Electric discharge machining apparatus, electric discharge machining method, and semiconductor substrate manufacturing method

Abstract

An electric discharge machining apparatus includes: electrodes E 1 to En the total quantity of which is equal to N; an alternating-current power source G; and capacitors C 1 to Cn the total quantity of which is equal to N. The alternating-current power source G applies an alternating voltage commonly to the electrodes E 1 to En. One end of each of the capacitors C 1 to Cn is connected to a corresponding one of the electrodes E 1 to En, whereas the other ends of the capacitors C 1 to Cn are commonly connected to the alternating-current power source G.

1 . (canceled) 
     
     
         2 . An electric discharge machining apparatus comprising:
 a plurality of electrodes, whose total quantity is equal to N (where N is an integer), each of the electrodes is arranged adjacent to a workpiece and separated from the workpiece by an electric discharge gap;   either one of an alternating-current power source and a pulse generator that applies an alternating voltage or a voltage pulse to each discharge gap; and   a plurality of capacitors whose total quantity is equal to N, a first end of each capacitor being connected to a first end of the alternating-current power source or the pulse generator, and a second end of each capacitor being connected to a different one of the electrodes, wherein   a second end of the alternating-current power source or the pulse generator is electrically connected to the workpiece, and   each of the N capacitors, a corresponding one of the N electrodes, and a corresponding one of the N discharge gaps are connected in series to form N serial circuits, and   when charging, the alternating-current power source or the pulse generator applies the alternating voltage or the voltage pulse simultaneously to each of the N serial circuits, and when discharging, the alternating-current power source or the pulse generator applies a voltage that is obtained by superimposing a voltage generated in each capacitor onto the alternating voltage or the voltage pulse to each of the N discharge gaps so that an electric discharge to any one of the N discharge gaps occurs while electric discharges to the others of the N discharge gaps are sustained, and wherein   the electrodes are wire electrodes that are arranged in parallel, and   each of the wire electrodes is a mutually-different part of a single wire.   
     
     
         3 . The electric discharge machining apparatus according to  claim 2 , wherein the wire is guided in the form of a loop so as to provide physical connections between the electrodes. 
     
     
         4 . The electric discharge machining apparatus according to  claim 3 , wherein a magnetic material is inserted to inside of the loop. 
     
     
         5 . The electric discharge machining apparatus according to  claim 2 , further comprising:
 diodes whose total quantity is equal to N, cathodes of which are electrically connected to the second end of the alternating current power source or the pulse generator, and an anode of each of which is individually electrically connected to a corresponding one of the electrodes whose total quantity is equal to N.   
     
     
         6 . The electric discharge machining apparatus according to  claim 5 , further comprising:
 resistors, each of which is electrically connected in series to a corresponding one of the diodes.   
     
     
         7 . The electric discharge machining apparatus according to  claim 2 , further comprising:
 a resistor that is connected in series to the alternating-current power source or to the pulse generator;   a switching element that is connected in parallel to the resistor; and   a controlling circuit that turns on the switching element during a time period in which a positive voltage is applied to the workpiece and turns off the switching element during a time period in which a negative voltage is applied to the workpiece.   
     
     
         8 . The electric discharge machining apparatus according to  claim 2 , further comprising:
 resistors, each of which is connected in series between a corresponding one of the capacitors and the first end of the alternating-current power source or the pulse generator.   
     
     
         9 . The electric discharge machining apparatus according to  claim 2 , further comprising:
 inductors, each of which is connected in series between a corresponding one of the capacitors and the first end of the alternating-current power source or the pulse generator.   
     
     
         10 . The electric discharge machining apparatus according to  claim 2 , further comprising:
 an inductor that is connected in series between the first end of the alternating-current power source or the pulse generator and the first end of each capacitor.   
     
     
         11 . The electric discharge machining apparatus according to  claim 2 , wherein
 the alternating-current power source or the pulse generator, each of the N capacitors, and the corresponding one of the N discharge gaps are connected in series.