JP7827445B2 - Robot Hand - Google Patents

Description

The present invention relates to a plate-shaped robot hand that holds a wafer.

When a dome-shaped warped wafer is held by suction with a robot hand and removed from a cassette, a robot hand equipped with suction cups, as disclosed in Patent Document 1, is used. In order to remove wafers stored in a cassette using a robot hand that is thick overall, including the suction cups, the distance between the shelves on which the cassette wafers are placed is increased. This reduces the number of wafers that can be stored in a cassette, posing the problem of having to replace the cassette more frequently.

To solve this problem, a robot hand equipped with suction cups that hold the outer periphery of the wafer by suction is used to transport wafers stored in cassettes with small distances between shelves, as disclosed in Patent Document 2, for example.

Japanese Patent Application Laid-Open No. 2020-202324 JP 2017-045784 A

However, the robot hand disclosed in Patent Document 2 has a problem in that if the wafer is thin, the wafer it holds may break.
Therefore, there is a demand for a robot hand that can take wafers in and out without cracking them even when the distance between cassette shelves is small.

In order to solve the above problem, the present invention provides a plate-shaped robot hand that is attached to a robot and has suction ports on its suction surface that suction-hold the convex spherical surface of a dome-shaped curved wafer, the robot hand comprising: an attachment section located at the rear end and attached to the robot; a first suction section and a second suction section that are formed so as to be bifurcated at the front end of the robot hand and have suction ports that suction-hold the wafer; the first suction section and the second suction section have slits that open on the inner side surface that is toward the center of the convex spherical surface and slits that open on the side surface opposite the inner side, alternately from the rear end to the front end , and the robot hand is bendable along the convex spherical surface of the wafer.

Because the robot hand of the present invention is a thin, plate-like robot hand without suction cups or the like, it can enter above wafers placed on shelves of a cassette with a small distance between shelves. By, for example, lowering the robot hand that has entered the cassette, the robot hand widens the width of the alternating slits, allowing the suction surface to contact the wafer so as to conform to the dome-shaped, convex spherical surface of the wafer. Then, for example, when a wafer recognition sensor located on the robot hand reacts and turns ON, the suction port of the robot hand can be connected to a suction source, allowing the dome-shaped, curved wafer to be properly suction-held without vacuum leakage. Furthermore, after a dome-shaped, curved wafer is, for example, ground, the thinned wafer loses its curve. The robot hand can also suction-hold this uncurved, thinned wafer, allowing it to be transported into a cassette storing uncurved wafers without breaking the processed wafers.

1 is a perspective view showing an example of a robot equipped with a cassette for accommodating wafers and a robot hand according to the present invention. FIG. FIG. 10 is a cross-sectional view illustrating wafers with a dome-shaped curvature housed in a cassette. FIG. 10 is a perspective view showing an example of a robot hand with its suction surface facing upward. FIG. 10 is a side view showing a state in which the robot hand is lowered to contact the upper surface (rear surface) of the dome-shaped curved wafer, which is a convex spherical surface. FIG. 10 is a side view showing a state in which a robot hand comes into contact with the convex spherical upper surface of a dome-shaped curved wafer, bending like a finger to follow the convex spherical surface of the wafer. FIG. 10 is a plan view showing a state in which a robot hand comes into contact with the convex spherical upper surface of a dome-shaped curved wafer, bending like a finger to follow the convex spherical surface of the wafer. FIG. 10 is a side view illustrating a state in which the robot hand holds the flat wafer by suction after grinding.

The robot 1 shown in Figure 1 is a robot for removing, for example, dome-shaped curved wafers 90 stored in a cassette 4 from the cassette 4, placing them on a chuck table or centering table (not shown), and loading them into the cassette 4. It is equipped with a robot hand 6 according to the present invention and is disposed, for example, on a grinding device, polishing device, or bit cutting device (not shown).

