Why Cleaning Matters in Semiconductor Manufacturing

Semiconductor manufacturing is all about precision at the atomic level. Even the slightest contamination on a wafer surface can result in defects, reduced chip performance, or costly rework. This is why cleaning is one of the most critical steps in semiconductor fabrication—it ensures that wafers are free from organic residues, metal ions, and particulate contamination before moving to the next processing stage.

The Problem with Traditional Cleaning Methods

For years, semiconductor fabs have relied on deionized water (DIW) and chemical-based cleaning solutions to remove surface impurities. While DIW is effective for rinsing, it often requires additional chemical additives to break down contaminants, leading to:

• Increased chemical waste and disposal costs.
• Potential safety hazards for fab operators handling acids and solvents.
• Incomplete removal of certain organic residues and metal ions.

This has driven fabs to seek safer, greener, and more effective alternatives—one of the leading solutions being ozone water generators.

The Role of Cleaning in Semiconductor Manufacturing

Why Semiconductor Wafers Need Ultra-Clean Surfaces

Every stage of semiconductor manufacturing requires a pristine wafer surface to ensure proper electrical functionality, adhesion, and structural integrity. A single particle or residue left behind can:

• Disrupt thin film deposition, causing uneven coatings.
• Introduce electrical inconsistencies, leading to performance failures.
• Reduce chip yields, resulting in higher production costs.

Types of Contaminants on Wafers

Contaminants in semiconductor processing fall into three main categories:

1. Organic Residues – Left behind from photoresist materials and etching processes.
2. Metal Ions – Introduced through plasma processing or chemical reactions.
3. Particulate Contamination – Dust, silica particles, and other debris from wafer handling.

If these impurities are not removed before the next manufacturing step, they can lead to lower yields and inconsistent chip performance.

This is why fabs are increasingly turning to ozone water generators, which offer a chemical-free yet highly effective cleaning method.

What is an Ozone Water Generator and How Does it Work?

Understanding Ozone Water Cleaning

An ozone water generator is a system that dissolves ozone gas (O₃) into ultra-pure water, creating an extremely powerful oxidizing solution capable of breaking down organic and inorganic contaminants on semiconductor wafers.

Unlike traditional cleaning chemicals, ozone naturally decomposes into oxygen after use, making it environmentally friendly and safe for operators.

How an Ozone Water Generator Works

1. Ozone Generation – An electrical discharge is used to convert oxygen (O₂) into ozone (O₃).
2. Dissolution into Deionized Water – The ozone gas is dissolved into ultra-pure DIW, creating a highly reactive solution.
3. Surface Cleaning Process – Ozone water is applied to wafers, where it:
   • Breaks down organic residues like photoresists.
   • Oxidizes and removes metal ions.
   • Ensures thorough, contamination-free cleaning.
4. Natural Breakdown into Oxygen – After cleaning, ozone reverts back to oxygen (O₂), leaving no harmful byproducts.

Because ozone water cleaning does not require acids or solvents, it reduces chemical waste, lowers operational costs, and improves overall fab sustainability.

Ozone Water vs. DIW: Which is Better for Semiconductor Cleaning?

For years, deionized water (DIW) has been the industry standard for wafer cleaning, primarily used to rinse away particulate contamination. However, as semiconductor nodes shrink and chip designs become more intricate, traditional DIW cleaning methods face limitations—especially when it comes to removing organic residues, metal ions, and post-etch contaminants.

Ozone water generators offer a superior cleaning alternative, providing stronger oxidation power without the need for additional chemicals. They are particularly useful in photoresist stripping, post-CMP cleaning, and surface oxidation control, making them an increasingly popular choice in next-generation semiconductor fabs.

