Method for producing ONO structure

Abstract

The invention discloses a method for producing an ONO structure, comprising the following steps: (1) depositing a lower-layer oxide film, a middle-layer nitric-oxide film and an upper-layer oxide film on a silicon substrate in sequence to form an ONO thin film, and then depositing a nitride film on the formed ONO thin film; (2) coating an anti-reflection coating and photoresist on the nitride film, and then using a photoetching technique to expose a position to be etched; (3) carrying out plasma etching at the position to be etched, and stopping on the lower-layer oxide film; (4) removing the residual photoresist and the anti-reflection coating; (5) further using a wet etching technique to etch the lower-layer oxide film; and (6) removing the residual nitride film by the wet etching technique to form the ONO structure. The structure can solve the problem of peeling off the photoresist, ensure uniformity of etching and effectively control side etching.

Description

technical field [0001] The invention relates to a method for preparing a semiconductor structure, in particular to a method for preparing an ONO (oxide film-oxynitride film-oxide film) structure in a semiconductor SONOS product. Background technique [0002] In SONOS products, ONO structures need to be prepared in specific regions. figure 1 Shown is a schematic diagram of the ONO structure obtained by a common ONO process. In this structure, size 5 represents the reduction in the effective size of the ONO in the ONO process. In order to increase the subsequent process flow and the working window of the device or increase the ONO structure density, the smaller the size 5, the better. [0003] Common ONO structure formation methods in industry include photolithography, plasma etching and chemical wet process. The first step is to use photolithography to define the photoresist pattern, and to compensate for the size change of the ONO line in the subsequent process. In the s...

AI Technical Summary

Problems solved by technology

[0005] The existing technology uses a photoresist mask when opening the lower oxide film by chemical wet method, and the type and quantity of the treatment solution are very limited. If the treatment time is too long, it will easily cause the problem of photoresist stripping. The etching rate of the oxide film of the chemical solution is too fast and it is easy to cause the problem of poor etching uniformity, especially if the upper oxide film is etched sideways too much, the size will be seriously increased.

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