Uniformity measurements in a helicon plasma etcher
- Univ. of Wisconsin, Madison, WI (United States). Engineering Research Center for Plasma-Aided Manufacturing
Recent research efforts on the UW helicon etcher have focused on the plasma density profile variation along the axis of the etching chamber. The goal of this research is to find ways to maintain a high plasma density while creating a radially uniform plasma. This study is unique because high magnetic fields are used in the source region.The UW helicon etcher consists of 21 magnetic field coils surrounding a 1 meter long, 10 cm diameter quartz tube. At one end of the tube is a Negoya Type 3 RF antenna which is run at 13.56 MHz. At the opposite end is the etching chamber containing a 20 cm diameter magnetic multidipole bucket. The purpose of the bucket is to both maintain a high plasma density and improve the radial uniformity in the etching chamber. This experiment was conducted using 20 sccm of argon at a pressure of 5 mT with an RF power of 900 W. It was found that the on-axis density in the chamber drops off in the axial direction in proportion to the magnetic field suggesting that the density drop-off is mainly due to the geometric effects of the flaring B-field. Radial density scans show that on the source side of the chamber the plasma density is highly peaked at the center with a density of 3.4 {times} 10{sup 11}/cm{sup 3} and an edge density of 5.6 {times} 10{sup 10}/cm{sup 3} giving a uniformity for {minus}7 cm {le} r {le} +7 cm of {+-} 42%. The effects of operating this device with a cusp field in the chamber in which there will be zero axial magnetic field in the center of the magnetic bucket will be discussed.
- OSTI ID:
- 160789
- Report Number(s):
- CONF-950612--; ISBN 0-7803-2669-5
- Country of Publication:
- United States
- Language:
- English
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