JP5422680B2 - Substrate holding device - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate holding apparatus, which forms a vacuum region on the suction surface of an object using the Bernoulli effect and ejector effect generated by an air flow so that the substrate can be held on the hand. About.

  In recent years, as the thickness of semiconductor wafers has been reduced, in substrate holding devices equipped with a vacuum suction mechanism, a thin substrate is warped or bent by its own weight during the substrate transport process, so that there is a gap between the substrate suction surface and the substrate at the tip of the hand. A gap is formed, the degree of adhesion cannot be maintained, vacuum suction is incomplete, and there is a problem in accuracy during conveyance.

  In addition, the pipe diameter that can be piped into the hand of the transfer robot as the substrate holding device is limited due to the space with the drive mechanism incorporated therein. For this reason, vacuum suction with a limited pressure difference from the atmospheric pressure makes it difficult to supply a large flow rate of vacuum, and it may not be possible to generate the negative pressure required to hold the substrate between the hand and the substrate. is there. Further, in the conventional suction mechanism, it is necessary to continue vacuum suction of several tens of kPa in order to hold the wafer, which increases the stress on the substrate to be transferred and may damage the substrate.

  Therefore, instead of the vacuum suction mechanism, by discharging compressed air from the suction surface of the suction plate to the side surface side, a negative pressure is generated between the suction target object such as a semiconductor wafer and the suction target side is placed on the suction plate side. There has been proposed a vacuum tweezers equipped with a suction holding mechanism using the Bernoulli effect that floats on the surface (Patent Document 1).

  In addition, as a mechanism for generating negative pressure using blown air having another configuration, a vortex (swirl flow) is generated on the hand side, and the negative pressure generated thereby and the positive pressure generated between the workpiece and the holding surface There has also been proposed a hand that can balance a workpiece and hold a workpiece in a non-contact state (Patent Document 2).

JP-A-2005-74606 JP 2011-138877 A

  With the vacuum tweezers disclosed in Patent Document 1, it is possible to hold a wafer with low stress. However, as the wafer having a large diameter is held, the suction holding portion is enlarged and supplied to the inner groove. Air also needs to have a large flow rate. That is, there is a problem of an increase in capacity of the flow path and a consumption cost of compressed air.

  In the case of the non-contact holding hand which conveys a work by generating a vortex (swirl flow) disclosed in Patent Document 2, the consumption of compressed air on each suction surface is less than that of the apparatus disclosed in Patent Document 1. However, since the negative pressure generation area is limited, in order to uniformly hold a large-diameter wafer having a thin film thickness, it is necessary to arrange a large number of holding portions that generate eddy currents on the wafer suction surface, which increases the size of the workpiece. As the diameter is increased, an increase in air consumption flow rate is unavoidable as in Patent Document 1. Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, initially perform suction holding by the Bernoulli effect, and then use a vacuum region using the ejecting effect of air from the region for sucking and holding the object It is an object of the present invention to provide a substrate holding device which can secure an object and hold an object at a relatively low vacuum pressure. Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and in addition to the adsorption of the substrate by the Bernoulli effect by the airflow, the substrate that can realize the vacuum region by the ejector effect and can hold the substrate by adsorption It is to provide a holding device.

In order to achieve the above-mentioned object, the present invention comprises a stack of flat plates, a groove-shaped air supply passage is formed in the longitudinal direction between the opposing flat plates, and a wafer is held on the outer surface of one flat plate. A hand main body having a wafer holding base formed therein, a nozzle portion in which an air discharge hole at the tip of the air supply path serves as an air nozzle, a diffuser portion formed by a recess defined by the wafer holding base, and a partition formed by the wafer holding base A wafer suction area having an air discharge port in the vicinity of the inlet of the diffuser part and the air nozzle, and air from the air supply path is ejected to the diffuser part through the air nozzle The wafer is held and the air in the wafer suction area is drawn from the air discharge port to lower the wafer suction area. To form an empty state, characterized in that for holding the wafer.

The present invention, wafer located on the wafer holding base, when the air from the air supply passage is ejected, the Bernoulli effect resulting from airflow inside the diffuser portion, the air of the wafer suction region from the air discharge port The wafer is sucked and held on the hand main body by an ejector effect that pulls out and places the wafer suction region in a low vacuum state.

