| 摘要 |
PROBLEM TO BE SOLVED: To detect a particle number with high sensitivity in real time with a simple mechanism by generating plasma in the upper part of a wafer in a chamber and detecting the existence of particles based on the size of an electron density or change. SOLUTION: In a plasma generation area 11, high frequencies are applied to a first and a second electrode 13 and 14 while generating a plasma, and a wafer on the second electrode 14 is processed. In this plasma processing device 10, through a quartz window 20, a microwave from a microwave oscillator 25 is transmitted to the plasma generation area. A phase differenceΔϕbetween before and after the transmission of the microwave is detected, and a plasma electron density Ne is calculated by an operation circuit 28 based on an expression: Ne=fΔϕ/0.842D (f is a microwave frequency, and D is a plasma width). If this electron density is smaller than a reference value, the existence of particles in the chamber is determined and required operations such as cleaning of the plasma generation area are performed.
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