Development of Experimental Methodology for Highly Efficient Wafer-Level Evaluation of X-Ray Radiation Effects on Semiconductor Devices

A high-speed experimental method to evaluate the X-ray radiation damage of a large number of transistors has been developed. In this method, test-element groups (TEGs), including approximately 10,000 metal-oxide-semiconductor (MOS) transistors, were formed on a silicon-on-insulator (SOI) wafer and irradiated with X-rays using novel equipment. After irradiation, fuses on the wafer were cut to isolate each transistor, and the transistor characteristics were measured by an automatic probe station. This method can provide approximately 10,000 lines of I-V curves of the transistors under 31 irradiation dose conditions in 10 days. Radiation damages are known to largely depend on the bias voltage conditions of the devices. In this method, the TEGs are located apart from one another on the wafer; then, the X-ray doses and bias voltage can be controlled specifically by each TEG. Using this equipment, a large amount of experimental data can be effectively acquired. The statistical data analysis enables highly effective radiation-resistant semiconductor development and reliability examination.