Patent ID: 7663904

Claim:
A method of operating a one-time programmable read only memory having at least a select transistor over a substrate, an electrode and a dielectric layer such that the electrode is set up on a source region of the select transistor and the dielectric layer is set up between the electrode and the source region, the method comprising the steps of: performing a programming operation to write a digital data value of ‘1’ into the memory, including: applying a first positive voltage to a drain region of the select transistor and applying a second positive voltage to the electrode; applying a third positive voltage to a gate of the select transistor so that a channel of the select transistor is formed; and reducing the bias voltage applied to the gate of the select transistor from the third positive voltage to a fourth positive voltage and raising the second positive voltage applied to the electrode to a fifth positive voltage to prevent F-N tunneling and a breakdown of the dielectric layer from happening; and performing a programming operation to write a digital data value of ‘0’ into the memory, including: applying a bias voltage of 0V to the drain region of the select transistor and applying the second positive voltage to the electrode; applying the third positive voltage to the gate of the select transistor so that the channel of the select transistor is formed; and reducing the bias voltage applied to the gate of the select transistor from the third positive voltage to the fourth positive voltage and raising the second positive voltage applied to the electrode to the fifth positive voltage to trigger F-N tunneling for breaking down the dielectric layer.