Plasma process method and plasma processing device

A plasma process method, used for etching a wafer and comprising:

• moving the wafer into a reaction chamber, introducing a reaction gas, using a source radio frequency to excite a plasma, and applying a bias radio frequency to perform a first processing stage and a second processing stage, wherein the wafer is etched downward to a first depth in the first processing stage, and is etched downward to a second depth based on the first depth in the second processing stage, and the second depth is greater than the first depth;
• the first processing stage comprises a first etching step and a first modification step;
• the second processing stage comprises a second etching step and a second modification step;
• the sum of power of the source radio frequency and power of the bias radio frequency applied to the reaction chamber in the first etching step is first etching net power, the sum of power of the source radio frequency and power of the bias radio frequency applied to the reaction chamber in the first modification step is first modification net power, and the first etching net power is less than the first modification net power;
• and
• the sum of power of the source radio frequency and power of the bias radio frequency applied to the reaction chamber in the second etching step is second etching net power, the sum of power of the source radio frequency and power of the bias radio frequency applied to the reaction chamber in the second modification step is second modification net power, and the second etching net power is less than the second modification net power.