A fabrication method of a semiconductor device comprises the steps of forming a metal thin film Whose oxide is insulative on sidewall of a hole formed in a semiconductor substrate and forming an insulating metal oxide film by oxidizing the metal thin film. The method including heating an optical fiber preform in a heating furnace including a first heater to melt the optical fiber preform, and fiber drawing an optical fiber from the molten optical fiber preform. The device includes a fixed base support attached to the handle support structure, and a bearing assembly to permit rotation of the contiguous handle, end caps and handle support structure by a user with the base support resting on a planar surface. Shapes of the depressed portions 8A and fitting portions 5b are both defined so that there occurs no relative displacement in the radial direction of the rotating shaft 1 between the rotor stacks 7B, 7A and the rotor collars 5A, 5B with the fitting portions 5b fitted into the depressed portions 8A.