Plasma processing apparatus

A plasma processing apparatus that turns a gas supplied to a processing chamber into plasma using a high frequency power and performs a plasma process on a processing object, the plasma apparatus comprising:

• an upper electrode arranged at the processing chamber and including a plurality of gas supplying zones, the upper electrode being configured to supply a processing gas including a main gas to the processing chamber via the gas supplying zones;
• a branch pipe including a plurality of branch parts, the branch pipe being configured to divide the processing gas according to a predetermined flow rate ratio and supply the divided processing gas to the plurality of gas supplying zones;
• an addition pipe that is connected to at least one branch part of the plurality of branch parts, the addition pipe being configured to add an adjustment gas to the processing gas;
• and
• a plurality of gas pipes that connect the plurality of branch parts of the branch pipe to the plurality of gas supplying zones;
• and
• a control unit that calculates a reaction time required for a gas mixture of the adjustment gas and the processing gas entering an inlet of a gas pipe of the plurality of gas pipes that has a distance of at least 150 mm to reach a uniform gas concentration at an outlet of the gas pipe, calculates a gas concentration ratio of the adjustment gas to the main gas based on the calculated reaction time, and controls a gas concentration of the adjustment gas and the main gas to be within the calculated gas concentration ratio,
• wherein at least one gas pipe of the plurality of gas pipes that is connected to the branch part to which the addition pipe is connected includes a gas flow path that is arranged to have a bending portion for preventing a gas concentration variation according to a molecular weight ratio of the adjustment gas to the main gas, and
• wherein the control unit controls the gas concentration of the adjustment gas and the main gas to be within the calculated gas concentration ratio calculated upon using the gas pipe having a distance of at least 150 mm based on the following formulas (A) and (B):
• SL/Q=V/Q=t (A)
• Ln(CAin/CAout)=−kt (B)
• wherein the symbols in the formulas represent the following:
• S:
• gas pipe cross-sectional area [cm2];
• L:
• gas pipe length [mm];
• Q:
• gas flow rate at gas pipe inlet/outlet;
• t:
• reaction time for the gas mixture of the main gas and the adjustment gas to reach a uniform gas concentration;
• CAin:
• gas concentration [M] at gas pipe inlet;
• CAout:
• gas concentration [M] at gas pipe outlet;
• and
• k:
• diffusion coefficient.