 4 as shown in FIG. 1, one processing station 3 or three or more processing stations may be installed.

[0011] The cassette station 2 is provided with a plurality of cassette mounting plates 21 and wafer transport devices 22 and 23. The cassette station 2 transports wafers between the cassettes C mounted on the cassette mounting plate 21 and the processing station 3 by the wafer transport device 22 or 23. To this end, the wafer transport devices 22 and 23 are each provided with drive mechanisms for directions such as the X direction, Y direction, up and down direction, and around the vertical axis (θ direction) as necessary, and may be provided with drive mechanisms for all directions. At least one of the wafer transfer devices 22 and 23 is capable of transferring wafers between the cassette C and the processing station 3. The transfer operation of the wafer between the processing station 3 means, for example, transferring the wafer between the processing station 3 and a third block G3 including a transfer device accessible by the wafer transfer device 33 in the processing station 3 described later. The third block G3 may include a plurality of transfer devices (not shown) arranged vertically.

[0012] An inspection device (not shown) for inspecting the wafer W may be provided at a position accessible to either the wafer transfer devices 22 and 23.

[0013] The processing station 3 is provided with a plurality of blocks, for example, three blocks G1, G2, and G4, i.e., the first, second, and fourth blocks. Also, as shown in FIG. 2, a plurality of layers 31 each including the first and second blocks G1 and G2 are stacked vertically. For example, the first block G1 is provided on the front side (negative side in the X direction in FIG. 1) of the processing station 3, and the second block G2 is provided on the rear side (positive side in the X direction in FIG. 1) of the processing station 3. The fourth block G4 is provided on the interface station 4 side (positive side in the Y direction in FIG. 1) of the processing station 3 or at a connection portion with another adjacent processing station 3. The fourth block G4 may be provided with a plurality of transfer devices arranged vertically. Also, the above-mentioned third block G3 may be provided within the processing station 3.

[0014] In the first block G1, a plurality of processing devices, such as a patterning film forming device and a development processing device (both not shown), are arranged. The patterning film forming device may include, for example, a resist film forming device and an anti-reflection film forming device.

[0015] For example, a plurality of processing devices are arranged in a horizontal direction. The number, arrangement, and type of these processing devices can be selected arbitrarily.

[0016] In these patterning film forming apparatuses and developing treatment apparatuses, for example, a predetermined processing liquid or a predetermined gas is supplied onto the wafer W. In this manner, in the patterning film forming apparatuses, a resist film used as a mask when forming a pattern of a lower layer film, and an anti-reflection film for efficiently performing a light irradiation process, for example an exposure process, are formed. Meanwhile, in the developing treatment apparatuses, a part of the exposed resist film is removed to form an uneven shape as the mask.

[0017] For example, in the second block G2, heat treatment devices (not shown) that perform heat treatment such as heating and cooling of the wafer W are arranged vertically and horizontally. Also, in the second block G2, although neither is shown, a hydrophobization treatment device that performs a hydrophobization treatment to improve the fixation of the resist liquid to the wafer W, and a peripheral exposure device that exposes the peripheral portion of the wafer W are arranged vertically (Z direction in FIG. 2) and horizontally. The number and arrangement of these heat treatment devices, hydrophobization treatment devices, and peripheral exposure devices can also be selected arbitrarily.

[0018] 1, a wafer transfer area 32 is formed in an area sandwiched between a first block G1 and a second block G2 in a plan view. In the wafer transfer area 32, for example, a wafer transfer device 33 is disposed.

[0019] The wafer transfer device 33 has a transfer arm 33a that is movable in, for example, the Y direction, the front-rear direction, the θ direction, and the up-down direction. The wafer transfer device 33 moves within the wafer transfer area 32 and can transfer the wafer W to a predetermined device within the surrounding first block G1, second block G2, third block G3, and fourth block G4. When there are multiple processing stations 3 as shown in Fig. 1, the wafer transfer device 33 provided in the processing station 3 located on the interface station 4 side can transfer the wafer W to a predetermined device within the fifth block G5 described below in addition to the first, second, and fourth blocks G1, G2, and G3.

[0020] A plurality of wafer transport devices 33 are arranged vertically, for example, as shown in FIG. 2. One wafer transport device 33 can transport a wafer W to a predetermined device located at the height of the upper layers 31 among the layers 31 stacked vertically. Another wafer transport device 33 can transport a wafer W to a predetermined device located at the height of the layers 31 located below the layers 31. A plurality of wafer transport areas 32 are provided to enable such transport of the wafer W. The number of wafer transport devices 33 and the number of layers 31 corresponding to one wafer transport device 33 can be selected arbitrarily, such as providing a wafer transport device 33 for each layer 31.

[0021] The wafer transfer area 32, the first block G1, or the second block G2 may include a shuttle transfer device (not shown). The shuttle transfer device linearly transfers the wafer W between a space adjacent to one side of the processing station 3 and another space adjacent to the opposite side.

[0022] The interface station 4 includes a fifth block G5 equipped with a plurality of transfer devices, and wafer transfer devices 41 and 42. The interface station 4 transfers the wafer W between the fifth block G5, where the wafer W is transferred by the wafer transfer device 33, and the exposure device using the wafer transfer device 41 or 42. To this end, the wafer transfer devices 41 and 42 each include a drive mechanism for the X direction, Y direction, up and down direction, and around the vertical axis (θ direction) as necessary, and may include a drive mechanism for all directions. At least one of the wafer transfer devices 41 and 42 can support the wafer W and transfer the wafer W between the transfer device in the fifth block G5 and the exposure device.

[0023] A cleaning treatment device for cleaning the surface of the wafer W and the above-mentioned peripheral exposure device may be provided in the interface station 4 at a position accessible to either of the wafer transfer devices 41 and 42 .

[0024] The inspection device may be provided in the cassette station 2 as described above, but it may also be provided in the processing station 3 and the interface station 4 at a position accessible to any of the transport arms (33, 41, 42 in Figure 1 or Figure 2) provided inside each of them.