The cassette 4 shown in FIG. 1 has, for example, a bottom plate 40, a top plate 41, a rear wall 42, two side walls 43 (left and right), and an opening 44 on the front side (+Y direction side), and is configured so that wafers 90 can be loaded and unloaded through the opening 44. Inside the cassette 4, multiple shelves 45 are formed at predetermined intervals in the vertical direction, and each shelf 45 can accommodate one wafer 90. Note that the configuration of the cassette 4 is not limited to this example.

1 and 2 is a silicon wafer or the like, which is circular in plan view and curves in a dome-like shape by gradually warping from the center of the wafer 90 toward its outer periphery 903. That is, this dome-like curvature is a curvature in which, when the wafer 90 is placed on the shelf 45 of the cassette 4 with its front surface 900 facing downward, the front surface 900 of the wafer 90 gradually becomes lower from its central region toward its outer periphery. The outer periphery 903 of the wafer 90 contacts the shelf 45 of the cassette 4, and the wafer 90 is placed on the shelf 45 with its back surface 906, which is a convex spherical surface, facing upward.
An example of a wafer 90 that is curved in a dome shape is when the surface 900, on which devices (not shown) are formed, is sealed with resin, and the dome-shaped curvature is caused by, for example, the contraction force of the resin that hardens when the resin is sealed.

The robot 1 shown in Figure 1 is an articulated robot and includes a drive unit 3 that moves the robot hand 6 to a predetermined position. The drive unit 3 includes, for example, a long, plate-shaped first arm 31, a long, plate-shaped second arm 32, a robot hand connecting column 30 extending in the Z-axis direction, a robot hand horizontal movement mechanism 34 that moves the robot hand 6 horizontally, and a simplified lifting mechanism 35.

The upper surface of one end of a first arm 31 is connected to the lower end of the robot hand connecting column 30. The upper surface of one end of a second arm 32 is connected to the lower surface of the other end of the first arm 31 via a pivot shaft or the like (not shown). The lower surface of the other end of the second arm 32 is connected to the lifting mechanism 35 via an arm drive motor 340.

The lifting mechanism 35 is, for example, an electric cylinder, and raises and lowers the robot hand 6 in the Z-axis direction. The robot hand horizontal movement mechanism 34 is, for example, a pulley mechanism consisting of an endless belt (not shown) arranged within the first arm 31 and second arm 32, a pulley (not shown), and an arm drive motor 340. The entire robot 1 can be rotated in a horizontal plane (within the X- and Y-axes) around the Z-axis by the rotational force generated by the motor (not shown). The rotational force generated by the arm drive motor 340 can move the first arm 31 and second arm 32 so that they intersect with each other or are aligned in a straight line in the horizontal plane, while translating the robot hand 6 in the horizontal plane.

A housing 37 is fixed to the upper end of the robot hand connecting column 30. The housing 37 rotatably supports a spindle 36, which has an axis in the X-axis direction, which is perpendicular to the vertical direction (Z-axis direction) in Figure 1. For example, a motor (not shown) that rotates the spindle 36 is housed inside the housing 37.

The tip of the spindle 36 protrudes from the housing 37 in the -X direction, and a holder 38 is disposed at this tip to which the rear end of the robot hand 6 is attached. As a motor (not shown) rotates the spindle 36, the robot hand 6, which is connected to the spindle 36 via the holder 38, rotates, and the suction surface 60 of the robot hand 6 and the surface opposite the suction surface 60 of the robot hand 6 are turned upside down.

The plate-shaped robot hand 6 according to the present invention, shown in Figures 1 and 3, includes an attachment section 61 located at the rear end on the holder 38 side for attachment to the robot 1, and a first suction section 64 and a second suction section 65 located at the front end of the robot hand 6 and bifurcated in a plan view, with suction ports 62 for suctioning the wafer 90. The surfaces of the first suction section 64 and the second suction section 65 form suction surfaces 60 with suction ports 62 for suction-holding the convex spherical back surface 906 of the dome-shaped curved wafer 90 (see Figure 2). When no external force is applied to the first suction section 64 and the second suction section 65 and they are not bent, the suction surfaces 60 are flat.

