Utilization of an ion gauge in the process chamber of a semiconductor ion implanter

A device to implant impurities into a semiconductor wafer, comprising:

• a process chamber having a wall;
• a pressure compensation unit;
• a support disk to support a plurality of semiconductor wafers within the process chamber, the support disk having a radialy extending slot arranged among the wafers;
• a beam gun positioned upstream from the process chamber to shoot an ion beam at the semiconductor wafers;
• a cryo pump to minimize the pressure within the process chamber;
• first and second ion gauges, the first ion gauge being positioned between the process chamber and the cryo pump, the second ion gauge extending through the wall of the process chamber;
• a switching device to selectively connect the first or second ion gauge to the pressure compensation unit;
• a disk faraday to receive ions from the ion gun after the ions travel through the slot in the support disk;
• and
• a current meter to count the number of electrons flowing to the disk faraday to neutralize the ions.