[0025] The above-described wafer processing system 1 is provided with a control device 100. The control device 100 is, for example, a computer, and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of the wafer W in the wafer processing system 1. The program storage unit also stores a program for controlling the operation of the drive systems of the above-described various processing devices and transfer devices, and for realizing the wafer processing in the wafer processing system 1. The above-described program may be recorded in a computer-readable storage medium H and installed from the storage medium H to the control device 100. A group of commands (steps) is incorporated in the program so that the installed program outputs a control signal to each unit of the wafer processing system 1, and the transfer of the substrate by each wafer transfer device and the operation of each processing device are controlled by the control signal.

[0026] <Operation of Wafer Processing System> The wafer processing system 1 is configured as described above. Next, an example of wafer processing performed using the wafer processing system 1 configured as described above will be described.

[0027] First, a cassette C storing a plurality of wafers W is carried into the cassette station 2 of the wafer processing system 1 and placed on the cassette mounting plate 21. Next, each wafer W in the cassette C is sequentially removed by the wafer transfer device 22 or 23 and transferred to a delivery device in the third block G3.

[0028] The wafer W transferred to the transfer device in the third block G3 is supported by the wafer transfer device 33 and transferred to the hydrophobization treatment device provided in the second block G2, where the hydrophobization treatment is performed. Next, the wafer W is transferred by the wafer transfer device 33 to the resist film forming device, where a resist film is formed on the wafer W, and then transferred to the heat treatment device, where the wafer W is pre-baked, and then transferred to the transfer device in the fifth block G5. In addition, when there are multiple processing stations 3 as shown in FIGS. 1 and 2, the wafer W is once placed in the transfer device in the fourth block G4 before being transferred to the transfer device in the fifth block G5, and then transferred between the multiple wafer transfer devices 33. In addition, the wafer W may be transferred to a peripheral exposure device by the wafer transfer device 33 as necessary, where the peripheral portion of the wafer is exposed.

[0029] The wafer W transferred to the delivery device in the fifth block G5 is transferred to the exposure device by wafer transfer devices 41 and 42 and is exposed to a predetermined pattern. Note that the wafer W may be cleaned in a cleaning device before the exposure process.

[0030] The exposed wafer W is transferred to a transfer device in the fifth block G5 by the wafer transfer devices 41 and 42. Thereafter, the wafer W is transferred to a heat treatment device by the wafer transfer device 33 and subjected to post-exposure baking processing.

[0031] The exposed and baked wafer W is transferred by the wafer transfer device 33 to a developing treatment device and developed. After the development is completed, the wafer W is transferred by the wafer transfer device 33 to a heat treatment device and post-baked.

[0032] Thereafter, the wafer W is transferred by the wafer transfer device 33 to a delivery device in the third block G3, and then transferred by the wafer transfer device 22 or 23 in the cassette station 2 to a cassette C on a predetermined cassette mounting plate 21. In this manner, a series of photolithography steps is completed.

[0033] It should be noted that the wafer processing system (substrate processing system) in the present disclosure is not limited to the configuration and operation described above. For example, in the above embodiment, the wafer W is transferred between the interface station 4 and the exposure device, but it does not have to be directly connected to the exposure device. In that case, for example, the wafer W is transferred from the cassette station 2 to the processing station 3, where it is subjected to necessary processing, and then transferred back to the cassette station 2 to be taken out to the outside. Also, among the processing devices listed, those that are not required may not be provided, or processing may not be performed in those devices.

[0034] <Configuration of the wafer transport device> The wafer transfer device 33, which is a substrate transfer device, will be described in more detail with reference to the perspective view of Fig. 3 and the plan view of Fig. 4. The wafer transfer device 33 transfers the wafer W to the processing devices and transfer devices for the wafer W described above. More specifically, it receives the wafer W from a placement unit provided in these devices and places the wafer W on the placement unit. The wafer transfer device 33 includes holders 6A and 6B, a base 60, a lifting platform 61, a frame 62, and a left-right drive block 63, and the holders 6A and 6B correspond to the transfer arm 33a described above.

[0035] The left-right driving block 63 is provided below the second block G2, and is a long member extending in the left-right direction (Y direction) along the wafer transfer area 32. The frame 62 is formed as an upright rectangular frame, and is located in front of the left-right driving block 63. The frame 62 is connected to a driving mechanism of the left-right driving block 63, and moves linearly left and right.

[0036] The rear end side of the lift platform 61 is surrounded by a frame 62, and is connected to a drive mechanism of the frame 62, so that it moves up and down in the vertical direction (Z direction). A base 60 formed in a rectangular shape in a plan view is provided on the lift platform 61, and the base 60 is rotatable about a vertical axis by the lift platform 61. The base 60 is provided with holding parts 6A and 6B. The left-right drive block 63, the frame 62, the base 60, and the lift platform 61 are configured as a movement mechanism for moving the holding parts 6A and 6B, and among them, the base 60 and the lift platform 61 are configured as a lift part that moves up and down together with the holding parts 6A and 6B.

[0037] The holders 6A, 6B are connected to a drive mechanism of the base 60 via a connection part provided on the rear side, and can advance and retreat independently of each other. More specifically, the holders 6A, 6B can move horizontally in a straight line along the length direction of the base 60. The holders 6A, 6B are configured as a first substrate holder and a second substrate holder, respectively, that suction-hold the back surface of the wafer W, and these holders 6A, 6B may be collectively referred to as the holder 6.

[0038] To describe the positional relationship of the holding parts 6A and 6B with respect to the base 60, the holding part 6A is provided higher than the holding part 6B, and each of them moves between a retreated position and an advanced position. Therefore, the holding part 6A advances and retreats in one height region with respect to the base 60, while the holding part 6B advances and retreats in another height region lower than the one height region. In a plan view, the advanced position and the retreated position of the holding part 6A are the same as the advanced position and the retreated position of the holding part 6B, respectively.

