Ion source for IMA with both polarities and its applications

It has been proven to be difficult to make the conventional ion proves for ion microprove analyzers (IMA) to operate well, due to poor ion current availability. The authors have developed a new ion gun for this purpose. The ion gun comprises a new control electrode as well as a conventional cathode, an intermediate electrode, an anode and an extracting electrode. The control electrode is supplied potential either in positive or negative polarity. Summarizing the experimental results, the authors have obtained the following results. (1) Large current output of both positive and negative ions can be extracted by the design with the control electrode, (2) primary ion current is varied over a wide range due to the voltage control of the control electrode, and (3) ion current efficiency is improved 10 times as high as conventional design by optimizing the control electrode potential. Also a new technique for the prevention of specimen charge-up utilizing secondary electron emission under the irradiation of negative ion beam is reported. The operating mechanism for charge neutralization is described. The analysis of insulator materials has been conducted on inorganic specimens such as NB, mica, Al2O3 and SiO2, and organic specimens such as mylar, silicone rubber, amino acids and gelatine. By these results, it is believed that an analytical technique has been established for insulating materials with charge neutralization. (Wakatsuki, Y.)