Why Semiconductor Factories Require Ultrapure Water

Introduction

In semiconductor manufacturing, water is not simply a utility resource — it is a critical process material directly affecting product yield, reliability, and manufacturing performance.

Modern semiconductor factories consume millions of liters of water every day for wafer cleaning, chemical dilution, photolithography processes, equipment cooling, and surface preparation. However, ordinary purified water cannot meet the strict requirements of advanced semiconductor production.

To prevent microscopic contamination and maintain stable production quality, semiconductor manufacturers require Ultrapure Water (UPW) , also known as Electronic Grade Water.

Ultrapure water is produced through advanced purification technologies that remove dissolved ions, organic contaminants, particles, microorganisms, and other impurities down to extremely low levels.

For advanced semiconductor fabrication, UPW systems are designed to achieve a resistivity of 18.2 MΩ·cm at 25°C , representing one of the highest water purity standards in industrial applications.

Applications of Electronic Grade Ultrapure Water

Electronic grade ultrapure water is widely used in industries where even trace contamination can affect product performance.

1. Semiconductor Manufacturing

The semiconductor industry is the largest consumer of ultrapure water. UPW is used throughout wafer fabrication processes, including:

• Wafer cleaning after chemical processes
• Photoresist removal
• Chemical Mechanical Planarization (CMP)
• Particle removal
• Final wafer rinsing
• Dilution of process chemicals

During semiconductor manufacturing, wafer surfaces must remain free from ionic contamination and particles. Even a few nanometers of contamination can cause defects in integrated circuits.

2. Display and Flat Panel Manufacturing

LCD, OLED, and other display industries require large quantities of ultrapure water for:

• Glass substrate cleaning
• Photo-etching processes
• Chemical rinsing
• Surface preparation

High-quality UPW helps prevent defects such as display spots, electrical failures, and reduced product lifetime.

3. Photovoltaic (Solar Cell) Production

Solar cell manufacturers use electronic grade water for:

• Silicon wafer cleaning
• Texturing processes
• Chemical rinsing
• Final surface treatment

Low contamination levels improve solar cell conversion efficiency and production yield.

4. Precision Electronics and Microelectronics

Other applications include:

• Semiconductor packaging
• MEMS manufacturing
• Precision sensors
• Optical components
• Laboratory electronics research

These industries require stable and reliable water quality to maintain production consistency.

Main Quality Parameters of Ultrapure Water

Semiconductor-grade ultrapure water must meet extremely strict quality requirements. The main parameters include:

Among these parameters, resistivity and TOC are two of the most important indicators.

High resistivity indicates extremely low ionic contamination, while low TOC ensures minimal organic contamination that could affect semiconductor surfaces.

What Happens If Semiconductor Factories Do Not Use Ultrapure Water?

Using insufficient-quality water can directly impact semiconductor manufacturing performance.

1. Increased Wafer Defects

Impurities such as sodium, calcium, iron, copper, and silica can attach to wafer surfaces during cleaning processes.

These contaminants may cause:

• Electrical leakage
• Circuit failure
• Reduced chip performance
• Lower manufacturing yield

2. Reduced Product Reliability

Semiconductor devices require long-term stability. Trace contamination can create:

• Metal migration
• Insulation failure
• Signal instability
• Shortened product lifespan

3. Higher Production Costs

Poor water quality can result in:

• Increased wafer rejection rates
• More frequent equipment cleaning
• Additional chemical consumption
• Production downtime

A properly designed UPW system helps manufacturers reduce operational risks and improve production efficiency.

Typical Ultrapure Water Treatment Process for Semiconductor Industry

A semiconductor ultrapure water system usually consists of multiple purification stages because no single technology can remove all contaminants.

A typical UPW configuration includes:

How It Works

An ultrapure water system works through a combination of physical separation, chemical removal, and advanced purification technologies.

The complete purification process can be summarized as:

After purification, ultrapure water is stored in a highly controlled distribution system to maintain continuous water quality before reaching semiconductor manufacturing equipment.

UPW Storage and High Purity Distribution Loop

The ultrapure water distribution system is a critical part of semiconductor water treatment. Even after purification, UPW can be contaminated if the storage and piping system are not properly designed.

Typical UPW Distribution Design Includes:

• High purity stainless steel or PVDF piping system
• Continuous circulation loop operation
• Online resistivity monitoring
• TOC monitoring system
• Particle monitoring equipment
• Temperature control system

Continuous circulation prevents stagnant water areas and minimizes microbial growth and contamination risks. The system is designed to provide stable ultrapure water quality at every point of use.

Engineering Control Points for Semiconductor UPW Systems

Advanced semiconductor factories require strict engineering control to maintain ultrapure water quality.

Frequently Asked Questions (FAQ)

1. What is the difference between purified water and ultrapure water?

Purified water removes most contaminants, but ultrapure water requires much stricter control. Semiconductor UPW systems typically achieve 18.2 MΩ·cm resistivity with extremely low ionic and organic contamination levels.

2. Why do semiconductor factories need 18.2 MΩ·cm water?

18.2 MΩ·cm represents the theoretical maximum resistivity of water at 25°C. It indicates almost complete removal of dissolved ions, which is essential for semiconductor process stability.

3. Can RO water be directly used for semiconductor production?

No. RO water still contains residual ions and organic substances. Additional purification technologies such as EDI, UV oxidation, and polishing systems are required.

4. What materials are used in UPW distribution systems?

Common materials include PVDF, PFA, high purity polypropylene, and electropolished SS316L stainless steel depending on purity requirements.

5. How is UPW quality monitored?

Modern UPW systems use online monitoring instruments including resistivity meters, TOC analyzers, particle counters, flow meters, and temperature sensors.

Ultrapure Water Is the Foundation of Semiconductor Manufacturing

As semiconductor technology continues to advance toward smaller chip sizes and higher integration levels, contamination control becomes increasingly important.

A reliable semiconductor ultrapure water system is not only a water treatment solution but also a critical production support system that directly influences product yield, equipment reliability, and manufacturing efficiency.

CHONGYANG Water provides customized electronic-grade ultrapure water solutions including:

• RO + EDI ultrapure water systems
• UPW polishing systems
• TOC reduction systems
• High purity storage and distribution loops
• Complete engineering design and validation support