A Dual-Material Phononic-Chimney Architecture for Zero-TCE Frequency Stabilization in Piezoresistive NEMS Resonators

Next-generation Nanoelectromechanical Systems (NEMS) utilizing Thermal-Piezoresistive Resonators (TPRs) are fundamentally limited by parasitic frequency drift induced by internal Joule heating. Current stabilization methods relying on external phase-locked loops negate the footprint advantage of nanoscale sensors. Furthermore, internal structural compensation—such as SiO2 composite cladding or Phononic Crystal (PnC) thermal drains—suffers from severe thermal insulation and nanoscale surface boundary scattering, respectively. In this paper, we propose and computationally verify a novel "Phononic-Chimney" architecture. By isolating an active monocrystalline silicon resonant core (85.5 MHz) with a PnC mechanical bandgap, and bypassing horizontal phonon scattering via Z-axis high-k metallic (Gold) thermal vents, we demonstrate a near-zero Temperature Coefficient of Elasticity (TCE) drift without external circuitry. Fully coupled, bare-metal finite element multiphysics simulations confirm exceptional acoustic isolation (Q-factor > 10^6) while reducing peak core thermal loads to safe ambient margins (311.2 K)