  The hand body is configured by stacking flat plates, and a groove formed on an opposing surface of the flat plate is used as the air supply path, and the diffuser portion and the wafer adsorption region are formed on an outer surface holding a wafer of one flat plate. It is preferable to form the wafer holding base so as to obtain a recess.

  It is preferable that the nozzle portion is configured by attaching a plate on which the groove is formed so that the air discharge hole at the tip of the air supply path is closed and the end of the groove communicating with the air discharge hole becomes an air nozzle.

The nozzle portion is provided in a center pad, and a ring-shaped pad that divides the wafer suction region is provided on an outer periphery of the center pad, and a part of the ring-shaped pad is provided in an air discharge port of the nozzle portion of the center pad. A notch is formed on the air flow path, and a low vacuum state is formed in the wafer adsorption region by an ejector effect with the air flow from the nozzle portion, and the wafer is held by the center pad and the ring-shaped pad. preferable. Further, by arranging as many suction pads as a combination of the center pad and the ring-shaped pad on the surface of the hand as necessary for holding the substrate, the operation can be sufficiently exerted.

  According to the present invention, in addition to the adsorption of the substrate by the Bernoulli effect by the air flow, by realizing the vacuum region by the ejector effect, it is possible to reduce the consumption of compressed air and provide an appropriate holding performance according to the target substrate. It has the effect of being able to.

The top view which showed the hand by one Example of the board | substrate holding apparatus of this invention. The perspective view which showed the hand shown in FIG. The disassembled perspective view of the hand shown in FIG. The top view which showed the hand by the other Example of a board | substrate holding | maintenance apparatus. Sectional drawing which expanded and showed the nozzle plate part of the hand shown in FIG. Explanatory drawing which showed the wafer adsorption state of the hand shown in FIG. The top view and sectional view showing the suction pad by one example of the substrate holding device of the present invention. The top view which showed the example of the hand which has arrange | positioned the suction pad shown in FIG.

  Hereinafter, as embodiments for carrying out a substrate holding device of the present invention, the following embodiments will be described with reference to the accompanying drawings.

  The first embodiment will be described below with reference to FIGS. FIG. 1 is a plan view showing a hand 10 of a substrate holding apparatus of the present invention. FIG. 2 is a perspective view showing the hand 10 in a three-dimensional view, and FIG. 3 is an exploded perspective view showing the assembled components shown in FIG.

  As shown in each drawing, a hand 10 as a substrate holding apparatus of the present invention is made by closely contacting two identically shaped flat plates 11 (hereinafter referred to as an upper plate 11a and a lower plate 11b). It has been. The hand 10 is attached to the tip of a swing arm such as a transport robot (not shown), and an air supply path led to the tip of the arm (not shown) is connected to an air supply hole 12 formed at the base of the hand 10. As shown in FIG. 1, the hand 10 according to the present embodiment has a substantially rectangular shape in plan view, sucks a small-diameter wafer 1 to a predetermined holding position at the tip, and moves the wafer 1 to a predetermined position by turning the arm. Moving.

  The tip of the hand 10 is formed by a flat plate surface 10a on which the wafer 1 can be directly placed and a recess 10b formed and partitioned at a predetermined depth from the flat plate surface 10a. The recess 10b is formed in a substantially U shape, and is formed with a wafer holding base 13 having the same shape and having an outer surface coinciding with the side end of the hand 10 and facing. The wafer holding base 13 has a shape in which a wafer suction region 14 is formed inside and four diffusers 15 are defined in the recess 10b. It functions as the air discharge port 16 of the wafer suction region 14 so as to be positioned in the vicinity of the front end of the wafer holding base 13, the air nozzle 21, and the diffuser inlet 15 a. In this embodiment, the hand 10 is a processed product of polyacetal (POM: polyoxymethyl), and the wafer adsorption region 14 and the diffuser 15 which are part of the recess 10b are three-dimensionally shown in FIG. This corresponds to the recess 10b in which the flat surface 10a of the hand 10 is ground to a predetermined depth so as to leave the wafer holding base 13 described above.

