What are airborne molecular contaminants, and how significant is their impact on semiconductors?
This article introduces the classification, causes, and control methods for airborne molecular contaminants, helping the semiconductor industry recognize their importance in creating flawless products.
What are Airborne Molecular Contaminants?
According to SEMI F21-1102 and ISO 14644-8:2022 standards, airborne molecular contaminants (AMCs) in cleanrooms are classified into four types, each with specific concentration guidelines.
MA (Acid Vapors)
These volatile acidic substances, such as hydrochloric acid (HCl), nitric acid (HNO₃), and hydrofluoric acid (HF), are present in cleanroom air as gases or vapors.
Their concentrations should be kept within 1-10 ppb to prevent damage to photoresist patterns and corrosion on surfaces like metal layers or wafers.
MB (Alkaline Vapors)
Volatile alkaline substances, such as ammonia (NH₃), fall into this category.
Their concentration should be below 5 ppb to avoid adverse reactions with acidic materials or damage to sensitive semiconductor processing materials.
MC (Condensable Compounds)
These include volatile organic compounds (VOCs) or polymer substances that can condense into liquids or solids on cleanroom surfaces at low temperatures.
Concentrations should remain below 10 ppb or 1 µg/m³ to avoid surface contamination and defects in photolithography or etching processes.
👉read more: How to remove VOC from air? 11 Methods to Remove VOCs
MD (Dopant Compounds)
These gaseous contaminants, such as phosphine (PH₃) and arsine (AsH₃), can alter the electrical properties of semiconductor materials.
Their concentration should be controlled to 1 ppb or lower to ensure process stability and device performance.
Why Should Airborne Molecular Contamination Be Taken Seriously?
Neglecting AMCs can affect semiconductor yield and complicate tracing contamination sources. This article further explains why controlling AMCs is crucial.
Impact on Semiconductor Yield
Initially, the industry managed only larger particles, but as process technology advanced, stricter standards were established. Now, even small organic contaminants are closely monitored to maintain quality.
Tracing Contamination Sources
Each processing stage uses different chemicals, resulting in various AMCs. To address contamination effectively, it’s essential to monitor pollutants at every stage and investigate potential sources thoroughly.
Sources of Airborne Molecular Contaminants
Where do AMCs originate, and do they only occur within the facility? Below are five common sources to help semiconductor manufacturers identify potential risks.
Nearby Factories
Organic sulfur compounds from neighboring factories can infiltrate semiconductor plants, affecting process environments and equipment.
Chemicals Used in Processes
Chemicals may accumulate in filters, reducing their effectiveness and releasing new contaminants into the cleanroom.
👉read more: What is Filter Media?
Chemical Off-gassing
Cleanroom materials, machinery, and equipment can emit VOCs over time, impacting the air quality in the cleanroom environment.
Petrochemical Processing Emissions
Petrochemical plants emit VOCs that can react with other gases in the atmosphere, creating secondary pollutants like ozone, which can affect distant semiconductor facilities.
Atmospheric Sulfur and Nitrogen Oxides
Sulfur oxides and nitrogen oxides from combustion processes can enter semiconductor facilities, compromising sensitive manufacturing environments and potentially leading to equipment failure.
How to Control Airborne Molecular Contaminants?
How can semiconductor manufacturers effectively control AMC levels? Based on SEMI and ISO standards, here are nine methods to enhance processing quality.
Cleanroom Design and Filtration Systems
HEPA and ULPA filters are essential for removing particulates and AMCs. These systems can effectively prevent AMC infiltration by removing particles as small as 0.3 microns.
👉read more: How to choose the right chemical filter?
Airflow Control
Maintaining a positive pressure environment and a well-ordered airflow within cleanrooms is fundamental, as recommended by ISO 14644-1.
Material Selection
Using low-emission materials for construction, coatings, and equipment can minimize the release of VOCs and avoid acidic or alkaline gas production.
Environmental Management
Regular cleaning of work surfaces, floors, walls, and ceilings reduces the accumulation of airborne or condensable contaminants.
Air Quality Monitoring
Monitoring AMC levels in real time is essential, utilizing advanced instruments such as optical detectors, mass spectrometers, or gas chromatographs.
Personnel and Equipment Management
Staff entering cleanrooms should wear appropriate protective clothing and undergo air showers to minimize AMCs. Equipment that may release chemical vapors should be isolated to prevent AMC spread.
Process Optimization
Processes involving chemicals should operate within sealed systems to minimize VOCs’ impact on the cleanroom environment.
Inlet Air Management
Air intake systems should feature multi-layered filters, including pre-filters, HEPA or ULPA filters, and chemical adsorbent materials.
Exhaust Management
Specialized exhaust treatment systems can remove pollutants from process emissions, preventing them from re-entering the cleanroom.
Solving Airborne Molecular Contaminant Issues – Getek
To effectively control the presence of airborne molecular contaminants (AMCs), it’s essential to ensure an optimal filtration design within the cleanroom.
If you’re unsure which supplier to consult, you may consider reaching out to Getek. We offer a “Total Air Filtration Solutions ” that can meet your specific needs.
Our process starts with an on-site survey, including environmental assessment, AMC sampling, and filter inspection. Following this, they conduct a root cause analysis to identify pollution sources and provide control recommendations.
Next, they develop a control plan, suggest appropriate chemical filters, and proceed with project execution, which involves manufacturing customized filters and performing on-site installation.
Finally, the effectiveness is verified through environmental sampling and laboratory analysis.
Do Airborne Molecular Contaminants Cause Major Impact? | FAQ
Achieving High Success Rates for Semiconductor Products | Getek
If you are looking for a reliable AMC filter supplier to effectively manage airborne molecular contaminants (AMCs), consider Getek.
We offer comprehensive filtration design solutions that have earned the approval of numerous clients both domestically and internationally. We invite you to become part of our network and benefit from our trusted solutions!
