Thin Film Pattern Formation Using Soluble Protective Layer
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Solution Overview
Problem
Existing thin film pattern formation methods, particularly in miniaturized electronic and magnetic devices, face challenges in achieving high precision due to resist pattern deformation during dry etching, leading to burrs and re-deposition issues, especially when forming fine patterns with small dimensions.
Innovation Solution
A method involving the use of a soluble layer as a protection film to cover the resist pattern and thin film, allowing for precise dry etching without deformation, and subsequent removal of the resist pattern and soluble layer using a solvent that dissolves both, ensuring accurate separation and reducing burr formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the dimension of the resist pattern is reduced to form fine thin film patterns, then the thin film pattern dimension is reduced, but the resist pattern shape is deformed due to heat during dry etching
Solution Approach 1:
An undercut portion is formed in the resist pattern before dry etching to create a protective overhang structure. This preliminary structural modification prevents the resist pattern from deforming under heat during the subsequent dry etching process, while still allowing the formation of fine-dimensional thin film patterns.
2Length of moving object
If the dimension of the undercut portion is reduced to form fine thin film patterns, then the thin film pattern dimension is reduced, but re-attachment occurs around the resist pattern
Solution Approach 1:
The dimensions and shape of the undercut portion are optimized to specific parameter ranges that prevent re-attachment while enabling fine pattern formation. By carefully controlling the undercut width, depth, and profile, the patent achieves fine thin film patterns without the harmful re-attachment effect that occurs when undercut dimensions are simply reduced.
3Ease of manufacture
If the lift-off operation is performed to remove the resist pattern, then the resist pattern is removed, but burrs occur in the peripheral portion of the thin film pattern
Solution Approach 1:
A soluble layer is deposited on the thin film pattern before lift-off to create a protective barrier. This preliminary action prevents burr formation during the lift-off process by controlling the separation interface, while still allowing complete removal of the resist pattern through solvent dissolution of the soluble layer.
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 formation of thin film patterns with high precision and small dimensions by preventing resist pattern deformation and re-deposition, facilitating smooth lift-off operations and reducing burr occurrence.
Implementation Method 1
a solvent which can dissolve both the resist pattern and the soluble layer
Implementation Method 2
by performing dry etching such as ion milling using the resist pattern in which the undercut is formed as a mask
Data Source
AI summary
The present invention provides a thin film pattern forming method capable of forming a thin film pattern having small dimensions at higher precision. A thin film pattern forming method of the invention includes: a step of forming a first thin film on a substrate; a step of forming a bilayer resist pattern; a step of forming a soluble layer as a covering layer; and a step of forming a first thin film pattern by selectively removing the first thin film by dry etching using the bilayer resist pattern as a mask. Since the soluble layer generally and continuously covering the periphery of the bilayer resist pattern and the first thin film in an area other than the area covered with the bilayer resist pattern is formed, deformation of the shape of the bilayer resist pattern can be suppressed at the time of dry etching and a deposition amount of a re-deposit 9 can be also reduced. Consequently, the isolated first thin film pattern having small dimensions and defined by a contour can be formed at higher precision. Further, the first thin film pattern 17 is formed by dry etching and, after that, the bilayer resist pattern covered with the soluble layer is removed by using a solvent which can dissolve both the bilayer resist pattern and the soluble layer. Thus, the first thin film pattern and the bilayer resist pattern can be separated from each other without a hitch.