Technology Behind EM-KLEEN and SEMI-KLEEN plasma cleaner

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 the turbopump.

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 a concept had been described on 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, a very small differential pumping aperture hinders 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 the aforementioned applications. If the plasma source can reliably 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 a larger extraction aperture.

Technology behind the PIE Scientific’s highly efficient plasma source

Dr. Jiang had been developing an 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 of 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 patented new technology—also marketed as Turbo Discharge™ has been successfully commercialized by PIE Scientific to produce highly efficient plasma sources.

Reference

1. Plasma cleaning device
2. Deposition chamber cleaning technique using a high power remote excitation source
3. Device for in-situ cleaning of inductively-coupled plasma chambers
4. Glow discharge ion source for film deposition
5. Mini rf-driven ion sources for focused ion beam systems
6. Development of a 27.12MHz radio frequency driven ion source with 3mTorr operation pressure for neutron generators