Air Filtration Systems for Semiconductor Cleanrooms

As one of the main application industries for air filters, the semiconductor sector has seen strong growth in recent years. A clean production environment is essential for semiconductor manufacturing. Regardless of how to improve and maintain the cleanliness of the production environment, it remains a common pursuit for both air filter manufacturers and semiconductor producers.

INTRODUCTION

Section 1: The Importance of Air Filtration for Semiconductor Manufacturing 

Section 2: The Contamination in Semiconductor Manufacturing

Section 3: The Air Filtration System Configuration

Section 4: The Airflow Design for Whole Cleanroom

Section5: Conclusion

 The Importance of Air Filtration for Semiconductor Manufacturing  

Semiconductor manufacturing is an incredibly complex process with strict requirements for air quality. During production, even the smallest contaminant can lead to serious defects in the product, which in turn affects the overall yield of the workshop and increases production costs.

As the semiconductor fabrication process continues to shrink, the requirements for air cleanliness in cleanrooms are also constantly increasing.

 The Contamination in Semiconductor Manufacturing 

For semiconductor manufacturing, the main contaminations include:

# Particulate Contamination

# Chemical Contamination

# Biological Contaminant

These contaminants can either adhere to the wafer surface, causing functional defects in the products, or interfere with the manufacturing process, thereby affecting product quality.

The sources of these contaminants mainly come from the following aspects:

>> Personnel Contamination: Staff entering and exiting carry a significant amount of particulate contaminants. This is why cleanrooms typically have air showers at the entrance, and personnel are required to wear cleanroom garments.

>> Equipment and Materials:The equipment and raw materials can generate a large number of particles and even harmful substances  when friction. It's essential for staff to maintain equipment properly and develop standardized work habits.

>> Work Processes: Certain manufacturing processes, such as the use of chemicals, etching, or sputtering, can produce particles and chemical vapors. Implementing sealing measures and maintaining proper ventilation are crucial to prevent the spread of these contaminants.

>> External Contamination: During cleanroom operations, outside air can occasionally enter unexpectedly. Therefore, real-time monitoring of air quality in the cleanroom is particularly important.

 The Air Filtration System Configuration 

1️⃣ Pre-filter

The pre-filter is the first line of defense in ensuring air quality in cleanrooms. It is placed at the inlet of the ventilation duct to capture larger particulate contaminants, thereby reducing the burden on HEPA/ULPA filters, extending their lifespan, and lowering energy consumption.

2️⃣ HEPA/ULPA Filter

HEPA/ULPA filters can efficiently capture particles in the range of 0.1-0.3 µm, playing a crucial role in maintaining workshop cleanliness.

3️⃣ Activated Carbon Filter

Activated carbon filters are used to remove chemical contaminants from the air, including volatile organic compounds (VOCs). They are essential for preventing chemical pollutants from interfering with semiconductor manufacturing processes.

4️⃣ FFU / High Efficiency Air Outlet

FFUs (Fan Filter Units) and high-efficiency air supply outlets are installed on the ceiling and can be selected based on the needs of the clean space, or they can be used in combination.

5️⃣ Laminar Air Flow Clean Bench

Laminar air flow clean benches are air purification devices that provide a localized high-cleanliness environment. They use FFUs to draw in air and further filter it, creating a vertical unidirectional airflow within the cleanroom.

 The Airflow Design for Whole Cleanroom 

Airflow is fundamental to semiconductor cleanroom production. A well-designed and maintained airflow system helps control contamination, maintain stable temperature and humidity, and reduce electrostatic discharge. We believe that an effective airflow system primarily involves the following elements:

>> Cleanroom Layout

The layout of a semiconductor cleanroom should follow a systematic plan. For example:

Setting up air showers at entrances and exits to handle particulate contamination brought in by personnel and materials.

Clearly defining requirements and planning the cleanroom layout in advance, using FFUs and clean benches to control localized laminar flow.

Properly managing supply and return air systems to balance product quality with energy consumption.

>> Air Filters

To ensure a continuous supply of clean, filtered air, HEPA and ULPA filters need regular maintenance and replacement.

>> Real-time Monitoring

Semiconductor cleanrooms must consistently maintain a high level of cleanliness, which requires real-time monitoring of indoor air quality (in complex scenarios, modular monitoring may be needed). Additionally, the system should be capable of promptly adjusting airflow as needed.

The integrity of the air within a semiconductor cleanroom is directly synonymous with the integrity of the devices produced there. Air filtration systems, therefore, form the critical first line of defense in ensuring high yield and device performance. As manufacturing complexities escalate, so too will the sophistication of filtration technologies. The future of semiconductor manufacturing depends on continuing to see the air we filter not as an obstacle, but as the ultimate controllable environment for precision engineering.