EFFECT OF FLUOROCARBON POLYMER BUILDUP AN ETCHING IN O-2 AR AND CF4/CHF3/AR PLASMA/

The effect of fluorocarbon polymer buildup on oxide etching was invest igated by monitoring the reactor chamber under an O-2/Ar plasma. Its e ffect on contact etching was also investigated by employing a CF4/CHF3 /Ar plasma. It was determined that the O-2/Ar plasma was very useful f or confirming polymer buildup on the inner chamber surface. This is be cause of arm increased oxide etch rate by fluorine radicals, formed by the dissociation of the fluorocarbon polymer. Meanwhile, contact etch ing in a CF4/CHF3/Ar plasma with a high CHF4/CE4 ratio caused a reduct ion in etch rate near the edge of the wafer (in some-cases even an etc h stop), a considerable loss of critical dimension, and higher etch se lectivity to polysilicon. These various etch behaviors are attributed to the polymer buildup on the inner surface of the chamber.