Substrate gripping device, substrate conveying robot provided with same, inverting device, and substrate gripping method

Abstract

Provided are a substrate gripping device for gripping a warped substrate (for example, a semiconductor substrate, a liquid crystal substrate, and other thin substrates), a substrate conveying method, and a substrate conveying robot and an inverting device that employ the same.　The substrate gripping device is provided with a plurality of rods 30 which have a plurality of suction attachment portions 33 for sucking and holding a semiconductor wafer or other substrate 60 and which are arranged spaced apart from each other, a base portion 12 that supports at least one rod among a plurality of rods 30a, 30b such that the longitudinal-direction angle thereof relative to a horizontal plane can be changed, and angle changing portions 15 and 20 to 25 that change the angles of the rods 30a, 30b, wherein a substrate suction-attachment point is searched for by changing the longitudinal-direction inclination angle of the rods 30a, 30b by means of the angle changing portions 15 and 20 to 25, allowing the substrate to be reliably suction-attached.

Description

Substrate gripping device, substrate transfer robot equipped with the same, inversion device, and substrate gripping method

[0001] The present invention relates to a substrate gripping device that adsorbs and grips a substrate in order to perform operations such as transferring or inverting a semiconductor wafer, a liquid crystal substrate, or other thin plate-like substrates (hereinafter simply referred to as "substrates"), a substrate transfer robot that includes this substrate gripping device and transfers the substrate between a FOUP and various processing devices, a substrate inversion device that inverts the substrate, and a substrate transfer method using this substrate.

[0002] Substrates for manufacturing precision electronic components such as semiconductor wafers and liquid crystal display panels are subject to various manufacturing processes and inspection processes such as photoresist coating, thin film deposition, creation of oxide films and nitride films, etching, heat treatment, and cleaning in sequence. Through various processes, semiconductor devices and liquid crystal display devices equipped with precise integrated circuits are manufactured. For example, in the case of a semiconductor wafer, in a processing step, when one processing step on the substrate surface is completed, the substrate is stored in a sealable clean container called a FOUP and transferred to the next step.

[0003] For these substrates, for various processing, they are taken out from the FOUP by a substrate transfer robot or the like in a clean space, inverted or position-adjusted as necessary, and transferred to a processing device. After one processing is completed, the substrate is taken out and stored again in the FOUP or directly carried into the next processing device.

[0004] In order to transfer, invert, position-adjust, or process the substrate in this way, the transfer robot needs to grip and transfer the substrate and deliver it to a processing device, an inversion device, an aligner, etc. The present invention relates to such a substrate gripping device. There are a clamp method of gripping by sandwiching the edge of the substrate and a method of gripping by sucking the back surface of the substrate. The present invention relates to a substrate gripping device that grips by the suction method.

[0005] As described above, various processing treatments are performed on the substrate. In particular, polishing and heat treatments subject the substrate to various physical stresses, which can cause warping. When the substrate warps, the suction part of a suction-type substrate gripping device may not be able to smoothly grip the back surface of the substrate, which can lead to unstable substrate gripping. Various prior arts have been proposed to enable substrate gripping in such cases.

[0006] For example, Patent Document 1 describes a device in which the position of a suction cup 61, which corresponds to an adhesive pad, is raised and made to protrude, thereby absorbing the amount of warping of the substrate by the raised height and facilitating the adsorption of the substrate W. Patent Document 2 also describes a configuration in which the support part (pad 20) that adsorbs and supports the substrate W is made of a deformable soft material, and when the substrate W is warped, the pad 20 deforms to adsorb the substrate W. Patent Document 3 discloses a robot hand equipped with a first suction part and a second suction part, each having a plurality of slits that can be bent like fingers along the convex spherical surface of the substrate, formed alternately (see paragraph

[0006] ).

[0007] Patent Document 4 describes a configuration in which a support bar 11 is supported by a rotating support means 13 that allows the support bar 11 to rotate around the axis in the longitudinal direction of the bar, and the support bar rotates in accordance with the warp of the wafer W, so that the support surface is tilted to match the wafer and the wafer can be stably held in place. Patent Document 5 is an improvement on Patent Document 4, and similar to Patent Document 4, discloses a configuration in which the support bar (arm portion 2, 3) of a robot hand is configured to be rotatable with the longitudinal direction of the support bar as the axis of rotation, and the substrate is supported in accordance with the convex or concave warp of the substrate.

[0008] Japanese Unexamined Patent Publication No. 2020-20224, Japanese Unexamined Patent Publication No. 2024-035688, Japanese Unexamined Patent Publication No. 2023-085799, Japanese Unexamined Patent Publication No. 2005-093893, Japanese Patent No. 4660586

[0009] In Patent Document 1, the suction cup 61 is raised, which increases the vertical thickness of the robot hand. Therefore, when substrates are stacked at narrow intervals in a FOUP or the like, it becomes difficult to access the substrates. Also, simply raising the position of the suction cup 61 does not allow it to accommodate the warping of complex shapes. The technology in Patent Document 2 also involves constructing the pad 20 from a soft material and absorbing the warping of the substrate W by the deformation of the pad, so the pad 20 before deformation needs to be at a height that corresponds to the expected warping, which presents the same problems as in Patent Document 1.

[0010] Patent Document 3 describes a robot hand equipped with multiple slits that can be bent like fingers along the convex spherical surface of the substrate, allowing it to bend flexibly along the convex surface and adhere to the substrate. However, due to the weight of the wafer, the tip of the robot hand may bend downward, making it difficult to stably and accurately transport the wafer to narrow spaces. Furthermore, with a rotational inclination where the longitudinal direction of the support bar is the axis of rotation, as in Patent Documents 4 and 5, adhesion may become difficult depending on the direction of the substrate's curvature. As will be described later, even with a wafer that is simply bent in one direction and curved in a convex or concave shape in the center, as exemplified in Patent Documents 1 to 5, the shape of the substrate's curvature as seen from the robot hand becomes complex depending on the direction in which it is placed on the FOUP, etc.