[0039] When a wafer W is transferred between the devices of the wafer processing system 1, the base 60 moves from the vicinity of any one device to the vicinity of any other device. At that time, the holders 6A and 6B are located at the retracted positions on the base 60. FIG. 3 shows a state in which the holders 6A and 6B are both located at the retracted positions. When the wafer W is transferred between the holders 6A and 6B and the placement part of the device (placing the wafer W or receiving the wafer W), the base 60 and the lifting platform 61 move up and down with the holder used for the transfer being located at the forward position among the holders 6A and 6B. FIG. 4 shows a state in which the holders 6B and 6A are located at the forward position and the retracted position, respectively.

[0040] The holding part 6A will be described with reference to FIG. 4. The holding part 6A is a horizontal plate-like body that is roughly C-shaped in a plan view with the forward movement direction open, and surrounds the side circumference of the wafer W to be held. The holding part 6A has four claws 64 protruding from the lower end of its inner circumference, and these claws 64 are formed apart from each other in the circumferential direction of the inner circumference. On each of the claws 64, a pad 66 having a suction hole 65 that opens upward is provided. The peripheral portion of the wafer W is placed on each of the pads 66 so as to close the suction hole 65, and the wafer W is supported horizontally by being placed in this manner. In order to prevent interference between the wafer W and the inner circumference of the holding part 6A, the diameter of a circular area surrounded by the holding part 6A and on which the wafer W is placed is formed slightly larger than the diameter of the wafer W.

[0041] An exhaust path 67 is embedded within the holding part 6A. The upstream side of this exhaust path 67 branches into four, and each branch end is connected to the suction hole 65. The downstream side of the exhaust path 67 is led out to the outside of the holding part 6A, and a valve V is provided on this downstream side.

[0042] The holding part 6B is configured similarly to the holding part 6A, and includes the same components as the holding part 6A described above. However, in the following description, the suction hole 65, exhaust path 67, and valve V in the holding part 6A are referred to as 65A, 67B, and VA, and the suction hole 65, exhaust path 67, and valve V in the holding part 6B are referred to as 65B, 67B, and VB, so that they may be distinguished from one another. The suction holes 65A and 65B correspond to the first suction hole and the second suction hole, respectively.

[0043] The exhaust path 67A of the holding part 6A and the exhaust path 67B of the holding part 6B merge with each other upstream of the position where the valves VA and VB are provided to form a merged exhaust path 68. A pressure sensor 69 is provided in this merged exhaust path 68, and the pressure sensor 69 transmits a detection signal corresponding to the pressure in the merged exhaust path 68 to the control device 100. The control device 100 can detect the pressure in the merged exhaust path 68 based on the detection signal. The upstream end of the merged exhaust path 68 is connected to an exhaust source 50. The exhaust source 50 is composed of an exhaust mechanism such as an exhaust blower provided in a factory where the wafer processing system 1 is installed.

[0044] As described above, the suction holes 65A, 65B are connected to the exhaust source 50 by the exhaust paths 67A, 67B in which the joint exhaust path 68 and the valves VA, VB are interposed. Therefore, for the holding part 6A, suction is performed from the suction hole 65A via the exhaust path 67A when the valve VA is open, and suction from the suction hole 65A stops when the valve VA is closed. Therefore, when a wafer W is placed on the pad 66 of the holding part 6A, a suction force acts on the wafer W and the wafer W is held by being attracted to the pad 66 when the valve VA is open, whereas this suction is released when the valve VA is closed.

[0045] That is, opening the valve VA puts the wafer W into a first state in which a first suction force acts on the wafer W toward the pad 66, and closing the valve VB puts the wafer W into a second state in which a second suction force smaller than the first suction force acts on the wafer W. Note that even after the valve VA is closed, a pressure difference may remain between the inside of the suction hole 65 and the periphery of the pad 66, so this second suction force is not necessarily zero. In this way, the valve VA corresponds to a suction force changing unit that switches the suction force.

[0046] Similarly to holding unit 6A, holding unit 6B switches between the presence and absence of suction from suction hole 65B by opening and closing valve VB, thereby switching the strength of the suction force acting on wafer W placed on pad 66. This switches between a state in which wafer W is suction-held to pad 66 and a state in which suction-holding is released.

[0047] As will be described in detail later, opening and closing of valves VA, VB in this manner changes the pressure in joint exhaust path 68 in which pressure sensor 69 is provided. When transferring wafer W, controller 100 determines whether or not wafer W is being sucked by suction hole 65A of holder 6 (i.e., whether or not wafer W is being held by suction by holder 6) based on the detected pressure value.

[0048] In addition, when the wafer W is placed on the pad 66, suction is applied from the suction holes 65 except when the lift table 61, the base 60, and the holder 6 are raised and lowered to deliver the wafer W to the placement part as described above. By applying suction in this manner, it is possible to prevent the position of the holder 6 and the wafer W from shifting, and thus prevent the wafer W from being placed out of position with respect to a predetermined position on the placement part.

[0049] The transfer of the wafer W by the wafer transfer device 33 will be described in more detail. The wafer transfer device 33 receives the wafer W at one of the holders 6A and 6B that does not hold the wafer W from the placement portion of any one of the devices, and then places the wafer W held at the other holder 6 on the placement portion of the one of the devices. The wafer W placed on this placement portion is the wafer W received from the device preceding the one of the devices on the transfer path of the wafer W in the wafer processing system 1. If such a transfer is called a replacement transfer, the replacement transfer is performed in a predetermined order for each device that the wafer transfer device 33 is set to access. As a result, the wafers W are moved one by one to the devices downstream on the transfer path in order and processed.