The robot hand 6, which is entirely made of a resin plate or the like, has a U-shaped opening 600 between the first suction part 64 and the second suction part 65, which accommodates the central region of the dome-shaped ceiling of the wafer 90 being suction-held. The mounting part 61 at the rear end of the robot hand 6 shown in Figure 3 is formed, for example, in a rectangular shape in a plan view. A rigid part 66, which is wider than the mounting part 61 and has a generally rectangular shape in a plan view, extends integrally from the mounting part 61 toward the tip of the robot hand 6. The mounting part 61 has a screw through-hole (not shown) formed through it in the thickness direction, and is fixed to the holder 38 with a bolt.

The rigid portion 66 shown in Figure 3 has a mounting recess 660 for mounting a sensor case 673, which is part of the wafer detection sensor 67 used by the robot hand 6 to detect the wafer 90. The mounting recess 660 is cut out to extend near the mounting portion 61 to match the shape of the sensor case 673.

The wafer detection sensor 67 includes, for example, a light-emitting unit 671 that emits detection light, a light-receiving unit 672 that receives the detection light emitted from the light-emitting unit 671 reflected by the wafer 90, and a sensor case 673 that houses the light-emitting unit 671, the light-receiving unit 672, and wiring 674 connected to the light-emitting unit 671 and the light-receiving unit 672. The light-emitting unit 671 and the light-receiving unit 672 are aligned horizontally and positioned in the central region of the tip of the rigid portion 66 near the U-shaped opening 600. Note that the wafer detection sensor 67 is not limited to the above-described retro-reflective photoelectric sensor, and may also be, for example, a pressure-sensitive sensor or a capacitance sensor.

The first suction portion 64 and the second suction portion 65, which are formed integrally with the rigid portion 66 so as to be bifurcated in a plan view, are, for example, symmetrical about the center line 602 of the robot hand 6. The first suction portion 64 (second suction portion 65) has multiple slits 640 (slits 650) formed alternately to allow the first suction portion 64 (second suction portion 65) to bend like fingers along the convex spherical back surface 906 of the wafer 90 it contacts. That is, the first suction portion 64 (second suction portion 65), which is formed as a long portion, has parallel linear slits 640 (slits 650) of a predetermined length cut out in a direction perpendicular to its extension direction, alternating from the U-shaped opening 600 side (inside) and from the outside. This provides the first suction portion 64 (second suction portion 65) with flexibility, allowing it to bend primarily in the thickness direction. The multiple linear slits 640 (slits 650) are not limited to being formed by cutting out parallel to one another, and the angle of the cutout direction may be changed to match the curvature of the dome-shaped convex spherical surface of the wafer 90, etc.

As shown in FIG. 3 , the suction ports 62, each of which is approximately circular, are located on the suction surface 60 of the robot hand 6, one at the tip and one at the base of the first suction unit 64 and the second suction unit 65. A total of four suction ports 62 are located on the suction surface 60 of the robot hand 6. The number and placement of the suction ports 62 are not limited to the example shown in FIG. 3 . Each suction port 62 is connected to an internal suction path 623. The internal suction path 623 is formed in a zigzag pattern inside the first suction unit 64 (second suction unit 65), passes through the rigid portion 66 and the mounting portion 61, and opens at its other end as a suction force transmission port on the surface of the mounting portion 61. The suction force transmission port is connected to a suction source 69, such as a vacuum generator, via a joint and an external piping 692 that is flexible so as not to interfere with the rotational movement of the robot hand 6. For example, the external piping 692 is provided with a solenoid valve (not shown) that can switch the suction port 62 between a state in which it is connected to the suction source 69 and a state in which it is not connected to the suction source 69.

For example, the suction surfaces 60 of the first suction portion 64 and the second suction portion 65, the surface of the rigid portion 66, and the exposed surface of the wafer detection sensor 67 embedded in the mounting recess 660 are all flush and flat. Furthermore, the edges (ridges) of the first suction portion 64 and the second suction portion 65 may be chamfered to prevent damage to the wafer 90 when they come into contact with the wafer 90.

