Interaction between gas rarefaction and metal ionization in ionized physical vapor deposition

The process known as ionized physical vapor deposition, or I-PVD, consists of the physical sputtering of metal atoms into a dense, inert gas plasma; i onization of the sputtered metal atoms, and subsequent deposition of the fi lms from these metal ions. Measurements have shown a decrease in electron t emperature coupled with an unexpected decrease in plasma density as a funct ion of increasing metal flux. Recent plasma modeling work has suggested gas rarefaction as the underlying factor in these declines. Measurements of ne utral gas density in the plasma region reported here confirm this model and are consistent with earlier studies of sputtered atom induced gas heating and rarefaction. (C) 1998 American Vacuum Society. [S0734-211X(98)01106-8].