We do a lot of cleaning and repair service at Plasma Process Group and we get a good chance to see your hardware throughout its life cycle. For the same reason, we also get to see what causes that life cycle to shorten. Here are a few quick things you can do or keep in mind to get the most out of your hardware:
RFNs are extremely vulnerable to oxygen and water. The life of the RFN collector diminishes when it is exposed to atmosphere when they are still hot. After running a process, the RFN should be cooled with Argon flowing continuously for 30 minutes prior to venting.
For the same reason, purging your gas line before starting your process is important. Every time you vent, air and water vapor can get into the gas line and thus contaminate the RFN. We recommend flowing Argon to the RFN for 5 minutes prior to starting process. We also recommend using electropolished stainless steel gas lines from the gas bottle to the RFN. Other types of gas lines may contaminate the collector.
Placement of your RFN makes a difference. Too far from your ion source, and the source may struggle to ignite. In the path of the deposition plume, and it will both interfere with your process and require much more frequent cleaning. Too close to your ion source, and it may be sputter eroded by the ion beam itself. The ideal location for an RFN is 8 – 10 inches away from the ion source, and on the opposite side of the ion source from the substrate fixtures.
The RFN is not water cooled. Instead, it radiates its heat out into the chamber. While this heat has no effect on the process, improperly shielding the RFN can lead to unexpected negative effects on the RFN itself. Many people put protective foil over the RFN in an attempt to keep it from getting coated during process run. However, if the foil blocks the RFNs ability to radiate heat, it is unable to cool and will eventually overheat, which can damage the antenna and gas isolator. If you are looking to protect your RFN from coatings, consider a piece of stainless steel sheet parallel with the RFN, mounted (or otherwise attached) to the chamber wall, and two to three inches off to the side. It should extend no further than the front of the RFN Keeper so that the emission from the RFN has a clear path to the ion source. The sheet also does not need to wrap 360° around the RFN – just shield the exposed side to the coating.
When the time comes for a refurbishment, send it to us and we’ll make it good as new without the expense of purchasing a new unit. Many of our refurbishment customers get over 2000 hours of RFN use between maintenance cycles.