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.
Jim Cannon – Head of OEM & Markets, Mettler Toledo Thornton
After receiving a B.S. in Biology, he earned a graduate degree in Microbiology, followed by a graduate degree in Biophysics. He also has an MBA in Marketing and International Management. Mr. Cannon has over 35 years of experience managing, designing, and developing ultrapure water treatment and technology. This includes measuring differential conductivity and UV oxidation for the detection of TOC in UPW, as well as the design and commercialization of electrodeionization modules. He has also been involved in the development and commercialization of alternative online microbial detection technology.
Mr. Cannon is currently involved in the standards and regulatory organizations for the Semiconductor, Photovoltaic, and Pharmaceutical markets, including the Facilities and Liquid Chemicals Committee, Energy and Water Sustainability Task Force, and the UPW Task Force.