[0011] Referring to Figure 11, we will explain how the shape of the wafer's curvature as seen from the robot hand becomes complex depending on the orientation of the wafer W. Figure 11 shows an example of a curved semiconductor wafer. Figure 11(a) is a perspective view showing an example of semiconductor wafer curvature, where the wafer W has a low, curved shape with the central part d of the a-a' line being slightly higher, and the opposing ends b and b' are bent along the a-a' line so that they are higher than the central part d. Figure 11(b) shows a side view of the wafer W from direction A in the top row, a side view of the wafer W from direction B in the middle row, and a side view of the wafer W from direction C in the bottom row. Wa is the surface of the wafer W, Wb is the back surface, and the shaded area indicates the back surface Wb. As is clear from Figure 11(b), the curvature of the wafer as seen from the robot hand is completely different depending on the orientation of the wafer W.

[0012] The shapes of the "wafer W curvature viewed from direction A" and the "wafer W curvature viewed from direction B" shown in the upper and middle sections of Figure 11(b) are the same as the curvature shapes shown in prior art documents Patent Documents 1-5. When the wafer W is stored in this orientation, it is possible to grip it relatively easily by suction by adjusting the tilt by rotating the support bar on the longitudinal axis of rotation.

[0013] However, since the wafer W is stored in any orientation regardless of the direction of warping, the possibility of it being placed in this orientation is extremely low, and in most cases it is placed in a position other than C, such as C, or an intermediate position between A and B. Therefore, although there are differences in the magnitude of the twist, as shown in the bottom row, it is necessary to adsorb the wafer W in a state where it is partially twisted. When the wafer W is twisted in this way, even if the support bar is rotated along the longitudinal axis of rotation, it will not be able to reach a point where adsorption is possible, and the likelihood of adsorption failure increases.

[0014] The present invention aims to provide a substrate gripping device or gripping method that can reliably suction and grip substrates that are arranged in different orientations than A and B, as represented by C in Figure 11(b), or substrates that are curved into complex shapes. The invention also aims to provide a substrate transport robot and a substrate inversion device equipped with such a gripping device.

[0015] To solve the above problems, a substrate gripping device according to one aspect of the present invention comprises a plurality of suction parts for attracting and holding a semiconductor wafer or other substrate, a plurality of spaced-apart rods, a base that supports at least one of the plurality of rods so as to be able to change the longitudinal angle of the rod with respect to the horizontal plane, and an angle changing part that changes the angle of the rod.

[0016] Furthermore, at least two of the plurality of rods are supported by the base so that their longitudinal angle with respect to the horizontal plane can be changed, and the angle changing part preferably changes the relative angle between the plurality of rods. Here, the relative angle refers to the angle between each rod. For example, in the case of two rods, even if one rod is stationary, if the other rod is moving, the relative angle changes.

[0017] By incorporating an angle-changing section that alters the longitudinal angle of the rod with respect to the horizontal plane, it becomes possible to search for an angle at which the suction section can adsorb the substrate, even if the substrate has a complex curvature, by changing the angle of the rod. This enables more reliable substrate adsorption.

[0018] Furthermore, it is preferable to include an adsorption detection unit provided in the suction path that supplies suction force to the adsorption unit, which measures the vacuum pressure in the suction path and outputs a vacuum pressure value signal or an adsorption signal, and the angle changing unit is configured to change the angle of each arm according to the output signal of the adsorption detection unit. This makes it possible to confirm whether the substrate is adsorbed by the adsorption unit by vacuum pressure, and to adjust the angle of the rod according to the adsorption state.

[0019] Furthermore, it is preferable that the angle changing unit includes a rod drive unit which is a drive source for changing the angle of the rod, and an angle adjustment unit which tilts the rod within a predetermined angle range in accordance with the movement of the rod drive unit.

[0020] Preferably, the base portion is provided with a pivot shaft extending horizontally perpendicular to the longitudinal direction of each rod, located closer to the rear end than the center of the longitudinal direction of the rod, and each rod is supported by the pivot shaft. The angle adjustment portion may be configured to include the rod drive portion and a cam or link connected to the rod and the pivot shaft at the rear end.

[0021] The substrate gripping device is equipped with two rods, and the angle adjustment unit preferably drives each rod so that the angles of each rod change while being offset from each other. This makes it possible to search for an inclination angle suitable for adsorption in a short time. The offset angle may be such that the periods of the two rods are in completely opposite phases (180 degrees offset), or it may be a smaller amount of offset.

[0022] It is preferable to include a control unit that controls the angle changing unit in accordance with the output of the output signal of the suction detection unit. The control unit may be provided within the substrate gripping device, or it may be integrated with the control unit of an external control device such as a substrate transport robot. Furthermore, the control unit may be formed as an electrical circuit, or it may be configured to be controlled by a CPU, memory, and a control program.

[0023] The control unit can be configured to control the angle changing section so as to drive the angle of the rod in a direction that reduces the warping of the substrate when the substrate is picked up. This reduces the warping of the substrate during transport and reduces the risk of interference with other devices when transporting the substrate in a narrow area.

[0024] Another embodiment of the present invention is a substrate transport robot equipped with a substrate gripping device having the above-described configuration. This makes it possible to grip and transport warped substrates more reliably.

[0025] Another embodiment of the present invention is a substrate gripping method for gripping a semiconductor wafer or other substrate by suction using a substrate gripping device having the above-described configuration, comprising: (a) moving the substrate gripping device below the substrate; (b) moving the substrate gripping device upward to lift the substrate; (c) suctioning and adsorbing the substrate with the suction part; and (d) changing the angle of each rod in response to the suction signal to perform suction by the suction part that is not adsorbing. This method makes it possible to grip and transport or process warped substrates more reliably.

