Goos-Hanchen-Shift Photonic Sensor for Nanometer-Scale Delayering and Tamper Detection in Semiconductor Packages

Abstract

We propose a co-packaged photonic tamper sensor that detects progressive delayering and localized drilling through changes in the Goos-Hanchen (GH) shift of a reflected optical beam. Frustrated total internal reflection (FTIR) couples the beam into a high-index sensing layer, where its transverse-wavevector components acquire a thickness-dependent propagation phase. Numerical simulations show an approximately linear response for sensing-layer thicknesses below 250 nm and a delayering sensitivity of 5.3 nm of beam displacement per nanometer of material removed, nearly three times that of a conventional total internal reflection (TIR) structure. The off-resonant response remains stable under representative refractive-index, wavelength, and incidence-angle variations. Localized drilling also produces a monotonic GH-shift change that increases with drill depth and width. These results establish GH-shift readout as a rapid, spatially encoded, and difficult-to-emulate approach for semiconductor-package tamper detection.