Isotope Effects on Ion Flux Composition, Ar metastables, and Etching of Hydrocarbon films for Ar/H2 and Ar/D2 Plasmas

We observe important isotopic differences in plasma composition as H 2 or D 2 are added to Ar. Specifically, Ar M density and ion flux composition depend on isotopic composition, which. enables novel tailoring of plasma surface fluxes/interactions, and presents a sensitive test/validation of models. Gas-phase impurities in plasmas cause changes in plasma properties and plasma-material interactions. We explored the consequences of adding reactive gases of different isotopes (H 2 or D 2) on the properties of an Ar low temperature plasma at low pressures. Using multiple diagnostic techniques on this inductively coupled low temperature plasma allows for real-time monitoring of plasma properties (e.g., ion composition, T e , n e , EEDF, and metastable densities) and plasma-material interactions (e.g. changes in material density and thickness). This setup allows one to determine and evaluate models for plasma effects when introducing gas-phase impurities into an Ar plasma and for surface of the etching material. Adding small amounts of H 2 or D 2 to the plasma causes a large drop in plasma density as they introduce more energy loss pathways. The effects on ion composition show that ions quickly transition from inert Ar + ions to reactive ArX + and X n + ions (n=1,2,3). Metastable densities also change drastically. The 420.1nm-to-419.8 nm emission intensity ratio provides a measure of the presence of argon metastables in Ar-based discharges [1] and is shown in Fig. 1. We find that the 420.1nm-to-419.8 nm emission intensity ratio when H 2 impurity is added decays faster than when D 2 is the impurity. We are currently modeling this behavior with complementary probe measurements to determine the total metastable densities in the respective plasmas [1]. There are large differences in plasma-surface interaction between H 2 and D 2 impurities in Ar plasma. When controlling and normalizing the ion energies using a substrate bias, we find that D 2 impurities have a higher etch rate in hard amorphous hydrocarbon films. This can be explained by the faster transition to reactive ions, along with the higher average mass of the incoming ions. Along with the increased erosion rate, D 2 causes lower amounts of modification to hydrocarbon surfaces than H 2. The feedback of the etched products is higher in the D 2 case than for the H 2 case as more C and H is etched from the surface and flows into the plasma at a higher …