JP5903282B2 - Robot hand with electrostatic chuck - Google Patents

Description

  The present invention includes a base end connected to a robot arm of a transfer robot, a finger extending forward from the base end, and an electrode for an electrostatic chuck, and holds a thin plate-like object by suction. The present invention relates to a robot hand with an electrostatic chuck.

  Such a robot hand is known from, for example, Patent Document 1. In this device, the robot hand has a base end portion connected to the robot arm of the transfer robot and a finger portion having a rectangular shape in plan view extending from the base end portion, and positive and negative electrodes are embedded therein. (So-called bipolar type). For example, the adsorption surface of a thin plate-like object to be transported of a robot hand is covered with a dielectric (insulating layer), and the electrostatic force generated by applying a DC voltage between both electrodes by a chuck power supply causes the substrate, wafer, etc. A thin plate-like object to be conveyed is held by suction.

  By the way, in the semiconductor manufacturing process, there is a tendency that a wafer which is an object to be transferred has a large diameter and a thin wall in order to further improve productivity. Such a wafer may be warped in various directions due to its own weight or various processes (such as a stress of a thin film by a film forming process). When the warped wafer is placed on the flat upper surface of the robot hand having the above-described configuration, a gap is formed in addition to the contact point between the upper surface and the wafer.

  Here, the voltage applied to the positive and negative electrodes is generally set to an optimum value for a wafer having a shape without warping. For this reason, if the wafer is attracted in the above state, the attracting force decreases as the distance between the electrode and the wafer becomes longer. Therefore, depending on the position of the electrode, the distance to the wafer becomes longer and sufficient attracting force is obtained. It may not be possible. As a result, when the robot arm is operated, a conveyance failure occurs such that the wafer sucked by the robot hand is displaced or detached.

  In such a case, it is conceivable to increase the attractive force by increasing the applied voltage. However, considering the dielectric strength of the dielectric, a high voltage may not be applied, and when a high voltage is applied, a large amount of charge remains after the voltage application to both electrodes is stopped at the wafer transfer position. Therefore, due to the residual electric charge, it takes a long time to detach the wafer, or another mechanism for detaching the wafer is required separately.

JP-A-6-63885

  In view of the above points, it is an object of the present invention to provide a robot hand with an electrostatic chuck capable of reliably attracting a warped conveyed object without applying a high voltage. Is.

In order to solve the above problems, the present invention comprises a base end connected to a robot arm of a transfer robot, a finger extending forward from the base end, and an electrode for an electrostatic chuck. the thin plate-like objects to be conveyed to an electrostatic chuck with a robot hand for holding suction, on the direction from the robot hand to the conveyed object, the direction from the conveyed object on the robot hand and lower, the upper surface of the robot hand A protrusion extending along the same circumference that is smaller than the inner diameter of the conveyed object, the protrusion has a side wall standing up from the upper surface of the robot hand, and the corner of the protrusion with the upper surface has an arcuate cross section In the rounded surface , an electrostatic chuck electrode is formed on the surface of the protrusion, and a dielectric is formed so as to cover the electrode .

  According to the present invention, the robot hand is provided with a ridge, and the corner portion between the side wall and the upper surface thereof is a rounded arc-shaped curved surface, and there is a curved surface extending in the circumferential direction inside and outside the radial direction of the ridge. For example, when a concave warpage occurs so that the periphery of a thin plate-like object is lifted upward, when the object is placed on a robot hand, the object is conveyed on the inner round surface formed on the ridge. Objects are received and come into line contact. On the other hand, when the object to be transported has a convex warp in which the periphery hangs downward, when the object to be transported is placed on the robot hand, the object to be transported is placed on the outer round surface formed on the ridge. It is received and comes in line contact. And since an electrode exists in the position just under the protrusion which is contacting the to-be-conveyed object, the space | interval between an electrode and a to-be-conveyed object becomes substantially constant, and without raising the voltage applied to an electrode so much Therefore, it is possible to reliably adsorb the object to be transported with the warp regardless of the direction of the warp. That is, the attracting force of the conveyed object per unit voltage applied to the electrode can be increased. As a result, the wafer is prevented from being displaced or detached during the operation of the robot arm, and the transfer robot can be operated at high speed. In such a case, as the radius of curvature of the round shape increases, the distance between the electrode and the wafer is reduced near the line contact point with the wafer, so that the voltage applied to the electrode can be reduced. That is, the attractive force per unit voltage can be increased.

