Patent ID: 7315174

Claim:
A method of measuring flat-band status capacitance of a gate oxide in a MOS transistor device, comprising: mounting a measurement object wafer in a probe station connected to a capacitance measuring unit; measuring accumulation capacitance (C ox ) of a gate oxide of the wafer using the capacitance measuring unit; measuring capacitance (C meas ) from the gate while changing a gate voltage (V gs ) of the wafer using the capacitance measuring unit; computing the thickness of a depletion layer (W inv ) using the measured accuulation capacitance (C ox ) and the measured gate capacitance (C meas ); computing bulk density (Nx) on the basis of the gate voltage (V gs ) in the case that the depth of a depletion layer is 90% of a predetermined reference depth; computing debye length L D using the bulk density (Nx); and computing flat-band status capacitance using the accumulation capacitance (C ox ) of the gate oxide and the debye length L D .