Neutralization of static electricity by soft X-rays and vacuum UV radiation

Abstract

The technology for neutralizing static electricity by soft X-ray radiation and vacuum UV radiation has been newly developed. This technology involves ionization of gas molecules in the vicinity of a charged substrate to generate ions and electrons to reduce electrostatic potential. The ULSI device substrate and the liquid crystal display substrate tend to get charged instantly to a high electric potential level (of several kVs) when they are handled in the manufacturing process. The amount of electric charge induced on their surface when they get charged, however, is small. This means the concentration of ions and electrons required for neutralization is considerably low. The wavelength of electromagnetic radiation to be utilized in neutralization is varied, depending on the neutralization atmosphere. Soft X-ray radiation is adequate in air or O 2 gas at atmospheric pressure while vacuum UV radiation is effective in N 2 gas, Ar gas, or at reduced pressure. This newly developed neutralization method is found to be superior to the conventional technique, i.e., an ionizer by using corona discharge, in every aspect. The new method features excellent neutralization capability and is able to completely reduce electrostatic potential to 0V within a short time. Moreover, this is a very clean antistatic technology free from particle generation, ozone generation, and electromagnetic noise, which are problems in using the corona discharge ionizer.