Diagnostic measurements and models of a compact ion source

Abstract

Summary form only given. Investigations of a compact 2.45 GHz microwave electron cyclotron resonance (ECR) ion source operating in argon, hydrogen and mixed argon-hydrogen discharges are described. The objective of this investigation is to develop a quantified understanding of the source operation in argon/hydrogen discharges. The approach is a combined numerical modeling and diagnostic measurement methodology. The ion source discharge region is 3.6 cm in diameter and 4.7 cm in length. The input parameters used in the source diagnosis include input microwave power (60-90W), chamber pressure (0.4-4 mTorr), and gas flow rate (8-30 sccm). The investigated source properties include positive charged species densities, electron temperature, and neutral (H-atom) concentration. The source properties are also evaluated at different positions including both the source and downstream regions in the chamber in order to understand the uniformity and distribution of charged species. In hydrogen discharges, optical emission spectroscopy (OES) is used in addition to the Langmuir probe measurement method to provide an alternative way of determining the electron temperature within the excitation region where Langmuir probe measurements are disruptive. A global model is applied to both the argon and hydrogen discharges for the investigated input parameter spaces. For hydrogen discharges, multiple positive charged species exist and considerations are made in the models for the more complex chemistry as compared to argon. Results of two-dimensional self-consistent microwave field and plasma simulations for the argon/hydrogen discharges are also presented. The modeling results will be discussed and compared to the diagnostic results from the experiment measurements.