Dissolved Oxygen Monitor (HD-960L) for Semiconductor Wet Process

By: Kentaro INOUE

30 January 2018

Figure 1 Measurement principle of membrane polarograph method

Author Information: Application Development Dept., Research & Development Division, HORIBA Advanced Techno, Co., Ltd.

Abstruct: The HD-960L dissolved oxygen monitor was launched for etching chemicals (HF and TMAH aqueous solutions) in semiconductor wet processes. The polarographic sensor has a guard electrode to improve the response in the low-concentration range. Optimizing the concentration of the electrolyte solution volume and configuring a current-restricting resistor for the guard electrode made it possible to measure high-temperature solutions and extend the life of the electrolyte solution. The evaluation test results showed that the saturated dissolved oxygen signal is not affected even if the chemical concentration changes, that the response to the concentration changing in the low-concentration range was fast enough, and that the signal was linear with respect to the concentration. A magnetic stirrer was installed in the flow chamber, which made it possible to take stable measurements of the dissolved oxygen, even in cases of samples with low flow rates.

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