CHARACTERIZATION OF THE ETCH RATE NONUNIFORMITY IN A MAGNETICALLY ENHANCED REACTIVE ION ETCHER

A constant concern in semiconductor manufacturing is plasma induced da mage. A non-uniform etching plasma can induce a de current at the wafe r surface that can damage the film and therefore the device. The magne tic field in an Applied Materials magnetically enhanced reactive ion e tch chamber has been enhanced to provide minimal self-bias non-uniform ity. The objective of this article is to characterize the magnetic fie ld through a comparison of experimental etch data and modeling. Both a nalytical and empirical modeling have been used to gain a better under standing of the particular magnetic field configuration under investig ation. At low pressure the etch rate pattern correlated well with the calculated stationary magnetic field gradient. For higher pressure thi s model failed to predict the etch rate uniformity behavior because of contributions from other effects in the plasma. In order to character ize these effects, experiments were conducted for both stationary and rotating magnetic fields. This was done to aid process optimization wi th respect to the potential for damage. (C) 1998 American Vacuum Socie ty.