Efficient Hydrogen Peroxide Removal in SPM and APM Wastewater

Innovative Solutions for Hydrogen Peroxide Removal in SPM and APM

In the semiconductor industry, cleaning solutions like Sulfuric-Peroxide Mixtures (SPM) and Ammonia-Peroxide Mixtures (APM) are essential for removing organic residues, photoresists, and particle contaminants during wafer processing. The most common cleaning method is called RCA Clean.

These mixtures leverage hydrogen peroxide (H₂O₂) as an oxidative agent, providing powerful cleaning action. However, as the industry progresses toward advanced nodes and more stringent environmental regulations, efficient removal of residual hydrogen peroxide from wastewater streams has become increasingly challenging.

Traditional methods of handling peroxide-laden effluent, such as chemical reduction or enzyme treatment, can fall short when applied to these complex mixtures due to their unique chemistry and the operational requirements of semiconductor fabs. This article explores the specific challenges posed by SPM and APM wastewater and introduces potential innovations for more sustainable and efficient solutions.

Challenges in Removing Hydrogen Peroxide from SPM and APM

SPM Challenges

Composition and Use: Sulfuric-Peroxide Mixtures (SPM), also known as piranha solution, consist of sulfuric acid (H₂SO₄) and hydrogen peroxide (H₂O₂). It is highly effective for organic contaminant removal, but its aggressive nature creates challenges for wastewater treatment.
Stabilization of Hydrogen Peroxide: The high concentration of sulfuric acid stabilizes hydrogen peroxide, slowing its natural decomposition. This stabilization complicates traditional removal methods, such as:
- Chemical Reduction with Bisulfite: Often requires higher doses and longer reaction times in acidic environments.
- Catalase Enzymes: Less effective in acidic conditions, requiring more enzyme and increasing the risk of over-treatment and secondary pollution.

APM Challenges

Composition and Use: Ammonia-Peroxide Mixtures (APM), or Standard Clean 1 (SC1), combine ammonium hydroxide (NH₄OH) and hydrogen peroxide. This alkaline mixture is effective for removing organic and inorganic particles, but ammonia adds complications in wastewater treatment.
Alkaline Decomposition of Hydrogen Peroxide: The alkaline environment accelerates the natural decomposition of hydrogen peroxide, which theoretically makes treatment easier. However, the ammonia in APM:
- Reacts with Reductants: Ammonia can react unpredictably with reductants like sodium thiosulfate or bisulfite, creating byproducts such as ammonium sulfate or ammonium thiosulfate.
- Increases TDS and Treatment Complexity: These reactions increase Total Dissolved Solids (TDS) and complicate downstream treatment processes.

Handling and Safety Concerns of Reagents

Peroxide removal is often aggressive – causing temperature spikes.
Chemical reductants must be carefully stored and transported to avoid spills or accidents.
Catalase may lead to organic residue contamination and may require additional steps for disposal.
Overdosing catalase can lead to excess oxygen production, creating safety hazards.

Innovations in Hydrogen Peroxide Removal: The Case for ElectraMet’s Advanced Catalytic Systems

To address the specific challenges of peroxide removal in complex mixtures like SPM and APM, semiconductor fabs are exploring more advanced solutions. One promising approach is ElectraMet’s Gamma System, which uses a heterogeneous catalytic process to efficiently decompose hydrogen peroxide without introducing additional contaminants or requiring consumable reagents.

Advantages of Heterogeneous Catalytic Technology

ElectraMet Gamma System offers several key advantages:

Stable Performance Across pH Ranges
- Unlike catalase, which loses efficiency in extreme pH conditions, the Gamma System maintains high catalytic activity in both acidic and alkaline environments. This makes it well-suited for SPM and APM wastewater streams.
No Added Dissolved Ions
- The system’s heterogeneous catalyst remains solid and does not dissolve into the wastewater. This avoids the TDS increases typically associated with chemical reductants or enzyme byproducts.
Reduced Operational Complexity
- By eliminating the need for continuous dosing of chemicals or enzymes, the system simplifies wastewater treatment operations.
- It reduces the risks of overdosing or reagent mismanagement, making the process more efficient and cost-effective.

Conclusion

The semiconductor industry’s reliance on powerful cleaning solutions like SPM and APM highlights the critical need for efficient, reliable methods of hydrogen peroxide removal. Traditional chemical and enzyme-based treatments often fall short due to the unique challenges posed by these mixtures, including pH instability, TDS increases, and operational complexity.

ElectraMet’s Gamma System offers a compelling alternative, leveraging advanced heterogeneous catalysis to decompose hydrogen peroxide effectively without introducing additional contaminants. For semiconductor fabs looking to enhance process efficiency, reduce compliance risks, and adopt more sustainable practices, this technology represents a significant step forward in wastewater treatment innovation.