Plasma treatment device and structure of reaction vessel for plasma treatment

A plasma treatment reaction vessel with an electrode plate having a main electrode plate, a diffuser plate and a shower plate, the plasma treatment reaction vessel being constituted so that process gas introduced in a space between the main electrode plate and the shower plate is exhausted toward a counter electrode through a plurality of first small holes formed in the shower plate,

• the plasma treatment reaction vessel comprising the diffuser plate having a plurality of second small holes, the diffuser plate being arranged between the main electrode plate and the shower plate,
• wherein the process gas is introduced between the main electrode plate and the diffuser plate, passes through the second plural small holes of the diffuser plate, reaches the shower plate and flows out from the first plural small holes of the shower plate toward the electrode plate, and
• wherein within the first small holes formed in the diffuser plate and the second small holes formed in the shower plate, the second small holes formed in the shower plate which exists more downstream along a flowing direction of the process gas are made in smaller diameters and an aperture ratio of each of the diffuser plate and the shower plate is made smaller in the diffuser plate which exists more upstream along the flowing direction of the process gas.