Influences and Diffusion Effects of Lithium Contamination During the Thermal Oxidation Process of Silicon

Abstract

Due to the increasing number of application fields using lithium compounds in the microelectronics sector, it is necessary to investigate the contamination influence and the effects of lithium on silicon and silicon oxide. To be able to use lithium in a controlled manner in CMOS clean room environments, the various diffusion effects during an important process in semiconductor manufacturing, the thermal oxidation of silicon to form silicon oxide, is investigated in this work. This includes the diffusion within the wafer, between wafers and into the furnace environment. For this purpose, wafers are intentionally contaminated, oxidized and then analyzed with vapor phase decomposition ‐ inductively coupled plasma ‐ mass spectrometry (VPD‐ICP‐MS). The results of this study are correlated with typical contamination levels in state‐of‐art cleanroom facilities to enable classifications of the results for the semiconductor sector. Furthermore, the effect on the growth rate and uniformity of silicon oxide is evaluated by ellipsometry and topography measurements. Finally, electrical measurements of the oxide layer have shown that there is a significant influence on the silicon oxide quality, means that lithium can have a detrimental effect on devices.This article is protected by copyright. All rights reserved.