## 2 Materials and Methods
### AMC Monitoring Sites in A Cleanroom at the University of Minnesota  
Figure 2 depicts the different monitoring sites in a cleanroom at the University of Minnesota for the measurements of AMCs through the portable soft X-ray radiolysis detector. The cleanroom air was well conditioned at 40% relative humidity (RH), 21 \({}^{\circ}\)C and consisted of 4 different ways with a common corridor as shown in Figure 2a. Among the bays, Bay 1 and 2 had different facilities used for semiconductor manufacturing processes. Bay 1 had a wet bench, chemical vapor deposition (CVD) furnace, and some analysis instruments including microscopes, and Bay 2 mainly had instruments for photoresists (PR) coating processes. Therefore, Bay 2 equipped yellow lamps, instead of normal cold cathode fluorescent ones installed in Bay 1. Bay 3 and 4 were used for the cleanroom utility and post processing of semiconductor products. In this study, the portable AMC monitoring system was operated in Bay 1 and Bay 2, where main semiconductor manufacturing processes were conducted and most personnel worked in. The several sub-locations for the AMC measurements in Bay 1 and 2 are shown in Figure 2a,b, where AMC can be emitted and suspended in the cleanroom air environment, such as an ellipsometer (Bay1-1), a wet-bench (Bay1-2), a CVD furnace (Bay1-3), and a nanoparticle deposition system (Bay1-4) in Bay 1; PR drying station (Bay2-1) and spincoater (Bay2-2) in Bay 2. Bay 1 may have acidic and basic AMCs from the wet bench and CVD furnace as well as personnel working with the analysis instruments, but Bay 2 was expected to have organic AMCs from the PR processes [18; 19; 20]. In addition, 2 sub-locations of the common corridor were also monitored (Corridor-1: at the entrance of the cleanroom, Corridor-2: at the opposite end of the corridor). Estimation of AMC from the Measured Size Distributions of Nanoparticles Synthesized through Soft X-Ray Radiolysis  
AMC in the cleanroom air is measured in terms of number size distributions of nanoparticles by the SMPS of the portable AMC detector. To compare the relative AMC levels at different sub-locations in the cleanroom, total particle number concentration (\(\mathrm{N_{p,total}}\)) was calculated for each sub-location in the cleanroom by integrating the measured number size distributions. Total particle volume concentration (\(\mathrm{V_{p,total}}\)) was also calculated by converting the number size distributions into volume ones and integrating the volume size distributions. In addition to \(\mathrm{N_{p,total}}\) and \(\mathrm{V_{p,total}}\), AMC concentration can be estimated using calibration curves between AMC and the particulate properties [7; 8]. Due to soft X-ray radiolysis being a mass- (or volume-) based gas-to-particle conversion, \(\mathrm{V_{p,total}}\) is appropriate for calculating equivalent AMC concentrations in the air. In this study, the equivalent AMC concentration was obtained in terms of the sulfur dioxide (\(\mathrm{SO_{2}}\)) (ppbV) from \(\mathrm{V_{p,total}}\) (nm\({}^{3}\)/cm\({}^{3}\)) of the nanoparticles through an equation obtained by [PERSON] and his colleagues [7] as  
\[[SO_{2}]=4.452\times 10^{-10}\big{[}V_{p,total}\big{]}-7.162\times 10^{-19} \big{[}V_{p,total}\big{]}^{2}+1.006\times 10^{-27}\big{[}V_{p,total}\big{]}^{3} \tag{1}\]Even though the cleanroom air can contain various kinds of gaseous compounds in addition to SO\({}_{2}\), we use the calibration curve for SO\({}_{2}\) because SO\({}_{2}\) is one of the major contributors to secondary particle formation [21; 22; 23] through gas-to-particle conversion under irradiation, and can infiltrate into the cleanroom after passing through particle filters. Later, more precise and systematic analyses will be conducted for investigating the chemical composition of AMCs converted into nanoparticles through soft X-ray radiolysis and developing better calibration curves to estimate the AMC concentration in the cleanroom air environment.