Mos transistor having lower gate-to-source/drain breakdown voltage and one-time programmable memory device using the same

Abstract

A MOS transistor includes a semiconductor substrate, a drain region and a source region in the semiconductor substrate, a channel region between the drain region and the source region, a gate electrode on the channel region, and a gate dielectric layer between the gate electrode and the semiconductor substrate. The gate dielectric layer has different thicknesses. The MOS transistor has a gate-to-source / drain breakdown voltage that is lower than a gate-to-channel breakdown voltage and a gated source / drain junction breakdown voltage.

Description

BACKGROUND OF THE INVENTION1. Field of the Invention[0001]The present disclosure relates generally to the field of semiconductor technology. More particularly, the present disclosure relates to a metal-oxide-semiconductor (MOS) transistor having lower gate-to-source / drain breakdown voltage and one-time programmable (OTP) memory devices using such MOS transistor.2. Description of the Prior Art[0002]As known in the art, non-volatile memory retains stored information even after power is removed from the non-volatile memory circuit. Some non-volatile memory designs permit reprogramming, while other designs only permit one-time programming. Thus, one form of non-volatile memory is a One-Time Programmable (OTP) memory.[0003]An OTP memory may contain an antifuse. An antifuse functions oppositely to a fuse by initially being nonconductive. When programmed, the antifuse becomes conductive. To program an antifuse, a dielectric layer such as an oxide is subjected to a high electric field to ca...

AI Technical Summary

Benefits of technology

The present disclosure provides a MOS transistor with lower gate-to-source / drain breakdown voltage and OTP memory devices using such MOS transistor. The MOS transistor has a gate dielectric layer with different thicknesses in different regions, which results in lower gate-to-channel breakdown voltage and gated source / drain junction breakdown voltage. The MOS transistor also includes a main gate electrode with two extension gate portions that are in direct contact with the gate dielectric layer. The method for fabricating the MOS transistor includes patterning a first conductive layer into a main gate portion, ion implantation to form drain and source regions, and forming dielectric spacers on the extension gate portions. The technical effects of this disclosure include lower gate-to-source / drain breakdown voltage, improved reliability, and reduced power consumption.

Problems solved by technology

However, some ruptured oxides could be in a soft breakdown condition.

Therefore, a complicate sensing amplifier is often needed to compare the source side and drain side gate oxide leakage currents.

Images