Comparing Ozone Water and Deionized Water (DIW) for Wafer Cleaning

Feature	Ozone Water Cleaning	Deionized Water (DIW) Cleaning
Oxidation Power	High, removes organic residues effectively	Low, requires chemical additives
Metal Ion Removal	Strong, oxidizes and eliminates metal contaminants	Requires acidic treatments
Particle Removal	Effective, especially in post-CMP cleaning	Good for general rinsing but requires surfactants for better results
Environmental Impact	No chemical waste, decomposes into oxygen	Produces hazardous chemical waste from cleaning agents
Cost Efficiency	Reduces chemical costs over time	Higher costs due to chemical dependency
Cleaning Performance	More effective for photoresist removal, metal ion elimination, and reducing surface oxidation	Limited to particle rinsing, requiring additional chemical treatments

When to Use Ozone Water vs. DIW

• Ozone Water is the preferred choice for organic residue removal, metal ion elimination, and eco-friendly wafer processing.
• DIW is still useful for particle rinsing steps but requires chemical additives to match the cleaning efficiency of ozone water.

As the semiconductor industry continues to evolve, fabs are increasingly adopting ozone water generators due to their higher cleaning efficiency, cost savings, and reduced environmental footprint.

Key Benefits of Ozone Water Generators in Semiconductor Cleaning

The semiconductor industry is under increasing pressure to reduce chemical waste, lower costs, and enhance process efficiency. Ozone water generators offer a cleaner, more sustainable alternative to traditional chemical-based cleaning solutions, making them an essential tool in modern wafer processing.

1. Chemical-Free Cleaning

One of the biggest advantages of ozone water is that it eliminates the need for hazardous chemicals, such as sulfuric acid (H₂SO₄) and hydrofluoric acid (HF). These chemicals, while effective, pose serious environmental and safety risks. Ozone water, by contrast, is a natural oxidizer that breaks down into oxygen after use, making it both effective and environmentally friendly.

2. Superior Contaminant Removal

Ozone water is highly effective at breaking down photoresists, eliminating metal ions, and removing organic residues. Unlike traditional DIW cleaning, which relies on chemical surfactants and acidic treatments, ozone water directly attacks contaminants at the molecular level. This makes it particularly valuable in:

• Post-Etch Cleaning – Ensuring complete removal of photoresist residues after patterning.
• Post-CMP Cleaning – Preventing residual slurry particles from causing defects.
• Oxidation Control – Maintaining a pristine wafer surface for better film deposition.

3. Reduced Chemical Waste & Lower Environmental Impact

Semiconductor fabs must comply with strict environmental regulations regarding chemical waste disposal. Since ozone water naturally decomposes into oxygen, it does not produce hazardous waste, making it a greener solution for wafer cleaning.

By reducing reliance on toxic chemicals, fabs can:

• Lower waste disposal costs.
• Meet sustainability goals with reduced carbon footprints.
• Enhance worker safety by minimizing exposure to hazardous substances.

4. Cost Savings in the Long Run

Although ozone water generators require an initial investment, they offer long-term cost savings by:

• Eliminating the need for expensive chemical purchases.
• Reducing waste treatment and disposal costs.
• Minimizing operational hazards and compliance costs related to chemical handling.

5. Improved Workplace Safety

Chemical-based cleaning solutions require fabs to enforce strict safety protocols, protective equipment, and hazardous material handling procedures. By transitioning to ozone water, fabs can create a safer, cleaner work environment for operators, reducing risks associated with toxic chemical exposure and accidental spills.

With these benefits, ozone water generators are proving to be one of the most significant innovations in semiconductor wafer cleaning.

How to Integrate Ozone Water Generators into a Semiconductor Fab

Implementing ozone water cleaning requires careful planning to maximize efficiency, ensure compatibility with existing processes, and maintain ultra-high cleaning standards. Here’s how fabs can successfully integrate ozone water generators into their operations.

1. Installation Considerations

For the best results, ozone water generators should be installed:

• Near wet processing stations to minimize ozone degradation during transport.
• Within close proximity to wafer cleaning tools, such as spray systems and immersion baths.
• With proper ventilation and ozone containment measures to ensure safe operation.

