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Outgassing: The Invisible Threat to Semiconductor Purity

How evolast® FFKM Keeps It Under Control

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December 2025

Key Facts at a Glance

  • evolast® sets a new benchmark for semiconductor purity: engineered to deliver ultra-low outgassing performance that safeguards process integrity in critical plasma, thermal, and chemical manufacturing environments.
  • The most advanced low-outgassing elastomer: evolast® ensures contamination-free sealing and long-term reliability in semiconductor sealing solutions, supporting higher wafer yields and reduced maintenance downtime.
  • 100% European-engineered and cleanroom-manufactured: evolast® combines four decades of perfluoroelastomer expertise with validated Thermal Desorption Spectroscopy (TDS) results confirming total outgassing as low as 0,02 ppm, setting a new standard for ultra-clean sealing materials.

In semiconductor manufacturing, precision and purity define success. Within the ultra-clean environments of wafer fabrication, even microscopic contaminants can jeopardize entire production runs. Outgassing the release of gases or vapors from materials under heat or vacuum is a silent but serious threat to process integrity.

This is the reason why Angst+Pfister's evolast®, a high-performance, low-outgassing elastomer, is essential in the development of next-generation semiconductor sealing solutions. Engineered and manufactured entirely in Europe, evolast® offers unmatched process stability, purity, and reliability under the industry’s most demanding plasma, thermal, and chemical conditions.

The Challenge: Outgassing in Semiconductor Environments

In wafer fabrication, material selection can determine whether a process achieves nanometer-level precision or experiences catastrophic contamination.

When exposed to vacuum, plasma, or elevated temperatures, elastomers may release volatile organic compounds (VOCs), moisture, or other contaminants. These vapors can deposit onto wafer surfaces, disrupt plasma uniformity, and lead to defect generation or reduced yield.

Even trace levels of outgassing can alter process chemistry in chemical vapor deposition (CVD) or etching chambers, causing costly downtime and cleaning cycles.

Engineers have long sought low-outgassing elastomers that combine purity with durability. Standard FKM materials often fall short, particularly under prolonged plasma exposure. The need for perfluoroelastomer O-rings that perform flawlessly at high temperatures and under aggressive chemical environments has never been greater.

The Solution: evolast® FFKM for Ultra-Clean Performance 

To address the persistent challenge of outgassing in semiconductor manufacturing, Angst+Pfister developed the evolast® FFKM range of engineered sealing compounds that redefine material stability. 

Each evolast® formulation combines precise polymer architecture and controlled cleanroom processing, ensuring minimal molecular release during operation. 

All evolast® grades undergo ultrapure post-cleaning and vacuum packaging, guaranteeing zero surface contamination before installation. 

Material Science Behind the Purity 

Through decades of compound development, Angst+Pfister optimized evolast® FFKM formulation based on polymer backbones ideal to resist both thermal degradation and chemical attack. 

  • The PS1 series offers superior resistance for wet chemical processes, ensuring that seals neither degrade nor leach contaminants into acid- or solvent-based baths. 
  • The PS2 series withstands extreme thermal environments such as LPCVD and rapid thermal processing, with operating temperatures up to +340 °C. 
  • The PS3 series, designed for plasma and gas deposition, exhibits exceptionally low outgassing and minimal metal content, critical for cleanroom operations. 

In each case, evolast® maintains sealing integrity across thousands of process cycles. 

Material  

Application Type Maximum Temperature (°C) Key Observation about evolast® FFKM
PS152 Wet chemical processes +275 Excellent chemical stability; negligible VOC emission
PS221 Thermal processes +275 Stable under vacuum and thermal load
PS251 High-temperature thermal processes +340 Lowest outgassing across all samples
PS321 Plasma & gas deposition +275 Maintains purity under reactive plasma
PS341 Plasma etching +330 Optimal performance in oxygen / fluorine plasma
PS342 Plasma etching +325 Similar stability; high structural integrity
PS343 Plasma etching +325 Minimal mass loss; exceptional molecular stability
Proof of Performance

Angst+Pfister conducted extensive Thermal Desorption Spectroscopy (TDS) tests to quantify outgassing behavior under vacuum conditions representative of semiconductor environments.

