A Development of Partial Surfaces Ion Balance Analyzer

Abstract

A sub-1V ion balance in the tightly ionized environment raises the requirement of the partial surfaces ion balance analysis. According to ANSI/ESD STM3.1-2014, the ion balance is defined by the resultant of voltage on standard charged plate with the floated 15 cm×15 cm square shape conductive exposure surface. The size of this plate does not suit with the present devices which are very much smaller than the standard charged plate. Therefore, this research aims to develop the partial surfaces ion balance analyzer using the multi-plate sensor. The finite element analysis of shape and size of the receiving plates which could affect the precision of ion balance measurement has been done. The results can be used for selecting the suitable plate for improving the measurement resolution. Then, the analysis revealed that the measurement resolution could be proportionally increased with the number of partial segments. Furthermore, the minimum partial segment number of the circular and square shape plates are 9- segment and 16-segment, respectively. Eventually, the proposed analyzer was designed by using the 25-segment square plates with the ultra-high input impedance charge induced meter to measure the electrostatic potential on the multi-plate sensor. The embedded microcontroller processes the multi-channel analogue signals synchronously, then presents the results in a graphical display. The inverse distance weighting interpolation enables the higher resolution results beyond the physically data from the multi-plate sensor. This developed analyzer is suitable for ion balance measurement in the electrostatic controlled areas where the small footprint devices such as an integrated circuit, or the head gimbals assembly of a hard disk drive are placing.