The following describes the operation of the robot hand 6 and the robot 1 when the robot hand 6 shown in Figures 1 and 3 holds the wafer 90 by suction and the robot 1 transports the wafer 90.

First, a motor (not shown) rotates the spindle 36 shown in FIG. 1, and the robot hand 6 is set in a position where the suction surfaces 60 of the first suction unit 64 and second suction unit 65 face downward. Next, the robot hand horizontal movement mechanism 34 of the drive unit 3 moves the robot hand 6 horizontally, and the robot hand 6 enters the cassette 4 through the opening 44 to a predetermined position inside the cassette 4. That is, the robot hand 6 is positioned above the wafer 90 shown in FIG. 4 so that the center of the back surface 906, which is a convex spherical surface of the dome-shaped curved wafer 90, is located within the U-shaped opening 600 of the robot hand 6. Furthermore, the center of the back surface 906 of the wafer 90 is located on the center line 602 of the robot hand 6 shown in FIG. 1.

Next, the robot hand 6 shown in Figures 5 and 6 descends, and the central dome-shaped ceiling portion of the wafer 90 enters the U-shaped opening 600 shown in Figure 6, bringing the first suction unit 64 and the second suction unit 65 into contact with the back surface 906 of the wafer 90. Furthermore, as the robot hand 6 descends, the width of the multiple slits 640 (slits 650) of the first suction unit 64 (second suction unit 65) increases, for example, causing the first suction unit 64 (second suction unit 65) to bend like fingers along the dome-shaped convex spherical back surface 906 of the wafer 90, as shown in Figures 5 and 6. This maximizes the contact area between the back surface 906 and the downward-facing suction surface 60, and the first suction unit 64 (second suction unit 65) presses mainly the middle region of the dome-shaped curved back surface 906 of the wafer 90 from the radial outside toward the center of the wafer 90.

Furthermore, as the first suction portion 64 (second suction portion 65) bends as shown in Figures 5 and 6, the outer peripheral region on the +X direction side of the back surface 906 comes into contact with the rigid portion 66, so the first suction portion 64 (second suction portion 65) does not bend excessively to the point where it is unable to properly hold the wafer 90 by suction.

5 and 6 , when the robot hand 6 starts to descend toward the wafer 90, the light-projecting unit 671 of the wafer detection sensor 67 shown in FIGS. 5 and 6 starts to emit detection light downward at unit time intervals. Then, in parallel with the first suction unit 64 (second suction unit 65) coming into contact with the wafer 90 and starting to bend, the outer circumferential region of the back surface 906 of the wafer 90 is positioned below the light-projecting unit 671, which is disposed in the region on the tip side of the rigid portion 66, and the detection light emitted by the light-projecting unit 671 begins to be reflected by the back surface 906. Then, when the light-receiving unit 672 receives the reflected light from the back surface 906, which gradually approaches the light-receiving unit 672 in the height direction, for a period of time (the period from when the light-projecting unit 671 emits the detection light to when the light-receiving unit 672 receives the reflected light) that is equal to or shorter than a predetermined period of time, it is recognized that the contact area between the back surface 906 and the suction surfaces 60 of the first suction unit 64 and the second suction unit 65 has been maximized. Alternatively, when the amount of reflected light received from the back surface 906, which gradually approaches the light receiving portion 672 in the height direction, becomes equal to or exceeds a predetermined amount of light received, it is recognized that the contact area between the back surface 906 and the suction surfaces 60 of the first suction portion 64 and the second suction portion 65 has been maximized.
In addition, the fact that the contact area between the back surface 906 of the wafer 90 and the suction surfaces 60 of the curved first suction portion 64 and second suction portion 65 has been maximized may be recognized from the height position of the robot hand 6, for example, by motor control of a lifting mechanism 35 such as an electric cylinder that raises and lowers the robot hand 6 shown in Figure 1.

