Plasma Damages of Thin Oxide Measured by a Large Charge Collecting Antenna Structure

Damage of the gate oxide induced by plasma processing, due to charge buildup on conductors in ohmic contact with the oxide, was studied by special test structures consisting of a small test capacitor connected to large charge collecting antennas on conducting layers. Effects of various plasma processing steps in amodel complementary metal oxide semicon-ductor process on the gate oxide quality, as revealed by the charge to breakdown (Qbd) measurements, after successive processing steps are reported. The most pronounced degradation of the oxide quality occurred at the metal-1 etch: AQbd = 2-1.9 C/cm or 360 pC/~m of exposed edge. About 220 pC/v~m of the cumulative value is due to the metal-1 etching and 140 pC/~tm is due to the partial photoresist ashing