Noncontact Monitoring and Imaging of the Operation and Performance of Thin-Film Field-Effect Transistors

In this study, the first noncontact and non-destructive methodology is developed for monitoring and imaging the operation and performance of thin-film field-effect transistors (TFTs) using second-harmonic generation (SHG) imaging. By analyzing the SHG signal intensity, which is directly related to the electric field at the interface between the semiconductor channel and gate insulator, critical electrical parameters such as the threshold voltage (V_TH) and flat-band voltage (V_FB) are successfully determined. These findings demonstrate a strong correlation between SHG signals and V_TH and V_FB in InGaZnO TFTs under various process conditions. Notably, the method achieves an unprecedented resolution of ΔV_FB below 100 mV in assessing electrical properties through SHG measurements, surpassing conventional spectroscopy techniques. Furthermore, a system is developed to monitor and image the TFT array operation and performance, enabling us to distinguish between pass and fail devices and measure the V_TH distribution based on the SHG intensity. This approach facilitates early failure detection and supports efficient curing during manufacturing, thereby marking significant advancements in TFT technology and quality control processes.