  • Testing conditions: Temperature ramp from ambient to +200°C over 120 minutes, then sustained for 120 minutes in a heated vacuum (total 240 minutes). 
  • Findings: All evolast® compounds demonstrated exceptionally low total volatile release.
  • Outcome: Minimal molecular emission translates directly into reduced wafer contamination, stable plasma conditions, and extended maintenance intervals.

Summary of Key Results:

Property Test Method Result (Typical) Benefit
Outgassing (TDS total mass loss) Internal Method < 0,0002% Ensures semiconductor purity
Max Continuous Temperature ASTM D1418 Up to +340°C* Long-term sealing stability
Metals Content ICP-MS     < 10ppm* No metallic contamination
Cleanroom Classification ISO 14644 ISO 6–8 Certified purity across production

*For details on each grade, please refer to your Angst+Pfister representative.

These results confirm that evolast® performs reliably under thermal, plasma, and chemical stress, maintaining cleanliness and consistency in every stage of chip production.
 

Use Case: Plasma Etching Chamber Sealing


Challenge:
A wafer etching tool operating under high plasma intensity required sealing materials that would not degrade or release molecular contaminants during prolonged plasma exposure. Conventional elastomers exhibited surface erosion and measurable VOC release after several hundred hours.


Solution:
By switching to evolast® PS341, a perfluoroelastomer developed for oxygen and fluorine plasma environments, the equipment achieved stable performance with negligible outgassing. The seals maintained integrity at up to +330°C with minimal compression set and no visible surface degradation.
 

Laboratory Validation:
To substantiate this performance, Angst+Pfister conducted TDS tests on multiple evolast® grades (PS221, PS251, PS321, PS341, PS342, PS343) to quantify the amount of gas released during high-temperature exposure under vacuum.

Each sample was linearly ramped from ambient temperature to +200°C over 120 minutes, then held for another 120 minutes. 

Conclusion

In the semiconductor industry, purity defines performance. Every sealing component plays a decisive role in ensuring process reliability, equipment uptime, and wafer yield.

With evolast®, Angst+Pfister establishes a new benchmark for low-outgassing elastomers, combining advanced polymer engineering with full European production control. Across all evolast® grades, rigorous TDS testing demonstrates exceptionally low total mass loss, confirming outstanding chemical and thermal stability under vacuum and high-temperature conditions.

This performance reflects the precision of evolast® perfluoroelastomer composition. A highly fluorinated polymer backbone, optimized crosslink density, and ultra-clean compounding result in a stable network that resists degradation and oxidation. These characteristics prevent the emission of contaminants and maintain the material’s integrity, even in the harsh plasma and chemical environments typical of semiconductor manufacturing. 

The outcome is measurable: consistent sealing performance, reduced maintenance intervals, and enhanced process purity that directly contribute to higher wafer yields and lower total cost of ownership. evolast® combines the resilience required by engineers with the cleanliness demanded by modern semiconductor production.

By ensuring molecular stability, purity, and process confidence, evolast® reinforces its position as a critical enabler of semiconductor innovation – delivering confidence at the core of every chip.

Frequently Asked Questions

Outgassing is the release of gases or vapors from solid materials under heat or vacuum. In semiconductor tools, these emissions can cause molecular contamination, leading to reduced wafer yield and increased cleaning cycles.

evolast® uses high-fluorine polymers with exceptional molecular stability, combined with cleanroom compounding and ultrapure packaging. This results in minimal volatile release even under plasma and thermal stress.

The PS3 family (PS321, PS341, PS342, PS343) is optimized for plasma and gas deposition applications, featuring low outgassing, low metal content, and high thermal resistance.

Low outgassing materials prevent molecular film formation on wafers, ensuring higher process purity, consistent yields, and less maintenance downtime.

Yes. Compounds such as PS221 and PS251 operate reliably at up to, respectively,  +275°C and +340°C, maintaining elasticity and purity even in extreme thermal environments.
 

evolast® FFKM PS152 is the go-to solution for wet chemical processing, thanks to its superior resistance to degradation and leach contaminants in acid- or solvent-based baths.
 

All evolast® compounds are 100% produced in Europe, ensuring complete control over compounding, testing, and packaging under ISO 6–8 cleanroom standards, as well as complete traceability.
 

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