[0026] Furthermore, in this substrate gripping method, the substrate gripping device is equipped with two rods, and step (d) preferably drives each rod so that the angles of each rod change while being offset from each other. This makes it possible to search for an inclination angle suitable for adsorption in a short time. The offset angle may be such that the periods of the two rods are in completely opposite phases (180 degrees offset), or it may be a smaller amount of offset. By driving the angles of each rod in opposite directions, it is possible to ensure that adsorption by the adsorption part is performed reliably.

[0027] Furthermore, step (d) of this substrate gripping method can be configured to change the angle of one of the rods, and then change the angle of the other rod. Also, whether the rods are driven simultaneously or alternately, each rod may be driven individually by a separate rod drive unit.

[0028] According to the present invention, by driving the rods so that the longitudinal angle of the left and right rods changes while the substrate is lifted, the suction part (suction pad) can be brought closer to a position where it is easier to suction, even if the substrate has a complex curved shape, making it possible to grip the substrate more securely.

[0029] A perspective view showing an example of a substrate transport robot equipped with the substrate gripping device of the present invention. A perspective view showing an example of the configuration of the substrate gripping device according to the present invention shown in Figure 1, with the upper cover portion 11 removed. A partially enlarged view illustrating a part of the configuration of the angle adjustment portion that engages with the rod and drive shaft, which are driven by a seesaw around a pivot axis. A schematic cross-sectional view showing an example of the suction portion. A flowchart illustrating the basic control procedure of the substrate gripping device. A schematic diagram showing the relationship between a warped substrate and the suction portion when one rod 30a of the substrate gripping device is tilted. A schematic diagram showing the relationship between a warped substrate and the suction portion when the rod 30a on the opposite side of the substrate gripping device, which has a period shifted by 180 degrees from the rod in Figure 6, is tilted. A schematic plan view showing an example of a mini-environment space in which a substrate transport robot is installed. A block diagram showing the drive unit and main sensors, etc., that are controlled by the robot control unit. A plan view showing one embodiment of a substrate inversion device. A diagram showing an example of a warped semiconductor wafer.

[0030] Next, embodiments of the present invention will be described in detail with reference to the drawings. The substrate gripping device according to the present invention can be used in various devices that require gripping a substrate, such as robotic transport devices that grip and transport semiconductor wafers, liquid crystal substrates, and other substrates, or substrate inversion devices that invert substrates. A typical device that uses the substrate transport device of the present invention is a substrate transport robot that removes semiconductor wafers from a FOUP in a clean space such as a mini-environment and transports them to various processing devices. In this specification, an example in which the substrate gripping device of the present invention is attached to a substrate transport robot will be used for explanation, but this is not intended to limit the use of the substrate gripping device according to the present invention to this.

[0031] First, let me briefly explain the substrate transport robot. Figure 1 is a perspective view showing an example of a substrate transport robot equipped with the substrate gripping device of the present invention. The substrate transport robot 50 shown in Figure 1 is an example of a substrate transport robot 50 in which two robot arms 52 and 53 are rotatably connected to each other by two rotatable links 52a and 52b (or 53a and 53b) on the upper part of a body 51 that can move up and down relative to a base 54, and the substrate gripping device 10 (corresponding to an end effector or robot hand) according to the present invention is rotatably connected to the tips of the robot arms 52 and 53.

[0032] The two robot arms 52 and 53 can independently move up and down, rotate clockwise and counterclockwise, and move horizontally forward and backward. Each of the two robot arms 52 and 53 is equipped with a substrate gripping device 10 (10a, 10b), and each substrate gripping device 10 is equipped with two rods 30 (30a, 30b). Since the basic configuration of the two substrate gripping devices 10 is the same, in the following description, only one substrate gripping device 10 will be described unless otherwise specified. Note that the substrate gripping device 10 in Figure 1 is shown as an example equipped with two rods 30a and 30b, but it is also possible to have a configuration equipped with two or more rods 30.

[0033] As shown by the dashed lines in Figure 1, the substrate gripping device 10 can transport a semiconductor wafer 60 by placing it on the two rods 30 (30a, 30b) of the substrate gripping device 10. In the substrate gripping device in Figure 1, an example is shown in which the wafer 60 is placed on the rods 30 and gripped, but it is also possible to configure the device so that the wafer 60 is placed upside down and the back surface of the wafer 60 is attracted from above, gripped, lifted, and transported. In the following description, the substrate is referred to as a semiconductor wafer 60, but in order to express wafers more generally, the wafer 60 will be referred to as "substrate 60" in the following description. Also, although Figure 1 shows an example of a substrate transport robot equipped with two robot arms 52 and 53, it can also be applied to a substrate transport robot equipped with one robot arm 52 or 53.

[0034] Figure 2 is a perspective view showing an example of the configuration of the substrate gripping device 10 (10a) according to the present invention shown in Figure 1, with the upper cover portion 11 removed. Figure 2 shows the substrate gripping device 10 detached from the robot arm 52, with the substrate gripping portion 10 connected to the robot arm 52 by the arm connection portion 14 shown in the upper right.

[0035] Figure 2 illustrates a substrate gripping device 10 comprising a base portion 12 formed as a lower frame, two rods 30 (30a, 30b) rotatably supported, a rod drive unit 20 that drives each rod 30 so that its tip tilts vertically, and position sensors 26 (26a, 26b) that detect the drive position of the rods. The rods 30 are divided into a substrate gripping portion 31 at the tip of the rod and a rod support portion 32 at the rear end. The substrate gripping portion 31 is equipped with suction portions (suction pads) 33 (33a to 33d) that adsorb and grip the substrate 60. The rod support portion 32 is covered by a cover 36, and furthermore, the base portion 12 of the substrate gripping device 10 is closed off from the outside space by an upper cover portion 11. This is to prevent dust generated by the operation of the rod drive unit 20 and pulleys 21, 22 etc. located inside the base 12 from being released into the external space where the substrate 60 is placed. The space enclosed by the base 12 and the upper cover 11 is maintained under negative pressure relative to the external space by suction means such as a pump or fan (not shown). The suction unit 33 has a suction opening 35 (see Figure 4), which communicates with the suction path 16, and the suction opening 35 is sucked in from the substrate transport robot 50 side via the suction path 16.