  As shown in FIGS. 1 and 2, the shape of the diffuser 15 is a planar taper shape that is slightly wider in plan view from the diffuser inlet 15a on the air nozzle 21 side to the exhaust port 15b. This taper shape is preferably determined so that a Bernoulli effect due to airflow generated from an air nozzle 21 described later can be effectively obtained for wafer holding. In the diffuser 15, it is also possible to provide a taper and a step for changing the depth of the recess 10b as required.

  The configurations of the air supply path 20 and the air nozzle 21 will be described with reference to FIGS. A groove 17 having a predetermined depth is formed in the longitudinal direction on the opposing surface of the flat plate 11 having the same shape of the hand 10. The groove 17 serves as an air supply path 20 that combines the flat plates 11a and 11b. Further, as shown in FIG. 3, in the groove formed on the upper plate (shown by a broken line in FIG. 3), the air supply hole 12 is provided on the root side, and the two air exhaust holes 23 are provided in the tip side recess 10b. Is formed. Among these, the nozzle plate 25 is attached so as to block the upper surface of the air exhaust hole 23. The nozzle plate 25 is a small flat plate, and a groove 26 having a predetermined width is formed on the lower surface thereof. The end of the groove 26 serves as the air nozzle 21 so as to face the diffuser inlet 15a and overlap with the substantially central position of the air exhaust hole 23. It is attached. As a result, the air supplied from the air supply hole 12 passes through the air supply path 20 in the hand 10, passes through the air exhaust hole 23 and the groove 26 in the nozzle plate 25, and passes through the air nozzle 21 at the groove end to the diffuser 15 with a predetermined pressure. The air can be ejected. The air ejected from the nozzle forms a predetermined air flow in the diffuser 15 and is exhausted to the outside from the exhaust port 15 b on the side surface of the hand 10. In addition, it is preferable that the components such as the flat plates 11a and 11b and the nozzle plate 25 described above are integrated while maintaining airtightness by screwing with a countersunk screw (not shown), bonding with an adhesive, or the like. In addition, each member can be made of a material according to the application, such as engineering plastics such as POM, synthetic resin materials having high strength and durability, and metal plates such as aluminum plates and stainless steel plates.

Here, the action of the Bernoulli effect by the air flow and the ejector effect in the wafer suction region 14 according to the present invention will be described with reference to FIG.
As shown in FIG. 1, in this embodiment, air with a predetermined pressure (0.25 to 0.5 MPa) is applied in a state where the wafer 1 (illustrated with phantom lines) is placed at a predetermined position at the tip of the hand 10. It is designed to eject from one air nozzle 25 at an air flow rate of about 5 to 10 liters / minute. Therefore, air is supplied to the air supply path 20 through the air introduction hole 12 from an air supply source (not shown) so that a flow rate of 20 to 40 liters / minute can be obtained in the air supply path 20. The air further flows through the air supply path 20 from the air exhaust hole 23 on the front end side into the groove 26 of the nozzle plate 25, and is ejected from the air nozzle 21 at the end of the groove toward the diffuser 15 whose upper surface is closed by the wafer 1. A predetermined air flow is generated in the diffuser 15 and exhausted from the exhaust port 15b. At this time, a static pressure difference due to the Bernoulli effect occurs between the inside of the diffuser 15 and the upper surface of the wafer 1, and a suction force that pulls the wafer 1 toward the hand 10 is generated. As a result, a part of the wafer 1 is adsorbed on the surface of the hand 10 and the air in the wafer adsorbing region 14 from the air discharge port 16 of the wafer adsorbing region 14 is drawn by the ejector effect so as to be drawn into the air flow entering the diffuser inlet 15a. Pulled out with the viscosity of the air in the airflow. The air drawn out from the wafer suction area 14 is further discharged from the exhaust port 15b together with the air flow. Due to the ejector effect, a low vacuum state is generated in the wafer suction region 14. For this reason, the wafer 1 placed on the wafer holding base 13 is applied with a sufficient wafer holding force due to this low vacuum state (about 1 to 2 kPa).

