<p>The growing use of silicon nitride (Si₃N₄) waveguides in data-center transceivers for achieving improved performance requires improved device architectures. One key challenge involves the necessity of integrating a thermo-optic phase shifter (TOPS) for fast switching, a technology currently developed primarily for silicon waveguides, which limit the efficiency of Si₃N₄ waveguides. The challenge arises from the requirements to integrate Si₃N₄ into silicon waveguide converter, leading to increased power losses and larger footprint device. To address this challenge, we present a design for a TOPS utilizing a titanium nitride (TiN) heater and a Si₃N₄ waveguide, to improve optical phase shifting efficiency in photonic circuits for optical interconnects. The design leverages the complementary material properties to optimize thermal stability and optical confinement while minimizing power consumption and losses, which is relevant for O-band photonic interconnects. By carefully selecting TiN for its superior thermal conductivity and Si₃N₄ for its exceptional optical characteristics and thermal stability, we addressed the challenges of unwanted thermal influence, improved efficiency, and low loss requirements. The results indicate a simulated excess attenuation of 1.27e-06 dB/µm at 1.31&#xa0;μm, and a phase shifting efficiency under P_π of 56.32 mW, with a response time of 0.591 µs and an overall figure of merit (FOM) of 33.56 mWµs. Experimental DC and AC measurements show good agreement with simulations, demonstrating good thermal performance, short transient response time, measurement-system bandwidth compatibility, and electrical stability over time. The device demonstrates efficient phase shifting in a short response time while maintaining overall thermal stability and low attenuation over the entire O-band spectrum which is useful for transceiver data-center applications.</p>