Megasonic Substrate Cleaning for Conductive Nanoparticle Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cleaning methods for photomasks and semiconductor substrates are ineffective in removing conductive nanoparticles, particularly from thin capping layers, leading to contamination and potential damage during EUV lithography, with removal rates often below 10% and compromising layer integrity.
Innovation Solution
A cleaning method involving a sequence of mixtures, including SC1 solution, deionized water, ozone, and hydrogen gas, combined with sonic agitation and spinning, effectively removes conductive nanoparticles with a removal rate greater than 90% while preserving the integrity of thin layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing cleaning methods are used, then the process is simple, but the nanoparticle removal rate is below 10%
Solution Approach 1:
The cleaning process is divided into multiple sequential stages: first mega sonic agitation with SC1 solution, then second mega sonic agitation with deionized water and ozone, followed by spin drying and hydrogen gas treatment. Each stage targets specific types of contamination and uses optimized parameters to remove different classes of particles, achieving cumulative removal rates exceeding 90%.
Solution Approach 2:
The patent employs varying sonic agitation frequencies (e.g., 20-100 kHz for first agitation, 50-200 kHz for second agitation) and adjusts chemical solution compositions (SC1 solution with specific NH4OH:H2O2:H2O ratios, ozonated water concentrations) to optimize removal efficiency for different nanoparticle types while protecting the capping layer.
2Reliability
If strong cleaning agents are used to increase removal rate, then nanoparticle removal improves, but thin capping layer integrity is compromised
Solution Approach 1:
Mega sonic agitation at controlled frequencies (20-200 kHz) creates cavitation bubbles that collapse to generate localized shock waves and micro-jets, mechanically dislodging nanoparticles from the capping layer surface without requiring harsh chemical etching, thus achieving high removal rates while preserving layer integrity.
Solution Approach 2:
The patent uses SC1 solution (containing H2O2) and ozonated water to chemically oxidize and dissolve conductive nanoparticles, particularly effective for metal-based particles. The controlled oxidation breaks down nanoparticle structures without attacking the silicon nitride or silicon oxide capping layer materials.
3Reliability
If conventional cleaning sequences are used, then the process is fast, but contamination remains on the substrate
Solution Approach 1:
The cleaning process maintains continuous action through sequential treatments without idle transitions: mega sonic agitation with SC1 solution immediately followed by mega sonic agitation with ozonated water, then spin drying, and finally hydrogen gas treatment. Each step builds on the previous one, with no interruption in the cleaning objective, maximizing removal efficiency within minimal time.
Solution Approach 2:
Ozone serves as an intermediary substance that enhances the cleaning action of water by forming ozonated water with strong oxidizing properties. The ozone bubbles attach to nanoparticles and facilitate their detachment during the second mega sonic agitation, acting as a mediator between the mechanical agitation and the nanoparticle removal process.
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 achieves a significant improvement in nanoparticle removal rates, maintaining the thickness and integrity of photomask and semiconductor substrate layers, enhancing the reliability and longevity of photolithography processes.
Implementation Method 1
A first mega sonic agitation is performed on the substrate with applying a first mixture. A second mega sonic agitation is performed on the substrate with applying a second mixture.
Implementation Method 2
A spin is performed after the first sonic agitation and the applying of the first mixture. A spin is performed after the applying of the second mixture.
Data Source
AI summary
A method for cleaning a substrate is provided. The method includes following operations. A substrate is received. The substrate includes a first layer over a surface of the substrate and a second layer over the first layer. A plurality of particles are disposed over the surface of the first layer. A first mega sonic agitation is performed on the substrate with applying a first mixture. A second mega sonic agitation is performed on the substrate with applying a second mixture. A frequency of the first mega sonic agitation is greater than 3 MHz, and a frequency of the second mega sonic agitation is greater than 3 MHz. A flow rate of the first mixture is between approximately 1000 ml/min and approximately 5000 ml/min. A flow rate of the second mixture is between 1000 ml/min and approximately 3000 ml/min.