[0050] As will be described in detail later with reference to the drawings, in order to place the wafer W on the placement part, the holder 6 holding the wafer W moves to the forward position, and the wafer W is placed directly above the placement part. After the wafer W is placed, the valve V corresponding to the holder 6 is closed to stop suction through the suction hole 65, and the holder 6, the base 60, and the lift table 61 are lowered in a state in which the wafer W is no longer held by suction by the holder 6. The reason why the suction of the wafer W is stopped when the holder 6 and the like are lowered in this manner is that if the wafer W comes into contact with the placement part when the valve V is open and suction is being performed, a relatively large force is applied to the wafer W. If such a large force is applied, there is a concern that the back surface of the wafer W may be damaged, or the wafer W may bounce off the placement part and not be placed at the desired position.

[0051] In order to reliably prevent the occurrence of this problem, after valve V is closed as described above, controller 100 determines whether the pressure in joint exhaust path 68 detected by pressure sensor 69 is within a preset allowable range. As described above, the pressure in joint exhaust path 68 corresponds to the open / closed state of valves VA, VB, i.e., the state of the suction force on wafer W in holding parts 6A, 6B, so controller 100 and pressure sensor 69 which detect the pressure in joint exhaust path 68 correspond to detection parts for detecting the state of the suction force.

[0052] Then, if it is determined that the amount is within the acceptable range, suction from the suction hole 65 is stopped by closing the valve V, and the operation of the wafer transport device 33 is controlled so that the holding part 6 is lowered and the wafer W is placed on the placement part, as described above.

[0053] On the other hand, if it is determined that the pressure does not fall within the allowable range, the control device 100 redetects the pressure in the joint exhaust path 68 after a predetermined time has elapsed since the previous pressure detection, and re-determines whether the pressure falls within the allowable range. If the re-determination determines that the pressure falls within the allowable range, the operation of the wafer transfer device 33 is controlled so that the wafer is placed on the placement unit. If it is determined that the pressure does not fall within the allowable range, the operation of each unit of the wafer transfer device 33 is stopped, and the transfer of the wafer W by the wafer transfer device 33 is stopped. The number of times that the pressure is redetected and re-determined before the transfer is stopped can be set as appropriate.

[0054] <Examples and Comparative Examples> Below, we will explain the operation of the comparative example and the operation of the embodiment when the wafer transport device 33, with the wafer W adsorbed and held by the holding portion 6A, performs a swap transport to the mounting portion of the patterning film forming apparatus provided in the first block G1.

[0055] As described above, the wafer W is transported surrounded by the holders 6, but in each explanatory diagram, in order to prevent the diagrams from becoming too complicated, the wafer W is shown as being transported positioned on the holders 6. As for the wafer transport device 33, only the base 60 and holders 6 are shown, and the display and description of other parts are omitted. The holders 6 that suction-hold the wafer W are shown with an arrow pointing from the wafer W to the holder 6. The wafer W that the wafer transport device 33 places on the placement part and the wafer W that it receives from the placement part are shown as W1 and W2, respectively. Wafer W1 corresponds to the first substrate, and wafer W2 corresponds to the second substrate.

[0056] The patterning film forming apparatus is further explained. The patterning film forming apparatus is equipped with a spin chuck 51 that rotates while horizontally suction-holding the central part of the back surface of the wafer W in order to form a film by spin coating, and three pins 52 on whose upper ends the wafer W is placed horizontally and each of which extends vertically. The pins 52 move up and down between a position (upper position) where the upper end is above the spin chuck 51 and a position (lower position) where the upper end is below the spin chuck 51, and this movement allows the wafer W to be transferred to and from the spin chuck 51. The pins 52 in the upper position correspond to the placement portion described above, and the pins 52 in the following explanatory drawings show the state in which they are positioned at this upper position.

[0057] In the patterning forming apparatus, the wafer W held by the spin chuck 51 is rotated to form a film by spin coating, and then a process called EBR (Edge Bead Removal) is performed in which a solvent is supplied from a nozzle to a predetermined position on the periphery of the wafer W while the wafer W is rotating. Unnecessary portions of the film are removed by this EBR.

[0058] <Operation of Comparative Example> 5 to 12 show the operation of the comparative example. With wafer W1 held by suction on holder 6A, base 60 moves from near the upstream device of the patterning film forming apparatus to near the patterning film forming apparatus, and is positioned at a predetermined height relative to pins 52 in the raised position (FIG. 5). Next, holder 6B moves from the retreated position to the advanced position, and is positioned below wafer W2 placed on pins 52 (FIG. 6), and base 60 and holder 6 rise, so that holder 6B scoops up and receives wafer W2.

[0059] Valve VB is opened to start suction, and wafer W2 is held by holder 6B. Then, when base 60 and holder 6 stop rising and holder 6A is positioned at a predetermined height H1 above pins 52 (FIG. 7), holder 6B moves toward its retracted position and holder 6A moves from its retracted position toward its advanced position (FIG. 8). When this movement to the advanced position is completed (FIG. 9), valve VA is closed to release wafer W1 from its suction hold (FIG. 10).

[0060] When the valve VA is closed with the suction holes 65A and 65B of the holder 6A and holder 6B blocked by the wafers W1 and W2, respectively, the region of the exhaust path 67A upstream of the valve VA is not exhausted by the exhaust source 50. That is, the volume of the joint exhaust path 68 and the exhaust paths 67A and 67B exhausted by the exhaust source 50 is reduced by closing the valve VA. Therefore, if the valve VA is normally closed, the detection value of the pressure sensor 69 decreases. Then, when it is determined that the detection value of the pressure sensor 69 falls within the allowable range, the suction from the suction hole 65A stops and the suction holding is released, and the base 60 and holder 6 are lowered in the vertical direction.

[0061] The base 60 and the holder 6 are lowered, so that the wafer W1 is placed on the pins 52. When the holder 6A is positioned at a predetermined height H2 below the upper ends of the pins 52, the lowering of the base 60 and the holder 6 stops (FIG. 11). In FIG. 11, the height difference between height H1, which is the distance the holder 6A is lowered, and height H2 is indicated as L1. After the lowering stops, the holder 6A moves to the retreated position, and the replacement transfer ends (FIG. 12).

