Modeling and validation of anisotropic thin-film deposition on cylindrical substrates for predictable resistance control in MEMS fabrication.

Precise control of electrical properties in conductive micro-structures is essential for the performance and reliability of micro-electro-mechanical systems (MEMS). However, the nature of anisotropic physical vapor deposition (PVD), such as electron-beam or thermal evaporation on curved or wire-like substrates, complicates the prediction of thin-film morphology and resulting electrical properties. This study develops and validates a geometrically explicit deposition model describing film growth on cylindrical substrates using a generalized pseudo-Lambertian cosine emission profile. Analytical expressions for local film thickness are derived as functions of deposition time, substrate geometry, and source collimation and characterized by a sensitivity analysis. Monte Carlo simulations confirm that the model accurately reproduces the deposition profile observed with simulated data ([Formula: see text]). A closed-form expression for resistance as a function of deposition parameters was also derived, integrating the Fuchs-Sondheimer and Mayadas-Shatzkes (FS-MS) frameworks to account for thin-film electron scattering and grain-boundary effects. Experimental validation was performed via electron-beam evaporation of gold onto cylindrical glass-core wires, with measured resistances spanning [Formula: see text] to [Formula: see text] across films 70 to 3000 nm thick. The FS-MS predicted resistances exhibited a Pearson correlation of [Formula: see text] ([Formula: see text]) with empirical measurements, confirming the model's predictive accuracy. Additionally, this study develops an empirical mathematical model that captures the anisotropic behavior of PVD deposition on cylindrical surfaces, offering a simulation framework that generalizes conventional planar thin-film modeling to complex, three-dimensional microfabrication topographies. The model enables predictive control of thin-film resistivity in MEMS and bio-MEMS structures and, by enabling precise conformal PVD metallization of polymer-based wires with minimal precious-metal loading, offers a pathway to substantially reduce the manufacturing cost of active medical implants that traditionally rely on bulk platinum-iridium conductors. All model and simulation materials have been made available and can be found in Supplementary Materials (Sec. 3). Supplementary Information: The online version contains supplementary material available at 10.1007/s44245-026-00233-8.