  Next, a second embodiment will be described with reference to FIGS. FIG. 4 is a plan view showing the hand 10 of the substrate holding apparatus of this embodiment. FIGS. 5A and 5B are cross-sectional views showing details of the nozzle by enlarging the nozzle plate 25 position.

  The configuration of the hand 10 is almost the same as that of the hand 10 shown in FIG. 1, but the diffuser 15 is formed in a shape projecting to the left and right of the hand 10, and the nozzle plate 25 is disposed at each diffuser inlet 15 a. The wafer holding base 13 that partitions the wafer suction region 14 can be made large, and the wafer 1 (substrate) having a larger diameter can be held. As shown in FIGS. 5A and 5B, this embodiment also has a structure in which two flat plates 11a and 11b are integrally bonded to each other. As shown in FIG. A groove serving as the supply path 20 is formed in the upper plate 11a and the lower plate 11b. Further, a nozzle plate 25 is arranged at the front end of the air supply path 20 so as to close the air exhaust hole 23 in a state where the distance from the air discharge port 16 at the end of the wafer suction region 14 is adjusted, and the direction along the hand 10 The diffuser 15 is formed on the upper surface to ensure sufficient extension.

  Each drawing in FIG. 5 is an enlarged cross-sectional view showing the position of the nozzle plate 25 attached to the recess 10b of the hand 10 body. As shown in FIG. 5A, as shown in the figure, an air discharge hole 23 (circular hole) is formed in the upper plate 11a corresponding to the groove end formed in the lower plate 11b of the hand 10 body. The nozzle plate 25 is attached so as to close the air discharge hole 23. The thickness of the nozzle plate 25 is equal to the depth of the recess 10b, and as shown in FIG. 5A, the upper surface of the nozzle plate 25 and the upper surface of the hand 10 constitute the same plane, and the vacuum suction function functions effectively. It is supposed to be. The groove 26 formed in the nozzle plate 25 is set to a depth of 0.2 mm and a width of 2 mm in this embodiment, and corresponds to a cross section of the air nozzle 21.

  The Bernoulli effect and ejector effect in the present embodiment will be described with reference to FIGS. In addition, in each figure, illustration of the mounted wafer 1 is abbreviate | omitted. When air is ejected from each air nozzle 21 toward the diffuser 15 at the opposite position, an air flow as shown in FIG. 6A is generated in a space surrounded by the wafer 1 and the diffuser 15 (not shown). Thereby, a static pressure difference due to the Bernoulli effect is generated between the upper surface of the wafer 1 and the diffuser 15, and the wafer 1 is moved to the hand 10 by a downward force (when the wafer 1 is placed on the hand 10) generated by the static pressure difference. To be adsorbed. Subsequently, as shown in FIG. 6B, due to the high-speed air flow in the vicinity of the diffuser inlet 15a, the air in the wafer suction area 14 is caused by the ejector effect from the air discharge port 16 in the wafer suction area 14 located in the vicinity thereof. Pulled out. Since the wafer 1 is placed on the wafer holding base 13, a low vacuum state is formed in the wafer suction region 14 that is a closed space. Thereby, holding of the wafer 1 becomes more reliable.

  Since the suction force of the wafer 1 can be increased in proportion to the area of the wafer suction region 14 surrounded by the wafer holding base 13, the holding force of the wafer 1 can be increased without increasing the amount of air to be supplied. In addition, the wafer 1 having a larger diameter can be held by expanding the diffuser 15 and the wafer suction region 14. In particular, the vacuum pressure generated in the wafer suction region 14 due to the ejector effect can be adjusted by the cross-sectional area of the air supply path 20, the vacuum port shape, and the like. For this reason, it is possible to cope with this by generating a vacuum pressure necessary for transporting and holding a thick substrate having a large diameter.

  Next, an example of a suction pad using the ejector effect will be described with reference to FIGS. As shown in FIGS. 7A and 7B, the suction pad 30 has a center pad 31 and a center pad 31 in a circular recess 10 d formed on the surface of the hand 10 at the tip exhaust hole position of the air supply path 20. It is comprised from the ring-shaped pad 32. FIG. The center pad 31 has a frustoconical shape with a smooth upper surface and a large diameter side, an air supply groove 33 is formed inside, and an air nozzle 33a is formed in the direction shown in FIG. ing. As shown in FIG. 7B, the ring-shaped pad 32 is formed with a tapered inner peripheral surface 32a facing the central direction, and a portion of the inner peripheral surface 32a facing the air nozzle 33a of the center pad 31. An air exhaust port 34 is formed in the front.

