A Non-Destructive and Effective Metrology to Automatically Monitor Kink Effect of MOSFETs

The kink effect is a harassed issue existing in metal-oxide-semiconductor field-effect transistors (MOSFETs) and usually degrades the whole chip performance, especially in analog circuit operation. No matter what the device isolation is with local oxidation of silicon (LOCOS) process or shallow trench isolation (STI) process, this effect more or less depicts. How to sense this effect in integrated-circuit (IC) mass-production is a crucial event. Through a second derivative method on Ids versus Vgs curves in MOSFET device, the unhealthy devices can be effectively screened out with the application of programmable auto testers. Using this derivative metrology implemented into the measurement testers, the distribution of kink devices on wafer is easily plotted. This information is very precious to the semiconductor process engineers in process improvement, too.