Once this is recognized, a solenoid valve (not shown) arranged in the external piping 692 shown in Figures 5 and 6 connects the suction source 69 to the suction ports 62 of the robot hand 6, and the suction force generated by the suction source 69 is transmitted from each suction port 62 to the suction surface 60 via the external piping 692 and the internal suction path 623. This maximizes the contact area between the suction surfaces 60 of the bent first suction section 64 and second suction section 65 and the back surface 906 of the wafer 90, allowing the robot hand 6 to suction-hold the wafer 90 without vacuum leakage.

Next, the robot hand 6 is raised by the lifting mechanism 35 shown in Figure 1, and the lifting mechanism 35 is stopped at a height where the outer edge 903 of the wafer 90 held by suction on the robot hand 6 is separated from the shelf portion 45. The robot hand 6 holding the wafer 90 by suction is moved in the +Y direction by the robot hand horizontal movement mechanism 34, and the wafer 90 is removed from the cassette 4 by the robot hand 6.

Then, for example, the wafer 90 is transported by robot 1 and held by suction on the chuck table of a grinding device (not shown) with the back surface 906, on which no devices or the like are formed, exposed upward. A rotating grinding wheel is then lowered from above the wafer 90, and the wafer 90 is ground while the grinding stone is brought into contact with the back surface 906 facing upward, thereby thinning the wafer 90 to a predetermined thickness.

7 is held by suction with the robot hand 6. The dome-shaped curvature of the thinned wafer 90 is eliminated by grinding, resulting in a flat wafer.
First, the robot hand 6 is set with the suction surfaces 60 of the first suction unit 64 and the second suction unit 65 facing downward, and the robot hand 6 is positioned so that the center of the back surface 906 of the wafer 90 is located within the U-shaped opening 600 (see FIG. 3 ) of the robot hand 6. Furthermore, the center of the back surface 906 of the wafer 90 is positioned on the center line 602 of the robot hand 6, and the outer peripheral region of the back surface 906 of the wafer 90 is positioned so that a predetermined area overlaps the lower surface of the rigid portion 66.

Next, the robot hand 6 shown in FIG. 7 descends and comes into contact with the back surface 906 of the wafer 90. For example, since the ground wafer 90 held on a table (not shown) is a flat wafer, the first suction unit 64 (second suction unit 65) does not bend, and the flat suction surface 60 comes into contact with the flat back surface 906 of the wafer 90. The wafer detection sensor 67 detects that the flat suction surface 60 has come into contact with the flat back surface 906 of the wafer 90, and the suction force generated by the suction source 69 is transmitted from each suction port 62 to the suction surface 60. As a result, the robot hand 6 holds the wafer 90 by suction on the suction surfaces 60 of the first suction unit 64 and second suction unit 65.

The robot hand 6 is raised by the lifting mechanism 35 shown in FIG. 1, and the wafer 90 held by the robot hand 6 is removed from a table (not shown). Here, the first suction unit 64 (second suction unit 65) bends due to gravity G1 acting on the wafer 90 shown in FIG. 7, causing it to sag along with the wafer 90 being held by suction. However, because a peripheral region of the back surface 906 of the wafer 90 is in contact with the underside of the rigid portion 66 over a predetermined area, a force G2 is applied, pushing the wafer 90 upward toward the contact portion of the rigid portion 66. Therefore, sagging due to the bending of the first suction unit 64 (second suction unit 65) is not excessive and is kept within an appropriate range, allowing the robot hand 6 to continue to properly hold the thin, flat wafer 90 by suction. Even when the curved wafer 90 shown in FIG. 5 is being held by the robot hand 6 by suction, excessive sagging due to the bending of the first suction unit 64 (second suction unit 65) is prevented for the same reasons as above.