  In the suction pad 30, as the air flow from the center pad 31 is exhausted from the air exhaust port 34 of the ring-shaped pad 32, the ejector effect from the ring-shaped pad 32 causes the center pad 31 and the ring-shaped pad 32 to be exhausted. A vacuum region 35 is formed in a circumferential space between the pads 32. Therefore, as shown in FIG. 8, for example, three suction pads 30 are arranged at predetermined positions on the hand 10 at appropriate intervals, and a wafer (not shown) is formed on the hand 10 using these suction pads 30. Can be placed and held. At this time, a path for supplying air to each suction pad 30 is formed in the hand 10 in the same manner as in the above-described embodiment.

  FIG. 7B shows a modification in which the vacuum region 35 is enlarged by increasing the diameter of the ring-shaped pad 32. In this case, the ejector effect acts in the same manner as in FIG. 7A, but since the area to be evacuated is large, the suction force according to the size of the ring-shaped pad 32 can be secured with the same air consumption. .

  In the above description, in the first and second embodiments, the air flow is set in the opposite direction from the air nozzle provided in the air discharge hole from the air supply path in the hand. The airflow formed in this way does not have to be exactly the same flow rate and flow velocity, and the direction need not be opposite. It is also possible to provide an air nozzle only on one side. In this case, it is preferable to prevent the wafer 1 from slipping by airflow before the Bernoulli effect occurs.

  In addition, this invention is not limited to the Example mentioned above, A various change within the range shown to each claim is possible. In other words, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Hand 13 Wafer holding base 14 Wafer adsorption | suction area 15 Diffuser 16 Air discharge port 20 Air supply path 21 Air nozzle 23 Air discharge hole 25 Nozzle plate 30 Adsorption pad 31 Center pad 32 Ring-shaped pad 35 Vacuum area

Claims (5)

A hand body in which a flat plate is overlapped, a groove-shaped air supply path is formed in the longitudinal direction between the opposing flat plates, and a wafer holding base for holding a wafer is formed on the outer surface of one flat plate ; An air discharge hole at the front end of the air supply path includes a nozzle portion serving as an air nozzle, a diffuser portion including a recess defined by the wafer holding base, and a recess defined by the wafer holding base. A wafer suction region having an air discharge port in the vicinity of the inlet and the air nozzle ;
With
Air is ejected from the air supply path to the diffuser section through the air nozzle to hold the wafer, and air in the wafer adsorption area is drawn from the air discharge port to bring the wafer adsorption area into a low vacuum state. A substrate holding apparatus formed to hold the wafer. When the wafer is positioned on the wafer holding base and air is ejected from the air supply path, the Bernoulli effect generated by the air flow in the diffuser section and the air in the wafer adsorption region are drawn out from the air discharge port, The substrate holding apparatus according to claim 1, wherein the wafer is sucked and held on the hand main body by an ejector effect that places the suction region in a low vacuum state. Said nozzle portion, closing the air discharge hole of the air supply passage leading end, to claim 1 or claim 2 the tip of the groove is formed by attaching a plate having a groove formed as a air nozzle to the air discharge hole communicating with The board | substrate holding apparatus of description.   The nozzle portion is provided in a center pad, and a ring-shaped pad that divides the wafer suction region is provided on an outer periphery of the center pad, and a part of the ring-shaped pad is provided in an air discharge port of the nozzle portion of the center pad. A notch is formed on an air flow path, and a low vacuum state is formed in the wafer adsorption region by an ejector effect in accordance with an air flow from the nozzle portion, and the wafer is held by the center pad and the ring pad. 2. The substrate holding apparatus according to 1. 5. The substrate holding apparatus according to claim 4 , wherein the number of suction pads, which are combinations of the center pad and the ring-shaped pad, are arranged on the surface of the hand in the number and position necessary for holding the substrate.

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