Etch Mask Film Evaluation via Etching Clear Time Ratio
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Solution Overview
Problem
The challenge in semiconductor processing is to achieve high accuracy and miniaturization of photomask patterns while maintaining the integrity of the resist film, as current etch mask films are either too thick for precise pattern transfer or too thin, leading to defects and damage during etching.
Innovation Solution
A method to evaluate the etch mask film by measuring the first and second etching clear times under specific etching conditions and computing their ratio, allowing for the selection of an etch mask film with optimal etching performance, which balances etch resistance and etchability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the etch mask film is reduced to enable miniaturization, then the aspect ratio is improved and resist pattern collapse is prevented, but the etch mask film becomes too thin to provide sufficient etch resistance during pattern transfer
Solution Approach 1:
The patent employs a composite etch mask film structure consisting of a first etch mask film layer (chromium compound) and a second etch mask film layer (silicon-based material). This composite structure combines the advantages of both materials: the chromium compound layer provides good etch resistance, while the silicon-based layer enables precise pattern transfer with reduced aspect ratio. The synergistic combination resolves the contradiction between thin film requirements and sufficient etch resistance.
2Reliability
If chromium compound film is used as etch mask film, then etch resistance is improved, but pattern transfer accuracy deteriorates due to high aspect ratio and resist pattern damage
Solution Approach 1:
The etch mask film is segmented into two distinct layers with different functions. The first layer (chromium compound) primarily provides etch resistance, while the second layer (silicon-based material) primarily enables accurate pattern transfer. This segmentation allows each layer to optimize its specific function, resolving the contradiction between etch resistance and pattern transfer accuracy.
3Manufacturing precision
If silicon-based material is used as etch mask film, then pattern transfer accuracy is improved, but etch resistance deteriorates
Solution Approach 1:
The patent combines silicon-based material with chromium compound material in a layered structure. The silicon-based layer provides excellent pattern transfer accuracy, while the chromium compound layer compensates for insufficient etch resistance. This composite material approach resolves the contradiction by distributing functional requirements across different materials.
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 evaluation method enables the selection of an etch mask film that ensures satisfactory pattern transfer with minimal defects, achieving high accuracy and miniaturization of photomask patterns.
Implementation Method 1
measuring a first etching clear time (C1) taken when the etch mask film is etched under the etching conditions to be applied to the pattern-forming film
Data Source
Figure 1
AI summary
In conjunction with a photomask blank comprising a transparent substrate, a pattern-forming film, and an etch mask film, the etch mask film is evaluated by measuring a first etching clear time (C1) taken when the etch mask film is etched under the etching conditions to be applied to the pattern-forming film, measuring a second etching clear time (C2) taken when the etch mask film is etched under the etching conditions to be applied to the etch mask film, and computing a ratio (C1/C2) of the first to second etching clear time.