In the semiconductor industry, maintaining ultrapure water (UPW) with extremely low dissolved oxygen (DO) levels is essential to ensure the quality and reliability of microelectronic devices.
Even trace amounts of DO can degrade water quality and damage sensitive wafer fabrication components, leading to defects and yield loss. To prevent these issues, DO concentrations are typically required to be below 5 parts per billion (ppb) at the point of use during wafer processing.
Controlling DO helps manage oxidation and corrosion on wafer surfaces. Precise DO control ensures uniform polishing, reduces defects, and enhances the effectiveness of the planarization process.
The growth of thin crystalline layers on wafers is highly sensitive to DO levels. Maintaining ultra-low DO supports consistent layer growth and optimal electrical properties, directly impacting device performance.
Traditional electrochemical sensors face a number of challenges:
In contrast, advanced optical dissolved oxygen sensors provide significant advantages:
Beyond accuracy, optical DO sensors help protect UPW system components from corrosion and degradation by enabling timely detection and control of oxygen ingress.
Their integration with multi-parameter transmitters allows simultaneous monitoring of conductivity/resistivity, temperature, total organic carbon (TOC), and pH. This integration simplifies system management by streamlining operator training and reducing spare parts inventory.
In this case study, METTLER TOLEDO’s optical DO sensor and M800 transmitter dramatically improved dissolved oxygen measurement for one of Asia’s largest semiconductor foundries, enhancing accuracy and response time, and reducing maintenance.
Maintaining strict DO control preserves UPW integrity and minimizes risks associated with wafer etching and CMP, both highly sensitive to oxygen contamination. Effective DO monitoring supports process stability, reduces yield loss, and helps manufacturers meet increasingly stringent purity and performance standards.
Overall, advanced optical DO sensors play a vital role in microelectronics manufacturing by providing precise detection and control of ultra-trace oxygen levels. This capability safeguards critical processes such as CMP and epitaxy, enhancing device quality, increasing production yields, and optimizing operational efficiency, making these sensors indispensable in the competitive semiconductor industry.
No single measurement captures the full picture of ultrapure water quality. Resistivity works alongside several other on-line parameters to ensure process integrity.
Select a parameter to explore:
With 35 years of experience, Jim Cannon is a recognized authority in the world of ultrapure water. His career is defined by a commitment to precision—whether he’s navigating the complexities of UV oxidation or advising the Facilities and Liquid Chemicals Committee on new regulations. Today, Jim continues to be a trusted advisor for the semiconductor and pharmaceutical sectors, ensuring that the water powering our most advanced technologies meets the highest possible standards of excellence.
