Indispensable Tools in Semiconductor Manufacturing – Residual Gas Analyzers (RGAs) and Leak Detectors

May 23, 2025

Semiconductor Metrology Series – 3

Residual Gas Analyzers (RGAs) and leak detectors are indispensable tools in semiconductor manufacturing, where vacuum integrity and contamination control are essential for high-yield, high-performance device fabrication.

Key Applications

RGAs monitor the composition and concentration of residual gases within vacuum chambers. These analyzers are critical for detecting trace contaminants, monitoring outgassing, and maintaining the purity of the environment in processes such as chemical vapor deposition (CVD), physical vapor deposition (PVD), and plasma etching.
Leak Detectors identify and quantify leaks in vacuum systems. Even minor leaks can introduce air, moisture, or other contaminants, undermining product quality and reducing process yields.

Use in Semiconductor Metrology

These tools are critical in processes such as chemical vapor deposition (CVD), physical vapor deposition (PVD), and plasma etching.

Process Monitoring: RGAs provide continuous analysis of gas composition within the vacuum chamber. This real-time monitoring helps detect contamination events, outgassing from materials, or unexpected chemical reactions, all of which can impact the integrity and repeatability of the process.
Leak Detection: Leak detectors are used during the assembly, installation, and ongoing maintenance of vacuum systems. Helium is commonly used as a tracer gas due to its small molecular size, inert properties, and absence in ambient environments, enabling accurate detection of even minute leaks.
Troubleshooting: Both tools are vital for diagnosing vacuum system anomalies. Whether identifying a leak, confirming seal integrity, or tracing contamination sources, RGAs and leak detectors help maintain operational reliability and process control.

Mass Spectrometry as the Core Technology

Both RGAs and helium leak detectors rely on mass spectrometry:

RGAs operate by ionizing gas molecules present in the vacuum. These ions are separated based on their mass-to-charge ratio (m/z) and detected to quantify the concentration of each gas species.
Helium Leak Detectors pressurize the vacuum system with helium, then monitor for helium ions using a mass spectrometer tuned to the specific m/z of helium. The detection of helium indicates a leak point or area of concern.

Tools in Semiconductor Manufacturing and the Role of Magnetic Sector Technology

A critical component in many mass spectrometry systems is the magnetic sector, which enables ion separation by mass. As ions pass through the sector, they are deflected by a magnetic field. The degree of deflection depends on their mass-to-charge ratio and the strength of the magnetic field.

Magnetic sectors must be carefully engineered to ensure precise ion trajectory and accurate detection. The uniformity and stability of the magnetic field directly influence resolution, sensitivity, and repeatability.

Design Considerations for Magnetic Sectors

Magnetic Field Uniformity
A highly uniform field ensures ions of identical mass-to-charge ratios follow consistent paths to the detector. This is essential for accurate signal processing and is achieved through precise magnetic circuit design and manufacturing.
Field Strength Control
Adjustable and stable electromagnets are necessary to fine-tune the magnetic field. Reliable power supplies enable operators to target specific ions for detection with precision.
Thermal Management
Heat generated during operation can destabilize the magnetic field. Integrated cooling systems are critical for maintaining thermal balance and ensuring consistent performance.
Material Selection
Soft magnetic materials with high permeability and low hysteresis loss are ideal for magnetic sectors. These materials help minimize energy loss and enable rapid field response.
Size and Geometry
The physical design must provide a strong, uniform magnetic field within a compact footprint. It must also align with space, weight, and integration constraints in modern metrology equipment.

Magnetic sector mass spectrometers are critical tools in semiconductor manufacturing, and foundational to the function of RGAs and helium leak detectors, enabling precise gas analysis and leak detection in semiconductor manufacturing environments. Optimized magnetic design is essential for delivering the accuracy, resolution, and reliability required for today’s advanced process control systems.

Let’s engineer precision—contact Dexter today to support your next-generation metrology solution.