NSF Award
9060603
The goal of this program is to investigate the causes of semiconductor wafer damage during oxygen photoresist stripping with a downstream microwave plasma. The use of oxygen plasmas for dry stripping of photoresist eliminates the handling, disposal, and resist degradation problems associated with liquid processes. A downstream, microwave- produced plasma has the additional advantages of no electrode contamination and low plasma potentials. However, as with other plasma etching methods, downstream microwave processing is associated with wafer damage including mobile ion contamination and electrostatic breakdown of oxide gates, wall-sourced contamination, and degradation from chemical or structural changes. The causes of such surface damage are not well understood. We propose to correlate such damage with plasma source phenomena such as UV radiation and surface charging. During phase I, we will make radial and axial scans of plasma density, electron temperature, and space potential in the vicinity of the wafer while monitoring neutral gas constitutents for a range of stripping rates and plasma source operating points. For phase II, on the basis of CV curve shift analyses we will correlate damage with plasma associated phenomena such as UV, surface charging, synergistic effects, and wall-sourced contaminants and develop means of effectively curtailing them.
