Terahertz testing of semiconductor devices and integrated circuits

The growing complexity and sophistication of Very Large Scale Integration (VLSI) circuits pose significant challenges for testing and fault diagnostics of VLSI. The detection of counterfeit VLSI, often referred to as “hardware Trojans,” has also become a critical issue. Another problem is the expected decrease in VLSI chip lifetimes when device sizes are scaled down. Existing VLSI test technologies can no longer meet these challenges. This paper presents a review of an emerging terahertz (THz) testing for evaluating transistors, Monolithic Microwave Integrated Circuits (MMICs), and VLSI chips. THz testing measures device and/or circuit responses to incident THz or sub-THz radiation at device pins or input/output leads and compares them with reference responses. The resolution is aperture-limited by the device dimensions and could be at the nanometer scale. THz testing method applies even to packaged devices and can extend to fault diagnosis and predictions of device reliability and lifetime. The THz testing provides a vast array of responses at multiple pins and leads under varied conditions, including THz beam positions, frequencies, polarizations, modulation frequency of impinging THz radiations, and intensities. Testing can be conducted with or without bias. Testing under varying bias significantly enhances characterization capabilities. The resulting multi-dimensional response images in the excitation parameter space are well-suited for analysis using machine learning algorithms, enabling self-learning and continuous improvement of the testing methodology. THz response data could be integrated with parameter extraction data using compact CAD and TCAD models. These enhancements improve fault identification, reliability assessments, and lifetime prediction, positioning THz testing as a powerful and versatile tool for addressing modern challenges in device and electronic circuit diagnostics and counterfeit detection.