Surface Photovoltage Spectroscopy as a Valuable Tool for Evaluating Oxidation Processes in the Microelectronics Industry

Abstract

In the present study, the minority carrier diffusion length (MCDL), determined by surface photovoltage spectroscopy measurements, is compared in n‐ and p‐type Si wafers after their oxidation under different conditions using various tools (horizontal and vertical furnaces, atomic layer deposition (ALD), low‐pressure chemical vapor deposition, and plasma‐enhanced chemical vapor deposition). It is shown that MCDL varies significantly depending on the design of furnaces, oxidation temperatures, the type of gases used before and during oxidation, and their flow ratios. The type and crystal growth method of Si wafers used for the oxidation also play a significant role and influence MCDL. Additionally, MCDL after the deposition of alumina layers using ALD techniques is found to be significantly larger compared to that observed after the thermal oxidation of Si. The larger values of MCDL after the ALD of Al2O3 are detected independent of temperature and precursors used for the deposition. The origin of different MCDL values after various oxidation processes, with an emphasis on the formation of electrically active defects in Czochralski (CZ)‐ and float‐zone (FZ)‐grown Si wafers is discussed.