[0036] Figure 2 illustrates a motor as the rod drive unit 20, showing an example configuration in which two suction units 33 are provided on one rod 30 (30a or 30b). However, the configuration is not limited to the example shown in Figure 2; one suction unit 33 may be provided on one rod 30, or three or more may be provided. Furthermore, other drive devices driven by air, hydraulics, or other pressure may be used as the rod drive unit 20. In addition, although two position sensors 26a and 26b are provided in accordance with the rotation direction in Figure 2, only one position sensor may be used, and if a drive device capable of precise position control, such as a stepping motor, is used as the rod drive unit 20, a position sensor is not necessarily required. The function of the position sensor and the adjustment of the tilt angle will be described later.

[0037] The base 12 of the substrate gripping device 10 is equipped with rod support shafts 15 (15a, 15b) that support each rod 30. The rod support shafts 15 extend horizontally in the width direction of each rod 30, perpendicular to the longitudinal direction of the rod. Each rod 30 is mounted on the rod support shafts 15 and supported so as to be rotatable. Each rod 30 is rotatable within a predetermined angular range around the rod support shafts 15, and each rod 30 performs a seesaw motion around the pivot axis 15, allowing the substrate gripping portion 31 at the tip to move up and down in the vertical direction and tilt to a desired angle.

[0038] The rod support portion 32 engages with the drive shaft 25 at a position further rear than the pivot axis 15 and constitutes an angle adjustment portion for adjusting the inclination angle of the rod. When the drive shaft 25 is rotated clockwise and counterclockwise by a predetermined angle by the rod drive portion 20, the rear end of the rod support portion 32 moves up and down in proportion to the amount of rotation. As a result, the rod 30 moves up and down like a seesaw around the rod support axis 15, and the inclination angles of the left and right rods 30a and 30b change. Generally, the amount of vertical movement of the tip due to the change in inclination angle should be such that the tip of the rod gripping portion moves 5 mm upward and 5 mm downward, for a total movement range of about 10 mm. However, it is not limited to this, and can be determined according to the maximum allowable warp of the substrate 60, the vertical spacing of the substrates housed in the FOUP, etc., for example, by setting the total vertical movement range to 5 mm.

[0039] Figure 3 is a schematic enlarged view of a part of an example of an angle adjustment section in which a rod 30, which is driven by a seesaw around a pivot axis 15, engages with a drive shaft. As shown in Figure 2, the rotating shaft of the motor 20 is equipped with a toothed pulley 21, and the external teeth of the toothed pulley 21 mesh with the external teeth of a driven pulley 22 fixed to the drive shaft 25. Eccentric drive pulleys 23 are provided at both ends of the drive shaft 25. A cam roller 24 is fixed to the eccentric drive pulley 23 at an eccentric position offset from the center of rotation, and one end of the cam roller 24 is inserted into an engagement groove hole 37 provided at the rear end of the rod 30.

[0040] When the drive shaft 25 is rotated clockwise or counterclockwise by the rod drive device 20, the cam roller 24, which is fixed at an eccentric position, moves up and down in a pendulum-like motion while engaged with the engagement groove hole 37, according to the rotational position of the eccentric drive pulley 23. This up and down motion causes the engagement groove hole 37 of the rod 30 to move up and down, and the rod 30 performs a seesaw motion around the rotation axis 15, tilting at an angle corresponding to the vertical position of the cam roller 24. To prevent contamination due to sliding, it is preferable that the cam roller 24 is configured to rotate and move within the engagement groove hole 37.

[0041] Figure 3(a) shows the rod 30 in a horizontal position without inclination. Figure 3(b) shows the rod 30 inclined downwards as the cam roller 24 moves upwards, causing the rod 30 to rotate counterclockwise around the pivot axis 15. Figure 3(c) shows the rod 30 inclined upwards as the cam roller 24 moves downwards.

[0042] Note that in the configuration example of FIG. 2, two rods 30a and 30b are driven simultaneously by one rod driving device 20, and a configuration in which the two rods 30a and 30b are driven respectively is illustrated. In this case, it is preferable that the two rods 30a and 30b are driven so as to incline in different directions from each other. For example, it is preferable to set the eccentric position of the cam roller 24 with respect to the engagement groove hole 37 so that the phase period of the vertical movement is shifted by 180 degrees, or about 150 degrees to 210 degrees. Note that two drive motors and other drive devices and drive shafts may be provided respectively, and the rods 30a and 30b may be configured to be driven by individual roller drive units. Further, a configuration may be adopted in which the rod drive unit 20 directly drives the rods 30a and 30b without using the cam roller 24 or the drive shaft 25.

[0043] FIG. 4 is a cross-sectional view schematically showing an example of the suction part. The suction part 33 is preferably formed of a material having appropriate flexibility that can be slightly deformed by the weight of the substrate 60 such as a wafer or the strength of the suction force, for example, silicone rubber, nitrile rubber, a flexible resin material, or the like. The suction part 33 has an opening 35 and is being suctioned by a suction pump (not shown) provided on the side of the substrate transfer robot 50 via the suction path 16. Note that the shape of the suction part 33 of the present embodiment is a bowl shape in which the diameter increases from the bottom to the top, but in addition to the bowl shape, it may be an elliptical shape or a rectangular shape when viewed from above.

[0044] FIG. 4(a) shows a state in which a flat substrate 60 without warpage is lifted, and FIG. 4(b) shows a state in which the suction part 33 is uniformly deformed by suctioning the substrate 60 through the suction part 33 from the state of FIG. 4(a). FIG. 4(c) shows a state in which the rod 30 is tilted upward in a state where the substrate 60 is lifted, or a state in which the substrate 60 is tilted due to a shift in the center of gravity of the substrate 60 when the substrate 60 is lifted. Due to the tilt of the substrate, the center of gravity is shifted, and one side of the suction part 33 is greatly "deformed" due to the weight of the substrate.

