ESD Systems - Questions And Answers

In your answer to question #133 it is recommended no conductive materials are supposed to be close to a teflon fixture to avoid ESD. Actually in all semiconductor wafer fabs teflon holders or fixtures are very popular and silicon wafers with IC built on the top are held by those. Are these wafers ( ICs ) safe? As far as I know ionizers are not utilized in most of the wafer foundry. Please advise. - Anonymous, UNNC, Taiwan, Hsin Road, NON, Taiwan

Teflon is very popular because it is a very good insulator, is good for cleanrooms because it hardly outgasses, can handle heat fairly well and is machinable. Teflon is also a charge generator. As long as this is taken into consideration when used around semiconductor wafers or chips, then you can take steps to minimize the effects of charge induction problems. To determine if your Teflon fixtures are a problem, you can measure them with a field meter. If you find static electric fields on them, then ionization is recommended to control these unwanted electric fields. Other solutions are topical treatments, abstinence of use, minimized contact (reduce the tribocharging), etc. There are special ionizers made for clean room environments that minimize outgassing and isolate contaminants.

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