Non-contact carrying device

#This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in International Patent Application No. PCT/JP2005/000491 filed on Jan. 17, 2005, and Japanese Patent Application No. 2004-032476 filed on Feb. 9, 2004.

#The present invention relates to a non-contact carrying device which carries a carried object while holding the carried object in a non-contact state.

#For a non-contact carrying device which carries a semiconductor wafer as a workpiece, i.e., as a carried object while keeping it in an non-contact state, there is developed a device having: a carrying head in which an annular holding surface is formed at a tip surface of the head and a concave portion having a gas guiding surface smoothly continuing from a center portion toward the holding surface is formed; and a nozzle provided in the concave portion, wherein air is discharged from a slit formed between a circular nozzle head portion and a tip surface of the carrying head (see Patent Document 1). In this kind of non-contact carrying device, gas discharged from the slit of the nozzle flows along and adheres to the gas guiding surface and reaches the holding surface and then flows radially outwardly, and a front of the tip surface of the carrying head always becomes a negative pressure state due to airflow toward the tip surface. Therefore, if the carried object is disposed in front of the carrying head, the carried object approaches the carrying head so as to be sucked in the carrying head due to the negative pressure. The airflow flowing along the holding surface prevents the carried object from directly contacting with the holding surface, so that the carried object is held in the non-contact state by the carrying head and the carried object can be carried by moving the carrying head.

#FIG. 1 is a sectional view showing a non-contact carrying device according to an embodiment of the present invention;

#FIG. 2 is a sectional view showing a state in which a slit is closed from a state shown in FIG. 1;

#FIG. 3 is a perspective view when viewed from a tip side of the non-contact carrying device;

#As shown in FIGS. 1 and 2, a non-contact carrying device 10 includes a disk-shaped base plate 11 and a carrying head 12, and the carrying head 12 is attached to the base plate 11 by a plurality of bolts 13. An unshown moving member is intended to be attached to the base plate 11, and the carrying head 12 is carried and moved by the moving member. Note that FIG. 4 shows only one among the plurality of bolts 13. The base plate 11 is provided with a screw aperture 14 that is screwed to an air supplying pipe for supplying compressed air. A communicating space 15, which communicates with the screw aperture 14, is formed in the base plate 11. A sealing member 16 with a diameter larger than that of the communicating space 15 is incorporated between the base plate 11 and the carrying head 12, whereby air is prevented from leaking between the base plate 11 and the carrying head 12.

#A concave portion 17 is formed in a tip of the carrying head 12, and a bottom surface of the concave portion 17 serves as a gas supplying surface 18. A plurality of gas supplying holes 19, which are opened in the gas supplying surface 18 and formed in the carrying head 12, communicate with the communicating space 15. An annular holding surface 21, which projects nearer a front side of the carrying head 12 than the gas supplying surface 18, is formed in the tip surface of the carrying head 12. A gas guiding surface 22, which is formed into a streamline shape and smoothly connects the gas supplying surface 18 with the holding surface 21, is formed between the gas supplying surface 18 and the holding surface 21. Further, a tapered surface 23, which is inclined toward a base end portion of the carrying head 12, is formed between an outer circumferential surface of the carrying head 12 and the holding surface 21.

#A nozzle 24 provided with a base portion 24a and a disk portion 24b is mounted on the carrying head 12, wherein the disk portion 24b faces the gas supplying surface 18 so as to cover the gas supplying surface 18 and a portion facing to the disk portion 24b in the entire bottom surface of the concave portion 17 serves as the gas supplying surface 18. An annular slit forming surface 26, which forms a slit 25 for discharging gas along with the gas supplying surface 18, is formed in an outer circumferential portion of the disk portion 24b. The slit forming surface 26 is parallel to the gas supplying surface 18, and an air pocket 27 is formed on an inner-radial side of the slit forming surface 26. Accordingly, the air flowing into the air pocket 27 from the plurality of gas supplying holes 19 is discharged through the slit 25 toward an outer-radial direction from the entire circumferential direction of the nozzle 24, and becomes in a state of adhering to the gas guiding surface 22 and flows along the gas guiding surface 22 in the outer-radial direction, and then becomes in a state of adhering to the holding surface 21 and flows along the holding surface 21 in the outer-radial direction. Next, flow of the air flowing along the holding surface 21 becomes in a state of adhering to the tapered surface 23, and is bent toward a side of the base end portion of the carrying head 12, and is directed to an outer direction of the carrying head 12.