Sources of variability in alpha emissivity measurements at LA and ULA levels, a multicenter study

摘要: Alpha emissivity measurements are important in the semiconductor industry for assessing suitability of materials use production processes. A recently published round-robin study that circulated same samples to several alpha counting centers showed wide center-to-center variations measured emissivity. separate analysis these results hypothesized much variation might arise from differences sample-to-entrance window separations. XIA introduced an ultra low background counter, UltraLo-1800 (“UltraLo”), operates a fundamentally different manner proportional counters used at most original study. In particular, by placing sample within volume, it eliminates separation issue noted above, and so offers opportunity test this hypothesis. work we briefly review how UltraLo describe new conducted entirely on instruments using set standard included two This shows that, LA (“Low Alpha” between 2 50 α/khr-cm2) measurements, only remaining site-to-site were due statistics. Variations ULA (“Ultra-Low Alpha”<2 reduced three-fold, compared earlier study, with suggesting residual activity now primarily cosmogenic background.