[0062] As described above, when the lower holder 6B receives the wafer W2, the holder 6B moves upward together with the base 60 and the holder 6A. Therefore, when the reception of the wafer W2 is completed, a relatively large height difference is formed between the holder 6A, which is provided above the holder 6B, and the upper ends of the pins 52. In this comparative example, the holder 6A moves down a relatively long distance L1 with the suction holding of the wafer W1 released, thereby placing the wafer W1 on the pins 52.

[0063] However, if the wafer W1 is lowered a long distance without being adsorbed in this way, the wafer W1 will be affected for a long time by the vibration of the holder 6A caused by the drive mechanism provided in the wafer transfer device 33 and by the wind pressure during the descent, and this may cause the wafer W1 to become misaligned with the holder 6A. If the wafer W1 is misaligned with the holder 6A in this way, the wafer W1 will be misaligned with respect to the predetermined position on the pins 52 and the predetermined position on the spin chuck 51, and therefore the width of the region from which the film is removed may deviate from the allowable range when the above-mentioned EBR is performed.

[0064] <Operation of the First Example> The first embodiment will be described, focusing on the differences from the comparative example, with reference to the explanatory diagrams in Figures 13 to 15, the chart in Figure 16, and the already-described Figures 5 to 9. In Figure 16 and each chart, which will be described later, the horizontal axis indicates time, and the vertical axis indicates the descending speed of the holding part 6 and the base 60, respectively.

[0065] First, the same operation as in the comparative example described in FIG. 5 to FIG. 9 is performed, and the holder 6B receives the wafer W2 from the pins 52, and the holder 6B moves to the retreated position, while the holder 6A moves to the advanced position. By receiving the wafer W2, the holder 6A is located at a predetermined height H1 above the pins 52 during this forward movement. Then, the base 60 and the holder 6 start to descend vertically (time t1 in the chart), and the descending speed reaches a predetermined speed S1. Thereafter, with the wafer W1 located above the pins 52, the descending speed of the base 60 and the holder 6 decreases (time t2). Note that, when the holder 6A descends from the height H1 in this manner, the wafer W1 continues to be held by suction.

[0066] Then, when the holding portion 6A reaches a predetermined height H3 above the pin 52, the descent of the base 60 and the holding portion 6 stops and they come to a standstill (FIG. 13, time t3). Therefore, the descent of the holding portion 6A continues from when the holding portion 6A is at height H1 until it reaches height H3. That is, the holding portion 6A descends without stopping midway until it reaches height H3.

[0067] Next, the valve VA is closed to release the suction hold of the wafer W1 (time t4, FIG. 14). Thereafter, when it is determined that the pressure detected by the pressure sensor 69 falls within the allowable range, the vertical descent of the base 60 and the holder 6 is resumed (time t5). That is, the suction force of the suction holes 65A on the wafer W1 is reduced, and after it is confirmed that the suction hold of the wafer W1 is released, the descent is resumed. Then, the descent speed of the base 60 and the holder 6 reaches S1 again.

[0068] Then, when the wafer W1 is placed on the pins 52, the descent speed of the base 60 and the holder 6 slows down, and the holder 6A is positioned at height H2, the descent of the base 60 and the holder 6 stops (FIG. 15, time t6). Therefore, the holder 6A continues to descend from the position at height H3 until it reaches height H2. After the holder 6A moves to height H2 in this manner, the holder 6A returns to the retracted position as shown in FIG. 12 for the comparative example.

[0069] If the wafer W1 is released from suction while the holder 6A is moving forward, there is a risk that the wafer W1 may be displaced from its position relative to the holder 6A due to inertial movement of the wafer W1 when the holder 6A stops moving forward. Therefore, in both the first embodiment and the comparative example, the wafer W1 is released from suction when the forward movement is completed, to prevent such a displacement from occurring. As shown in Figures 13 to 15, in the first embodiment, the descent of the holder 6A is stopped midway, and the suction of the wafer W (stop of suction and holding) is confirmed based on the pressure detected by the pressure detection (i.e., it is determined that the detected value is within the allowable range), and then the wafer W is landed on the pins 52.

[0070] In this way, the distance L2 (see FIG. 15) from the height H3 at which the descent of the holder 6 and the like is temporarily stopped to release the suction hold to the height H2 at which the descent ends is shorter than the distance L1 (see FIG. 11) from the height H1 at which the suction hold is released to the height H2 in the comparative example. That is, the distance by which the holder 6A descends without suction holding the wafer W1 until the wafer W1 lands on the pins 52 is shorter in the first embodiment. Therefore, in the first embodiment, the wafer W can be placed at a predetermined position on the pins 52 with high accuracy, and as a result, the occurrence of the above-mentioned problems when performing EBR can be suppressed. For example, the height H3 is an intermediate height between the heights H1 and H2, and the distance L2 is 1 / 2 the length of the distance L1. The height H1 corresponds to the first height, the height H2 corresponds to the third height, and the height H3 corresponds to the second height.

[0071] <Supplementary explanation of the operation of the first embodiment> The operation of the wafer transfer device 33 when transferring the wafer W to the next device of the patterning film forming device on the transfer path will be described with reference to Figures 17 to 20. That is, the operation shown in Figures 17 to 20 is the operation performed after the operation described in Figures 13 to 15, in which the wafer W2 received by the holder 6B is sent to the next device of the patterning film forming device, and the holder 6A receives the wafer W (assumed to be W3) from the next device. The next device is, for example, a transfer device in the fourth block G4 (see Figure 1), which has three pins 59 extending vertically as a mounting portion for the wafer W, and the wafer W is mounted horizontally on the upper ends of the pins 59.

