As semiconductor manufacturing approaches the sub-3 nm and sub-1 nm regime, heat and mass transport inside ultra-confined features can no longer be fully described by conventional continuum models. In advanced processes such as chemical mechanical polishing, wafer cleaning, thin-film deposition, nanofiltration, and nanoscale etching, the characteristic transport length becomes comparable to only a few molecules or atomic layers. At this scale, fluid flow, ion motion, heat transfer, pressure variation, and interfacial resistance are strongly governed by molecular ordering, surface forces, hydration structure, phonon mismatch, and discrete occupancy rather than by bulk continuum properties.

My recent research focuses on developing molecular-level transport frameworks for these extreme confinement conditions using non-equilibrium molecular dynamics simulations. The goal is to understand where classical descriptions such as Navier–Stokes, Hagen–Poiseuille, Sampson’s equation, Fourier’s law, and conventional slip models break down, and how they can be replaced or corrected using atomistic descriptors. These descriptors include accessible flow depth, molecular exclusion region, hydration-shell stability, interfacial thermal resistance, vibrational density of states, occupancy-controlled velocity reconstruction, and ergodic time averaging.

This research provides a physics-based route to interpret transport in semiconductor-relevant nanostructures where direct experimental measurement is difficult. By connecting molecular mechanisms with continuum-limit predictions, the work aims to support more reliable design of sub-1 nm manufacturing processes, including controlled etchant delivery, wafer cleaning, CMP lubrication, ion filtration, and nanoscale thermal management.

Navier-stokes equation is the fundamental concept of describing the motion of viscous fluid substance. Also, the Euler, Hagen-Poiseuille, and Sampson equation, talks about the behavior of the fluid flow. These equations explain how momentum, density, and pressure contribute to viscous fluid flow in continuum mechanics. It has been undoubtedly proven that these equations work perfectly in continuum applications. But when the system size becomes comparable to the molecular level, local variants like interfacial viscosity, density layering, and interatomic forces become dominant, which may affect the flow behavior. These local variants were ignored in those continuum equations, leading to difficulty in the nanoscale applications like Bioseparation, Immunoisolation, Drug delivery, Lab on a chip, Fuel cell, Water desalination, MEMS technology, etc. In this regard, the study of nanoscale fluid transport phenomena will pave the way for nanoscience to move forward. 

Published in Langmuir 2021. View Article

Every day, technology is moving forward, and devices in our hands are getting smaller for the convenience of humankind. For decades, the electronics industry followed a roadmap codified by Moore’s law of doubling the number of transistors on a chip roughly every two years. In order to meet the market demand companies are reducing the sizes of the transistors which are the units of electronic chips. For instance, IBM unveils 2nm transistors in 2021. The efficiency of these devices mostly depends on heat management. But, the heat management on nano-structures is very challenging due to the lack of understanding of the nanoscale heat transport phenomena. At this point, it is crucial to understand the mechanism of nanoscale heat transport behavior through the solid-solid grain boundaries so that this understanding can support the practical implementation in the field of Fuel Cell, Electronics, 3D printing, Biological applications, etc.   

Published in AIP Advances 2021. View Article