Why do fab FFU pay special attention to wind speed uniformity?
Fabs have different airflow requirements than ordinary clean rooms
The clean rooms of wafer fabs have high requirements for particle control, and the cleanliness of some areas can reach ISO Class 1 to Class 3 levels. In this environment, FFU not only needs to provide sufficient air supply volume, but also needs to ensure uniform air supply.
Wind speed uniformity refers to the uniformity of wind speed distribution in the FFU air outlet surface or protection area. If the air supply is uneven, the wind speed will be higher in some locations and lower in some locations. Locations with low wind speeds may form areas of weak airflow where particles can easily accumulate. Locations with high wind speeds may cause airflow disturbances, affecting the wafer surface or process equipment.
Therefore, wafer fabs pay special attention to the uniformity of FFU wind speed, rather than just looking at the average wind speed on the wind surface. Aili Industrial has complete production capabilities in FFU complete machines and semiconductor project supporting, and can provide air supply solutions according to the air flow requirements of the wafer factory. For the basic structure of the FFU machine, please refer toAili Industrial FFU fan filter unit。
What impact does uneven wind speed have on particle control?
Fab clean rooms usually use unidirectional flow or mixed flow airflow organization. Clean air is sent out from the FFU, passes through the wafer area, and is discharged from the return air path. If the wind speed is uniform, the airflow can steadily carry the particles toward the return air path. If the wind speed is uneven, particle retention may occur in local weak airflow areas.
Particle retention can affect wafer surface cleanliness. For processes such as photolithography, etching, and film deposition, particle contamination may affect pattern accuracy or film quality. Therefore, wind speed uniformity directly affects the particle control effect.
What impact does uneven wind speed have on airflow organization?
Uneven wind speeds may change the direction of airflow. When local wind speeds are high, the airflow may deflect or form vortices. When the local wind speed is low, the surrounding air flow may supplement it and form a cross flow. These changes can destroy the unidirectional or laminar flow regime of the design.
In a fab, airflow organization is often coordinated with process equipment, ceiling arrangements, and return air paths. If the FFU wind speed is uneven, the originally designed airflow path may change, affecting the cleanliness of the local area.
What impact does uneven wind speed have on wafer protection?
Wafers may be exposed to airflow during the manufacturing process. If the wind speed is too high, it may cause particles on the wafer surface to move or the photoresist coating to be affected. If the wind speed is too low, particles may be deposited on the wafer surface.
For precision processes, air speed uniformity is more important than simply increasing the air speed. Uniform airflow can stably protect the wafer surface without causing disturbance.
What factors affect FFU wind speed uniformity
Factors that affect the uniformity of FFU wind speed include: filter folding structure and installation status; fan and box air duct design; air outlet surface protection net or diversion structure; splicing method of multiple FFUs; ceiling structure and lamp position; return air path and room air flow.
If the filter is not installed in place or is unevenly sealed, the air velocity on the outlet surface may be unevenly distributed. If the fan and cabinet are not well matched, the local wind speed may be too high or too low. If there are gaps in the splicing of multiple FFUs, weak areas may appear at the boundaries.
How to set measuring points
To verify the uniformity of FFU wind speed, measuring points need to be set. The measuring points should not only be arranged in the center of the FFU, but also cover the edges of the air outlet surface, the splicing boundaries of multiple FFUs, and key areas of the wafer.
The height of the measuring point should be consistent with the position of the wafer, rather than just measuring the wind surface. The number and distribution of measuring points should reflect the actual wind speed distribution. Regarding the expression of wind speed uniformity, you can refer toHow does FFU wind speed uniformity express the solution point and deviation calculation method.
How to cooperate with control methods
The FFU of the wafer factory is usually connected to the group control system and can be adjusted by zone. If the wind speed in some areas is low, the FFU speed in that area can be appropriately increased. If the wind speed is high in some areas, it can be reduced appropriately. Zonal control can reduce local wind speed deviations.
If the project usesFFU/EFU group control touch screen controller orFFU computer group control system can confirm whether the system supports zone setting and wind speed feedback. Aili Industrial has complete self-research capabilities in FFU control systems and can provide control solutions according to the zoning control needs of the fab.
Issues that should be confirmed in advance during project communication
During the FFU selection and debugging stage of the fab, it is recommended to confirm the following with the FFU manufacturer and designer: target cleanliness level and air flow form; wind speed uniformity requirements; measuring point arrangement and measurement method; FFU quantity and arrangement; ceiling structure and lamp position; return air path; control method; debugging and verification method.
If you are planning an FFU solution for your fab, you can visitAili Industrial FFU fan filter unit to learn about the complete machine configuration, you can also refer toFFU is equipped with ULPA ultra-high efficiency filter to learn about the filter configuration, or contact Aili Industrial for air supply support for semiconductor projects.
in conclusion
Wafer fabs pay special attention to FFU wind speed uniformity because wind speed deviations can affect particle control, airflow organization, and wafer protection. Uneven wind speed may cause local particle accumulation or air flow disturbance, affecting process yield. Measuring point setting, zoning control and debugging verification are the main links to confirm the uniformity of wind speed.
Aili Industrial has complete production capabilities in FFU complete machines and semiconductor project supporting, and can provide air supply solutions according to the air flow requirements of the wafer factory. If you need to know more about the fab FFU configuration, you can visitAili Industrial FFU fan filter unit , you are also welcome to contact Aili Industrial for project support.
