PURPOSE: To prevent fine particles of quartz or other clouds of very small sand from creeping between substrates and to realize a high grade by a method wherein a plurality of semiconductor substrates where oxide films have been formed on a wafer are placed apart from each other inside a semitight quartz container in a state that the oxide films are faced, the quartz container is brought into a heating furnace and the substrates are bonded by means of a heat treatment.

CONSTITUTION: Two holding tools 18 and a moving jig 20 are placed inside a boat 12; two semiconductor substrates 22 are erected against the holding tools 18 at the inside of the two holding tools 18 separated at a definite amount in such a way that their mirror faces are faced. Then, a cover 14 is mounted on the boat; the inside of the boat and the cover is set to a semiairtight state. Then, a bonding apparatus which has been assembled in this manner is conveyed to a heating furnace from mounting surroundings and is put into the furnace. The heating furnace is provided with a heater 24 which heat-treats the semiconductors inside the bonding apparatus; the semiconductor substrates are heat-treated for a definite time at a high temperature of 500°C or higher; an organic substance or the like which has adhered to the semiconductor substrates is decomposed and removed. Then, a stopper 20C of the moving jig 20 is pushed by means of a quartz rod 26; the two semiconductor substrates are pressed slightly and are brought into contact. These substrates are heat-treated for a definite time in a contact state; the two semiconductor substrates are bonded.