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 plasma processing apparatus, comprising:
a chamber;
an introducing part configured to introduce a process gas into the chamber;
a substrate electrode disposed in the chamber and configured to mount a substrate directly or indirectly thereon, the substrate electrode including a plurality of first and a plurality of second electrode elements alternately arranged;
a high-frequency power source configured to output a high-frequency voltage of 40 MHz or more 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 first and the second electrode elements.
2 . The plasma processing apparatus of claim 1 ,
wherein the switching mechanism applies a voltage in which the low-frequency voltage and the high-frequency voltage are superposed, alternately to the first and the second electrode elements.
3 . The plasma processing apparatus of claim 1 , further comprising a counter electrode facing the substrate electrode,
wherein the high-frequency voltage is applied to the counter electrode.
4 . The plasma processing apparatus of claim 1 ,
wherein the substrate electrode further includes a plurality of third electrode elements disposed between the first and the second electrode elements; and
wherein the plasma processing apparatus further comprises a second high-frequency power source configured to apply a second high-frequency voltage for stabilizing the plasma to the third electrode elements.
5 . The plasma processing apparatus of claim 1 ,
wherein the substrate electrode includes a plurality of dielectric members disposed at least between the first and the second electrode elements.
6 . The plasma processing apparatus of claim 5 ,
wherein dielectric constants of the dielectric members are 7 or more.
7 . The plasma processing apparatus of claim 5 ,
wherein the dielectric members have plate shapes; and
wherein the first and the second electrode elements include a plurality of conductive layers disposed on the dielectric members.
8 . The plasma processing apparatus of claim 1 ,
wherein widths of the first and the second electrode elements are not less than 1 mm nor more than 5 mm; and
wherein intervals between the first and the second electrode elements are not less than 1 mm nor more than 5 mm.
9 . The plasma processing apparatus of claim 1 ,
wherein the switching mechanism includes:
a first switch configured to switch a connection state between the first electrode elements and the low-frequency power source;
a second switch configured to switch a connection state between the second electrode elements and the low-frequency power source; and
a switch controller configured to control the first and the second switch.
10 . The plasma processing apparatus of claim 9 ,
wherein the switch controller controls the first and the second switch so as to connect ones of the first and the second electrode elements to a ground when the others of the first and the second electrode elements are connected to the low-frequency power source.
11 . The plasma processing apparatus of claim 9 ,
wherein the switch controller configured to control the first and the second switch so as to repeat a first to a fourth state in sequence,
the first state being defined by the first electrode elements connected to the low-frequency power source, and the second electrode elements not connected to the low-frequency power source;
the second state being defined by both of the first and the second electrode elements connected to the low-frequency power source;
the third state being defined by the first electrode elements not connected to the low-frequency power source, and the second electrode elements connected to the low-frequency power source; and
the fourth state being defined by both of the first and the second electrode elements connected to the low-frequency power source.
12 . The plasma processing apparatus of claim 1 ,
wherein the substrate electrode includes a plurality of electrode elements arranged in lines in two directions; and
wherein the plasma processing apparatus further comprises a selecting mechanism configured to select the first and the second electrode elements from the plurality of electrode elements.
13 . The plasma processing apparatus of claim 12 ,
wherein the selecting mechanism repeatedly selects the first and the second electrode elements so as to rotate directions of arranging the first and the second electrode elements.
14 . The plasma processing apparatus of claim 1 ,
wherein the switching mechanism switches a first and a second state in accordance with a progress of processing, the first state being defined by the low-frequency voltage applied alternately to the first and the second electrode elements, the second state being defined by the low-frequency voltage applied to both of the first and the second electrode elements.
15 . The plasma processing apparatus of claim 1 ,
wherein the switching mechanism changes a period of alternately application of the low-frequency voltage to the first and the second electrode elements in accordance with a progress of processing.
16 . The plasma processing apparatus of claim 1 , further comprising a rotating mechanism configured to relatively rotate between the substrate and the substrate electrode.
17 . The plasma processing apparatus of claim 16 ,
wherein a period T of switching the first and the second electrode elements is not 0.5n times a period Tr of the rotation, where n: integer.
18 . A method of plasma processing 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,
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;
ionizing the process gas in the chamber to generate plasma; and
applying an voltage of 20 MHz or less for introducing ions from the plasma, alternately to the first and the second electrode elements.