Patent ID: 7849815

Claim:
A plasma processing apparatus, comprising: a process chamber; a pumping line; a gas introduction line configured and positioned to introduce a gas into the process chamber; a substrate holder that is provided in the process chamber and comprises a top surface on which a substrate to be processed by plasma is held; an opposite electrode located higher than the substrate holder and facing the substrate holder, a plasma power source to apply voltage to the opposite electrode or the substrate holder to generate the plasma at a plasma generation region between the substrate holder and the opposite electrode; a plasma shield that surrounds the plasma generation region between the substrate holder and the opposite electrode to prevent the plasma from diffusing; and a surface of the plasma shield exposed to the plasma is made of electrically insulating material, the plasma shield interconnects an upper wall and a bottom wall of the process chamber to partition the process chamber, and an evacuation room to which the pumping line is connected is outside the plasma shield in the process chamber, the plasma shield has an evacuation opening, the evacuation opening provided in the plasma shield is located lower than the top surface of the substrate holder, and a diffusion prevention electrode, wherein the diffusion prevention electrode is located where electrons diffusing to or having diffused through the evacuation opening, to prevent the plasma from diffusing through the evacuation opening, and the diffusion prevention electrode is located lower than the top surface of the substrate holder on which the substrate is placed, and is located adjacent to or in the evacuation opening.