OES device, plasma processing apparatus including the same and method of fabricating semiconductor device

An OES (Optical Emission Spectroscopy) device comprising:

• a rotation module coupled to a viewport of a chamber, the rotation module configured to transmit plasma light generated in the chamber, the rotation module configured to be rotatable around a rotation axis;
• a light-receiving part coupled to the rotation module and configured to receive the plasma light;
• a spectroscope configured to separate the plasma light and analyze intensities of corresponding wavelengths;
• and
• an optical cable which connects the light-receiving part and the spectroscope,
• wherein the rotation module includes a first surface coupled to the viewport and a second surface coupled to the light-receiving part,
• wherein the first surface is configured to block a part of the plasma light, and includes a first opening through which an inside of the rotation module is configured to be exposed to a part of the plasma light, and
• wherein the second surface includes a second opening configured to be in optical communication with the first opening.