DEVELOPMENT OF AMMONIA ADSORPTION FILTER AND ITS APPLICATION TO LSI MANUFACTURING ENVIRONMENT

Activated carbon treated with a hydrogen salt is found to be effective in suppressing ammonia concentration in LSI cleanrooms. The hydrogen salt which contains neither phosphor nor metals is utilized. Its adsor ption capacity is about 1000 mol/m3-carbon. This corresponds to a life time of about two years in an ordinary cleanroom. Compared to this, un treated activated carbon adsorbs less than 10 mol/m3, so it cannot be used for more than 10 days. A chemically amplified resist, known to be susceptible to degradation from alkaline gaseous substances in cleanr ooms, is shown to maintain its 0.25-mum line and space patterns under hydrogen salt treated carbon filtered air, even when the developing is delayed for 60 min after excimer laser exposure.