Wafer transfer method

A wafer transfer method according to the present invention comprises taking out a plurality of wafers from a cassette while holding the wafers by a chuck mechanism, transporting the held wafers to a region over a boat, transferring all the wafers from the chuck mechanism to the boat so that the wafers are arranged in a predetermined position on the boat, relatively moving the chuck mechanism with respect to the boat for a distance equal to an integral multiple of a distance corresponding to the spacing of each wafer, and holding a required number of wafers, out of the plurality of wafers on the boat, by use of the chuck mechanism to dislocate the wafers on the boat or return the wafers to the cassette, and thereafter transferring a plurality of wafers from another cassette to the boat. According to the present invention, monitor wafers are arranged with predetermined distances between wafers on the boat, and product wafers are transferred from the second cassette to the spaces between the monitor wafers. Thus, the monitor wafers are arranged on the boat for each lot of product wafers. If the wafers in the cassette are subject to an omission, the wafers on the boat are moved for a distance corresponding to an omitted wafer or wafers so that the wafers are continuously arranged at regular pitches on the boat.