Method and apparatus for improved low pressure collimated magnetron sputter deposition of metal films

摘要

A method and apparatus are provided which increase the collimation of sputter deposited films by increasing the mean free path (MFP) of sputtered atoms so as to reduce redirecting collisions with the buffer gas. This is accomplished by reducing buffer gas pressure while employing mechanisms to maintain or increase plasma electron density so as to sustain the plasma in the absence of normally required gas pressure. A first mechanism used to permit reduced gas pressure is to provide gas flow directly to the immediate region of the plasma discharge rather than to another remote area of the sputter deposition chamber. A second mechanism used to permit reduced gas pressure is to provide an electron emitting source near the plasma discharge to increase the plasma electron density without requiring further ionization of buffer gas atoms. These two mechanisms can be used either alone or together, as desired, in view of the circumstances presented.