Two-Step SPM Supply for Substrate Resist Removal and Acid Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing substrate processing methods struggle to recover sulfuric acid with high concentration while efficiently removing resist films from substrates, as increasing hydrogen peroxide concentration enhances removal ability but decreases sulfuric acid concentration, and vice versa, leading to inefficient reuse of the sulfuric acid mixture (SPM).
Innovation Solution
A substrate processing method involving a two-step SPM supply process, where a first SPM with a higher hydrogen peroxide concentration is used for initial resist removal, followed by a sulfuric-acid-rich liquid to recover sulfuric acid, and then remixing to maintain high sulfuric acid concentration for reuse, with a guard switching mechanism to manage contaminants and optimize SPM flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hydrogen peroxide water concentration in SPM is increased to enhance resist removal ability, then the removal ability is improved, but the concentration of sulfuric acid in the recovered SPM decreases, making it unsuitable for reuse after repeated recovery
Solution Approach 1:
The patent segments the SPM supply process into two distinct phases: a first SPM supplying step using SPM with higher hydrogen peroxide concentration for effective resist removal, and a second SPM supplying step using SPM with higher sulfuric acid concentration for maintaining high sulfuric acid levels during recovery. This segmentation allows each phase to optimize for its specific function without compromising the other parameter.
Solution Approach 2:
The patent dynamically adjusts the composition of SPM between two different formulations depending on the process stage. The system transitions from using SPM with higher hydrogen peroxide content during the resist removal phase to SPM with higher sulfuric acid content during the recovery phase, optimizing performance for each specific operational requirement.
2Quantity of substance
If the hydrogen peroxide water concentration is decreased to increase the concentration of sulfuric acid in recovered SPM, then the sulfuric acid concentration is improved, but the removal ability of SPM decreases
Solution Approach 1:
The patent divides the processing into two sequential steps: first using SPM optimized for resist removal (higher hydrogen peroxide), then using SPM optimized for sulfuric acid recovery (higher sulfuric acid). This eliminates the need to compromise either parameter in a single SPM formulation.
Solution Approach 2:
The first SPM supplying step performs the resist removal function preliminarily before the second step focuses on sulfuric acid recovery. By completing the removal task first with appropriately formulated SPM, the system prepares the conditions for effective sulfuric acid recovery in the subsequent step.
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 efficient resist removal while maintaining high sulfuric acid concentration in the recovered SPM, reducing contaminant contamination and extending the reuse period of the SPM, thus optimizing the substrate processing process.
Implementation Method 1
SPM (a liquid mixture of sulfuric acid and hydrogen peroxide water)... removing a resist film
Implementation Method 2
the SPM is increased in removal ability (ability of the SPM to remove the resist)
Data Source
AI summary
A first SPM, prepared by mixing sulfuric acid and hydrogen peroxide water at a first mixing ratio, is supplied to a substrate. A second SPM, prepared by mixing the sulfuric acid and the hydrogen peroxide water at a second mixing ratio greater than the first mixing ratio, is supplied to the substrate after the supply of the first SPM is stopped. The first SPM expelled from the substrate flows into a drain piping. The second SPM expelled from the substrate flows into a recovery piping. SPM is prepared by mixing the hydrogen peroxide water with sulfuric acid contained in the second SPM guided by the recovery piping.