A consideration about ionizer balance in HGA process

Using ionizers is one of the most popular ways to prevent ESD damage. Ionizer balance in the HGA process is controlled to less than 5 V using a CPM (Charge Plate Monitor), because it was reported that the DCDM (Direct Charged Devices Model) ESD robustness of 30 Gb/in2 is less than 5 V and most likely decreasing. It is shown theoretically and experimentally in this study that the voltage of CPM is very different from the voltage on actual devices because ionizers act as charge density sources. Maintaining ionizer balance is of dubious importance in this application.