Plasma etching unit
The present invention is a plasma etching method including: 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 arranged between the electrodes, the substrate having an organic-material film and an inorganic-material film; and an etching step of applying a high-frequency electric power to at least one of the electrodes to form a high-frequency electric field between the pair of the electrodes, supplying a process gas into the chamber to form a plasma of the process gas by means of the electric field, and selectively plasma-etching the organic-material film of the substrate with respect to the inorganic-material film by means of the plasma; wherein a frequency of the high-frequency electric power applied to the at least one of the electrodes is 50 to 150 MHz in the etching step.
1. A plasma etching unit for selectively plasma-etching an organic-material film of a substrate having the organic-material film and an inorganic-material thereon while using the inorganic-material film to function as a mask, said unit comprising:
a chamber configured to contain the substrate to be processed,
first and second electrodes oppositely arranged in the chamber, the second electrode being configured to support the substrate to be processed,
a process-gas supplying system configured to supply a process gas into the chamber,
a gas-discharging system configured to discharge a gas in the chamber, and
a first high-frequency electric power source configured to supply a high-frequency electric power of 50 MHz to 150 MHz for forming a plasma to the second electrode,
a second high-frequency electric power source configured to apply a second high-frequency electric power of 500 kHz to 27 MHz to the second electrode, the second high-frequency electric power being overlapped with the first high-frequency electric power, and
a magnetic-field forming unit configured to form a magnetic field around a plasma region between the first and second electrodes, the magnetic-field forming unit consisting of a magnetic annular unit having a plurality of synchronously and oppositely rotatable segment magnets concentrically arranged around the chamber such that
magnetic-pole directions of adjacent segment magnets are opposite, and
each segment magnet is vertically bisected into two associated magnets to define an upper set of annularly arranged magnets and a lower set of annularly arranged magnets, and
each associated upper magnet and lower magnet are vertically moveable with respect to each other in order to set a vertical gap therebetween.
2. A plasma etching unit according to claim 1 , wherein the second high-frequency electric power is 13.56 MHz.
3. A plasma etching unit according to claim 1 , wherein the second high-frequency electric power is 3.2 MHz.
4. A plasma etching unit according to claim 1 , wherein a distance between the first and second electrodes is shorter than 50 mm.
5. A plasma etching unit according to claim 1 , wherein a strength of the magnetic field formed around the plasma region between the first and second electrodes by the magnetic-field forming unit is 0.03 to 0.045 T (300 to 450 Gauss).
6. A plasma etching unit according to claim 1 , wherein
a focus ring is provided around the substrate to be processed, and
when the magnetic-field forming unit forms a magnetic field around the plasma region between the first and second electrodes, a strength of the magnetic field on the focus ring is not lower than 0.001 T (10 Gauss) and a strength of the magnetic field on the substrate to be processed is not higher than 0.001 T.
7. A plasma etching unit according to claim 1 , wherein the first electrode is a shower head configured to supply a mixed gas of an N 2 gas and an O 2 gas, or a mixed gas of an N 2 gas and an H 2 gas from the process-gas supplying system.
8. A plasma etching unit according to claim 1 , wherein
adjacent magnets in each set of annularly arranged magnets are arranged in such a manner that their magnetic-pole directions are opposite.
9. A plasma etching unit according to claim 1 , wherein
the segment magnets are arranged in a multi-pole state.
10. A plasma etching unit according to claim 1 , wherein
the magnetic-field forming unit is configured to generate the magnetic field around the plasma region while generating a substantially non-magnetic field state in a region where the substrate is placed.
11. A plasma etching unit, comprising:
a chamber configured to contain the substrate to be processed,
first and second electrodes oppositely arranged in the chamber, the second electrode being configured to support the substrate to be processed,
a process-gas supplying system configured to supply a process gas into the chamber,
a gas-discharging system configured to discharge a gas in the chamber, and
a first high-frequency electric power source configured to supply a high-frequency electric power of 50 MHz to 150 MHz to the second electrode for forming a plasma,
a second high-frequency electric power source configured to apply a second high-frequency electric power of 500 kHz to 27 MHz to the second electrode, such that the second high-frequency electric power is overlapped with the first high-frequency electric power, and
a magnetic-field forming unit configured to form a magnetic field around a plasma region between the first and second electrodes, the magnetic-field forming unit comprising a magnetic annular unit having a plurality of synchronously and oppositely rotatable segment magnets concentrically arranged around the chamber such that
magnetic-pole directions of adjacent segment magnets are opposite, and
the segment magnets are vertically bisected into two associated magnets to define an upper set of annularly arranged magnets and a lower set of annularly arranged magnets, and
at least one of the associated upper magnet and lower magnet of the respective segment magnets is vertically moveable with respect to the other in order to set a vertical gap therebetween.
12. A plasma etching unit according to claim 11 , wherein the second high-frequency electric power is 13.56 MHz.
13. A plasma etching unit according to claim 11 , wherein the second high-frequency electric power is 3.2 MHz.
14. A plasma etching unit according to claim 11 , wherein a distance between the first and second electrodes is shorter than 50 mm.
15. A plasma etching unit according to claim 11 , wherein a strength of the magnetic field formed around the plasma region between the first and second electrodes by the magnetic-field forming unit is 0.03 to 0.045 T (300 to 450 Gauss).
16. A plasma etching unit according to claim 11 , wherein
a focus ring is provided around the substrate to be processed, and
when the magnetic-field forming unit forms a magnetic field around the plasma region between the first and second electrodes, a strength of the magnetic field on the focus ring is not lower than 0.001 T (10 Gauss) and a strength of the magnetic field on the substrate to be processed is not higher than 0.001 T.
17. A plasma etching unit according to claim 11 , wherein the first electrode is a shower head configured to supply a mixed gas of an N 2 gas and an O 2 gas, or a mixed gas of an N 2 gas and an H 2 gas from the process-gas supplying system.
18. A plasma etching unit according to claim 11 , wherein
adjacent magnets in each set of annularly arranged magnets are arranged in such a manner that their magnetic-pole directions are opposite.
19. A plasma etching unit according to claim 11 , wherein
the segment magnets are arranged in a multi-pole state.
20. A plasma etching unit according to claim 11 , wherein
the magnetic-field forming unit is configured to generate the magnetic field around the plasma region while generating a substantially non-magnetic field state in a region where the substrate is placed.