This study examines the optimization and characterization of stoichiometric and carbon‐free boron nitride interphase coatings using triethylamine borane complex as a precursor in the Fluidized Bed Chemical Vapor Deposition process. It highlights the importance of optimizing chemical vapor deposition parameters to control coating formation, limit carbon contamination, and assess the feasibility of stoichiometric boron nitride from triethylamine borane complex coatings. The study investigates the thermal decomposition of triethylamine borane complex and its effect on carbon contamination through theoretical thermodynamic calculations, corroborated by Fourier‐transform infrared spectroscopy. Analysis shows a consistent, uniform microstructure. Auger electron spectroscopy and X‐ray photoelectron spectroscopy confirm the presence of boron, nitrogen, carbon, and oxygen, with negligible carbon inclusions. Transmission electron microscopy and electron energy loss spectroscopy reveal a low‐crystalline, isotropic structure. Carbon‐rich areas in boron nitride coatings indicate intricate chemical interactions during deposition, while disordered structures highlight the need to understand the effects of structural variations. Despite using a high‐carbon precursor, boron nitride coatings are remarkably stoichiometric with low carbon and oxygen contamination, demonstrating the benefits of non‐chlorinated precursors.Read less <