Ultrapure Water: The "Liquid Gold" of Modern High-Tech Industries—A Panoramic View of Application Fields

Ultrapure Water (UPW), characterized by a resistivity of up to 18.2 MΩ·cm, Total Organic Carbon (TOC) below 5 ppb, and near-zero levels of microorganisms and particles, has long transcended the ordinary concept of "pure water" to become a strategic foundational material supporting modern precision manufacturing and cutting-edge scientific research. The breadth and depth of its application fields directly reflect the technological sophistication and developmental level of contemporary technology industries.

I. Semiconductor and Integrated Circuit Industry: The "Lifeblood" of Chip Manufacturing

This is the most demanding and highest-volume application field for UPW. In nanometer-scale chip fabrication, water purity directly determines product yield.

Core Application Stages:

• Wafer Cleaning: Each silicon wafer undergoes hundreds of cleaning steps during manufacturing. UPW is used to remove photoresist residues, etch by-products, and metal ion contamination. A single dust particle or bacterium can render an entire wafer useless.

• Chemical Dilution: High-purity chemicals like photoresists and etchants must be precisely diluted with UPW. Any impurity will alter their chemical properties.

• Equipment Cleaning and Cooling: Internal tubing and reaction chambers of fabrication tools require UPW for cleaning, and some precision equipment uses it for cooling to prevent contamination and scaling.

Special Requirements: Beyond standard parameters, there are ppt-level limits for specific elements (e.g., boron, sodium, potassium), and strict control of dissolved oxygen and gases is required.

II. Biopharmaceuticals and Life Sciences: The "Pure Matrix" for Life Research

In drug production and biological research, water purity is directly linked to product safety and experimental reproducibility.

Key Application Scenarios:

• Injectable and Infusion Solutions Production: Pharmacopeial "Water for Injection (WFI)" must meet UPW standards. Any endotoxin or chemical contaminant can cause severe clinical reactions.

• Biologics and Vaccine Manufacturing: Preparation of cell culture media, buffers, and cleaning of bioreactors all require UPW to avoid interference from foreign substances affecting cell growth or product purity.

• Gene Sequencing and Molecular Diagnostics: In experiments like PCR, gene microarrays, and mass spectrometry, water contamination can lead to false positive/negative results, compromising diagnostic accuracy.

• Cell Culture and Stem Cell Research: Trace heavy metals or organics in water can interfere with cell metabolism or even induce abnormal differentiation.

Special Requirements: Focus on Bacterial Endotoxin levels (must be <0.25 EU/mL), absence of DNase/RNase activity, and control of specific organic contaminants.

III. Power and Energy Industry: The "Pure Medium" for Energy Conversion

Thermal and Nuclear Power Generation:

• High-Pressure Boiler Feedwater: UPW minimizes scaling and corrosion in thermal systems, ensuring generation efficiency and equipment safety. Impurities accelerate equipment degradation under high temperature and pressure, potentially causing tube failures.

• Nuclear Power Plant Primary Coolant: Prevents deposition of radioactive material in piping and reduces generation of neutron-activated products.

New Energy Sector:

• Solar Panel Production: Silicon wafer cleaning and texturing processes require UPW to remove surface contaminants.

• Fuel Cells: Proton Exchange Membrane Fuel Cells require UPW to maintain proton conduction efficiency.

IV. Precision Instrumental Analysis and Laboratory Research: The "Flawless Matrix" for Scientific Discovery

• Chromatography and Mass Spectrometry: Used as mobile phase or sample solvent; impurities create background noise, masking target signals.

• Spectroscopic Analysis: In UV, fluorescence, etc., impurities can absorb or emit interfering signals.

• Material Surface Analysis: Sample preparation and cleaning for Scanning Electron Microscopes (SEM), Atomic Force Microscopes (AFM), etc.

• Reference Material Preparation: Used for preparing calibration curves and standard solutions; water quality sets the upper limit for measurement accuracy.

V. Other High-Tech Manufacturing Fields

Flat Panel Display and LED Manufacturing:

• Glass substrate cleaning, photolithography, and etchant preparation all require UPW. Particles can cause bright or dark pixel defects on displays.

Aerospace and Precision Optics:

• Cleaning optical lenses before coating, production of gyroscopes and navigation systems require particle-free, ion-free UPW.

High-Performance Material Synthesis:

• During the synthesis of nanomaterials, graphene, superconductors, etc., water quality influences crystal growth and intrinsic material properties.

Technological Challenges and Development Trends

Evolving Water Quality Standards:

As chip fabrication processes advance below the 2nm node, stricter control of nanobubbles, colloidal silica, and trace organics in UPW is required. The semiconductor industry is beginning to address the concept of "Ultra-Ultrapure Water."

Integrated Innovation in Production Technology:

Modern UPW systems feature a "multi-barrier + online monitoring" approach:

1. Pretreatment: Multi-media filtration + Ultrafiltration to remove colloids and particles.

2. Primary Purification: Two-pass RO + Electrodeionization (EDI) to remove >99% of ions and organics.

3. Polishing Purification: Vacuum Degasification + UV Oxidation + Fine Mixed-Bed Polishers to remove trace contaminants.

4. Distribution Loop: Uses double tube sheet welded piping, maintained with continuous circulation and turbulent flow to prevent microbial growth.

Intelligent Monitoring and Predictive Maintenance:

• Integration of online TOC analyzers, particle counters, and rapid microbial detection systems.

• Big data-based water quality prediction and fault diagnosis systems.

• Modular design for maintenance and upgrades without system shutdown.

Sustainability Considerations:

• System recovery rates increasing from traditional ~70% to over 85%.

• Application of energy recovery devices (e.g., pressure exchangers).

• Safe treatment and reuse of chemical cleaning agents.

Conclusion

The application boundaries of Ultrapure Water are continuously expanding alongside technological progress. From the nanometer-scale cleaning that determines the fate of chips, to the sterile production that ensures drug safety; from the precise analysis underpinning fundamental scientific discoveries, to the critical processes enabling the new energy transition—Ultrapure Water is deeply embedded in every key link of the modern high-tech industrial chain. Each order-of-magnitude improvement in its purity often signifies a major breakthrough in the technological capabilities of related industries. In the future, with the rise of frontier fields like quantum computing, bioelectronics, and synthetic biology, the demand for UPW will become more refined and differentiated, driving purification technologies towards continued evolution in intelligence, low-carbon footprint, and ultimate performance. In this sense, Ultrapure Water is not merely an industrial consumable but also an invisible benchmark measuring a nation's capabilities in high-end manufacturing and scientific research.