[0045] As schematically shown in Figure 2, a vacuum pressure sensor 17 is provided in the suction path 16, and a detection signal is transmitted to the rod control unit 45. The vacuum pressure sensor 17 is a pressure sensor that detects the vacuum pressure in the suction path 16 and outputs a detected value or detection signal. Since the vacuum pressure changes according to the degree of contact between the suction parts 33a to 33d that are adsorbing the substrate 60, the state of contact between the suction parts 33 and the substrate 60 due to suction can be detected by the value detected by the vacuum pressure sensor 17. The vacuum pressure is lowest when all the suction parts 33a to 33d are adsorbing the substrate 60.

[0046] As schematically shown in Figure 2, the signals from the position detection sensors 26a and 26b are input to the rod control unit 45. The rod control unit 45 receives signals from various sensors such as the pressure sensor 17, position detection sensors 26a and 26b, and distance sensors 41a and 41b, and controls the rod drive unit 20 based on the received signals. The position detection sensors 26a and 26b are sensors for detecting the rotational position according to the rotational direction of the drive shaft 25, and only one may be provided, or they may not be provided in the case of a stepping motor, etc.

[0047] Distance sensors 41a and 41b can be provided as needed. Distance sensors 41a and 41b are sensors that detect how close the substrate 60 is and can be used as control information for the tilt angle. Note that power lines and the like that that drive the rod drive unit 20 are omitted from the diagram. The rod control unit 45 can be installed in the substrate gripping device 10, or it can be integrated into a robot control unit that controls the operation of the transport robot, or a higher-level control unit.

[0048] Further, a substrate presence / absence sensor 27 for detecting whether or not a substrate 60 is held on the rods 30a and 30b can be provided. The substrate presence / absence sensor 27 includes a light source and a light receiving part (both not shown) inside. The irradiation light from the light source is propagated by an optical fiber for irradiation light (not shown) to a position where the irradiation light from the light source is irradiated onto the substrate 60 when the substrate gripping device 10 has correctly moved under the substrate 60. On the opposite side sandwiching the substrate 60, a light receiving fiber (not shown) for receiving the irradiation light from the optical fiber is provided, and the light received by the light receiving fiber is propagated to the light receiving part of the substrate presence / absence sensor 27. FIG. 2 illustrates the irradiation light 42 that is irradiated to the light receiving fiber when there is no substrate 60 (near the rotation shafts 15a and 15b).

[0049] By providing the substrate presence / absence sensor, the presence or absence of the substrate 60 can be optically detected. The substrate presence / absence sensor 27 is a sensor that detects the presence or absence of the substrate 60 based on whether or not the light receiving part receives the detection light irradiated from the light emitter. In this embodiment, since the detection light 42 irradiated by the substrate presence / absence sensor 27 is blocked by the substrate 60, the substrate presence / absence sensor 27 cannot receive the detection light 42, and the substrate presence / absence sensor 27 sends a signal indicating no detection light to the robot control unit 45. Based on this signal, the robot control unit 45 can detect that the substrate 60 is held on the rods 30a and 30b.

[0050] Figures 5-7 illustrate the basic operation of the substrate gripping device 10 for gripping a substrate. Figure 5 is a flowchart illustrating the basic control procedure of the substrate gripping device 10. The control procedure shown in Figure 5 shows an example of the basic operation from gripping a substrate 60 stored on a predetermined shelf of a FOUP with the substrate gripping device 10 according to the present invention, which is attached to the tip of the robot arm 52 of a substrate transport robot 50, to removing it from the FOUP. Figures 6 and 7 show the positional relationships of the warped substrate 60, rod 30, and suction parts 33a to 33d during each operation in which the substrate gripping device 10 moves the rod under the substrate 60 and lifts it, and then tilts the rods 30a and 30b. Figures 6(a) to (e) show the operation of 30a, and Figures 7(a) to (e) show the operation of 30b, and the vertical movement periods of rods 30a and 30b are shown to be shifted by 180 degrees and driven in opposite directions.

[0051] The substrate transport robot 50 drives the robot arm 52 to advance the substrate gripping device 10 toward a predetermined substrate in the FOUP and move it to a position directly below the desired substrate 60 (step S1). Then, the robot arm 52 is raised to lift the substrate 60 (step S2), and a solenoid valve for suction (not shown) is driven to start suction (step S3). Figures 6(a) and 7(a) show the state in which the rods 30a and 30b have entered the underside of the substrate 60 at step S1, respectively, while Figures 6(b) and 7(b) show the state in which the substrate 60 has been lifted (step S2) and suction has started (step 3).

[0052] Figures 6 and 7 illustrate a state in which the substrate 60 is bent in opposite directions at the positions of rods 30a and 30b. As explained in Figure 4, when the substrate is lifted, the substrate may tilt in one direction and the center of gravity may shift, or the shape of the suction part 33 may deform due to the suction force, but these deformed states are not depicted in Figures 6 and 7.

[0053] Next, it is checked whether the vacuum pressure has reached a predetermined threshold (step S4). If the vacuum pressure is below the predetermined threshold, it is determined that the substrate 60 is firmly held by the suction unit 33 (step S4; Yes), and the robot arm 52 is retracted to remove the substrate 60 from the FOUP, completing the substrate gripping and removal procedure (step S8).

