In situ sample temperature measurement in plasma immersion ion implantation

Plasma immersion ion implantation (PIII) is an excellent surface modificati on technique because it is not restricted by the line-of-sight limitation t hat plagues conventional beamline ion implantation. However, the lack of in situ monitoring has hampered wider acceptance of the technique in industry . It is known that the implantation temperature has a large influence on th e surface properties of the treated specimens in addition to the more obvio us parameters such as implantation voltage, pulse duration, pulsing frequen cy, and so on. Direct measurement of the target temperature is complicated by the sample high voltage as well as by interference from the electromagne tic field and plasma. In this article, we present a novel interference-free , in situ temperature measurement technique employing a shielded thermocoup le directly attached to the sample stage. Our experiments show that the set up can monitor the target temperature in real time, even under severe arcin g conditions. Our results also indicate that in a hot filament glow dischar ge radiation heating is quite small, and sample heating is primarily caused by ion bombardment during the PIII cycles. The new design will open up oth er possibilities such as in situ dose monitoring if, for example, the therm ocouple is replaced by a Faraday cup. (C) 1999 American Institute of Physic s. [S0034-6748(99)03606-0].