On-chip direct synthesis of boron nitride memristors

Two-dimensional materials hold promise for advanced complementary metal-oxide-semiconductor (CMOS) and beyond-CMOS electronics, including neuromorphic and in-memory computing. Hexagonal boron nitride (hBN) is particularly attractive for non-volatile resistive-switching devices (that is, memristors) due to its outstanding electronic, mechanical and chemical stability. However, integrating hBN memristors with Si-CMOS electronics faces challenges as it requires either high-temperature synthesis (exceeding thermal budgets) or transfer methods that introduce defects, impacting device performance and reliability. Here we introduce the synthesis of hBN films at CMOS-compatible temperatures (<380 °C) using electron cyclotron resonance plasma-enhanced chemical vapour deposition to realize transfer-free, CMOS-compatible hBN memristors with outstanding electrical characteristics. Our studies indicate a polycrystalline structure with turbostratic features in as-deposited hBN films and good wafer-level uniformity in morphology (size, shape and orientation). We demonstrate a large array of hBN memristors achieving high yield (~90%), stability (endurance, retention and repeatability), programming precision for multistate operation (>16 states) and low-frequency noise performance with minimal random telegraph noise. Furthermore, we directly integrate memristive devices on industrial CMOS test vehicles to demonstrate excellent endurance, achieving millions of programming cycles with a high technology readiness level. This represents an important step towards the wafer-scale CMOS integration of hBN-memristor-based electronics.