Novel Noncontact Enhanced Throughput Electrical Characterization for AlGaN/GaN HEMT Technology

A new approach for characterizing AlGaN/GaN HEMT structures increases wafer measurement throughput by a factor of ten compared to standard Corona noncontact C-V (CnCV) HEMT measurements. The novel principle involves a linear illumination-induced corona charge bias sweep rapidly changing the HEMT 2DEG from a depopulated to populated state in the time of seconds controlled by illumination intensity and wavelength. The process is monitored with surface voltage measured with a noncontact Kelvin probe providing a means to determine HEMT active layer parameters such as the pinch-off voltage ($\mathrm{V}_{\mathrm{P}}$), the AIGaN thickness and the 2DEG density. The results include discreet site wafer testing and whole wafer mapping. A micro-scale measurement is demonstrated using a KFM technique. The latter illustrates the potential for HEMT fabrication monitoring on micrometer sites analogous to scribe line testing in Si IC fabrication.