Substrate Ozone Exposure After Sulfuric Acid for Uniform Resist Removal
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Solution Overview
Problem
Existing substrate processing methods using sulfuric acid/ozone/water mixtures face issues with reduced oxidative power due to dilution, leading to insufficient removal of organic films like resist, and uneven film removal across substrate surfaces.
Innovation Solution
A method involving immersing substrates in sulfuric acid, followed by exposure to ozone gas, which dissolves in the sulfuric acid to form peroxodisulfuric acid, ensuring high ozone concentration and uniform film removal, with controlled attitude changes and gas supply/exhaust mechanisms to maintain evenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If sulfuric acid/ozone is mixed with water to generate sulfuric acid/ozone/water mixture liquid, then the temperature is increased by dilution heat enabling resist removal, but the concentration of peroxodisulfuric acid is reduced leading to insufficient oxidative power
Solution Approach 1:
The invention extracts the water mixing step from the process, using only sulfuric acid and ozone gas without adding water. This eliminates the dilution effect that reduces peroxodisulfuric acid concentration while still achieving the necessary temperature increase through the exothermic reaction between sulfuric acid and ozone.
Solution Approach 2:
The invention changes the composition parameters of the treatment liquid by eliminating water and using only sulfuric acid and ozone. This parameter change maintains high peroxodisulfuric acid concentration while achieving sufficient temperature through the exothermic reaction, resolving the contradiction between temperature increase and concentration maintenance.
2Quantity of substance
If a greater amount of ozone gas is dissolved in sulfuric acid by using relatively low temperature, then more peroxodisulfuric acid can be generated, but the temperature may be insufficient for speedy organic film removal
Solution Approach 1:
The invention performs preliminary dissolution of ozone gas in sulfuric acid at lower temperature to maximize the amount of dissolved ozone and peroxodisulfuric acid generation. Then, the exothermic reaction provides the necessary temperature increase for speedy organic film removal, achieving both high concentration and high productivity.
Solution Approach 2:
The invention utilizes the phase transition and exothermic reaction characteristics of sulfuric acid mixing with ozone. The reaction releases heat that naturally increases the temperature after ozone dissolution, providing both high dissolved ozone concentration and sufficient temperature for fast processing without external heating.
3Productivity
If substrates are treated with sulfuric acid/ozone/water mixture, then organic films can be removed, but the removal may be uneven due to concentration reduction
Solution Approach 1:
The invention achieves homogeneity by using only sulfuric acid and ozone without water, ensuring uniform distribution of peroxodisulfuric acid throughout the treatment liquid. This homogeneous composition ensures uniform oxidative power across all substrate surfaces, achieving even organic film removal while maintaining high productivity.
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 enables rapid and thorough removal of organic films like resist with consistent thickness and concentration, preventing uneven film removal and maintaining oxidative power.
Implementation Method 1
ozone contained in the ozone-containing gas is dissolved in the sulfuric acid-containing liquid adhering to the substrates taken out of the sulfuric acid-containing liquid, whereby peroxodisulfuric acid is generated in the adhering sulfuric acid-containing liquid
Implementation Method 2
peroxodisulfuric acid is generated in the adhering sulfuric acid-containing liquid. As a result, organic films such as of a resist can be speedily and sufficiently removed from the substrates
Data Source
AI summary
A substrate processing method is provided, which includes: a sulfuric acid immersing step of immersing a plurality of substrates in a sulfuric acid-containing liquid within a sulfuric acid vessel; a transporting step of taking out the substrates from the sulfuric acid vessel and transporting the substrates to an ozone gas treatment unit; and an ozone exposing step of exposing the substrates transported to the ozone gas treatment unit to an ozone-containing gas. The ozone gas treatment unit may include a gas treatment chamber which accommodates the substrates. The ozone exposing step may include the step of placing the substrates taken out of the sulfuric acid vessel in a treatment space within the gas treatment chamber to expose the substrates to the ozone-containing gas.