Wire electrical discharge machining apparatus and method of manufacturing semiconductor wafer

A wire electrical discharge machining apparatus that generates electrical discharge between a workpiece and a wire electrode and performs electrical discharge machining on the workpiece with energy due to the electrical discharge, the wire electrical discharge machining apparatus comprising:

• a plurality of parallel wire sections that are formed by winding a piece of the wire electrode around a plurality of guide rollers and includes a region facing the workpiece;
• a power source to apply voltage across each of the parallel wire sections and the workpiece arranged to face the parallel wire sections;
• an ascending/descending stage to move the workpiece relative to the parallel wire sections;
• and
• a controller to control an operation of the wire electrical discharge machining apparatus, wherein
• the controller controls cutting and shape correction under different machining conditions, the cutting being performed to simultaneously cut a plurality of wafers by performing electrical discharge machining while moving the workpiece relative to the parallel wire sections and leave a connection at which a part of each of the wafers that are incompletely cut is still connected to the workpiece;
• and the shape correction being performed to cause the parallel wire sections to perform relative movement while performing electrical discharge machining along a path identical to a path of the parallel wire sections in a cutting direction so that an interelectrode distance between each of the two surfaces and the wire during the shape correction is identical to each other, at the time of the cutting to correct a shape of each of two surfaces of a plurality of cut surfaces that are cut at the time of the cutting, the two surfaces facing each other while interposing the parallel wire section between the two surfaces.

A method of manufacturing a semiconductor wafer by generating electrical discharge between a plurality of cutting wire sections that are running and a workpiece made of a semiconductor material, performing electrical discharge machining on the workpiece with energy due to the electrical discharge, and cutting the workpiece into a plurality of wafers simultaneously, the method comprising:

• forming the cutting wire sections that are damped by interposing a plurality of wire members running in parallel with each other between a pair of damping guide rollers and a pair of wire pressing sections;
• a cutting process of performing cutting of simultaneously cutting the workpiece into the wafers by performing electrical discharge machining while moving the workpiece relative to the cutting wire sections and performing the cutting while leaving a connection at which a part of each of the wafers that are incompletely cut is still connected to the workpiece;
• and
• a shape correction process of causing the cutting wire sections to perform relative movement while performing electrical discharge machining along a path identical to a path of the cutting wire sections in a cutting direction at a time of the cutting and correcting a shape of each of two surfaces of a plurality of cut surfaces that are cut at a time of the cutting, the two surfaces facing each other while interposing the cutting wire section between the two surfaces, wherein
• a machining condition is different between the cutting process and the shape correction process.