Preparation method of semiconductor structure

Abstract

The invention provides a preparation method of a semiconductor structure. The preparation method comprises the following steps of providing a semiconductor substrate, wherein an oxide layer is formedon at least a first part of the surface of the semiconductor substrate, and a photoresist layer is formed on at least the second part of the surface; removing the oxide layer with the partial thickness by wet etching so as to retain a residual oxide layer with a preset thickness; and removing the photoresist layer by dry etching. Due to the fact that the residual oxide layer with the preset thickness is still kept in the wet etching process, oxidation and loss of substrate silicon caused by direct exposure of the substrate silicon during dry etching can be prevented. According to the preparation method of the semiconductor structure, the oxide layer with the partial thickness is removed by wet etching, no other process steps need to be added or changed, and the electrical stability of thedevice can be improved on the premise that the cost is not increased.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for preparing a semiconductor structure. Background technique [0002] SONOS flash memory devices have the characteristics of small cell size, low operating voltage, and compatibility with CMOS processes. SONOS flash memory devices use silicon substrate-tunnel oxide layer-silicon nitride-blocking oxide layer (Silicon-Oxide-Nitride) -Oxide-Silicon, SONOS) gate stack replaces the floating gate structure in traditional FLASH memory devices, and is a charge trap type flash memory device. [0003] However, the existing SONOS flash memory device generally has a high-voltage device and a core device, and the high-voltage device and the core device often have the problem of uncertain channel current during conduction, which affects the electrical stability of the device, especially the use of insulators For devices with upper silicon substrates, the thickness of the t...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a method for preparing a semiconductor structure to solve the problem of uncertain channel current when the existing SONOS flash memory device is turned on

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