Patent ID: 8083888

Claim:
A plasma processing apparatus comprising an upper electrode for supplying material gas into a vacuum reactor via a shower plate, a lower electrode opposed to the upper electrode on which is placed a sample being processed, and a detector for detecting light from a surface of the sample being processed via the shower plate, so as to process the sample by generating plasma between the shower plate and the lower electrode; wherein the detector comprises a light transmitting unit including a light guide into which the light is entered and a spectroscope for analyzing the light obtained through the light transmitting unit; the shower plate includes a plurality of gas through holes through which the material gas passes, and a light introducing through hole through which the light from the sample being processed passes; the upper electrode has a multilayered structure including a gas transmitting member having passages for the material gas communicated with the gas through holes of the shower plate, and a discharging member connected to a high frequency power supply; the light transmitting unit is disposed on the discharging member; the light guide is composed of a first light guide and a second light guide; the first light guide and the second light guide are cylindrical rods with steps and having multiple varying diameters; the first light guide is positioned between the second light guide and the spectroscope; and the second light guide has a cylindrical hollow space formed by hollowing an interior of the cylindrical rod of the second light guide, and having a projected structure formed of an electrically insulating member arranged at a center of the cylindrical hollow space thereof so that no light introducing through holes of the shower plate are arranged opposite to the projected structure and a minute gap is formed between the projected structure and the shower plate; and the second light guide has an end portion which faces the shower plate and which extends outwardly to form a flange portion.