| 摘要 |
PROBLEM TO BE SOLVED: To detect an end point with high accuracy by retarding ions which become obstacles to the analysis, and negatively ionizing neutral chemical species softly, and mass-separating the produced negative ions for separation. SOLUTION: Xe gas is introduced from a gas introduction part 112 so as to produce xenon in very high excitation state by the shock of electrons emitted from a filament. A concentric grid hinders electrons or Xe<+> ions from penetrating the center collision area. The xenon and the neutral chemical species of a reactive product collide against each other, and become Xe<+> and product negative ions. Together with the start of etching, the strong signal of SIF3 is observed, but about one minute later equivalent to the time of etching SiO2 by 1μm, the signal intensity begins to decrease, and then the signal intensity is settled to about one fourtieth as high as initial one.
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