Abstract: A wafer (22) is placed on an upper surface of a holder body (23), and the holder body is inserted into a plurality of holder-aimed concave recesses (14) formed on supporters (12) accommodated in a heat treatment furnace such that the holder body is held horizontally. The holder body is formed into a disk shape free of recessed cut portions, and the holder body is formed with an upwardly projecting ring-like projection (24) extending in the circumferential direction of the holder body around the axis of the holder body. The wafer holder is constituted such that the wafer is placed on the holder body while contacting with the upper surface of the projection, and such that the outer diameter of the projection is formed to be in a range of 0.5D to 0.98D wherein D is the diameter of the wafer, so that the outer periphery of the wafer is kept from contacting with the projection. Occurrence of slips in the wafer is restricted by preventing warpage of the holder body upon fabricating the holder body.

Abstract: An ultra-high-temperature heat treatment apparatus includes an electric furnace, a furnace tube made of porous SiC/CVD-SiC, a heat-insulating apparatus fitted into the furnace tube for interrupting heat conduction from the furnace tube, a contamination control apparatus disposed beneath the furnace tube for preventing contamination in the furnace tube, and a separator mechanism for separating a wafer, subject to heat treatment in the furnace tube, from an annular holder. The electric furnace includes a heater comprised of heater elements which are replaceable independently of each other. Each heater element includes a heat-generating portion disposed along the inner wall face of the heat insulator so as not to be in close contact therewith, and a fixture portion fixed to the heat insulator. This heater construction makes it possible to reduce heater repair costs, suppress reactions between the heat-generating portions and the heat insulator, and suppress a contraction of the heat insulator.