Substrate Etching for Narrow Gaps Using Low-Surface-Tension Liquid
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Solution Overview
Problem
Existing substrate processing methods fail to efficiently etch targets both inside and outside narrow gaps on substrates while minimizing the use of processing liquids, leading to inefficiencies and potential environmental impact.
Innovation Solution
A method involving two-stage etching using an outer etching step with a standard etching liquid followed by an inner etching step with a low-surface-tension mixed liquid that can penetrate narrow gaps, accompanied by a rinse step to minimize liquid usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a standard etching liquid is continuously supplied to etch both outer and inner portions of the etching target, then the outer portion can be etched effectively, but the liquid cannot efficiently penetrate into the narrow gap to etch the inner portion
Solution Approach 1:
The etching process is divided into two distinct stages: first etching the outer portion with standard etching liquid, then etching the inner portion with mixed etching liquid containing low-surface-tension liquid. This segmentation allows each liquid to be used optimally for its specific purpose, reducing overall liquid consumption while achieving complete etching.
Solution Approach 2:
The surface tension parameter of the etching liquid is changed by adding low-surface-tension liquid (such as IPA) to create mixed etching liquid. This parameter change enables the liquid to penetrate into the narrow gap where standard etching liquid cannot reach, allowing effective etching of the inner portion.
2Productivity
If mixed etching liquid containing low-surface-tension liquid is supplied from the beginning, then the inner portion can be etched efficiently, but the overall consumption of low-surface-tension liquid increases
Solution Approach 1:
The outer portion is etched first using standard etching liquid before introducing the mixed etching liquid. This preliminary action removes the outer material that would otherwise block access to the inner portion, allowing the low-surface-tension liquid to be used only when necessary for penetrating the narrow gap.
Solution Approach 2:
The etching process uses periodic action by switching between two different etching liquids at different time periods. Standard etching liquid is used in the first period for outer etching, then mixed etching liquid is used in the second period for inner etching, optimizing both efficiency and resource usage.
3Device complexity
If the same etching liquid is used throughout the process, then the process is simple, but the inner portion disposed in the narrow gap cannot be effectively etched
Solution Approach 1:
Low-surface-tension liquid (such as IPA) acts as an intermediary substance that modifies the properties of the etching liquid. When added to the etching liquid, it reduces surface tension and enables penetration into the narrow gap, serving as a mediator that allows the etching process to reach the inner portion effectively.
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 approach allows for complete etching of both outer and inner portions of the target while reducing the overall consumption of low-surface-tension liquids, thereby enhancing efficiency and minimizing environmental burden.
Implementation Method 1
a low-surface-tension liquid having a surface tension smaller than a surface tension of the etching liquid is dissolved
Data Source
AI summary
A substrate processing method includes an outer etching step of etching an outer portion by supplying an etching liquid to a substrate including an end surface, an inner surface forming a gap which has a width smaller than a depth of the gap and is open at the end surface, and the etching target having an outer portion disposed outside the gap and an inner portion disposed in the gap, and an inner etching step of etching the inner portion with a mixed etching liquid which has entered the gap by supplying, to the substrate, the mixed etching liquid which is an etching liquid obtained by dissolving a low-surface-tension liquid having a surface tension smaller than a surface tension of the etching liquid, after the outer portion of the etching target is etched.