[0072] First, the base 60 moves near the transfer device and is positioned at a predetermined height relative to the pins 59, and then the holder 6A moves to the forward position (FIG. 17). Then, the base 60 and the holder 6 rise, and the holder 6A receives the wafer W3, and the valve VB is opened so that the wafer W3 is suction-held by the holder 6A. Thereafter, the rise of the base 60 and the holder 6 stops, and the holder 6A moves to the retreated position while the holder 6B moves to the forward position (FIG. 18), and the wafer W2 is positioned at a predetermined height H4 above the pins 59. Then, the valve VB is closed to release the suction-held wafer W2 (FIG. 19).

[0073] Thereafter, when it is determined that the detection value by the pressure sensor 69 falls within the allowable range, the suction of the wafer W2 in the holder 6B is stopped, the base 60 and the holder 6 are lowered vertically, and the wafer W2 is placed on the pins 52. Then, when the holder 6B is positioned at a predetermined height H5 below the upper ends of the pins 59, the lowering of the base 60 and the holder 6 is stopped (FIG. 20), the holder 6B is moved to the retreated position, and the replacement transfer is completed. Note that, for example, the difference in height between the height H5 and the upper ends of the pins 59 is the same as the difference in height between the height H2 (see FIG. 15) and the upper ends of the pins 52. Also, for example, the distance L3 (height difference between the height H4 and the height H5, see FIG. 20) by which the holder 6B that has released the suction state descends is the same as the distance L2 (see FIG. 15) by which the holder 6A that has released the suction state descends.

[0074] As described above, when placing the wafer W by the holder 6B, unlike when the wafer W is placed by the holder 6A, there is no temporary stop during the descent of the holder 6 to the placement portion to detect whether the wafer W is being sucked or not. This is because, due to the positional relationship between the holders 6A and 6B, when the holder 6A that has received the wafer W stops rising, the difference in height between the holder 6B and the upper ends of the pins 59 is relatively small, and the distance L3 by which the holder 6B descends to place the wafer W on the pins 59 is short.

[0075] In this way, the operation pattern of the wafer transfer device 33 is different between when the wafer W is placed on the placement portion by the holder 6A and when the wafer W is placed on the placement portion by the holder 6B. By making the operation pattern different in this way and not temporarily stopping during descent when the wafer W is placed on the placement portion by the holder 6B, a decrease in transfer efficiency is suppressed. As a result, a decrease in throughput in the wafer processing system 1 is suppressed.

[0076] <Operation of the second embodiment> Next, replacement transport for the patterning film forming apparatus in the second embodiment will be described with reference to FIGS. 21 to 23 and the already described FIGS. 5 to 7, focusing on the differences from the transport in the first embodiment.

[0077] First, the base 60 is positioned near the patterning device, and the wafer W2 is received by the holder 6B from the pins 52 in the same manner as in the first embodiment and the comparative example. That is, the operation described in Fig. 5 to Fig. 7 is performed, and the lifting of the holder 6 and the base 60 stops when the holder 6A is in the retreated position and at a predetermined height H1 above the pins 52.

[0078] As in the first embodiment, the holding part 6A moves from the retracted position to the forward position, and the holding part 6B moves from the forward position to the retracted position, but at the same time as these forward and backward movements, the holding part 6 and the base 60 descend (FIG. 21). Therefore, the holding part 6A moves diagonally downward and forward.

[0079] Thereafter, when the holder 6A reaches the forward position and reaches a predetermined height H3 above the pins 52, the descent of the holder 6 and the base 60 stops, and the holder 6A comes to a stationary state (FIG. 22). After the holder 6A comes to a stationary state at height H3 in this manner, the valve VA is closed, the detection value of the pressure sensor 69 is determined, and the holder 6A is lowered to height H2 to place the wafer W1 on the pins 52, as in the first embodiment (FIG. 23). Note that in this second embodiment, as in the first embodiment, the descent speed of the holder 6A is controlled as described in the chart of FIG. 16 until the holder 6A descends from height H1 to height H3.

[0080] In the second embodiment, the forward movement and downward movement of the holder 6A are performed in parallel so that the holder 6A moves obliquely downward from a position at height H1 to a position where it stops at height H3. Therefore, the holder 6A can be quickly positioned at height H3. Therefore, according to the second embodiment, in addition to being able to increase the accuracy of the placement position of the wafer W1 on the pins 52 like the first embodiment, the transfer efficiency of the wafer transfer device 33 can be increased, which is preferable.

[0081] However, in the second embodiment, the holder 6A is not limited to only moving obliquely from the height H1 until it reaches the height H3 at which the suction of the wafer W1 is stopped. The holder 6A may move obliquely downward from the height H1 and then vertically downward to reach the height H3, or may move vertically downward from the height H1 and then obliquely downward to reach the height H3.

[0082] <Operation of the third embodiment> In the first and second embodiments, the descent of the holder 6A is temporarily stopped at a predetermined height H3, and the descent of the holder 6A is resumed after the detection value of the pressure sensor 69 is determined in order to reliably prevent the occurrence of the above-mentioned malfunction caused by the wafer W1 landing on the pins 52 while the holder 6A is holding the wafer W1 by suction. In other words, if the holder 6A is assumed to descend relatively quickly and the detection value of the pressure sensor 69 is determined during the descent, it may be too late to control the descent to stop if an abnormality is determined, and the above-mentioned malfunction may occur. In order to prevent such malfunction, in the first and second embodiments, the determination is made while the descent is temporarily stopped.

[0083] However, the descent of the holder 6A is not limited to being temporarily stopped in this manner. A third embodiment in which the temporary stop is not performed will be described with reference to the chart in FIG. 24, focusing on the differences from the first embodiment. As described in FIG. 5 to FIG. 9, the holder 6B receives the wafer W2, the holder 6A is positioned at a predetermined height H1, and the holder 6A moves to the forward position and the holder 6B moves to the backward position. After that, the base 60 and the holder 6 start to descend in the vertical direction and reach a predetermined speed S1 (time t11), after which the descent speed of the base 60 and the holder 6 decreases (time t12). After that, the descent speed becomes a constant and relatively low speed S0 (time t13), and the base 60 and the holder 6 continue to descend at the speed S0.

