AVS 49th International Symposium
    Plasma Science Tuesday Sessions
       Session PS2-TuA

Paper PS2-TuA4
Generating High-efficiency Neutral Beams by Using Negative Ions in an Inductively Coupled Plasma Source

Tuesday, November 5, 2002, 3:00 pm, Room C-105

Session: Plasma Surface Interactions I
Presenter: S. Samukawa, Tohoku University, Japan
Authors: S. Samukawa, Tohoku University, Japan
K. Sakamoto, Tohoku University, Japan
K. Ichiki, Ebara Research Co., Ltd., Japan
Correspondent: Click to Email
To minimize radiation damage caused by charge build-up or ultraviolet and x-ray photons during etching, we developed a high-performance neutral-beam etching system. The neutral-beam source consists of an inductively coupled plasma (ICP) source and parallel top and bottom carbon plates. The bottom carbon plate has numerous apertures for extracting neutral beams from the plasma. When a direct current (DC) bias is applied to the top and bottom plates, the generated positive or negative ions are accelerated toward the bottom plate. Most of them are then efficiently converted into neutral atoms, either by neutralization in charge-transfer collisions with gas molecules during ion transport and with the aperture sidewalls in the bottom plate, or by recombination with low-energy electrons near the end of the bottom plate. We found that negative ions are more efficiently converted into neutral atoms than positive ions. The neutralization efficiency of negative ions was almost 100%, and the maximum neutral flux density was equivalent to 4.0 mA/cm@super 2@. A neutral beam can thus be efficiently produced from the ICP source and apertures in our new neutral-beam source.