Introduction
As semiconductor process nodes continue to shrink to the nanometer scale, tiny contaminants on the wafer surface (such as particles, organic matter, and metal ions) can lead to circuit malfunctions and directly affect chip yield. Since its introduction by RCA Laboratories in 1965, the RCA cleaning method has become an indispensable core process in semiconductor manufacturing due to its high cleanliness and controllability. Ke Xin Wei Company, through innovative process design and equipment research and development, has further improved the efficiency and stability of RCA cleaning, providing a reliable solution for atomic-level cleanliness of the wafer surface.

RCA Cleaning Process Flowchart

Detailed Explanation of the Four-Step RCA Cleaning Method
The standard RCA cleaning method uses four key steps to remove different contaminants in stages, ensuring that the wafer surface cleanliness reaches atomic-level standards:
1. SPM Cleaning (H₂SO₄/H₂O₂, 120～150℃)
Function: Removes heavy organic contaminants and some metals.
Chemical Principle: Sulfuric acid (H₂SO₄) and hydrogen peroxide (H₂O₂) generate strong oxidizing radicals at high temperatures, decomposing organic matter into CO₂ and H₂O, and simultaneously oxidizing metal ions to dissolve them in the cleaning solution.
Ke Xin Wei Innovation: Uses dynamic temperature control technology to prevent organic matter carbonization and improve cleaning efficiency.
2. DHF Cleaning (HF/H₂O, 20～25℃)
Function: Removes native oxide films and adhering metals (such as Al, Fe).
Chemical Principle: Hydrofluoric acid (HF) dissolves the oxide layer (SiO₂) on the silicon wafer surface, allowing metal contaminants to detach from the surface.
Surface Activation: Exposes a fresh silicon surface, providing a highly active interface for subsequent processes (such as film deposition).
Process Challenges: HF concentration must be strictly matched to the oxide layer thickness (usually 0.5%-5%); excessive amounts will cause excessive etching of the silicon substrate;
Real-time monitoring of the etching endpoint to avoid batch-to-batch variations.
Ke Xin Wei Advantage: Precisely controls HF concentration to ensure zero corrosion of the silicon substrate and protect wafer integrity.
3. SC-1 Cleaning (NH₄OH/H₂O₂/H₂O, 30～80℃)
Function: Removes particles and light metal residues.
Chemical Principle: Ammonium hydroxide (NH₄OH) corrodes the silicon surface, and H₂O₂ simultaneously oxidizes to form a new oxide film, causing particles to detach from the surface.
Process Control: The solution temperature is usually controlled at 70-80℃ to accelerate the reaction rate;
H₂O₂ concentration needs to be precisely controlled to avoid excessive oxidation and surface damage.
Technological Breakthrough: Optimizes solution ratio to reduce surface roughness and provide a smooth substrate for subsequent lithography processes.
4. SC-2 Cleaning (HCl/H₂O₂/H₂O, 65～85℃)
Function: Removes alkali metals (Na, K) and transition metals (Fe, Cu).
Chemical Principle: Hydrochloric acid (HCl) and hydrogen peroxide work together to remove metals efficiently through chloride ion complexation.
Surface Passivation: H₂O₂ generates an oxide film in an acidic environment to prevent metal ion re-adsorption.
Special Applications: HNO₃+HF combination is used for difficult-to-dissolve metals (such as tungsten and titanium) to completely remove them through complexation reactions.
Safety Regulations: HF must be used in closed equipment, and operators must wear anti-corrosion equipment to avoid contact risks.
Ke Xin Wei Practice: Introduces a high-purity water circulation system to ensure zero chemical residue and avoid secondary contamination.
Process Technology Advantages
1. Multi-contaminant Removal in Stages: The four-step method designs exclusive reaction pathways for different contaminants to achieve precise cleaning.
2. Chemical Compatibility and Safety: Ke Xin Wei uses acid and alkali corrosion-resistant PFA/PVDF filter materials to ensure the stability of the cleaning solution circulation.
3. Fully Automated Process Control: Real-time monitoring of solution temperature, concentration, and flow rate through intelligent sensors ensures process consistency.
4. Environmental Protection and Cost Effectiveness: The cleaning solution recycling rate is increased to 90%, reducing waste liquid treatment costs and complying with green manufacturing concepts.
Conclusion
The four-step RCA cleaning method is a core process for achieving atomic-level cleanliness of wafers in semiconductor manufacturing. Ke Xin Wei Company, through process optimization and technological innovation, improves cleaning efficiency while ensuring equipment reliability and environmental friendliness, providing a solid guarantee for advanced processes below 5nm. In the future, Ke Xin Wei will continue to cultivate the semiconductor cleaning field, helping the global chip industry move towards higher precision and reliability.

Ke Xin Wei Company - Leading the Innovation of Semiconductor Cleaning Technology

For more technical details, please contact our technical consultant: 13861996325!