Low-Stress Silicon Nitride Mask for Semiconductor Etching
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Solution Overview
Problem
The existing methods for forming fine patterns on semiconductor wafers using silicon oxide films face challenges such as high film stress, pattern deformation, and limited selection ratio, which hinder the formation of precise and stable patterns necessary for advanced semiconductor devices.
Innovation Solution
A pattern-forming method involving the formation of an organic film pattern, followed by a silicon nitride film deposited at low temperatures using plasma processing, with the silicon nitride film being etched to remain only on the lateral walls and the organic film removed, allowing for a low-stress silicon nitride film to serve as a mask for etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a silicon oxide film is formed on a resist pattern at temperatures of no more than 300°C, then the film can be formed, but the film stress becomes high (hundreds of MPa) causing pattern deformation and collapse
Solution Approach 1:
The patent changes the material parameter from silicon oxide to silicon nitride, and adjusts the temperature parameter to no more than 100°C during plasma processing. This combination of parameter changes achieves low film stress (no more than 100 MPa) while maintaining proper pattern formation, resolving the contradiction between temperature and stress.
2Temperature
If the temperature of the wafer becomes high (100°C or more), then processing can be performed, but the organic resist pattern may be damaged or collapsed
Solution Approach 1:
The patent changes the temperature parameter to no more than 100°C during plasma film formation and processing. This temperature control prevents damage to the organic resist pattern while still enabling effective plasma processing, thus resolving the contradiction between temperature and pattern integrity.
3Ease of manufacture
If a silicon oxide film is used as a mask, then etching can be performed, but the selection ratio is low limiting the scope of applicable films
Solution Approach 1:
The patent uses silicon nitride film as a mask material, which provides both etching capability and high selection ratio. This material substitution resolves the contradiction by offering superior performance in both ease of manufacture (etching capability) and adaptability (selection ratio for various films including polysilicon, silicon oxide, and silicon nitride).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the proper formation of a mask with a predetermined pattern at low temperatures, preventing pattern deformation and offering a higher selection ratio for etching, thus broadening the scope of applicable films and improving pattern precision.
Implementation Method 1
a processing gas is excited to generate a plasma and a plasma processing by the plasma is performed to form the silicon nitride film
Data Source
AI summary
A pattern-forming method for forming a predetermined pattern serving as a mask when etching film on a substrate includes the steps of: an organic film pattern-forming step for forming an organic film pattern on a film to be processed; forming a silicon nitride film on the organic film pattern; etching the silicon nitride film so that the silicon nitride film remains only on the lateral wall sections of the organic film pattern; and removing the organic film, thereby forming the predetermined silicon nitride film pattern on the film to be processed on a substrate. With the temperature of the substrate maintained at no more than 100° C., the film-forming step excites a processings gas and generates a plasma, performs plasma processing with the plasma, and forms a silicon nitride film having stress of no more than 100 MPa.