A New Test Structure for Shallow Trench Isolation (STI) Depth Monitor

A non-destructive electrical process monitor has been developed for shallow trench isolation (STI) depth control in an advanced high voltage analog process. An implanted p-body (LDMOS back gate) pinch resistor has been demonstrated to accurately measure the depth of the shallow trench isolation. STI depth can be further correlated to critical LDMOS parameters such as Rdson (on resistance) and BVdss (off-state device breakdown). This technique can be easily implemented in the scribe line to monitor STI depth as well as to characterize variation in high voltage component.