| 摘要 |
PURPOSE: To facilitate the electric discharge machining of extremely high purity silicon functioning as an insulating material by electric discharge machining the extremely high purity silicon after heating it for giving conductivity to it. CONSTITUTION: The resistivity fo extremely high purity silicon at room temperature is 30Ω.cm, and when the silicon is gradually heated up to 250 deg.C, 300 deg.C, 350 deg.C, 400 deg.C and 450 deg.C, the resistivity severally becomes 4Ω.cm, 0.6Ω.cm, 0.43Ω.cm, 0.26Ω.cm and 0.09Ω.cm. Thus, the extremely high purity silicon can be electric discharge machined when heated to 250 deg.C, but when heated to high temperature more than 300 deg.C, the resistivity becomes lass than 1Ω.cm, and the electric discharge machining becomes easier. But since a temperature limit where heat resistance, insulating ability and viscosity required by electric discharge machining liquid can be maintained is 450 deg.C, the upper limit of heating temperature of the extremely high purity silicon is fixed at 450 deg.C.
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