Challenges in low pressure plasma source development
Many plasma applications require high vacuum in the process chamber such as ion or electron beam production and remote plasma cleaning. If the pressure in the process chamber is too high, high voltage arcing may happen between high voltage electrodes. It may also impact the operation of turbo pump.
A well-known method is to add a very small differential pumping aperture or a flow restrictor between the plasma source and the downstream process chamber. Such concept had been described in page 3 of reference 1
in 1978. Microwave plasma cleaner
and inductively coupled plasma cleaner
with flow restrictor have been disclosed in reference 2
and reference 3
respectively. However, very small differential pumping aperture hiniders the transportation of radical species from the remote plasma source to the processing chamber and limits the amount of electron or ion current that can be extracted from the plasma source. Therefore, an efficient plasma source that can be operated at low pressure inside the plasma source is very important for aformentioend applications. If the plasma source can relaiably work at lower pressure, then the diameter of the differential pumping aperture can be increased. The cleaning speed can be greatly improved if the size of the differential pumping aperture can be increased. Higher ion or electron current can be extracted out of the plasma source with larger extraction aperture.
High efficiency inductively coupled plasma source developed by Dr. Jiang. It's also the basic technology of the first generation SEMI-KLEEN plasma cleaner.
Technology behind the PIE Scientific's highly efficient plasma source
Dr. Jiang had been developing inductively coupled plasma source (ICP) since 2001 at the Lawrence Berkeley National Laboratory. Two of his innovative plasma source designs have been published in the Review of Scientific Instruments 5, 6
. Based on his previous work at the Lawrence Berkeley National Laboratory, Dr. Jiang further improved the performance his previous design at the low pressure operation region. His latest design improved the plasma density by as much as 3 times at the low operation pressure region. This patent pending
new technology---also marketed as Turbo Discharge™
has been successfully commercialized by PIE Scientific to produce highly efficient plasma sources.