| 摘要 |
PROBLEM TO BE SOLVED: To provide a device for evaluating the content of silicon dioxide in a phosphoric acid bus and to provide a system for etching silicon nitride. SOLUTION: The device evaluates the content of silicon dioxide in the phosphoric acid bus etching silicon nitride. The device is provided with a sensor (5) measuring the concentration of NH3 in the phosphoric acid bus, a storage unit (8) storing data regulating the relation between the content of silicon dioxide and the concentration of NH3 , and a device (7) calculating the content of silicon dioxide based on the measured concentration of NH3 and stored data. |
