Electrical description of an inductively coupled plasma processing reactor with discharge parameters calculated from a global model

Abstract

A commercial inductively coupled plasma processing reactor is modeled by an equivalent electrical circuit combined with a global model, which calculates the electron temperature and the plasma density for Ar discharges at the pressures of 15 mTorr and 30 mTorr. Based on the transformer model, a refined electrical branch of the capacitive coupling is incorporated to obtain a complete electrical description for the reactor, which takes the coil interturn stray capacitance, wafer, and chuck into full consideration. Voltages and currents at the driving coil are recorded by using a voltage/current probe radio frequency analyzer installed after the matching unit. Using the measured voltage as an input, the total discharge current is calculated from Kirchhoff’s laws and shows excellent agreement with the measurements. The experimentally verified electrical circuit provides a comprehensive and accurate description for the reactor, which can serve as a guideline for process window planning in industrial applications.