Monitoring system of reliability and repeatability of pressure compensation

It is well known that charge exchange phenomena are great issues on ion implanters, because they cause discrepancies such as dose shifts. To reduce the dose shifts, we introduced the system, so-called pressure compensation (Pcomp). On the Pcomp it is assumed that there is a simple relation among the true beam current (I₀), the detected beam current (I_m) and the beam line pressure (P). From I_m and P, we can calculate I₀, which is used to control the dosimetry during implantation. However, for example, when the vacuum condition of the implanter system changes, the relation among I₀ , I_m and P might change. Therefore, we developed a monitoring system to check how well the Pcomp works at every actual implantation batch