Patent ID: 6894517

Claim:
A method for monitoring a tunnel oxide layer, the method comprising: (a) providing a semiconductor substrate and forming at least one memory cell on a surface of the semiconductor substrate, the memory cell comprising a first gate, a second gate, and the tunnel oxide layer from top to bottom in a stack; (b) electrically connecting the first gate and the second gate; (c) applying a first gate voltage to the first gate, the first gate voltage being a swing time-dependent DC ramping voltage; (d) measuring a first gate leakage current of the memory cell to calculate a first constant from an equation; (e) applying a second gate voltage to the first gate, the second gate voltage being a swing time-dependent DC ramping voltage; (f) measuring a second gate leakage current of the memory cell to calculate a second constant from the equation; (g) calculating a first ratio of the second constant to the first constant; and (h) performing a comparing step to compare the value of the first ratio with a predetermined value.