  In the present invention, it is preferable to install the protrusions on the outer side in the radial direction from the radius of the conveyed object. According to this, the circumferential length of the portion in contact with the wafer can be reliably increased, the contact area between the both can be increased, and the object to be transported can be more reliably adsorbed.

  Moreover, in this invention, it is preferable to make the part except the round surface of the upper surface of the said protrusion into a flat surface. According to this, for example, when the object to be conveyed has no warp, the object to be conveyed is in line contact with the flat portion, and the object to be conveyed without warping is surely applied without applying a high voltage. Can be adsorbed.

The perspective view of the conveyance robot provided with the robot hand of this invention. The top view which expands and demonstrates a robot hand. Sectional drawing which follows the III-III line of FIG. 1 explaining the state which mounted the to-be-conveyed object. The top view explaining arrangement | positioning of the electrode to a robot hand abbreviate | omitting a protrusion. The fragmentary sectional view explaining the robot hand concerning a modification.

  In the following, referring to the drawings, a thin plate-like object to be transferred is a φ300 mm silicon wafer (hereinafter referred to as “wafer W”), and the robot hand according to the embodiment of the present invention is used as an example for transferring the wafer W. explain.

  Referring to FIG. 1, reference numeral 1 denotes a transfer robot provided with a robot hand according to the present embodiment. The transfer robot 1 includes a robot main body 2 that can move up and down and turn, and a robot arm 3 that can be bent and extended on the robot main body 2, and a robot hand 4 is connected to the tip of the robot arm 3.

  2 to 4, the robot hand 4 includes a base end portion 41 connected to the robot arm 3 and a pair of finger portions 42 and 42 that branch from the base end portion 41 into a bifurcated shape and extend forward. It consists of and. In the following, the direction from the robot hand 4 toward the wafer W is up, the direction from the wafer W toward the robot hand 4 is down (the vertical direction in FIG. 1), and the wafer W is held by suction on the upper surface of the robot hand 4 Explained as

  The base end portion 41 of the robot hand 4 is formed thicker than the finger portions 42 and 42, and a step portion 41 a extending in the circumferential direction corresponding to the outer periphery of the wafer W is provided at the boundary. Further, a stepped portion 42a corresponding to the outer periphery of the wafer W is formed on the upper surface of the tip of the finger portion 42, and the wafer W is regulated and positioned inside the stepped portions 41a and 42a.

  An electrode 5 is formed on the upper surface of the robot hand 4 so as to be positioned on a virtual circle C having a predetermined radius r from the center of the wafer W when the wafer W is seated. In this case, the radius r is determined in accordance with the formation position of the protrusion 6 to be described later in consideration of the diameter and warpage amount of the transferred object W. In the present embodiment, the radius r is radially outside the midpoint of the radius of the wafer W. (For example, 100 mm).

  The electrode 5 is composed of a thin film of conductive metal such as copper or aluminum. The electrode 5 is composed of a strip-like positive electrode 5a and a negative electrode 5b extending in the circumferential direction of the virtual circle C, and the positive and negative electrodes 5a and 5b are formed alternately and at equal intervals in the circumferential direction. . In this case, the positive electrodes 5a and the negative electrodes 5b are connected to each other by connection lines 5c and 5c, and a terminal portion 5d provided on the base end portion 41 is connected to a predetermined portion between the positive and negative electrodes 5a and 5b from a chuck power supply (not shown). A voltage is applied. Since a well-known method can be used as the chuck power source and the power supply method from the chuck power source, detailed description is omitted here. In addition, as a method for forming the electrode 5 on the robot hand 4, a patterning film forming method using a sputtering device or a vapor deposition device, an ink jet method, or screen printing is used.

