JPH0250012B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to the configuration of an apparatus for floating and conveying a flat object, and in particular to an apparatus for conveying a wafer using ultrasonic waves used in the manufacture of semiconductors. Regarding.

(Prior art and problems to be solved by the invention) Conventionally, wafers have been conveyed by mechanical methods such as belts or walking beams, or by air, but mechanical methods do not remove dust due to friction. In the case of air-based methods, dust is blown up by air currents.

Ultrasound is a compressional wave, and normally it travels through dense and dense areas of the air, but by making the ultrasonic generation surface and the ultrasonic reflection surface face each other with an appropriate distance between them, it is possible to It is known that a standing wave can be generated between two surfaces, and that an object can be levitated at the nodes of this standing wave.

An object of the present invention is to realize a non-contact ultrasonic floating type conveyance device by performing floating conveyance using the properties of ultrasonic waves.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a plurality of ultrasonic generation surfaces arranged in the conveying direction, and an ultrasonic reflection surface facing the ultrasonic generation surfaces, so that the ultrasonic waves from the ultrasonic generation surfaces are provided. The object to be transported is levitated by the standing waves generated between the ultrasound generating surface and the ultrasound reflecting surface, and the ultrasonic waves are generated from the ultrasound generating surface facing the tip of the transported object in the transport direction. The conveyed object is moved by decreasing the amplitude of the object, and the amplitude of the ultrasonic waves generated from the ultrasonic generation surface is increased during a predetermined period before falling,
The movement of the object is controlled by reducing the amplitude of the ultrasonic waves generated from the ultrasonic generation surfaces arranged in the next transport direction, and the standing wave fronts at both ends of the object are moved upward along the transport direction. It is characterized by being bent.

Furthermore, the configuration in which the standing wave fronts at both ends of the transported object in the transporting direction are bent upward is characterized by bending both ends of the opposing ultrasonic generation surface and the ultrasound reflecting surface along the transporting direction of the transported object. do.

(Operation and Effect) That is, the present invention provides an ultrasonic generation surface divided into a plurality of sections and an ultrasonic reflection surface opposite to this ultrasonic generation surface, and generates ultrasonic waves from the ultrasonic waves of the ultrasonic generation surface. The conveyed object is levitated by the standing waves generated between the surface and the ultrasonic reflecting surface, and the conveyed object is conveyed by changing the intensity of the ultrasonic waves in each section of the ultrasonic generation surface. Since the mechanism and the conveyed object are not in contact, there is no generation of dust due to friction, and the amount of dust blown up by air flow is reduced, making it difficult for dust to adhere to the conveyed object.

(Example) FIG. 1 shows a schematic front view of an example of an ultrasonic levitation type conveyance device according to the present invention. 1, 2, 3, 4,
5 and 6 are ultrasonic generators, and 7 is an ultrasonic reflector, which are fixed at a distance necessary for generating standing waves so that the ultrasonic generation surface and the ultrasonic reflection surface face each other. There is. On the other hand, 8 is an object to be transported, which in this example is a wafer. An arrow 9 indicates the direction in which the object to be transported is transported. Here, if all ultrasonic generators generate ultrasonic waves with the same frequency, phase, and amplitude, a standing wave will be generated between the ultrasonic generation surface and the ultrasonic reflection surface, and the transported object will be affected by the standing wave. floats to the position of the node. In this state, when the amplitude of the ultrasonic generator 4 is reduced, the buoyancy of the object directly above the ultrasonic generator 4 is reduced, and the object begins to slide toward the ultrasonic generator 4. Therefore, before the conveyed object falls, the output of the ultrasonic generator 4 is increased to float the conveyed object back to its original position, and the amplitude of the ultrasonic generators 5 arranged in the conveyance direction is decreased. Slide the transported object. In this way, conveying force can be obtained continuously.

However, with this alone, there is a risk that the object to be transported may fall off the transport path, so it is necessary to add a mechanism to prevent this. This mechanism will be explained below.

FIG. 2 shows a schematic side view of an example of the ultrasonic levitation type conveyance device according to the present invention, as viewed from a plane perpendicular to the conveyance direction. In the figure, 21 is an ultrasonic generator, and 22 is an ultrasonic reflector, in which an ultrasonic generation surface and an ultrasonic reflection surface face each other, and a standing wave is generated between them. 23 is an object to be transported. Both ends of the ultrasonic generator and the ultrasonic reflector are curved upward, so that the standing wave fronts also have similar curved surfaces, and the nodes thereof also have similar curved surfaces. The barriers at both ends of this joint allow the object to be transported to move without falling off the transport path.

By carrying out the conveyance using ultrasonic standing waves in this manner, there are no contact areas or air flow, and the generation and blowing up of dust is reduced, making it difficult for the dust to adhere to the conveyed object.

This concludes the detailed explanation of the ultrasonic levitation type conveyance device according to the present invention, but it is possible to change the configuration method, shape, etc. of the members for generating standing waves without changing the gist of the present invention. Needless to say.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a front view of an example of an ultrasonic levitation type conveyance device according to the present invention, and FIG. 2 is a schematic diagram of a side view of an example of an ultrasonic levitation type conveyance device according to the present invention. 1, 2, 3, 4, 5, 6... Ultrasonic generator, 7
...Ultrasonic reflector, 8...Object to be transported.

Claims (1)

[Claims] 1. A plurality of ultrasonic generation surfaces arranged in the conveyance direction and an ultrasonic reflection surface facing the ultrasonic generation surfaces, and ultrasonic waves generated by the ultrasonic waves from the ultrasonic generation surfaces. The object to be conveyed is levitated by a standing wave generated between the surface and the ultrasonic reflecting surface, and the amplitude of the ultrasonic waves generated from the ultrasonic generation surface facing the tip of the object in the conveyance direction is reduced. The amplitude of the ultrasonic waves generated from the ultrasonic generation surface is increased during a predetermined period before the object is moved, and the ultrasonic waves generated from the ultrasonic generation surfaces arranged in the next conveyance direction are generated. An ultrasonic levitation type conveyance device characterized in that the movement of the conveyed object is controlled by decreasing the amplitude of the conveyance object, and the standing wave fronts at both ends of the conveyed object are bent upward along the conveying direction of the conveyed object. 2. The configuration in which the standing wave fronts at both ends of the transported object in the transport direction are bent upward is characterized by bending both ends of the opposing ultrasonic generation surface and the ultrasound reflecting surface along the transport direction of the transported object. An ultrasonic levitation type conveyance device according to claim 1.