Nitrogen-Doped Czochralski Silicon Wafers as Materials for Conventional and Scaled Insulated Gate Bipolar Transistors

Nitrogen-doped silicon wafers manufactured using the Czochralski technique (Cz-Si) with an oxygen concentration ([O_I]) of 2.5–5.6 × 10¹⁷ atoms cm⁻³ are heat treated to simulate the conventional and scaled manufacturing processes of insulated gate bipolar transistors (IGBTs). Subsequently, the oxygen precipitation, lifetime, and gate oxide integrity (GOI) of the Cz-Si wafers are evaluated. After the high-temperature heat treatment that simulates the conventional process, the lifetime of the Cz-Si with an [O_I] of 5.6 × 10¹⁷ atoms cm⁻³ only degrades slightly even when oxide precipitates are not detected. In contrast, after the low-temperature heat treatment that simulates the scaled process, oxide precipitates are detected and the lifetime reduces substantially at an [O_I] of 5.6 × 10¹⁷ atoms cm⁻³. The Cz-Si with [O_I] values below 3.3 × 10¹⁷ atoms cm⁻³ are considered suitable materials for IGBTs because no oxide precipitate is formed, and the lifetime is not degraded after high- and low-temperature heat treatments. Upon using GOI evaluation, the nitrogen-doped Cz-Si wafers are found to exhibit a breakdown voltage equal to that of an annealed Cz-Si wafer conventionally used for IGBTs. Therefore, nitrogen-doped Cz-Si wafers with [O_I] below 3.3 × 10¹⁷ atoms cm⁻³ are potential materials for conventional and scaled IGBTs.