Evaluation of plasma damage in blanket and patterned low-k structures by near-field scanning probe microwave microscope: effect of plasma ash chemistry

The effect of ash chemistry on dielectric constant of blanket and patterned low-k was studied using a near-field scanning probe microwave microscope, known commercially as NeoMetriK^TM technology. Two common photoresist ash approaches with the same etch sequence were studied: plasma assisted sublimation of photoresist at elevated temperature and ion-assisted ash at room temperature. The results for blanket low-k agree well with the FTIR and water source ellipsometric porosimetry (WEP) measurements. The amount of sidewall damage measured in patterned structures before metallization confirms the expected trends.