VLSI Design Challenges in Nanotechnology and Future Transistor

The rapid scaling of semiconductor devices has pushed CMOS technology close to its physical limits. As the feature sizes approach the nanometer regime, conventional planar MOSFETs face severe challenges such as excessive leakage current, pronounced short-channel effects, reliability degradation and increased power density. Despite these limitations, nanotechnology-enabled transistor structures have been adopted including FinFETs, Gate-All-Around FETs (GAAFETs), Carbon Nanotube FETs (CNTFETs), Tunnel FETs (TFETs) and other emerging hybrid architectures. It critically analyzes fifteen peer-reviewed research papers published from 2018 to present major design challenges, performance trends, fabrication constraints and future research directions for nanoscale VLSI design. Comparison reveals that although FinFETs and GAAFETs provide improved electrostatic control, issues related to process variability, fabrication complexity, thermal management and accurate compact modeling persist. Similarly, emerging devices such as CNTFETs and TFETs exhibit promising electrical characteristics such as near-ballistic transport and ultra-low leakage behavior however their practical deployment remains limited due to material imperfections, manufacturing challenges and scalability concerns. In this paper the paper highlights open research problems and discusses potential solutions to enable reliable and energy-efficient VLSI systems using future transistor technologies.