[0054] If the substrate 60 is warped and in the state shown in Figures 6(b) and 7(b), even if suction is started, the suction parts 33b and 33c, which are away from the substrate 60, cannot suck the substrate 60, and therefore the vacuum pressure will not fall below a predetermined threshold (Step S4; No). For this reason, the rod drive unit 20 is driven to start the operation of sequentially tilting the rods 30a and 30b in the up and down directions (Step S5). By gradually tilting the rods 30a and 30b in this way, a position in which the vacuum pressure falls below a predetermined threshold is searched (Step S6). When the rods 30a and 30b are tilted slightly up and down, the suction parts 33a and 33d, which have not yet been sucked, move closer to the substrate 60 due to the tilting of the rod 33 or deformation of the suction parts due to the weight of the substrate or the suction force, and a sucking point in which it becomes easier to suck is found.

[0055] In the example shown in Figure 6, as shown in Figure 6(c), when the rod 30a is tilted upward, it reaches the suction point of the suction part 33a and picks up the substrate. On the other hand, as shown in Figure 7(c), the suction part 33d of the rod 30b, which is driven to tilt downward with a 180-degree phase difference, has not yet reached the suction point and has not picked up the substrate 60. Therefore, if the vacuum pressure at which all of the suction parts 33a to 33d are in contact with the substrate 60 is set as the threshold, the vacuum pressure is not below the threshold (step S6: No), and the vertical tilting motion of the rods 30a and 30b continues.

[0056] In the subsequent operation, as shown in Figures 6(c) to (e), the suction parts 33a and 33b of the rod 30a have already attracted the substrate 60, so they continue to move up and down while still attracted. As shown in Figures 7(c) to (e), the up and down tilting of the rods 30a and 30b continues until the attraction point of the suction part 33d of the rod 30b is found. In Figure 7, at (e), the suction part 33d is attracted to the substrate 60. At this stage, the vacuum pressure reaches the threshold (step S6; Yes), so the up and down movement of the rods is stopped (step S7). Subsequently, the robot arm moves backward, and the substrate gripping device moves outside the FOUP, etc., while still gripping the substrate (step S8).

[0057] Figures 6 and 7 show an example where all suction parts 33a- or 33d adsorb the substrate at the end of one cycle of the rod's vertical movement. However, if the vacuum pressure reaches a predetermined threshold during the vertical movement, the vertical movement can be stopped at that point, and the substrate can be removed. Also, although Figures 6 and 7 show an example where both rods move up and down simultaneously, the system can be configured so that the rods move up and down one at a time, or so, or so, so that only one rod moves up and down.

[0058] If the vacuum pressure does not reach a predetermined value even after tilting the rods 30a and 30b vertically within a predetermined range through a series of vertical movements (step S6; No), a suction error signal is output (step S9). After outputting the suction error signal, various other processing options are possible, such as displaying the signal and stopping the operation, reducing the tilting speed of the vertical movement of the rods and driving the rod drive device again to tilt the rods and search for the suction point, increasing the suction force to search for the suction point, and other various countermeasures.

[0059] Furthermore, the predetermined vacuum pressure used to confirm whether or not the substrate has been gripped can be arbitrarily set, taking into account the strength of the suction force, the weight of the substrate, etc., to determine whether the vacuum pressure is set to the value when all of the suction parts 33a-33d have gripped the substrate 60, or whether the predetermined value is reached even if only a part of the suction part (for example, one) has not gripped it.

[0060] Furthermore, as shown in Figures 6(d) and 7(d), after all the suction parts have attracted the substrate, it is also possible to drive the rods 30a and 30b in a direction that corrects the warping of the substrate (returning the rod 30 to the horizontal direction). By forcibly bringing the substrate 60 closer to a flat shape in this way, it is possible to reduce the risk of interference when passing the substrate 60 through a narrow storage space such as a FOUP while it is being held by the substrate gripping device 10.

[0061] In Figures 6 and 7, the tilt angles of rods 30a and 30b are tilted with a 180-degree shift in period. However, it is not necessary to shift by exactly 180 degrees; it is sufficient for the rods to be relatively offset and have a relative angle. Here, the relative angle refers to the angle between each rod. For example, using two rods, even if one rod is stationary, the relative angle changes if the other rod is moving.

[0062] Next, an example of the operation of the substrate transfer robot 50 will be described with reference to Figures 8 and 9. Figure 8 is a schematic plan view showing an example of a mini-environment space in which the substrate transfer robot is installed. The substrate transfer robot 50 is installed in a mini-environment space 80 that is covered by an isolation frame 81 and maintained in a clean environment. The mini-environment space 80 has an openable and closable front door 82 at the front and an openable and closable rear door 83 at the rear that leads to various processing equipment.

[0063] The substrate transfer robot 50 of this embodiment is a horizontal articulated SCARA type robot, and is a clean robot capable of preventing dust scattering. By moving the body 51 up and down or rotating, and bending and extending the robot arms 52 and 53 respectively, the substrate gripping devices 10 at the tips of the robot arms 52 and 53 can be moved freely up, down, left and right, and wafers can be gripped by the substrate gripping devices 10.

[0064] The substrate transport robot 50 in this embodiment is fixed to the travel section 84 of the X-axis travel mechanism provided in the transport device, and can also move laterally (in the X-axis direction). Therefore, the substrate transport robot 10 can move to a position that the robot arm cannot reach, and can grip and transport wafers with the substrate gripping device.

[0065] For example, by opening the front door 82, the wafer 60 can be removed from anywhere in the FOUP 61a-61d, and the rear door 83 can be opened to transfer the wafer to the processing device. Also, as shown in Figure 8, it is possible to grasp the wafer at the right end, move it to the left end, transfer the wafer to the substrate inversion device, and invert the front and back sides of the wafer.

[0066] Therefore, the substrate transport robot 50 is equipped with various motors and sensors, as illustrated as block 71 in Figure 9, and these are controlled by the robot control unit 70. Figure 9 is a block diagram showing the drive unit and the main sensors for controlling the drive unit that are controlled by the robot control unit 70. The robot control unit 70 shown in Figure 9 shows an example in which both the drive control of the substrate transport robot 10 and the substrate gripping control that controls the substrate gripping operation of the substrate gripping device 10 are integrated and controlled by the robot control unit 70. The robot control unit 70 can be configured to include a CPU, memory, various control programs, etc.

