Method for Automatic Measurement of Failure in Subthreshold Region of MOS Transistor

摘要

The invention particularly relates to an inspection system anomalies of the MOS transistor, variation in the gate voltage of the MOS transistor a first step of measuring the characteristic curve due to the fluctuation of the drain current corresponding to; A second step of calculating a curve according to the transconductance (Trans conductance) of variable values for each of the gate voltage based on the characteristic curve be measured in the first step; The third step of the value of a variable curve been calculated in the second process, the second derivative; In the second and third differential been function curve, including a fourth step of determining the presence or absence of abnormality by counting the number of inflection points is the charge density of the channel region of the MOSFET in the process of a shallow trench isolation (Shallow Trench Isolation: STI) If not uniform because of a process of generating a hump (Hump) or MOSFET phenomenon as the cause of the other of the subthreshold (Sub-threshold) drain (Drain) of the current characteristic distortion of the gate (Gate) voltage in the region makes it possible to automatically measure the presence or absence.