Molecular contamination control technologies for high volume production in high NA 193-nm lithography (phase II)

The current semiconductor resist process requires a clean atmosphere for 193-nm immersion exposure. Processing involving such small dimensions and short wavelengths requires an atmosphere with extremely low concentrations of various amines, as well as ammonia. This clean space is secured by using an ion-exchange type chemical filter. In addition, a variety of organic contaminants cannot be ignored. For example, in the exposure process, siloxane and other low molecular weight compounds are transformed into high molecular weight compounds by short-wavelength light, and cause lens fogging. To deal with these organic compounds, an activated carbon filter has been used. This paper establishes an optimized design theory for an ion exchange filter based on the molecular diameters of targeted amines by examining the adsorption of various types of amines by ion-exchange resin. We verified the adsorption behavior of a chemical filter by considering the actual environment around the wafer, and established a clean environment by using adsorption theory for various types of contaminants.