In semiconductor nodes below 10nm, particles are not the only enemy. Airborne Molecular Contamination (AMC)—invisible gases comprising acids, bases, and organics—has become a primary cause of yield loss.
For process engineers, the challenge is twofold: preventing external pollutants from entering the cleanroom and ensuring the filtration equipment itself does not become a source of contamination.
At Deshengxin, we address AMC with a rigorous Dual-Stage Filtration Strategy, combining advanced chemical adsorption with zero-outgassing materials. This article details how we neutralize MA, MB, MC, and MD contaminants to protect your critical process zones.
The Invisible Threat: Understanding AMC
AMC is categorized by the SEMI F21-1102 standard into four key families. Our filtration systems are designed to target each specifically:
MA (Molecular Acids): e.g., Hydrofluoric acid, SOx, NOx. Can cause corrosion on metal interconnects.
MB (Molecular Bases): e.g., Ammonia, Amines. The #1 enemy of Lithography, causing T-topping defects in photoresists.
MC (Molecular Condensables): e.g., Organics, DOP. Can deposit on lenses and wafer surfaces, causing haze.
MD (Molecular Dopants): e.g., Boron, Phosphorus. Can unintentionally alter the electrical properties of the silicon.
Solution Stage 1: Integrated Chemical Filtration
Standard HEPA filters capture particles, but gases pass right through them. To stop AMC, we integrate Chemical Fan Filter Units (Chemical FFUs) equipped with specialized media:
Ion Exchange Media: Specifically formulated to neutralize acids (MA) and bases (MB) through chemisorption. This is critical for Photolithography and Etching bays.
Activated Carbon (Impregnated): Optimized with specific impregnants to target volatile organics (VOCs) and condensables (MC).
The Result: Our chemical filters achieve a removal efficiency of 99.9% for target gases, ensuring a pristine molecular environment for the wafer.
Solution Stage 2: The Shift to PTFE (Low-Outgassing)
This is the most critical upgrade for modern fabs. Traditional FFUs use Glass Fiber (Borosilicate) filters. While effective for particles, glass fiber naturally contains Boron. Under airflow, trace amounts of Boron can "outgas" (release) from the filter media, becoming a contaminant (MD) itself.
The Deshengxin Solution: PTFE Media
We utilize e-PTFE (Expanded Polytetrafluoroethylene) membrane filters for all critical semiconductor applications.
Zero Boron Risk: PTFE is a synthetic material that is chemically inert and boron-free.
Superior Resistance: PTFE is immune to acid/alkali corrosion, making it durable in harsh chemical environments (like Wet Bench areas).
Lower Pressure Drop: PTFE provides better airflow efficiency, reducing energy consumption for the fab.
Technical Comparison: Glass Fiber vs. PTFE
| Primary Material | Borosilicate Microfiber | Expanded PTFE Membrane |
| Boron Outgassing | High Risk (Source of MD) | Zero (Boron-Free) |
| Acid/Alkali Resistance | Poor (Degrades over time) | Excellent (Chemically Inert) |
| Mechanical Strength | Fragile (Risk of damage) | High (Robust membrane) |
| Recommended Zone | General Cleanroom / Corridors | Wafer Fab / Lithography / Process Tools |
Conclusion
Controlling AMC is no longer optional—it is a requirement for yield assurance. By combining Chemical Filtration to remove incoming gases and PTFE Media to eliminate filter-generated contamination, FFUFAN provides a comprehensive shield for your wafers.
Is AMC affecting your yield?
Contact our AMC Control Specialists
