1/f noise reduction in PMOSFETs by an additional preoxidation cleaning with an ammonia hydrogen peroxide mixture

摘要

1/f noise magnitude in a 15 μm × 0.5 μm PMOSFET was remarkably reduced by simply adding a cleaning step using an ammonia hydrogen peroxide mixture (APM) prior to gate oxidation. Gate input-referred noise level for APM-finished PMOSFETs at f = 10 Hz was around - 128 dBV{sup}2/Hz whereas for standard, HF-finished devices, the level was around -114 dBV{sup}2/Hz. Flat-band voltages (V{sub}(FBS)) determined by a capacitance-voltage(C-V) measurement were -0.19 V for an APM-finished PMOS and -0.34 V for a HF-finished PMOS. Based on the V{sub}(FB) values, interface state densities were determined to be Nv(it) =3.02 × 10{sup}11 cm{sup}(-2) for APM-finished PMOS and N{sub}(it) 6.47 × 10{sup}11 cm{sup}(-2) for HF-finished PMOS. Lower interface state density obtained by the APM preoxidation cleaning is consistent with the remarkable reduction in the 1/f noise magnitude.