Ion energy distribution measurement device using a capillary plate with high-aspect ratio

Abstract

An ion energy measurement method using a capillary plate with a high-aspect ratio is proposed to obtain ion energy distribution (IED). When a capillary plate is used, an electron-shading (ES) effect is introduced in which a potential difference occurs between the top and bottom of the capillary plate because of a difference in the mobility of ions and electrons. Electrons are repelled by the potential difference, and only ions reach the bottom of the capillary plate. Additionally, the measured IED at the bottom of the capillary plate is similar to the value at the bottom of the contact hole in the etch process. This means that the actual ion energy reaching the inside of the contact hole can be predicted in the etch process. In our experiment, the IED was obtained using the ES effect at various discharge conditions, such as RF bias power, pressure, and aspect ratio (L/D), of the capillary plate. The ES effect was verified by a particle trajectory simulation, and the ion current measured at the collector was compared with the increasing aspect ratio. The obtained IEDs were in good agreement with previous works.