Terahertz Barcodes Enabled by All‐Silicon Metasurfaces for Process Control and Monitoring Applications

Abstract Process control and monitoring (PCM) is crucial for the quality control and yield improvement of semiconductor products. Terahertz inspection of semiconductor devices has been of interest since the progress of terahertz spectroscopic techniques. However, due to the diffraction limit, high‐resolution measurement of geometric sizes and multiple parameter monitoring are challenging for terahertz PCM techniques. In this article, XX present terahertz all‐dielectric metasurfaces as the interface on a silicon substrate for monitoring material properties and fabrication errors in the silicon deep reactive ion etching (DRIE) process. It is shown that four different metasurfaces can encode multiple information simultaneously, including the carrier density of silicon substrates, etching depth and linewidth error, forming a terahertz barcode for PCM. By correlating the measured reflection spectra of the barcode with those in the simulation database, the three parameters are retrieved with a mean square error (MSE) of ≈0.5. The results indicate that this proposed technique using emerging artificial photonic materials as PCM structures paves a pathway toward high‐efficiency semiconductor quality control and other sensing applications.