Modified Magnetron Type Plasma Source for Etching Applications

The applicability of modified magnetron-type plasma source for SiO2 etching was investigated. The plasma source is comprised of a cylindrical shaped rf electrode with two magnetic rings attached to its outer surface, and an electrically isolated top plate made of Al. The substrate holder lies parallel to the top plate. This basic configuration was slightly modified twice by placing two punched-plates at the height of substrate as a plasma shield at one time and by connecting an LC circuit to the top plate at the other time in order to confine the plasma between the top plate and the substrate. Variations of plasma density, uniformity and etching rates of thermally grown SiO2 for the above different configurations were observed. When the plasma shield is attached, the plasma can be confined between the substrate and the top plate by changing the value of the capacitor of the LC circuit. The plasma generated with this configuration yields a higher plasma density (9.8 × 1010 cm-3) and a higher etch rate (506 nm/min) at 9.1 Pa.