Abstract: A device for subdividing semiconductor bars into wafers comprises a grinding tool having two concentrically arranged grinding discs. A rough grinding disc is arranged inside of an outer smooth polishing grinding disc. The grinding tool grinds a lower face of a semiconductor bar to a smooth planar form. A first electrolytic truer operates in conjunction with the outer smooth polishing grinding disc while a second electrolytic truer operates in conjunction with the inner rough grinding disc. The truers are arranged to define an axial offset between the grinding surfaces of the grinding discs so that a lower face of the bar is smoothed. The device also has a slicing tool for slicing the bar into wafers which will have a smooth planar form.

Abstract: Wafers are manufactured from an ingot of semiconductor material by first machining a front face of the ingot to provide a substantially planar reference surface and then slicing the ingot using looped cutting wire apparatus. The cutting wire apparatus includes a looped cutting wire and at least two drive rollers over sectors of which the cutting wire is wrapped. Each drive roller is provided with its own drive motor which has shunt motor characteristics. The speed and torque of each motor is adjustable relative to the load applied to its drive roller by the cutting wire such that all of the drive rollers participate in driving the cutting wire with substantially the same reliability against slippage so that wear is distributed uniformly over all of the drive rollers.