Gj. Norga et al., SIMULATION AND IN-SITU MONITORING OF METALLIC CONTAMINATION AND SURFACE ROUGHENING IN WET WAFER CLEANING SOLUTIONS, Materials science and technology, 11(1), 1995, pp. 90-93
The steady decrease in the minimum feature size of Si integrated circu
its has led to an increase in the wafer cleanliness standards necessar
y to achieve satisfactory device yields. In the foreseeable future, we
t cleaning cycles will continue to be used because of their excellent
ability to remove particles and native oxides. However, trace metal de
position from contaminated solutions and surface microroughening by lo
calised etching, which are known to impact device yield severely, are
important concerns. The thermodynamic basis for simulating the effect
of solution composition on cleaning effectiveness is contained in E-pH
diagrams where E is the redox potential of the solution. Successful i
mplementation of advanced cleaning chemistries in the fabrication proc
ess depends critically on in line monitoring of cleaning performance.
For this purpose, a radio frequency photoconductance decay apparatus h
as been developed for the monitoring of cleaning solutions in real tim
e. The sensitivity of the apparatus to trace level Cu deposition from
dilute HF and surface roughening in deionised water is demonstrated. (
C) 1995 The Institute of Materials.