Third-Harmonic Generation Imaging of Local Doping, Mechanical Stress, and Stray Electric Fields in Silicon Microchips

We employ third-harmonic generation (THG) imaging for noninvasive characterization of silicon wafers and microchips and demonstrate that a much higher contrast can be achieved in THG compared to reflection imaging. In particular, the THG signal clearly distinguishes between n-type and p-type silicon samples coated with native silicon dioxide, which were indistinguishable in the reflection imaging mode. The THG response showed a higher contrast in mechanically stressed samples and under in-plane electric fields. Our experimental results, supported by first-principles calculations, demonstrate that THG imaging is a robust tool for assessing doping, mechanical stress, and electric fields in silicon-based structures, offering significant potential for advanced semiconductor diagnostics and the development of next-generation electronic components.