Method for Improving the Leakage of Self-aligned Contact Holes in Sonos Devices

Abstract

This invention discloses a method for improving automatic alignment contact hole electric leakage of an SONOS device, comprising steps of 1) performing SONOS device automatic alignment contact hole etching, 2) growing silicon nitride films on the side walls and the bottom of the contact hole and above the undoped oxide film in the SONOS device, 3) etching silicon nitride films which enable the side walls of the contact hole to keep the silicon nitride films, 4) cleaning and removing polymer by using the traditional hydrometallurgy process to obtain the automatic alignment contact hole of the SONOS device. This invention can compensate the excessive loss on the side wall of the grid caused in the process of traditional automatic alignment contact hole etching, dramatically increases the thickness of the residual thickness of the silicon nitride film side wall, prevents the grid and the metal wire from short circuit, improves the automatic alignment contact hole of the product, increases the contact hole breakdown voltage, expands the SONOS device automatic alignment contact hole etching technology window.

Description

technical field [0001] The invention relates to a method for improving leakage of self-aligned contact holes, in particular to a method for improving leakage of self-aligned contact holes of SONOS (Silicon-Oxide-Nitride-Oxide-Silicon) devices. Background technique [0002] SONOS (Silicon-Oxide-Nitride-Oxide-Silicon) device is a non-volatile memory that is closely related to flash memory. [0003] In the self-aligned contact hole process of SONOS devices, in order to reduce the alignment difficulty of photolithography, reduce the chip area, and improve the integration of products, the silicon nitride (SiN) barrier layer as a barrier layer is canceled. When etching through the bud-shaped shell pattern, it is easy to cause too much loss in the side wall of the nitride film, and the barrier between the contact hole and the gate (Poly) is too thin, and it is easy to break down under high voltage and cause the metal line and the gate Extremely short circuit, resulting in self-ali...

AI Technical Summary

Problems solved by technology

When etching through the bud-shaped shell pattern, it is easy to cause too much loss in the side wall of the nitride film, and the barrier between the contact hole and the gate (Poly) is too thin, and it is easy to break down under high voltage, causing the metal line and the gate Extremely short circuit, resulting in self-aligned contact hole leakage, reducing the breakdown voltage of the device, and ultimately resulting in low yield around the wafer

in, figure 1 In order to self-align the contact hole pattern after cleaning (extreme case), the sidewall of the contact hole has too much loss, which is likely to cause a short circuit between the filled metal and the gate, thereby causing device leakage

Images