| The "term" plasma cleaning has taken on special significance in the EM world in recent months as a result of there being issued US Patent No 5,510,624 which issued on April 23, 1996. |
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While most users of high resolution TEM utilizing side-entry goniometer
stages are doing materials science work and in general are studying
non-organic containing samples (meaning they can be plasma cleaned or etched
with oxygen without concern about sample damage), there is a minority of
researchers would not fall into that category. One obvious example
would be the examination of diamond thin film coatings on substrates and
with even the most gentle of oxygen plasma treatments, one could expect
there to be at least something done to the sample itself during the
"cleaning" cycle. Therefore there is the desire to use argon which would not etch or
change the diamond or other carbon containing domains. However, the use of argon at "normal" power levels for, for the SPI Plasma Prep II Plasma Etcher, that is, 100 watts, just might cause etching of the metal of the specimen stage and rod assemblies and that would be obviously undesirable. We are not aware of anyone who has ever found that such damage does in fact occur, but we point out that possibility. Certainly others have speculated that is could occur SPI Prep II Plasma Etcher. We therefore want to make the point that the newly introduced SPI Plasma Cleaner, while from a distance, has the appearance like it is the Plasma Etcher, we want it made clear that the system (e.g. the Cleaner) operates at 10 watts maximum power. One can safely clean using argon without concern about injury or etching to the metal parts of the stage assembly. One also has to realize that the SPI Plasma Cleaner is clearly a low cost system and was never meant to have all the bells and whistles of a more expensive unit, including the ability to carefully monitor and measure power levels at the low end of the power range. This means that the user can not determine precisely what is the power level actually being used in the SPI Plasma Cleaner. So is this really an "issue"? We think not. The proof of the product working is in the resulting images. In our own laboratory, we tried the SPI Plasma Cleaner, on a metallurgical sample, both before and after "cleaning", using a not-so-clean JEOL 100CX TEM, and our technicians were absolutely astonished at the difference. So the SPI Plasma Cleaner is not just for those purchasing brand new very expensive TEMs, at least some of the benefits can be realized right now by users of even quite ancient TEMs. But we do want to stress that the SPI Plasma Cleaner is not a $35,000 or $45,000 system. It does not have all of the bells and whistles one might expect on a system that is far more expensive. But if the need is for plasma cleaning, and no one has ever shown that in that respect this additional money purchases any better end result in terms of the cleaning, then the SPI Plasma Cleaner might be for you. NOTE: At the present time, it is not possible to switch back and forth in the field, from the cleaner configuration to the etcher configuration. However, if you do have an SPI Plasma Prep II plasma etcher or other etchers having a similar appearance, such as the Plasmod™ made by March Instruments, Inc. or the etcher made at one time by EMSL Supplies, contact us for a price for a conversion package which would convert the system you have into a plasma cleaner. However it would not be configured for plasma cleaning and it could not be expected to function any longer as an etcher. |
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