Patent DE-102007028439-A1 (DE)
Title: Separating flat-parallel silicon wafers from cuboid crystalline or polycrystalline silicon ingot using wire saw for photo-voltaic applications, comprises moving wire around rolls, and attaching the ingot to reception of the wire saw
Inventor: SCHARF HELMUT
IPC: H01L21/304
Filed: 2007-06-18
Abstract: The method for separating flat-parallel silicon wafers from a cuboid crystalline or polycrystalline silicon ingot (1) using a wire saw for photo-voltaic applications, comprises moving a self-moving wire around rolls provided with grooves for forming a wire group (3), attaching the ingot to a reception (5, 6) of the wire saw, adjusting an angle of inclination of the plane lateral surfaces relative to a plane stretched by the wire sections, and separating the wafers by relative motion of the ingot and the wire groups. The ingot is connected with the reception over an intermediate plate (4). The method for separating flat-parallel silicon wafers from a cuboid crystalline or polycrystalline silicon ingot (1) using a wire saw for photo-voltaic applications, comprises moving a self-moving wire around rolls provided with grooves for forming a wire group (3), attaching the ingot to a reception (5, 6) of the wire saw, adjusting an angle of inclination of the plane lateral surfaces relative to a plane stretched by the wire sections, and separating the wafers by relative motion of the ingot and the wire groups. The ingot is connected with the reception over a wedge-shaped intermediate plate (4) such as an adhesive connection or an adhesive joint, and has uniform surface area. An acute angle (alpha ) is enclosed between plane lateral surfaces of the ingot turned to the wire groups and the plane stretched by the wire sections for beginning the separation. For beginning the separation, the sections of the moving wire touch the edge of the plane lateral surfaces in a series of point manner. The point-contacting takes place under formation of an angle given by the acute angle and the mechanical pre-stressing of the sections, where the angle is enclosed between the plane stretched by the wire sections and the lateral surfaces of the ingot. A tilting of the plane lateral surfaces to the plane stretched by the wire sections is maximum 1 mm on 200-800 mm breadth of the plane lateral surfaces. The reception is aligned parallel to the plane stretched by the wire sections. The angle of inclination and/or the acute angle are given by a wedge angle of the intermediate plate. An inclination mechanism is arranged to the reception. The reception is inclined by the adjustment of the inclination mechanism relative to the plane stretched by the wire sections. The ingot has another uniform surface area, which lies opposite to the plane lateral surfaces, is aligned parallel to the lateral surfaces and is connected over the flat-parallel intermediate plate with the reception. An angle of inclination of the plane lateral surface of the ingot and/or the front surface of the intermediate plate is determined relative to the plane stretched by the wire sections and is adjusted on the basis of the regulation. The reception is tilted by adjusting the inclination mechanism after the beginning of separation of the wafer in such a way that a front surface of the intermediate plate turned to the ingot is parallel to the plane for ending the separation process. The inclination device is adjusted so that wire sections stretching the plane of the group of wires are merged over the entire width of the ingot.