[0084] During the descent at the speed S0, the valve VA is closed (time t14) to release the wafer W1 held by the holder 6A, and it is determined whether the detected pressure value is within the allowable range. If it is determined that the detected pressure value is within the allowable range, the base 60 and the holder 6 continue to descend and the wafer W1 is placed on the pins 52. Then, when the holder 6A is positioned at a predetermined height H2 as shown in FIG. 15, the descent of the base 60 and the holder 6 is stopped (time t15). Therefore, in this third embodiment, if it is determined that the pressure is within the allowable range, the holder 6A continues to descend from the height H1 to H2, and the descent is not stopped midway. Then, the height of the holder 6A at the time when it is determined that the pressure is within the allowable range during the descent corresponds to the second height.

[0085] On the other hand, if it is determined that the wafer W1 does not fall within the allowable range, the descent of the base 60 and holder 6 is stopped. Because the base 60 and holder 6 are in a state of descending at a low speed, this can be stopped before the wafer W1 lands on the pins 52. After this descent has stopped, as described above, the pressure is redetected by the pressure sensor 69, and it is determined again whether or not the pressure falls within the allowable range. Depending on the result of this re-determination, the descent is resumed to place the wafer W1 on the pins 52, or the transfer by the wafer transfer device 33 is stopped.

[0086] In FIG. 24, the descent speed of the holding part 6A is shown as being maintained at speed S0 after being reduced to speed S0 until just before the descent stops, but after it is determined that the detected pressure is within the allowable range as described above, the speed may be increased from S0 to improve the conveying efficiency.

[0087] Incidentally, even when the forward movement of the holding part 6A is performed before the holding part 6A reaches the height H2 from the height H1 as in the second embodiment, the control of the lowering operation described in FIG. 24 may be applied. That is, the lowering operation of the holding part 6A is not stopped during the lowering, and the lowering speed is reduced before the wafer W1 comes into contact with the pins 52, and the valve VA is closed and it is determined whether the detected pressure value falls within the allowable range. The time t12 (see FIG. 24) at which the lowering speed starts may be during the forward movement of the holding part 6A or after the forward movement is completed. Note that the time t14 at which the valve VA is closed may be after the forward movement of the holding part 6A is completed so as to prevent the positional deviation of the wafer W1 with respect to the holding part 6A.

[0088] <Operation of the Fourth Example> In the fourth embodiment, the same control as in the first embodiment is performed, except that the transition of the descent speed of the holding part 6A from height H1 to height H2 is different from that in the first embodiment. The chart in FIG. 25 shows the transition of the descent speed in the fourth embodiment. As in the first embodiment, the maximum descent speed of the holding part 6A is S1 from height H1 at which the holding part 6A starts to descend until it reaches height H3 at which the descent pauses. The maximum descent speed of the holding part 6A from height H3 to height H2 at which the descent pauses again is controlled to be S2, which is lower than S1.

[0089] Controlling the descent speed as described above reduces the impact when the wafer W1 is placed on the pins 52, and more reliably prevents the above-mentioned displacement of the wafer W1 on the pins 52 and damage to the back surface of the wafer W. The control of the descent speed shown in Fig. 25 may also be applied to the second embodiment, and the maximum speed during descent may be made different before and after the temporary stop of the descent of the holder 6A.

[0090] In order to perform the speed control shown in Figure 25, the positional relationship between the height H1 at which the descent of the holding portion 6A begins, the height H2 at which the descent stops, and the height H3 at which the descent is temporarily stopped is not limited to the positional relationship described above, and may be changed as appropriate from the relationship described above.

[0091] <Other Modifications> In the first and second embodiments, the valve VA is closed after the descent of the holding unit 6A is stopped at the height H3. However, the timing of closing the valve VA is not limited to this. For example, the valve VA may be closed at the same time as the descent of the holding unit 6A is stopped. That is, the valve VA may be closed at time t3 in the chart of FIG. 16. The valve VA may be closed before time t3, for example, at time t2 when deceleration starts, but as described above, it is desirable to shorten the descent distance of the holding unit 6A with the valve VA closed. Therefore, it is preferable that the valve VA is closed after time t3 when the descent of the holding unit 6A is stopped. Incidentally, a time lag occurs between the output of a control signal from the control device 100 instructing the closing of the valve VA and the actual completion of the closing of the valve VA. The timing of closing the valve VA referred to here is the timing of the output of the control signal from the control device 100.

[0092] Incidentally, the holder 6A has been described as being stationary at height H3 by stopping its descent and completing its movement to the forward position. "Stationary" here means being stationary according to an instruction from the control device 100. Therefore, movement due to unavoidable forces, such as vibrations caused by the action of each driving mechanism of the wafer transport device 33, may occur.

[0093] Monitoring of the open / closed state of the valve V, i.e., monitoring of the suction force by the suction hole 65, is not limited to monitoring the pressure in the exhaust path. For example, a configuration may be adopted in which the movement of a valve element constituting the valve V is monitored by a position sensor, and the open / closed state or suction force of the valve V is monitored based on the detection result of this position sensor.

[0094] Although an example has been shown in which the suction force of the suction hole 65 is switched by switching the valve V between open and closed, the valve V does not have to be closed to change the suction force. Specifically, the valve V is configured to be switched between a first opening and a second opening that is smaller than the first opening and is not in a closed state. The suction force can be changed by setting the valve V to the first opening during the period described above in which the valve V is in an open state, and setting the valve V to the second opening during the period described above in which the valve V is in a closed state.

