PURPOSE: To eliminate the generation of thermal stress dislocation in a wafer even at a quick cooling rate at which gold does not precipitate, by providing a space part in the part of a heat treatment jig corresponding to the central region of the wafer or the region crossing the central part in such a way that said part does not in contact tightly with the rear of the wafer.

CONSTITUTION: A wafer 2 placed on the imposing surface 3 of a triangular jig 1 which is a heat treatment jig is adhered tightly to the surface 3 only in the top edge part 10 and bottom edge part 11 thereof, and is supported by means of a stopper 4. The intermediate part indicating the central part of the wafer 2 does not in contact directly with an imposing plate 7 on account of the presence of a space part 12 formed by a groove 9. If such jig 1 is removed from the inside to the outside of the furnace, air flows into the groove 9 and the central part of the wafer 2 is cooled from the front and rear and is therefore uniformly cooled together with the parts 10, 11, whereby the temp. difference in the wafer 2 is reduced. The generation of thermal stress dislocation is thus suppressed and the deterioration in characteristics on account of the generation of dislocation is prevented.