Patent ID: 7869283

Claim:
A method of determining a native threshold voltage of a nonvolatile memory, comprising: providing a memory cell, wherein the memory cell comprises a control gate, a charge storage layer, a source region, and a drain region; performing a programming operation on the memory cell by using a Fowler-Nordheim tunneling effect to obtain a programming curve of time versus threshold voltage, and applying a first voltage to the control gate in the programming operation; performing an erase operation on the memory cell by using the Fowler-Nordheim tunneling effect to obtain an erasure curve of time versus threshold voltage, and applying a second voltage to the control gate in the erase operation, wherein absolute values of the second voltage and the first voltage are the same, but polarities of the second voltage and the first voltage are opposite; and determining the native threshold voltage of the memory cell from a cross point of the programming curve and the erasure curve.