Patent ID: 8427879

Claim:
A method for enabling a SONOS transistor to be used as both a switch and a memory, said transistor comprising a gate, a source, a drain, and a charge storage layer, comprising steps of: providing a first operating voltage to said gate in such a way that electrons are accumulated in said charge storage layer, and a threshold voltage of said transistor is increased from a first threshold voltage up to a second threshold voltage, the threshold voltage of said transistor maintains at said second threshold voltage stably; performing a switch mode or a memory mode; entering said switch mode, and then determining whether a second operating voltage provided on said gate is higher than said second threshold voltage, if the second operating voltage is higher than the second threshold voltage, said transistor switches into a turn-on state, and if the second operating voltage is not higher than the second threshold voltage, said transistor switches in a turn-off state; entering said memory mode, and then determining a memory state of said transistor by applying a first determining voltage on said gate and providing a second determining voltage on said source or said drain; performing a programming operation by applying a programming voltage on said gate with said source and said drain being grounded, wherein the programming voltage applied on said gate when performing said programming operation is smaller than the first operating voltage provided to said gate, such that a value of threshold voltage of said transistor will not be affected; performing an erasing operation by applying an erasing voltage on one of said drain and said source, and the other of said drain and said source on which the erasing voltage is not applied is grounded, wherein said switch mode and said memory mode are two independent modes and operations are ended after said modes have been performed; wherein a first duration operating time for providing the first operating voltage to said gate is longer than a second duration operating time for applying the programming voltage on said gate when performing said programming operation.