Embedding Process Intelligence into Long-Line Leak Detection

To maintain the highest standards of safety and purity, fabs employ a combination of inspection, testing, and continuous monitoring of piping systems. Long gas lines must be tested to leak rates as low as 1x10⁻⁷ mbar l/s after installation or maintenance. The conventional method for verifying the integrity of gas delivery piping is helium leak testing and involves:

1. Evacuating the inside of the pipe
2. Spraying helium on the external surface
3. Detecting helium that enters the system through leaks due to the pressure differential

Complementing helium leak testing, real-time gas analyzers are used during processing to continuously monitor gas purity and pressure, providing early warning of deviations that may indicate integrity loss.

While highly sensitive, this approach is inherently challenging due to the complexity of the piping system itself, and these challenges increase further as pipe length and diameter grow. In long or complex piping systems, helium can take a significant amount of time to travel from the leak location to the detector. This results in:

• Longer test times
• Delayed signal response
• Reduced efficiency during fab construction or expansion

These challenges demand not just better tools—but deep application expertise.

With decades of experience supporting semiconductor fabs worldwide, INFICON enhances standard leak detection by combining proven technology with deep application experience.

To address the limitations of conventional helium spray testing on long gas lines, experts integrate helium leak detection with a controlled carrier gas flow. Even very low carrier‑gas flow rates, on the order of only a few standard cubic centimetres per minute (sccm), can significantly improve measurement effectiveness. Lab tests prove that flows on the order of ~100 sccm are often sufficient to enhance signal propagation and detection, without requiring large gas flows or altering fundamental test conditions. In this method:

• A carrier gas (typically air or nitrogen) is introduced at one end of the pipe
• The leak detector is connected at the opposite end
• Helium entering through a leak is immediately mixed with the carrier gas
• The gas mixture is rapidly transported to the detector

This approach dramatically reduces response time, enabling leak detection within seconds, even in long or complex piping systems.

“Using nitrogen as the carrier gas provides a critical additional advantage,” explains Anja Sutorius, Application Engineer at INFICON. “It significantly reduces the amount of residual helium trapped inside long gas lines, and with lower background helium levels, the system achieves a cleaner signal, greater detection sensitivity, faster stabilization between sequential tests, and far less risk of tracer‑gas carryover. This improvement is especially valuable in cleanroom environments, where even small accumulations of helium can interfere with other testing routines or sensitive process measurements.” 

Engineers can choose between carrier gases when leak testing, allowing an inert environment to be maintained when required.

INFICON’s advanced leak testing methodology and application expertise deliver measurable advantages:

• Significantly faster leak detection for long pipes and extended systems
• Improved testing reliability in hard-to-access or complex installations
• Enhanced sensitivity through reduced background helium
• Lower environmental impact by minimizing tracer gas usage

INFICON is more than an equipment supplier. We are a long-term partner to the semiconductor industry, delivering innovative leak detection solutions , smart sensors, and intelligent manufacturing systems that support faster fab ramp-up, reliable operation, and optimized resource management.

By combining world-class instruments with deep application expertise, we help semiconductor manufacturers safeguard purity, ensure safety, and sustain peak performance, today and into the future.