Control of performance degradation induced by contact etching for a ferroelectric capacitor using a pulsed-power inductively coupled plasma

Using a pulsed-power inductively coupled plasma technique, etching characteristics for a SiO₂ film were investigated and applied to control the ferroelectric performance degradation induced by plasma etching when a ferroelectric capacitor structure is built to make a FeRAM device. It was found that the pulsed-power plasma helps to effectively suppress the degradation of the remanent polarization 2P_r, an important ferroelectric parameter, compared with the conventional continuous wave plasma. The polarization degradation sensitivities were characterized as a function of the duty ratio and time-modulation frequency in the pulsed plasma mode and we observed a strong dependency of the polarization on the duty ratio. We also tried to understand how the plasma composition change in the pulsed-power mode is correlated with the electrical characteristics degradation of the ferroelectric capacitor by means of ion mass spectrometry