Ultrapure Water Treatment

Process Overview

In semiconductor manufacturing, the extreme precision of production equipment and the complexity of fabrication processes place stringent demands on all supporting utilities. Among these, the ultrapure water (UPW) system is one of the most critical infrastructures and is often referred to as the “lifeline” of semiconductor manufacturing.

Ultrapure water is used throughout wafer fabrication, including cleaning, rinsing, and surface treatment processes. Any fluctuation in water quality may directly impact device performance and yield.

Typical Ultrapure Water Process Configuration

Pretreatment Section

The pretreatment stage is designed to remove suspended solids, colloids, and organic matter from raw water, protecting downstream membranes and ion removal systems.

• Multi-media filters
• Activated carbon filters
• Coarse filters
• Ultrafiltration (UF) systems

Reverse Osmosis (RO) Section

The RO section is responsible for removing the majority of dissolved salts, organic compounds, and microorganisms.

• Reverse osmosis membranes significantly reduce total dissolved solids (TDS)
• RO concentrate and backwash streams can be recovered and reused to improve water efficiency

Deionization Section

The deionization stage further removes ionic contaminants to achieve the required resistivity.

Depending on raw water quality and target product water specifications, semiconductor facilities may use:

• Electrodeionization (EDI) modules
• Continuous electrodeionization (CEDI) modules
• Ion exchange systems (cation and anion beds)

Polishing Mixed Bed Section

The polishing mixed bed serves as the final purification step, ensuring ultrapure water meets the most stringent semiconductor-grade requirements before distribution to point-of-use systems.

Advantages of Advanced Ultrapure Water Treatment Systems

• Elimination of large volumes of acid and alkali used for resin regeneration
• Improved environmental performance
• Shorter regeneration cycles compared with conventional ion exchange systems
• Recovery and reuse of UF backwash water, RO concentrate, and CEDI concentrate streams
• Reduced water consumption and lower operating costs

Role of Filtration in Ultrapure Water Systems

• Protection of membranes and ion removal units
• Control of particulate contamination
• Maintenance of stable system performance
• Support for long-term reliability and water quality consistency

Typical Applications in Ultrapure Water Treatment

• Pretreatment filtration for raw water conditioning
• Membrane protection in RO systems
• Fine filtration in deionization and polishing stages
• Point-of-use (POU) ultrapure water filtration