REMOTE AND DIRECT CLEANING BY USE OF MICROWAVE PLASMA SOURCE SLAN-II - COMPARATIVE-STUDY

A 2.45 GHz slot antenna microwave plasma source with a quartz tube as plasma chamber (diameter 66 cm and length 42 cm) has been applied for the removal of organic lubricants from glass substrates in a remote pl asma. Optionally, a remote cage separating the primary discharge direc tly at the quartz tube wall from the diffusion bulk plasma in the proc ess chamber was used. The radial and axial distributions of the ion co ncentrations (double-Langmuir-probe) and the removal rates (gravimetri c technique) for source versions with and without the remote cage were investigated. Typical process conditions are power of 4 kW, pressure of 2-5 Pa, oxygen flow of 100 sccm. Ion concentrations of 8 x 10(10) a nd 1.5 x 10(10) cm(-3) were measured for direct and remote plasma, res pectively. The removal rates are 800 and 150 nm min(-l), respectively. The remote cage allows the suppression of local heating of substrates by microwaves and a reduction of the removal rate variation along the source length (less than 20%).