Cassette conveyance method and cassette conveyance apparatus

Abstract

A cassette conveyance apparatus ( 10 ) includes: a first conveyance means ( 20 ) for conveying a first cassette ( 40 ) in a horizontal and vertical direction; and a second conveyance means ( 30 ) for conveying a second cassette ( 50 ) in a horizontal and vertical direction. In the cassette conveyance apparatus ( 10 ), the first and second cassettes are circulated between a predetermined wafer accommodation position (P 1 ), at which a wafer ( 2 ) is accommodated in the cassette, and a predetermined cassette replacement position (P 0 ) at which a cassette accommodating a plurality of wafers is replaced with an empty cassette. Due to the foregoing, the wafers are continuously accommodated in the cassette without stopping an operation of a pretreatment step.

1 . A cassette conveyance apparatus comprising: a first conveyance means for conveying a first cassette in a horizontal and vertical direction; and a second conveyance means for conveying a second cassette in a horizontal and vertical direction, wherein the first and the second cassettes are circulated by the first and second conveyance means between a workpiece accommodation position, at which a workpiece is accommodated in the cassette, and a cassette replacement position at which the cassette accommodating a plurality of workpieces is replaced with an empty cassette. 
   
   
       2 . A cassette conveyance apparatus according to  claim 1 ,
 the first conveyance means including: a first horizontal rail; a first horizontal slider sliding on the first horizontal rail; a first vertical rail attached to the first horizontal slider; a first vertical slider sliding on the first vertical rail; and a first table, which is attached to the first vertical slider, on the top face of which the first cassette is arranged, and   the second conveyance means including: a second horizontal rail arranged in parallel with the first horizontal rail; a second horizontal slider sliding on the second horizontal rail; a second vertical rail attached to the second horizontal slider; a second vertical slider sliding on the second vertical rail; and   a second table, which is attached to the second vertical slider, on the top face of which the second cassette is arranged.   
   
   
       3 . A cassette conveyance apparatus according to  claim 1 , wherein
 the first table extends toward the second horizontal rail,   the second table extends toward the first horizontal rail, and   the first and the second table can be at least partially overlapped with each other on a face vertical to the first and the second horizontal rail.   
   
   
       4 . A cassette conveyance apparatus according to  claim 3 , wherein distances, by which the first and the second table extend from the vertical sliders corresponding to the first and the second table, are shorter than the distance between the first and the second horizontal rail. 
   
   
       5 . A cassette conveyance apparatus according to one of  claims 2  to  4 , wherein the lengths of the first and the second vertical rails are set in such a manner that the second table and the second cassette can pass under the first table when the first vertical slider is located at the lowermost position of the first vertical rail and when the second vertical slider is located at the uppermost position of the second vertical rail. 
   
   
       6 . A cassette conveyance apparatus according to one of  claims 2  to  4 , wherein the lengths of the first and the second vertical rails are set at minimum values in such a manner that the second table and the second cassette can pass under the first table when the first vertical slider is located at the lowermost position of the first vertical rail and when the second vertical slider is located at the uppermost position of the second vertical rail. 
   
   
       7 . A cassette conveyance method comprising:
 a first accommodation step in which a workpiece is accommodated in a first cassette at a workpiece accommodation position for accommodating the workpiece in the cassette;   a first conveyance step in which the first cassette is conveyed to a cassette replacement position at which a cassette accommodating a plurality of workpieces is replaced with an empty cassette and in the first conveyance step the second cassette replaced at the cassette replacement position is conveyed to the workpiece accommodation position;   a second accommodation step in which the workpiece is accommodated in the second cassette at the workpiece accommodation position; and   a second conveyance step in which the second cassette accommodating a plurality of workpieces is conveyed to the cassette replacement position and in the second conveyance step the first cassette replaced at the cassette replacement position is conveyed to the workpiece accommodation position, wherein   the first accommodation step, the first conveyance step, the second accommodation step and the second conveyance step are repeated.   
   
   
       8 . A cassette conveyance method according to  claim 7 , wherein the cassette is lowered by a predetermined distance each time the cassette accommodates one workpiece at the workpiece accommodation position,
 the cassette accommodating all of the plurality of workpieces is located at a position lower than the workpiece accommodating position, and   in the first and the second conveyance step, the one cassette of the first and the second cassettes conveyed from the cassette replacement position to the workpiece accommodation position passes above the other cassette conveyed from the workpiece accommodation position to the cassette replacement position.   
   
   
       9 . A cassette conveyance method according to  claim 8 , wherein the first and the second conveyance step include a process in which the other cassette is raised.