Since ozone is an unstable gas, fabs must optimize system design to maintain consistent ozone concentrations for effective cleaning.

2. Ongoing Maintenance Needs

Like any high-precision equipment, ozone water generators require regular monitoring and maintenance to ensure optimal performance. Key maintenance tasks include:

• Routine ozone concentration checks to verify cleaning effectiveness.
• Calibration of ozone injection systems to maintain the proper ozone-to-water ratio.
• Periodic inspection of water filtration systems to prevent contamination buildup.

Proper maintenance ensures consistent cleaning efficiency while prolonging the lifespan of the ozone generator.

3. Best Practices for Maximizing Efficiency

• Real-Time Monitoring – Use inline sensors and concentration analyzers to track ozone levels throughout the cleaning process.
• Hybrid Cleaning Approach – Combine ozone water with DIW rinsing to ensure both oxidation-based cleaning and thorough particle removal.
• Process Optimization – Adjust ozone exposure time, concentration levels, and flow rates based on wafer type and contamination levels.

4. Addressing Common Challenges in Ozone Water Integration

Some fabs may hesitate to adopt ozone water due to concerns about process adjustments and compatibility with existing tools. However, these challenges can be mitigated by:

• Conducting pilot tests to fine-tune ozone concentration levels.
• Integrating ozone water gradually, starting with specific cleaning stages.
• Collaborating with ozone water technology providers to optimize system parameters.

When implemented correctly, ozone water generators can enhance wafer cleaning efficiency, lower costs, and contribute to a more sustainable semiconductor manufacturing process.

With semiconductor fabs pushing for higher yields, better efficiency, and eco-friendly alternatives, ozone water is emerging as the next-generation cleaning solution. By offering chemical-free, highly effective cleaning, ozone water generators are set to replace traditional chemical-based cleaning methods in many applications.

The Future of Semiconductor Cleaning with Ozone Water

As semiconductor technology advances, the need for ultra-clean wafer surfaces becomes even more critical. Traditional deionized water (DIW) and chemical-based cleaning solutions have served the industry for years, but they come with limitations in effectiveness, environmental impact, and cost-efficiency.

Ozone water generators provide a breakthrough alternative by offering:

• Superior contaminant removal without the need for harsh chemicals.
• Lower environmental impact by eliminating hazardous waste disposal.
• Long-term cost savings by reducing reliance on expensive chemical reagents.
• Safer working conditions for fab operators by removing exposure to toxic substances.

With the semiconductor industry moving toward greener, more efficient manufacturing processes, ozone water cleaning is becoming the new standard for wafer surface preparation.

Key Takeaways:

• Ozone water outperforms DIW in removing organic residues and metal ions while reducing the need for additional chemicals.
• Fabs integrating ozone water generators benefit from cleaner wafers, reduced chemical waste, and lower long-term costs.
• Proper integration, monitoring, and process optimization ensure maximum efficiency and consistent performance.
• As environmental regulations tighten, fabs adopting ozone water technology will have a competitive advantage.

FAQs

Why is ozone water better than traditional chemical-based wafer cleaning?

Ozone water offers high oxidation power without hazardous chemicals, reducing waste, costs, and safety risks while ensuring effective contaminant removal.

Can ozone water completely replace DIW in semiconductor cleaning?

Ozone water is more effective for organic residue and metal ion removal, but DIW is still used for final rinsing steps to remove particulate matter.

What are the cost savings of using ozone water generators in fabs?

Fabs save money by reducing chemical purchases, waste disposal costs, and compliance expenses, making ozone water a cost-effective long-term solution.

Is ozone water safe for semiconductor manufacturing processes?

Yes. Ozone water naturally decomposes into oxygen, leaving no harmful residues while maintaining ultra-high purity for wafer processing.

How do semiconductor fabs integrate ozone water into existing cleaning systems?

Fabs can install ozone water generators near wet processing stations, integrate them with existing wafer cleaning tools, and monitor ozone concentration levels for optimal performance.