  A ridge 6 is provided on the virtual circle C immediately above the electrode 5. The ridge 6 includes a side wall 61 erected in an orthogonal direction from the upper surface of the robot hand 4 (and thus the electrode 5), and a flat portion 62 parallel to the upper surface of the robot hand 4, and the side wall 61 and the flat portion 62 are The corner portion is a round surface 63 having a circular arc cross section over the entire length in the circumferential direction. In this case, the height from the upper surface of the robot hand 4 to the flat portion 62, the radius of curvature of the rounded surface 63, and the width of the flat portion 62 are appropriately set in consideration of the diameter of the wafer W to be transferred, the amount of warpage, and the like. The Depending on the height up to the flat part 62, the flat part 62 and the upper surface of the robot hand 4 may be all connected by a rounded surface, that is, the side wall 61 may be a rounded surface having an arcuate cross section.

  The protrusion 6 is made of an insulating material such as quartz glass, alumina or resin, or at least the surface thereof is covered with an insulating material, and is attached to a predetermined position of the robot hand 4. In this case, the attachment method is not particularly limited as long as insulation can be secured, and it may be bonded using an adhesive or may be fixed using screws.

  According to the above-described embodiment, the protrusion 6 on which the wafer W is seated is provided at a predetermined position of the robot hand 4, and the corner between the side wall 61 and the upper surface 62 is the rounded arc-shaped surface 63. For example, when a concave warp is generated on the wafer W so that the periphery of the wafer W is lifted upward, the wafer W is placed on the robot hand 4. The wafer W is received by the inner round surface 63 formed on the protrusion 6 and comes into line contact (see FIG. 3). On the other hand, when the wafer W is convexly warped with its periphery hanging downward, when the wafer W is placed on the robot hand 4, the wafer W is received by the outer round surface 63 formed on the protrusion 6. And come into line contact (see FIG. 3). In this case, since the distance from the center of the wafer W to the center of the flat portion 62 of the protrusion 6 is set closer to the outside in the radial direction than the midpoint of the radius of the wafer W, the peripheral length of the portion in contact with the wafer W is long. Become. Furthermore, when the wafer W is not warped, when the wafer W is placed on the robot hand 4, the wafer W comes into contact with the upper surface of the protrusion 6 over the entire length and comes into line contact (see FIG. 3).

  And since the electrode 5 exists in the position just under the protrusion 6 which is line-contacting with the wafer W, the space | interval between the electrode 5 and the wafer W becomes substantially constant, and the voltage applied to the electrode 5 is so high. Therefore, the wafer W can be reliably adsorbed regardless of the presence or absence of the warp and the warp direction. That is, the attracting force of the object to be transferred per unit voltage applied to the electrode can be increased, and as a result, problems such as the wafer W being displaced or detached during the operation of the robot arm can occur. Therefore, the transfer robot can be operated at high speed. In such a case, as the radius of curvature of the round shape increases, the distance between the electrode 5 and the wafer W decreases near the line contact portion with the wafer W, so that the voltage applied to the electrode 5 can be reduced. That is, the attractive force per unit voltage can be increased.

  In order to confirm the above effects, the following experiment was performed using the robot hand 4. In this case, the flat portion 62 has a width of 6 mm with a center point of 100 mm from the center of the wafer W, and the flat portion 62 is connected to the upper surface of the robot hand 4 by an arc of R10 to form a round surface 63. Is provided at the above position of the robot hand 4. In addition, a φ300 mm wafer (sample 1) having a 0.3 mm convex warp, a φ300 mm wafer (sample 2) having a 0.3 mm concave warp, and a 1 mm convex shape. A φ300 mm wafer (sample 3) in which a warp is generated and a φ300 mm wafer (sample 4) in which a 1 mm concave warp is generated, and each sample was adsorbed by a robot hand. In this case, the voltage applied to the positive and negative electrodes was 300V.

