A self-aligned secondary molding process method for preventing side wall deformation

By reintegrating the thin film layers in the self-aligned secondary molding process, using the polysilicon layer as a hard mask to define the pattern and etch the sidewalls, the problem of sidewall deformation caused by the mismatch of the film combination stress is solved, and the accurate definition of the metal line shape is achieved.

CN114496776BActive Publication Date: 2025-09-26SHANGHAI HUALI INTEGRATED CIRCUIT CORP
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Patent Information

Application Number
CN202011251161.X
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2020-11-11
Publication Date
2025-09-26
Estimated Expiration
2040-11-11

AI Technical Summary

Technical Problem

In the existing self-aligned secondary molding process, stress mismatch of the film combination at high temperature causes sidewall deformation, affecting the shape definition of the metal line.

Method used

By growing a composite film layer on the through-hole layer, including a first silicon nitride layer, a first silicon oxide layer, a titanium nitride layer, a second silicon oxide layer, a second silicon nitride layer and a polysilicon layer, the polysilicon layer is used as a hard mask to define the pattern and etched to form a silicon nitride pattern structure, then the side wall is formed and the inner layer structure is removed, and finally the titanium nitride pattern structure is used as a hard mask to etch other layers to achieve stress matching of each film layer.

Benefits of technology

Completely solve the side wall tilt problem at high temperatures, ensure the accuracy of pattern definition in the secondary molding process, and prevent metal wire deformation.

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Abstract

The present invention provides a self-aligned secondary molding process method for preventing sidewall deformation. The method comprises growing a first silicon nitride layer, a first silicon oxide layer, a titanium nitride layer, a second silicon oxide layer, a second silicon nitride layer, and a polysilicon layer sequentially from bottom to top on a through-hole layer. The polysilicon layer is used as a hard mask to define a pattern and the second silicon nitride layer is etched to the upper surface of the second silicon oxide layer, forming the second silicon nitride layer into multiple silicon nitride pattern structures. Sidewalls are formed on the sidewalls of the multiple silicon nitride pattern structures. The silicon nitride pattern structures within the sidewalls are removed. The second silicon oxide layer and the titanium nitride layer are etched using the sidewalls as a hard mask to form a titanium nitride pattern structure. The first silicon oxide layer and the first silicon nitride layer are etched using the titanium nitride pattern structure as a hard mask to pattern the first silicon oxide layer and the first silicon nitride layer. By integrating the composite film layers, the present invention achieves stress matching between the film layers at high temperatures, completely resolving sidewall tilt and achieving pattern definition for secondary molding.
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