[0067] The X-axis travel motor 72 shown in block 71 of Figure 9 is the drive unit of the X-axis travel mechanism for moving the transport robot in the X-axis direction. The substrate transport robot is further equipped with a lifting drive motor 73 for moving the body 51 up and down, and a swivel drive motor 74 for rotating the body 51. The links 52a and 53a of the robot arms 52 and 53 are rotatably attached to the body 51. The body 51 is also equipped with arm drive motors 75 for bending and extending the robot arms 52 and 53, respectively. A substrate gripping device 10 is attached to the tip of each of the robot arms 52 and 53 of this substrate transport robot 50.

[0068] The substrate transport robot 50 in the embodiment shown in Figure 9 can be equipped with motors capable of rotational angle control, such as stepping motors or servo motors, as the X-axis travel motor 72, lifting drive motor 73, swivel drive motor 74, and arm drive motor 75. Furthermore, the X-axis travel motor is provided with an X-axis sensor 76 for detecting the rotational angle of the rotation axis, the lifting drive motor 73 is provided with a lifting sensor 77 for detecting the rotational angle of the rotation axis, and the swivel drive motor 74 is provided with a swivel sensor 78 for detecting the rotational angle of the rotation axis.

[0069] The arm drive motor 75 is equipped with an arm sensor 79 that detects the rotation angle of its rotation axis. It is desirable to use encoders that precisely detect the rotation axis angle of each motor 72-75 as these sensors 76 to 79. Each of the motors and sensors is electrically connected to the robot control unit 70, which activates the control software stored in the memory unit 70 and drives each motor in accordance with commands from the host PC and input signals from each sensor. With this configuration, the robot control unit can safely move the substrate gripping device 10 of this embodiment to a predetermined location.

[0070] In the embodiment shown in Figure 9, the robot control unit 70 also controls the operation of the substrate gripping device 10. In the embodiment shown in Figure 9, block 90 includes a motor 20 as a rod drive unit for driving the rods, an encoder 92, position sensors 26a and 26b, and a substrate presence sensor 27 as drive control sensors. Blocks 95a and 95b also show an example configuration in which the supply of vacuum pressure for suction and the detection or measurement of vacuum pressure are performed separately by the left and right rods 30a and 30b. When the substrate transport robot 50 completes the lifting operation of the substrate, the robot control unit 70 activates the solenoid valve 96a for right rod suction and the solenoid valve 96b for left rod suction to start suctioning the substrate 60. At this point, the robot control unit 70 can also receive an on / off signal from the substrate presence sensor 94 indicating whether or not the substrate 60 has been detected, and detect whether or not the substrate 60 is being held by each rod 30a and 30b.

[0071] When the robot control unit 70 starts picking up the substrate 60, it receives on / off signals from the right rod pressure sensor 97a and the left rod pressure sensor 97b, which detect or measure vacuum pressure, to indicate whether the vacuum pressure has exceeded a threshold. If the vacuum pressure has not exceeded the threshold, the robot control unit 70 sends an operation command to the motor 20 to raise and lower each rod and receives signals from the right rod pressure sensor 97a and the left rod pressure sensor 97b. If the robot control unit 70 receives signals from the right rod pressure sensor 97a and the left rod pressure sensor 97b indicating that the vacuum pressure has exceeded the threshold, it sends a command to the motor to stop operation. It also receives the value from the encoder 92 and sends a command to the motor 20 to rotate each rod to a horizontal position.

[0072] Once the signals from the right rod pressure sensor 97a and the left rod pressure sensor 97b confirm that all suction units 33 are holding the substrate 60, the robot control unit 70 transmits commands to the motors 72-75 of the substrate transport robot 50 according to the software to transport the substrate 60 to a predetermined location. Furthermore, by providing distance sensors 41a and 41b on each rod 30a and 30b, the robot control unit 70 can detect the distance from the upper surface of the rods 30a and 30b to the lower surface of the substrate 60, thereby detecting the degree of warping in the substrate 60.

[0073] The substrate gripping device 10 of the present invention can be mounted on various devices other than those used on substrate transport robots. As another embodiment of the present invention, a substrate gripping device 101 mounted on a substrate inversion device 100 will be described below. The substrate inversion device 100 is a device that rotates a gripped substrate 60 by 180° to invert its front and back surfaces.

[0074] Generally, substrates 60 are transported with the surface to be processed (the surface to be treated) facing upwards. However, there are processing steps, such as CMP processing and cleaning, where the surface to be processed must be facing downwards. Before being transported to these processing steps, substrates transported from FOUPs 61a to 61d by the substrate transport robot 50 are rotated 180° by the substrate inversion device 100. Then, with the substrate 60 inverted 180°, the parts other than the surface to be processed are held by a dedicated transport device and transported to each processing step.

[0075] Figure 10 is a plan view showing one embodiment of the substrate inversion device 100. The substrate inversion device 100 illustrated in Figure 10 includes a substrate gripping device 101 for gripping a substrate 60, and a rotation mechanism 110 for rotating the substrate gripping device 101 180° around a horizontally extending axis as the center of rotation. The substrate gripping device 101 provided in the substrate inversion device 100 of this embodiment has substantially the same configuration as the embodiment shown in Figure 2. However, the substrate gripping device 10 in the embodiment shown in Figure 2 is connected to robot arms 52, 53 via an arm connection part 14. In contrast, in the substrate gripping device 101 of this embodiment, a hollow shaft 103 fixed to the rear end of the base part 102 is rotatably attached to the plate 111 of the substrate inversion device 100 via a bearing, and a driven pulley 112 is fixed to the tip of the shaft 103 so as to rotate around the shaft 103 as an axis.