  As a comparative experiment, the flat portion 62 has a width of 6 mm with a center point of 100 mm from the center of the wafer W, and a ridge 6 connecting the flat portion 62 with a side wall standing upright from the upper surface of the robot hand 4. The sample was provided on the upper surface of the robot hand, and each sample was adsorbed by the robot hand. The adsorption force (N) when each sample was adsorbed with a robot hand was measured. In this case, the suction force was measured from the transfer speed at which the wafer W was displaced in consideration of the acceleration applied to the wafer W and the frictional resistance between the wafer W and the robot hand 4. In the inventive experiment, the adsorption force of sample 1 was 6.20 N, the adsorption force of sample 2 was 6.16 N, the adsorption force of sample 3 was 3.89 N, and the adsorption force of sample 4 was 3.79 N. On the other hand, in the comparative experiment, the adsorption force of sample 1 is 4.97 N, the adsorption force of sample 2 is 4.97 N, the adsorption force of sample 3 is 2.82 N, and the adsorption force of sample 4 is 2.80 N. It can be seen that the adsorption force is improved by providing the rounded surface.

  Next, a projecting ridge 6 having a rounded surface formed by connecting the flat portion 62 to the upper surface of the robot hand 4 with an arc of R20 was provided on the upper surface of the robot hand, and other experiments were performed under the same conditions. According to this, the adsorption force of sample 1 is 6.72N, the adsorption force of sample 2 is 6.66N, the adsorption force of sample 3 is 4.41N, and the adsorption force of sample 4 is 4.27N. It can be seen that the adsorption power for the samples 3 and 4 having a large amount of warpage is improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited above. In the above embodiment, the ridge 6 has a form that is continuous in a C-shape in plan view on the upper surface of the robot hand 4, but the ridge does not need to be continuous as long as it is located on the same circumference. It may be provided intermittently or may be provided endlessly. Moreover, in the said embodiment, although the finger parts 42 and 42 demonstrated as an example what has the form which branches into a bifurcated shape and makes a pair, it is not limited to this. For example, the present invention can be applied to a flat plate extending forward.

Moreover, although the said embodiment demonstrated to what attached a separate protrusion to a robot hand as an example, it is not limited to this, A protrusion can also be integrally formed in a robot hand. In such a case, an electrode may be provided from the lower surface side of the robot hand. Moreover, although the said embodiment demonstrated the example which provided the protrusion 6 after forming the electrode 5 in the upper surface of the robot hand 4, it is not limited to this. For example, as shown in FIG. 5, a protrusion 6 is integrally formed on the finger part 42 of the robot hand 4 by cutting or the like, and a metal film 7 is formed on the surface of the protrusion by a known film forming apparatus such as a sputtering apparatus. The insulating film 8 (for example, SiO ₂ ) may be patterned using a known film forming apparatus such as a sputtering apparatus so as to cover the metal electrode 7. According to this, since the electrodes can be arranged uniformly at a fixed distance from the surface of the ridge over both the round shape portion and the flat portion of the ridge, the distance between the non-conveyed object and the electrode becomes close. Even when the same attractive force is obtained, the voltage applied to the electrode can be lowered.

DESCRIPTION OF SYMBOLS 1 ... Transfer robot, 4 ... Robot hand, 41 ... Base end part, 42 ... Finger part, 5a, 5b ... Electrode, 6 ... Projection, 61 ... Side wall, 62 ... Flat surface, 63 ... Earl surface, C ... Virtual circle , W: Conveyed object.

Claims (5)

An electrostatic device that has a base end connected to the robot arm of the transfer robot, a finger portion extending forward from the base end, and an electrode for an electrostatic chuck, and attracts and holds a thin plate-like object on the surface. A robotic hand with a chuck ,
The direction from the robot hand toward the object to be transported is up, the direction from the object to be transported toward the robot hand is down, and the upper surface of the robot hand has a ridge extending along the same circumference that is smaller than the inner diameter of the object to be transported The ridge has a side wall standing up from the upper surface of the robot hand, and the corner of the ridge with the upper surface of the ridge is a rounded arc-shaped section ,
A robot hand characterized in that an electrode for an electrostatic chuck is formed on the surface of a ridge and this electrode is covered with an insulating material . 2. The robot hand according to claim 1, wherein the electrode for the electrostatic chuck is formed directly on the surface of the ridge by a film forming process. 3. The robot hand according to claim 1, wherein the dielectric is formed directly on the surface of the ridge by a film forming process. The robot hand according to claim 1, wherein the protrusion is formed integrally with the robot hand. The robot hand according to any one of claims 1 to 4, wherein a portion of the upper surface of the protrusion excluding the rounded surface is a flat surface.

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