Patent ID: 7749914

Claim:
A plasma etching method comprising an arranging step of arranging a pair of electrodes oppositely in a chamber and making one of the electrodes support a substrate to be processed in such a manner that the substrate is between the electrodes, the substrate having an organic-material film, and an etching step of applying a first high-frequency electric power and a second high-frequency electric power to the electrode made to support the substrate to form a high-frequency electric field between the pair of electrodes, of supplying a process gas into the chamber to form a plasma of the process gas by means of the electric field, and of plasma-etching the organic-material film of the substrate by means of the plasma partway in order to form a groove having a flat bottom with a width not less than 0.5 μm, wherein, in the etching step, the frequency of the first high-frequency electric power is 50 MHz to 150 MHz, the frequency of the second high-frequency electric power is 500 kHz to 27 MHz, the first and second frequencies are applied concurrently in order to achieve high etching rates, a pressure in the chamber is 53 to 133 Pa, a self-bias electric voltage of the electrode supporting the substrate to be processed is not higher than 600 V, and a residence time of the process gas in the chamber is 70 to 180 msec, to achieve high plasma density, low self-bias voltage, uniform plasma and inhibition of micro-trenching.