Plasma processing apparatus and plasma processing method
A plasma processing apparatus of an embodiment includes a chamber, an introducing part, a substrate electrode, a high-frequency power source, a low-frequency power source, and a switching mechanism. The introducing part introduces a process gas into the chamber. The substrate electrode is disposed in the chamber, a substrate is directly or indirectly mounted on the substrate electrode, and the substrate electrode includes a first and a second electrode elements alternately arranged. The high-frequency power source outputs a high-frequency voltage of 40 MHz or more for ionizing the process gas to generate plasma. The low-frequency power source outputs a low-frequency voltage of 20 MHz or less for introducing ions from the plasma. The switching mechanism applies the low-frequency voltage alternately to the first and the second electrode elements.
1. A method of plasma processing method with a plasma processing apparatus,
the apparatus comprising:
a substrate electrode disposed in a chamber, the substrate electrode including a plurality of first and a plurality of second electrode elements alternately arranged;
a counter electrode facing on the substrate electrode;
a high-frequency power source configured to output a high-frequency voltage of 40 MHz or more to apply the high-frequency voltage to the substrate electrode for ionizing the process gas to generate plasma;
a low-frequency power source configured to output a low-frequency voltage of 20 MHz or less for introducing ions from the plasma; and
a switching mechanism configured to apply the low-frequency voltage alternately to the plurality of first electrode elements and the plurality of second electrode elements,
the plasma processing method comprising:
mounting a substrate directly or indirectly on the substrate electrode;
decreasing a pressure in the chamber and introducing a process gas;
generating plasma from the process gas; and
attracting ion included in the plasma to the substrate by switching application of the low-frequency voltage to the plurality of first electrode elements and the plurality of second electrode elements, the attracted ion being obliquely incident on the substrate,
wherein
the switching application of the low-frequency voltage is performed so as to repeat a first to a fourth state in sequence while applying the high-frequency voltage to the counter electrode,
the first state being defined by the plurality of first electrode elements connected to a low-frequency power source applying the low-frequency voltage, and the plurality of second electrode elements not connected to the low-frequency power source,
the second state being defined by both of the plurality of first electrode elements and the plurality of second electrode elements connected to the low-frequency power source,
the third state being defined by the plurality of first electrode elements not connected to the low-frequency power source, and the plurality of second electrode elements connected to the low-frequency power source, and
the fourth state being defined by both of the plurality of first electrode elements and the plurality of second electrode elements connected to the low-frequency power source.
2. The method according to claim 1 , wherein
widths of the first and the second electrode elements are not less than 1 mm nor more than 5 mm; and
intervals between the plurality of first electrode elements and the plurality of second electrode elements are not less than 1 mm nor more than 5 mm.
3. The method according to claim 1 , wherein
the substrate electrode is relatively rotated to the substrate, and
a period T of switching the plurality of first electrode elements and the plurality of second electrode elements is not 0.5n times a period Tr of the rotation, where n:
integer.
4. The method according to claim 1 , wherein
the switching mechanism is configured to apply the low-frequency voltage to the plurality of first electrode elements simultaneously in the first state.
5. The method according to claim 1 , wherein
the counter electrode is a shower head.
6. The method according to claim 1 , wherein
the plasma processing apparatus does not require an accelerator.
7. The method according to claim 1 , wherein
an electric field is generated in a direction parallel to a plane of the substrate electrode by switching the application of the low-frequency voltage to the plurality of first electrode elements and the plurality of second electrode elements.
8. The method according to claim 1 , wherein
the plurality of first electrode elements and the plurality of second electrode elements are arranged in a first direction and each extending in a plane direction.