Nitrogen-doped silicon wafers manufactured using the Czochralski technique (Cz-Si) with an oxygen concentration ([ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{O}_{I}$ </tex-math></inline-formula> ]) of 2.5– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.6\,\,\mathbf {\times }\,\,10^{17}$ </tex-math></inline-formula> atoms cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-3}$ </tex-math></inline-formula> 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 [ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{O}_{I}$ </tex-math></inline-formula> ] of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.6\,\,\mathbf {\times }\,\,10^{17}$ </tex-math></inline-formula> atoms cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-3}$ </tex-math></inline-formula> 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 [ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{O}_{I}$ </tex-math></inline-formula> ] of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.6\,\,\mathbf {\times }\,\,10^{17}$ </tex-math></inline-formula> atoms cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-3}$ </tex-math></inline-formula> . The Cz-Si with [ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{O}_{I}$ </tex-math></inline-formula> ] values below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.3\,\,\mathbf {\times }\,\,10^{17}$ </tex-math></inline-formula> atoms cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-3}$ </tex-math></inline-formula> 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 [ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{O}_{I}$ </tex-math></inline-formula> ] below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.3\,\,\mathbf {\times }\,\,10^{17}$ </tex-math></inline-formula> atoms cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-3}$ </tex-math></inline-formula> are potential materials for conventional and scaled IGBTs.