[0076] Furthermore, a reversing drive motor 113, which is part of the rotation mechanism 110 that rotates the substrate gripping device 101, is located inside the substrate reversing device 100, and a drive pulley 115 is fixed to the rotation shaft 114 of the reversing drive motor. A timing belt 116 is stretched between the driven pulley 112 and the drive pulley 115, and with the above configuration, the substrate gripping device 101 rotates in the forward or reverse direction when the reversing drive motor 113 operates and rotates the rotation shaft 114 in the forward or reverse direction.

[0077] The substrate inversion device 100 is equipped with an inversion control unit 117 that controls the operation of the substrate gripping device 101 and the inversion drive motor 113. The inversion control unit 117 includes a CPU for performing calculations, a receiving device for receiving signals output from each sensor of the substrate gripping device 101, a transmitting device for transmitting control signals to electrical components such as motors, and storage means for storing programs for operating each electrical component in response to input signals from each sensor, as well as various setting data and teaching data.

[0078] In this embodiment, the reversing drive motor 113 is preferably a stepping motor with controllable rotation angle, and the rotating shaft is preferably equipped with an encoder capable of precisely detecting the rotation angle. With the above configuration, the substrate reversing device 100 can receive the substrate 60 from the substrate transport robot 50 and then reverse the substrate 60 by 180° while holding it by suction. Furthermore, the reversed substrate 60 can be transferred to the next substrate transport robot 50.

[0079] Although the present invention has been described in detail, the present invention is not limited to the disclosed embodiments, and the detailed structure of each embodiment can be appropriately modified by those skilled in the art without departing from the scope of the present invention as described in the claims. For example, one of the multiple rods 30a and 30b may be fixed to the base 12, and only the other rod may be moved up and down by the rod drive unit 20 to change the relative angle of the rods 30a and 30b. In addition, in the substrate gripping devices 10 and 101 of the above embodiments, an eccentric drive pulley 23 and a cam roller 24 are rotated by the rod drive unit 20 as a mechanism to change the relative angle of the rods 30a and 30b, but it is also possible to use a known link mechanism instead of these configurations. Furthermore, the drive source of the rod drive unit 20 can be appropriately changed from a motor to, for example, an air cylinder or a linear actuator, and the material and shape of each part can also be appropriately selected according to the necessary conditions.

[0080] 10 (10a, 10b), 101 Substrate gripping device 11 Upper cover 12, 102 Base 15 (15a, 15b) Rod support shaft 16 Suction path 17 Vacuum pressure sensor 20 Rod drive unit 23 Eccentric drive pulley 24 Cam roller 25 Drive shaft 30 (30a, 30b) Rod 31 Substrate gripping unit 32 Rod support unit 33 (33a-33d) Suction unit 35 Opening 36 Cover 37 Engagement groove hole 50 Substrate transport robot 60 Substrate 100 Substrate inversion device

Claims

1. A substrate gripping device comprising: a plurality of suction parts for attracting and holding semiconductor wafers or other substrates, a plurality of spaced-apart rods; a base that supports at least one of the plurality of rods so as to be able to change the longitudinal angle of that rod with respect to the horizontal plane; and an angle changing part for changing the angle of the rod.

2. The substrate gripping device according to claim 1, wherein at least two of the plurality of rods are each supported by the base so as to be able to change their longitudinal angle with respect to the horizontal plane, and the angle changing part changes the relative angles formed by the plurality of rods.

3. The substrate gripping device according to claim 2, further comprising an adsorption detection unit provided in the suction path that supplies suction force to the adsorption unit, which measures the vacuum pressure in the suction path and outputs a vacuum pressure value signal or an adsorption signal, wherein the angle changing unit changes the angle of each arm in accordance with the output signal of the adsorption detection unit.

4. The substrate gripping device according to claim 3, characterized in that the angle changing unit comprises a rod drive unit which is a drive source for changing the angle of the rod, and an angle adjustment unit which tilts the rod within a predetermined angle range in accordance with the movement of the rod drive unit.

5. The substrate gripping device according to claim 4, characterized in that the base portion is provided with a pivot shaft extending in a horizontal direction perpendicular to the longitudinal direction of each rod, located closer to the rear end than the center portion in the longitudinal direction of the rod, and each rod is supported by the pivot shaft.

6. The substrate gripping device according to claim 5, characterized in that the angle adjustment section comprises the rod drive section and a cam or link connected to the rod at a rear end side of the pivot shaft.

7. The substrate gripping device according to claim 4, wherein the substrate gripping device comprises two rods, and the angle adjustment unit drives each rod such that the angles of each rod change while being offset from each other.

8. The substrate gripping device according to claim 1, wherein the substrate gripping device comprises two rods, and the angle changing unit is driven so that the angles of the rods change in opposite directions.

9. The substrate gripping device according to claim 3, further comprising a control unit that controls the angle changing unit in accordance with the output of the output signal of the adsorption detection unit.

10. The substrate gripping device according to claim 9, characterized in that the control unit controls the angle changing unit to adjust the angle of the rod in a direction that reduces the warping of the substrate when the substrate is adsorbed.

11. A substrate transport robot for transporting semiconductor wafers or other substrates, equipped with a substrate gripping device according to any one of claims 1 to 10.

12. A substrate inversion device for inverting a semiconductor wafer or other substrate, comprising a substrate gripping device according to any one of claims 1 to 10.

13. A substrate gripping method for gripping a semiconductor wafer or other substrate by suction using a substrate gripping device according to any one of claims 3 to 6, comprising: (a) moving the substrate gripping device below the substrate; (b) moving the substrate gripping device upward to lift the substrate; (c) suctioning and adsorbing the substrate with the adsorption part; and (d) changing the angle of each rod in response to the adsorption signal to perform adsorption by the adsorption part that is not adsorbing.

14. The substrate gripping device comprises two rods, and step (d) is characterized in that suction is performed by non-suction parts by driving the angles of each rod in opposite directions.

15. The substrate gripping method according to claim 13, characterized in that step (d) involves changing the angle of one of the rods and then changing the angle of the other rod.

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