Ultra-High Purity Gas Filtration

Electronic specialty gases are fundamental raw materials in semiconductor manufacturing and are widely used in thin film deposition, etching, doping, passivation, and cleaning processes.

From wafer fabrication to final device packaging, electronic gases are involved in almost every process step and are often referred to as the “blood” of semiconductor manufacturing. Any deviation in gas purity or cleanliness can lead to product defects, cross-contamination, or even full batch rejection, making gas quality control essential.

Gas Usage in Semiconductor Fabrication

A typical semiconductor manufacturing process consists of hundreds of process steps and involves a wide range of process gases, generally classified into:

• Bulk gases
• Specialty gases

Bulk Gases

Bulk gases are supplied in large volumes and stored in external tanks at semiconductor facilities.

Common Bulk Gases

• Inert gases: Argon (Ar), Helium (He)
• Reducing gases: Hydrogen (H₂)
• Oxidizing gases: Oxygen (O₂)

Bulk gas purity typically reaches 3N (99.9%) or higher, depending on process sensitivity.

Specialty Gases

Specialty gases are supplied in smaller quantities but are critical to semiconductor processes.

Characteristics of Specialty Gases

• Highly reactive and chemically sensitive
• Potentially toxic or hazardous
• Extremely sensitive to contamination

Typical examples include:

• Corrosive gases: HCl, Cl₂
• Pyrophoric gases: Silane (SiH₄)
• Toxic gases: Arsine (AsH₃), Phosphine (PH₃)
• Highly reactive gases: Tungsten hexafluoride (WF₆)

Purity Requirements for Semiconductor Gases

• Bulk gases: approximately 3N purity
• Specialty gases: typically 5N–6N purity (up to 99.9999%)

In addition to overall purity, semiconductor processes require:

• Metal ion control at 10⁻⁹ to 10⁻¹² levels
• Strict particle control to prevent wafer contamination

Importance of Gas Filtration in Ultra-High Purity Systems

Particles can be generated within gas distribution systems due to mechanical vibration, flow turbulence, or material shedding from piping and components.

To prevent contamination of process tools, filtration systems are installed upstream of point-of-use locations, acting as a critical final barrier.

Ultra-High Purity Gas Filtration Solutions

Ultra-High Purity Gas Filter Cartridges

• Filtration accuracy down to nanometer level (≈3 nm)
• Impurity control at 10⁻⁹ levels
• High mechanical strength for pressure stability
• Suitable for high-temperature and high-pressure gas systems

Pleated Filter Cartridges

• High-density pleated structure for increased filtration area
• Hydrophobic media for high flow and low pressure drop
• Extended service life
• Filtration accuracy down to 0.003 μm

PTFE Microporous Membrane Filter Cartridges

• Hydrophobic PTFE membrane construction
• Excellent chemical resistance
• Low extractables for high-purity applications
• Suitable for gas filtration and tank venting

Benefits of Proper Ultra-High Purity Gas Filtration

• Stable and repeatable process performance
• Reduction of particle-induced defects
• Improved device yield and reliability
• Protection of critical semiconductor equipment
• Compliance with stringent purity standards