[0095] Furthermore, when the suction force is monitored by the pressure sensor 69, the position at which the pressure sensor 69 is provided is not limited to the position described above. For example, the pressure sensor 69 may be provided upstream of the valves VA and VB in the exhaust paths 67A and 67B, respectively. That is, the pressure sensor 69 may be provided individually in the holding parts 6A and 6B. When the pressure sensor 69 is provided in this manner, when the suction of the corresponding holding part 6 stops due to the closing of the valve V, the detected pressure value increases as the atmosphere around the holding part 6 flows in through the suction hole 65, and it is possible to confirm that the valve V is closed.

[0096] The above-described transfer of the wafer W by the holders 6A and 6B can also be applied to transfer by a wafer transfer device other than the wafer transfer device 33, and the wafer W can be placed with high precision on the placement position of the placement part in the transfer destination device. This can prevent the occurrence of processing problems in the device due to placement abnormalities.

[0097] The wafer transfer device does not necessarily have to be provided with the holder 6B. Therefore, although the wafer W is placed by the holder 6A as an operation during replacement transfer using both the holders 6A and 6B, this placing operation is not limited to an operation during replacement transfer. However, as described above, when performing replacement transfer, the holder 6A after receiving the wafer W2 by the holder 6B is positioned relatively far from the placement part due to the positional relationship between the holders 6B and 6A. Therefore, it is particularly effective to apply the present technology to a wafer transfer device that performs replacement transfer.

[0098] Furthermore, in each embodiment (each example), the substrate to be processed and transported is not limited to a wafer, and may be, for example, a substrate for manufacturing a flat panel display, or a mask substrate for manufacturing a mask for exposure. The shape of the mounting portion on which the substrate is placed is also not limited to pins, and may be a mounting portion with an upper end formed as a flat surface.

[0099] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, modified, and combined in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0100] W wafer VA Valve 6A holding part 60 Foundations 61 Lift platform 65A Suction hole 69 Pressure Sensor 100 Control device

Claims

1. a first substrate holder having a first suction hole for holding the substrate by suction; a suction force changing unit for switching a suction force by the first suction hole between a first state and a second state lower than the first state; A detection unit for detecting a state of the suction force; a moving mechanism that moves the first substrate holding unit, which holds the substrate in the first state, by decelerating the first substrate holding unit during descent from a first height to a second height above the placement unit, and then, after a change to the second state is detected, by descent from the second height to a third height below an upper end of the placement unit, so that the substrate is transported from the first substrate holding unit to the placement unit; A substrate transport apparatus comprising:

2. The substrate transport apparatus according to claim 1 , wherein the second height is a height at which the first substrate holder stops descending.

3. an exhaust passage connecting the first suction hole to an exhaust source for generating the suction force; a valve that constitutes the suction force changing unit and is provided in the exhaust path, 3. The substrate transport apparatus according to claim 1, wherein the second state is achieved by closing the valve.

4. the second substrate holding portion including a second suction hole for holding the substrate by suction; a lifting unit that is included in the moving mechanism and lifts and lowers together with the first substrate holding unit and the second substrate holding unit, the first substrate holding portion is movable forward and backward with respect to the lifting and lowering portion at one height region, and the second substrate holding portion is movable forward and backward with respect to the lifting and lowering portion at another height region below the one height region, 3. A substrate transport device as described in claim 1 or 2, wherein while the first substrate holding portion holds a first substrate, the second substrate holding portion receives and holds a second substrate separate from the first substrate from the loading portion, and then the first substrate holding portion transports the first substrate to the loading portion.

5. The substrate transport device of claim 4 , wherein the first substrate holding portion moves from the first height to the second height by the lifting portion lowering at the same time as the first substrate holding portion advances relative to the lifting portion.

6. A substrate transport device as described in claim 2, wherein the maximum descent speed of the first substrate holding part when moving from the second height to the third height is smaller than the maximum descent speed of the first substrate holding part when moving from the first height to the second height.

7. a step of sucking and holding the substrate by a first suction hole provided in the first substrate holding part; switching, by a suction force changing unit, a suction force by the first suction hole between a first state and a second state lower than the first state; detecting a state of the suction force by a state detection unit; a first lowering step of decelerating the first substrate holder, which holds the substrate in the first state, by a moving mechanism while lowering the first substrate holder from a first height to a second height above the placement part; a second lowering step of lowering the first substrate holding part from the second height to a third height below an upper end of the placement part by the moving mechanism after the change to the second state is detected, thereby transporting the substrate from the first substrate holding part to the placement part; A substrate transport method comprising:

8. The substrate transfer method according to claim 7 , wherein the first lowering step includes a step of stopping the lowering of the first substrate holding part at the second height.

9. To switch from the first state to the second state, 9. The substrate transport method according to claim 7, further comprising the step of closing a valve provided in an exhaust path connecting the first suction hole to an exhaust source for generating the suction force.

10. a step of sucking and holding the substrate by a second suction hole provided in a second substrate holding portion; raising and lowering a lifting unit included in the movement mechanism together with the first substrate holding unit and the second substrate holding unit; a step of moving the first substrate holding part forward and backward with respect to the lifting and lowering part at one height region and the second substrate holding part forward and backward with respect to the lifting and lowering part at another height region below the one height; a receiving step in which the second substrate holding portion receives and holds a second substrate separate from the first substrate from the placement portion while the first substrate holding portion holds a first substrate.

9. The substrate transport method according to claim 7, wherein the first lowering step and the second lowering step are performed after the receiving step.

11. The first lowering step includes: The substrate transfer method according to claim 10 , further comprising the step of moving the first substrate holding part forward relative to the lift part and lowering the lift part at the same time.

12. 9. The substrate transport method according to claim 8, wherein a maximum descending speed of the second substrate holding part in the second descending step is smaller than a maximum descending speed of the first substrate holding part in the first descending step.

13. A storage medium for storing a computer program used in a substrate transport device, A storage medium in which the computer program is programmed with steps for executing the substrate transport method according to claim 7.

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