Patent ID: 7939441

Claim:
A method for heat-treating p-type silicon wafers, the method comprising: transferring p-type first silicon wafers having a resistivity of 10 Ω·cm or more to a wafer boat; inserting the loaded wafer boat into a vertical furnace; holding the first silicon wafers in an argon gas ambient atmosphere at a temperature of 1100 to 1300° C. for one hour; moving the wafer boat from the vertical furnace to a transfer chamber; discharging the heat-treated first silicon wafers from the wafer boat; and transferring second silicon wafers to be subsequently heat treated to the wafer boat, after discharging the heat-treated first silicon wafers, wherein a waiting time, representing the time in which the wafer boat waits in the transfer chamber and being defined as a time interval from when the heat-treated first silicon wafers are discharged from the wafer boat in the transfer chamber to when the second silicon wafers are transferred to the wafer boat, is set to be less than two hours, and wherein during the transfer of the second silicon wafer to the wafer boat, the first and second silicon wafers are transferred from a wafer container situated outside a vertical thermal processing apparatus having the wafer boat, the vertical furnace, and the transfer chamber, to the wafer boat disposed in the transfer chamber.