Substrate Organic Film Removal Using Ozone-First Sulfuric Acid
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Solution Overview
Problem
Existing substrate processing methods using sulfuric acid and ozone mixtures face inefficiencies due to ozone decomposition before reaching the substrate, leading to high costs and waste disposal burdens, as ozone diffusion through the liquid layer is inefficient and ozone concentration maintenance is difficult.
Innovation Solution
A substrate processing method involving the introduction of ozone-containing gas into a chamber above the substrate, followed by spraying a heated sulfuric acid solution, ensuring ozone concentration thresholds are met, and continuous ozone supply during processing to maintain reaction efficiency, with separated chemical liquid reuse to minimize waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ozone is contained in sulfuric acid before being discharged from a nozzle, then the processing efficiency may be improved, but most of the ozone decomposes at an excessively early timing before reaching the vicinity of the substrate
Solution Approach 1:
The process is divided into two separate stages: first, the substrate surface is treated with ozone-containing gas to prepare it; second, heated sulfuric acid is sprayed onto the substrate. This segmentation prevents premature mixing of ozone and sulfuric acid, avoiding early decomposition of ozone before it reaches the substrate surface where it is needed.
Solution Approach 2:
The substrate surface is pre-treated with ozone-containing gas to create a prepared surface state before the sulfuric acid is applied. This preliminary action ensures that when the sulfuric acid eventually contacts the substrate, the ozone is already positioned at the substrate surface, maximizing its effectiveness and preventing decomposition in the liquid phase.
2Productivity
If ozone diffusion that causes ozone to penetrate a liquid layer on a substrate is used, then substrate processing may be achieved, but diffusion that causes ozone to penetrate a liquid layer is not likely to occur
Solution Approach 1:
Instead of attempting to diffuse ozone through the liquid sulfuric acid layer (which is unreliable), the approach is inverted: ozone-containing gas is applied first to the substrate surface, then heated sulfuric acid is sprayed. This reverses the conventional approach of gas diffusion through liquid, achieving reliable ozone delivery without depending on inefficient diffusion processes.
Solution Approach 2:
The sulfuric acid is heated to a high temperature (100°C or higher) before being sprayed onto the substrate. This parameter change (temperature increase) enhances the reactivity and effectiveness of the sulfuric acid while maintaining the sequential application method that prevents premature ozone decomposition.
3Productivity
If increasing ozone concentration by raising the pressure at which ozone is injected in chemical liquid is attempted, then processing efficiency may be improved, but it is practically difficult to stably maintain a high pressure state
Solution Approach 1:
The ozone is extracted from the liquid chemical mixture and delivered separately as a gas to the substrate surface before the heated sulfuric acid is applied. This extraction eliminates the need for high-pressure injection systems, simplifying the equipment and improving operational stability while maintaining effective ozone delivery to the substrate.
4Productivity
If sulfuric acid and ozone are mixed to generate peroxodisulfate ions as active species, then organic film removal may be achieved, but much of the ozone decomposes at an excessively early timing
Solution Approach 1:
The substrate surface is pre-treated with ozone-containing gas to generate active species directly at the substrate surface before the sulfuric acid is applied. This preliminary action ensures that ozone has sufficient time to decompose and generate active species only when and where needed, maximizing the utilization of ozone's short half-life for effective organic film removal.
Solution Approach 2:
The substrate surface acts as an intermediary that facilitates the controlled decomposition of ozone and generation of active species. By applying ozone to the substrate surface first, the substrate itself becomes the medium where the chemical reactions occur, preventing premature decomposition in the liquid phase while ensuring effective organic film removal.
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 enhances the efficiency of organic film removal on substrates by ensuring active species reach the substrate effectively, reducing chemical costs and waste, while maintaining processing consistency and minimizing ozone consumption.
Implementation Method 1
introduction of ozone-containing gas into a substrate processing chamber to fill at least a space above the substrate in the substrate processing chamber with ozone-containing gas
Implementation Method 2
starting spraying through the space a heated chemical liquid containing sulfuric acid onto the substrate
Implementation Method 3
sulfuric acid and ozone are mixed to generate peroxodisulfate ions (S2O82−) as active species (etchants)... ozone tends to quickly decompose in sulfuric acid
Implementation Method 4
sulfuric acid and ozone are mixed to generate peroxodisulfate ions (S2O82−) as active species
Implementation Method 5
starting spraying through the space a heated chemical liquid containing sulfuric acid onto the substrate
Data Source
AI summary
A substrate processing method for removing an organic film on a substrate includes a) carrying out introduction of ozone-containing gas into a substrate processing chamber to fill at least a space above the substrate in the substrate processing chamber with ozone-containing gas, b) starting spraying through the space a heated chemical liquid containing sulfuric acid onto the substrate after the a), c) continuing the spraying started in the b), and d) stopping the spraying continued in the c).