How to choose FFU for local clean air supply of semiconductor front-end equipment?
Characteristics of local clean air supply for front-end equipment
Semiconductor front-end equipment includes glue developing machines, cleaning machines, etching equipment, EFEM, etc. These equipment usually contain wafer handling mechanisms, process chambers and precision sensors. The microenvironment inside the equipment has high requirements for cleanliness, and some scenes can reach ISO Class 1 level.
As the front-end module of the equipment, EFEM has a compact internal space and needs to maintain high cleanliness during the wafer transfer process. In this scenario, the FFU cannot be selected based on the idea of a clean room ceiling. It needs to be matched based on the internal space of the equipment, wafer handling actions, and airflow organization.
To understand the basic structure and configuration of the FFU machine, you can start withStart with the Aili Industrial FFU fan filter unit to establish an overall understanding of the relationship between the complete machine, filter, fan and controller.
How does cleanliness level correspond to filter selection?
Semiconductor front-end equipment has higher cleanliness level requirements. The internal cleanliness of EFEM can reach ISO Class 1 level. Corresponding to this cleanliness level, the filter matching FFU usually requires ULPA level, such as U15 or higher efficiency.
The filter efficiency grade needs to comply with EN1822 or IEST standards. For ISO Class 3 to 5 semiconductor clean scenarios, H14 HEPA filters can meet the needs. However, when the internal microenvironment of the front-end equipment requires higher requirements, ULPA filters need to be selected. Regarding the matching of filters and machine interfaces, please refer toFFU equipped with ULPA ultra-high efficiency filter。
The factory leak test of the filter is only the basis, and the sealing integrity after installation also needs to be confirmed. Liquid tank seals or knife edge seals are usually used inside the equipment, and the leakage rate needs to be controlled at a low level. For the selection of liquid tank seal and gasket seal, please refer toTank seal high efficiency filter andLearn about the structural features of liquid tank sealed ULPA ultra-high efficiency filter .
How to check internal space and structure
The space inside front-end equipment is usually occupied by wafer handling robots, guide rails and sensors. When FFU is installed on the top or side of the equipment, the following clearance conditions need to be confirmed: whether the height of the FFU matches the space on top of the equipment; the distance between the FFU air inlet and the top structure of the equipment; the distance between the FFU air outlet surface and the highest point of the wafer handling mechanism; whether the FFU affects the robot's motion trajectory; and the operating space for FFU maintenance and filter replacement.
When the internal space of the equipment is tight, conventional FFU may not be installed. An ultra-thin FFU or a custom EFU may be more suitable. For applications with extremely limited space, you can refer to70mm ultra-thin EFU andCustomize the EFU equipment-side fan filter unit to understand the compact solution. Aili Industrial has a complete production chain and R&D capabilities in the equipment-end fan filter unit. It launched the 70mm ultra-thin EFU earlier. It has accumulated practical project experience in ultra-thin structural design and complete machine matching. It can provide ultra-thin FFU or customized EFU solutions based on the internal space and air supply requirements of the equipment.
How to control wind speed and uniformity
Wind speed control is strict inside semiconductor front-end equipment. During processes such as wafer coating, development, and cleaning, wind speeds that are too low may prevent pollutants from being removed in time, while wind speeds that are too high may blow the photoresist coating on the wafer surface or interfere with the spray water flow.
Different equipment types have different wind speed requirements. The wind speed of glue coating and developing equipment usually needs to be controlled at 0.3 to 1.0 meters per second, and the wind speed of cleaning equipment is set at 1.0 to 1.5 meters per second. The wind speed needs to be evenly distributed within the cavity cross-section to avoid local eddies or sudden changes in wind speed.
The uniformity of FFU air supply should be confirmed through multiple measuring points. The measuring points should cover the FFU air outlet surface, above the wafer transfer path and the key areas of the cavity. The wind speed uniformity deviation is usually required to be controlled within plus or minus 20%. 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 consider vibration and noise
The front-end equipment contains precision wafer handling robots. Vibration during FFU operation may affect robot positioning accuracy or wafer handling stability. If the FFU is mounted directly on the equipment structure, vibrations may be transmitted to the robot.
Vibration reduction measures can consider vibration-absorbing pads, flexible installation or choosing low-vibration fans. The internal noise of equipment usually needs to be controlled at a low level, and some applications require low noise and anti-vibration design. Aili Industrial has complete production capabilities in FFU fans and complete machine structures, and can adjust the installation method and fan configuration according to equipment vibration requirements. For equipment-side supporting solutions, please refer toEquipment side fan filter unit。
How is the air circulation path organized?
The airflow organization inside the equipment usually adopts the circulation method. The FFU supplies air downward from the top of the equipment. After the air flow passes through the wafer handling area, it returns from the bottom or side return air path and then circulates through the FFU. This circulation method can reduce the entry of external gas and maintain the cleanliness of the internal microenvironment.
The airflow path design needs to consider: whether the FFU air supply direction matches the wafer handling area; whether the return air path is blocked by mechanisms or cables; whether the airflow can cover key areas without generating turbulence; whether an inert gas environment is required.
How to cooperate with pressure difference
Positive pressure is usually maintained inside the equipment to prevent the ingress of unfiltered air from the outside. The balance of FFU supply air volume and return air volume determines the internal pressure. Different equipment has different pressure difference requirements. Glue coaters and developing machines have strong sealing properties, and the pressure difference is usually 5 to 50 Pa; glue removers and single-chip cleaning machines need to expedite the discharge of volatile gases, and the pressure difference is 50 to 200 Pa.
Issues that should be confirmed in advance during project communication
In the FFU selection stage of semiconductor front-end equipment, it is recommended to confirm the following with the FFU manufacturer and equipment provider: internal cleanliness level requirements of the equipment; internal headroom size and movement range of the wafer handling mechanism; target wind speed and uniformity requirements; vibration and noise requirements; air flow circulation path; pressure difference control requirements; filter efficiency level and sealing method; maintenance space and method; whether an inert gas environment is required.
If you are choosing FFU or EFU for your semiconductor front-end equipment, you can visitAili Industrial FFU fan filter unit to learn about the complete machine configuration, you can also refer to70mm ultra-thin EFU andCustomize the EFU equipment-side fan filter unit to learn about the equipment-side compact solution, or contact Aili Industrial for semiconductor equipment supporting support.
in conclusion
Selecting FFU for local clean air supply of semiconductor front-end equipment needs to take into account the process cleanliness level, internal space, air flow uniformity and vibration requirements. Equipment such as EFEM may require ISO Class 1 internal standards, and FFU selection must match ultra-thin structure, low vibration, and sealed interfaces. Filter efficiency, wind speed control, vibration and pressure differential all need to match the equipment process requirements.
Aili Industrial has complete production capabilities in FFU complete machines and equipment-side supporting. From box structure, fan matching, filter matching to control system, it is all completed within its own system. It can provide ultra-thin or customized air supply solutions according to the internal structure of the front-end equipment. If you need to learn more about semiconductor equipment FFU applications, you can visitAili Industrial FFU fan filter unit , you are also welcome to contact Aili Industrial for project support.
