Substrate Organic Layer Removal With Staged SPM Reactivity
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Solution Overview
Problem
Conventional substrate processing methods using a mixed solution of sulfuric acid and hydrogen peroxide (SPM solution) struggle to effectively remove cured layers in resist layers, and there is a need to reduce the usage of sulfuric acid to minimize environmental impact.
Innovation Solution
A substrate processing method involving multiple steps with varying concentrations and forms of the SPM solution application, including droplet and continuous stream, to efficiently remove different layers of the resist, with recycling of sulfuric acid to reduce usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a highly reactive SPM solution is used to remove cured layers, then removal effectiveness is improved, but sulfuric acid usage increases causing environmental harm
Solution Approach 1:
The removal process is divided into multiple sequential steps, each targeting a specific layer type (first cured layer, non-cured layer, second cured layer) with appropriately optimized SPM solution concentrations. This segmentation allows effective removal of each layer type while minimizing overall sulfuric acid usage compared to using a single high-concentration solution for all layers.
Solution Approach 2:
The SPM solution concentration parameter is dynamically adjusted across different processing steps based on the specific layer being removed. Lower concentrations are used for the non-cured layer while higher concentrations are reserved for the more resistant cured layers, optimizing both removal effectiveness and environmental impact.
2Reliability
If a single high-concentration SPM solution is used for all layers, then removal effectiveness is improved, but process complexity and chemical usage increase
Solution Approach 1:
The resist layer removal process is segmented into distinct steps targeting different layer types sequentially. This segmentation enables the use of optimized concentrations for each step rather than requiring a single high-concentration solution, thereby reducing overall chemical usage while maintaining effectiveness.
Solution Approach 2:
The SPM solution concentration is made dynamic, changing across different processing steps according to the specific layer being removed. This dynamic adjustment optimizes chemical usage and reduces environmental impact while maintaining removal effectiveness, avoiding the need for consistently high concentrations throughout the entire process.
3Reliability
If droplet form SPM solution is used, then removal effectiveness on cured layers is improved, but sulfuric acid consumption increases compared to continuous stream
Solution Approach 1:
Different SPM solution application methods and concentrations are applied locally to different layer types. Droplet form with higher concentration is used specifically for cured layers where it provides superior removal effectiveness, while continuous stream with lower concentration is used for non-cured layers to minimize chemical consumption.
Solution Approach 2:
The physical state parameter of the SPM solution (droplet vs. continuous stream) and its concentration are changed based on the target layer. This parameter optimization ensures effective removal of cured layers using droplets while reducing overall sulfuric acid consumption by using continuous stream for non-cured layers.
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
The method effectively removes cured and non-cured layers of the resist while reducing sulfuric acid usage and minimizing residue, achieving efficient substrate processing with reduced environmental impact.
Implementation Method 1
a first step of supplying the main surface of the substrate with a mixed solution of sulfuric acid and aqueous hydrogen peroxide to remove the first cured layer
Data Source
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AI summary
Provided is a technology that can appropriately remove an organic layer on a substrate while contributing to reduction in the usage of sulfuric acid. A substrate processing method includes a holding step (S1), a first step (S3), a second step (S4), and a third step (S5). In the holding step (S1), a substrate on a main surface of which an organic layer is formed is held, the organic layer including a first cured layer, a non-cured layer, and a second cured layer. In the first step (S3), a mixed solution of sulfuric acid and aqueous hydrogen peroxide is supplied to the main surface to remove the first cured layer. In the second step (S4), the main surface is supplied, after the first step (S1), with the mixed solution mixed at a mixing ratio lower reactive than the mixed solution in the first step (S1) to remove the non-cured layer. In the third step (S5), the main surface of the substrate is supplied, after the second step (S4), with the mixed solution mixed at a mixing ratio higher reactive than the mixed solution in the second step (S4) to remove the second cured layer.