What is the difference between advanced packaging and semiconductor front-end ULPA selection?

Advanced Packaging and Semiconductor FrontlineULPA filter selection should be based on specific process, product exposure, particle and AMC sensitivity and equipment conditions. Industry names cannot directly correspond to unique filtering levels. A common misunderstanding is that 'the front-end requirements are high and the packaging requirements are low.' Therefore, it is enough to use ULPA for the front-end and HEPA for the encapsulation. This judgment is roughly true in the traditional packaging era, but it is no longer accurate in advanced packaging (Flip Chip, Fan-Out, wafer-level packaging, 3D stacking). The bump size of advanced packaging has been pushed to tens of microns or even smaller. A particle with a size of one-fifth of the bump diameter may cause solder voids or bridge short circuits. The bump production area usually requires ISO level 5 or higher cleanliness. At the same time, in addition to being 'clean', packaging testing also needs to control vibration, static electricity, local temperature rise and chemical pollutants. The sensitive dimensions of environmental parameters are wider than the previous process. The selection should go back to the specific process and protection objects, rather than one-size-fits-all labeling of 'front line' or 'packaging'. Aili Industrial's product line covers the equipment sideEFU equipment end fan filter unit andHEPA/ULPA filter , front-end photolithography area and advanced packaging bump area can match filtering solutions according to their respective working conditions.-2

1. Identify requirements from the process: look at the photolithography path at the front end, and look at the bumps and bonding interface for packaging.

Different front-end processes and mounting, bonding, coating or testing in packaging may have different pollution sources and protection scopes, so the actual goals need to be clarified.

The core particle risks in the front-end are concentrated in the photolithography, etching and film deposition areas. The photolithographic area is extremely sensitive to particles, as particles falling on the mask or wafer can directly destroy the pattern. The risk points of advanced packaging are more scattered: photolithography alignment and inspection of bump production, chip mounting, and bonding interface. Each link has different exposed surfaces and sensitive particle sizes. Wafer-level packaging (WLP) completes rewiring and bump production directly on the wafer. The exposure time is long and the cleanliness requirements are close to those of the front process. The first step in selection is to list the exposure locations, sensitive particle sizes and allowable concentrations for the specific process, rather than selecting a grade first. Aili Industry isHEPA/ULPA filters, confirm the gear according to the particle size and protection range.When selecting Non-standard ULPA filter projects can confirm the installation conditions according to the equipment structure. The relationship between levels and particle limits can be found inISO cleanliness level comparison。-2

2. Compare equipment and system conditions: the front equipment is sealed and the packaging equipment is more open.

Check the air supply area, fan margin, mechanism shielding, static control, materials and maintenance space to avoid just copying the filter element grade of another line.

Front-end equipment (such as photolithography machines and etching machines) is usually highly sealed. The wafers are transferred and processed inside the equipment, and environmental control is concentrated in the microenvironment inside the equipment. Advanced packaging equipment has a higher degree of openness: In processes such as flip-chip mounting, wire bonding, and inspection, chips or substrates may be transferred between different equipment and exposed to the workshop environment for a longer period of time. This means that the background cleanliness and local protection of the packaging workshop need to be designed together, rather than relying solely on the internal ULPA of the equipment. Aili Industry isWhen supporting the fan filter unit at the EFU equipment end, confirm the local air supply plan according to the equipment structure and degree of opening.The ultra-thin EFU configures the air outlet direction in the compact space of the packaging equipment.The FFU fan filter unit can be used in background areas or above workstations. For comparison of equipment and system conditions, please refer toHEPA FAQs and Selection Guide。

3. AMC and material outgassing: packaging is highly sensitive to chemical pollution

The front-end photolithography area focuses on the impact of AMC on optical components and photoresist, while advanced packaging focuses on the impact of chemical contaminants on plating uniformity, bonding interfaces and material compatibility.

In the chemical plating process of wafer-level packaging, the organic additives in the copper plating solution are sensitive to alkaline molecules in the environment and may affect the uniformity of plating. Front-end and packaging have different requirements for the specific type of AMC, but the fact that 'ULPA only solves particles' is the same. Particle filtration and gas control should be evaluated separately during selection. Aili Industry isIn the PTFE HEPA/ULPA filter package, materials can be evaluated according to low outgassing requirements.Chemical filters are configured for target gaseous pollutants,FFU chemical filters can be used with FFU. For the coordination of materials and AMC, please refer toULPA ultra-high efficiency filter FAQ and selection guide。-2

4. Determined by prototype and operation verification: the same level does not mean the same performance

Confirm filtration and installation integrity, and evaluate airflow and related environmental indicators under corresponding operating conditions. Key materials and AMC requirements should be listed separately.

Even if the front channel and packaging are of the same level, the actual protection effect may be different if the equipment structure, air flow path and operating status are different. Verification should cover their respective actual actions: the front-end looks at the internal transmission and exposure process of the lithography machine, and the packaging looks at the placement, bonding and detection actions. Aili Industry isthe EFU equipment end fan filter unit .The air supply conditions can be confirmed according to the equipment action sequence when matching The FFU computer group control system records the operating air volume and equipment status, and compares them according to actual working conditions during verification. For verification methods, please refer toEFU FAQ and technical support。

5. Related questions and answers

Can advanced packaging be uniformly selected at a lower level?
Unified judgment cannot be made based on industry labels and should be determined jointly by process objectives, structure and test results. The bumping area may require the same cleanliness as some front-end processes.

Use U16 for the front channel and U15 for packaging. Is this correct?
It cannot be divided so simply. The grade depends on the determined particle size and particle sensitivity of the specific process, and the needs of different processes within the same industry may also be different.

Will vibration and static electricity in the packaging workshop affect ULPA selection?
It will affect the overall solution, but will not change the particle filtering function of ULPA. Vibration and static electricity need to be evaluated separately, and ULPA selection still needs to be determined based on particle targets.

6. Related articles

ULPA ultra-high efficiency filter FAQ and selection guide

PTFE HEPA/ULPA high efficiency filter

chemical filter

Ultra-thin EFU

7. Key points for selection and acceptance inspection

8. Product matching and technical support from Aili Industrial

Aili Industrial's product line covers the equipment sideEFU equipment end fan filter unit andHEPA/ULPA filter , front-end photolithography area and advanced packaging bump area can match filtering solutions according to their respective working conditions.HEPA/ULPA filter selection is based on the determined particle size and protection range.Non-standard ULPA filter projects confirm the installation conditions according to the equipment structure;The EFU equipment end fan filter unit is equipped with a local air supply plan based on the equipment structure and opening degree.The ultra-thin EFU configures the air outlet direction in the compact space of the packaging equipment.The FFU fan filter unit can be used in background areas or above workstations.PTFE HEPA/ULPA filters evaluate materials according to low outgassing requirements,chemical filters andFFU chemical filters are configured for target gaseous pollutants;The fan filter unit at the EFU equipment end is equipped with a fan filter unit to confirm the air supply conditions according to the equipment action sequence.The FFU computer group control system records the operating air volume and equipment status for easy verification. Provide process objectives, installation drawings, operating conditions and acceptance requirements, and can further communicate ULPA standard specifications, non-standard interfaces, samples and batch matching. The specific parameters and test range are based on the confirmed model and technical documents.