We report on the physical attributes of an argon-hydrogen plasma and the effects that induced changes in these attributes have on the physical and electrical characteristics of the plasma itself. Changes in the plasma conditions of these argon-hydrogen plasmas due to variations in microwave power, DC biasing, gas concentrations, and pressures were measured. We determined that increasing the hydrogen flow increases the sheath potential of the plasma, thereby increasing the arrival energy of ions at the surface of a sample placed in the plasma. Even with the decrease in plasma density from an increase in hydrogen input flow, we found the ion current is maintained in the predominately hydrogen plasma and is likely compensated by the high velocity and long mean free path of the hydrogen. We also observed that increasing total pressure also results in hydrogen ions dominating the total number of ions reaching the Langmuir probe and therefore the sample during processing. Last, a model based on the ion/electron energy ratio was developed and used to determine the relative ion concentrations of hydrogen and argon ions.

It has been observed in semiconductor processing that the etch rates for materials subjected to an electron-cyclotron resonance (ECR) plasma change with the total sample area. This phenomenon is known as loading. Loading effects can result in pattern definition errors during micromachining. In argon/hydrogen plasmas, designed to etch II-VI materials, loading appears to primarily affect photoresist deterioration. Using an 80% argon-20% hydrogen gas chemistry optimized for HgCdTe, we observe a factor of 2 variation in photoresist etch rate. Loading may also affect semiconductor etch rates to a lesser extent. The observed trends suggest that radical changes in the plasma are the likely cause of this phenomenon.