As described above, the robot hand 6 according to the present invention is a thin, plate-like robot hand that does not include suction cups or the like, and therefore can enter above the wafers 90 placed on the shelves 45 of the cassette 4, which have a small distance between them. By lowering the robot hand 6 that has entered the cassette 4, the width of the alternating slits 640 (slits 650) of the robot hand 6 changes, and the suction surface 60 can be brought into contact with the dome-shaped convex spherical back surface 906 of the wafer 90. Then, for example, the wafer detection sensor 67 disposed on the robot hand 6 reacts, detects the wafer 90, and recognizes that the contact area between the back surface 906 of the wafer 90 and the suction surfaces 60 of the first suction unit 64 and the second suction unit 65 has been maximized. Then, by connecting the suction port 62 of the robot hand 6 to the suction source 69, the dome-shaped warped wafer 90 can be appropriately suction-held without vacuum leakage. Furthermore, after a dome-shaped curved wafer 90 is ground, for example, the curve is eliminated from the thinned wafer 90. The robot hand 6 can suction and hold the uncurved and thinned wafer 90, and can carry the processed wafer 90 into a cassette 4 that stores uncurved wafers 90 without breaking it.
A load sensor may be disposed in the holder 38 of the robot 1 to which the robot hand 6 is attached, to detect the force with which the robot hand 6 is pressed against the wafer 90. In other words, the load sensor value may be used to recognize that the suction surface 60 has conformed to the back surface 906, which is a dome-shaped convex spherical surface of the wafer 90, and the suction port 62 may be connected to the suction source 69.

The robot hand 6 according to the present invention is not limited to the above-described embodiment, and may be embodied in various different forms within the scope of its technical concept. Furthermore, the shapes of the components of the robot 1 and cassette 4 shown in the accompanying drawings, and the steps of suction-holding and transporting the wafer 90 by the robot hand 6 are not limited to those shown in the accompanying drawings, and may be modified as appropriate within the scope of the effects of the robot hand 6 according to the present invention.
For example, the suction ports 62 may be formed on both the upper and lower surfaces of the first suction portion 64 and the second suction portion 65 of the robot hand 6, with the upper and lower surfaces serving as suction surfaces. In this embodiment, the robot hand 6 holds the wafer 90 by suction while descending. However, the wafer 90 shown in FIG. 2 may be placed on the shelf 45 of the cassette 4 with the top facing downwards so as to be curved in a dome shape. The robot hand 6 may then be raised from below the wafer 90 toward the back surface 906, which is a convex spherical lower surface, of the wafer 90, and the first suction portion 64 and the second suction portion 65, which are in contact with the wafer 90, may be bent like fingers along the convex spherical surface of the wafer 90 to hold the wafer by suction.

1: Robot 3: Drive unit 30: Robot hand connecting column 31: First arm 32: Second arm
34: Robot hand horizontal movement mechanism 35: Elevation mechanism 36: Spindle 37: Housing 38: Holder
4: Cassette 44: Cassette opening 45: Shelf portion 6: Robot hand 60: Suction surface 61: Mounting portion 62: Suction port 623: Internal suction path 64: First suction portion 640: Slit 65: Second suction portion 650: Slit 66: Rigid portion 660: Mounting recess 67: Wafer detection sensor 671: Light-emitting portion 672: Light-receiving portion 673: Sensor case 69: Suction source 692: External piping 90: Dome-shaped curved wafer 900: Front surface of wafer 903: Outer periphery of wafer 906: Convex spherical back surface of wafer

Claims (1)

A plate-shaped robot hand is attached to a robot and has a suction port on its suction surface for suction-holding the convex spherical surface of a dome-shaped curved wafer,
a mounting part that is disposed at the rear end and is attached to the robot, a first suction part that is formed so as to be bifurcated at the front end of the robot hand and that has the suction port that sucks the wafer disposed therein, and a second suction part,
The first suction portion and the second suction portion are provided with slits that open on an inner side surface that is on the center side of the convex spherical surface and slits that open on a side surface opposite the inner side, alternately from the rear end to the front end , and are bendable along the convex spherical surface of the wafer.
Robot hand.