Performance and modeling of a permanent magnet electron cyclotron resonance plasma source

Abstract

A plasma etch reactor with a permanent magnet electron cyclotron resonance (ECR) source and multipolar process chamber has been characterized with plasma parameter and etch measurements. The ECR source uses a compact permanent magnet structure, rather than current‐driven electromagnet coils, to establish the axial magnetic field required for ECR operation. The source is compact and requires no input electrical or cooling power. Plasma densities greater than 1011 cm−3 and ion current densities above 10 mA cm−2 are obtained; the plasma parameter uniformity is 1.2% (1σ) over 20 cm. The etch rate in undoped polysilicon is 3450 A/min without applied bias, and the etch rate uniformity is 1.8% (1σ) over a 14 cm wafer diameter. The radial and axial plasma parameter profiles agree with the predictions of an ambipolar diffusion model.