<p>Hexagonal boron nitride (hBN) has emerged as an indispensable material for next-generation electronics and quantum technologies, yet the controlled synthesis of iso-topically engineered hBN with both macroscopic scalability and atomic-level precision remains challenging. Here, we present a breakthrough plasma-enhanced chemical vapor deposition (PECVD) method that utilizes elemental boron (B) and nitrogen (N) precursors to simultaneously achieve wafer-scale growth and precise isotopic control of hBN films. We demonstrate the synthesis of high-quality hBN films on Cu substrates through optimized B evaporation and N₂ plasma activation. The growth mechanism reveals an oxygen-mediated pathway for B transport and a layer-by-layer (Frank-van der Merwe) mode for multilayer formation. Crucially, by employing isotopically enriched B powders (¹⁰B and ¹¹B) and N₂ gases (¹⁴N₂ and ¹⁵N₂), we demonstrate tunable isotopic compositions with phonon mode shifts quantitatively matching harmonic oscillator predictions. Furthermore, we realize unprecedented in-plane h¹⁰BN-h¹¹BN heterostructures through dynamic B source switching during growth. This PECVD strategy establishes a transformative synthesis platform that merges industrial-scale production capacity with atomic-scale isotopic precision, enabling new opportunities to engineer thermal transport, optical response, and quantum coherence in two-dimensional materials.</p>