Online monitor of heavy ion flux in an ion irradiation apparatus for semiconductor irradiation test

摘要

An online monitor of heavy ion flux for semiconductor irradiation test was developed and tested. The monitor consists of four annular-shaped segmented secondary electron emission monitors (S-SEMs) arranged in a quadrature around the central area of a beam line. Each SEM detects heavy ions diffused to the outer side from the center of the beam by a scatterer to expand the beam size without interference with the central part of the beam. Each SEM is independent, then the count of each SEM reflects the beam position or profile. Therefore, the device can be used as an online monitor for beam intensity and position. The device is named S-SEM. S-SEM was installed in an ion irradiation apparatus for semiconductor devices at the Tohoku University K = 110 AVF cyclotron. We tested its performance and demonstrated that the S-SEM enables us to monitor the heavy ion flux down to lower than 10~4 #/cm~2s, without any energy loss to the beam. Further, S-SEM provides information on the beam position in both vertical and horizontal directions as expected.