Plasma etching apparatus and method
A plasma etching apparatus includes a second electrode configured to support a target substrate thereon, a second RF power supply unit configured to apply a second RF power for providing a bias for ion attraction to the second electrode, and a control system including and an RF controller. The RF controller is configured to switch the second RF power supply unit between a continuous mode that executes continuous supply of the second RF power at a constant power level and a power modulation mode that executes modulation of the second RF power between a first power and a second power larger than the first power. The RF controller is preset to control the second RF power supply unit such that the second RF power supply unit is first operated in the continuous mode for plasma ignition and then is switched into the power modulation mode.
1. A plasma etching apparatus comprising:
a process container configured to be vacuum-exhausted;
a first electrode disposed inside the process container;
a second electrode disposed opposite to the first electrode and configured to support a target substrate thereon;
a first radio frequency (RF) power supply unit connected to the first electrode or the second electrode and configured to apply a first RF power for plasma generation to the first electrode or the second electrode;
a second RF power supply unit connected to the second electrode and configured to apply a second RF power for providing a bias for ion attraction to the second electrode;
a process gas supply unit configured to supply a process gas into the process container; and
a control system including and an RF controller configured to control the first and second RF power supply units, wherein
the RF controller is configured to switch the second RF power supply unit between a continuous mode that executes continuous supply of the second RF power at a constant power level and a power modulation mode that executes modulation of the second RF power between a first power and a second power larger than the first power, and the RF controller is preset to perform control the second RF power supply unit such that the second RF power supply unit is first operated in the continuous mode, then the first RF power supply unit starts RF power supply when a first predetermined time has elapsed since the second RF power supply unit has started its operation in the continuous mode, and then the second RF power supply unit is switched into the power modulation mode when a second predetermined time has elapsed since the second RF power supply unit has started its operation in the continuous mode.
2. The plasma etching apparatus according to claim 1 , wherein the RF controller is preset to perform control such that the second RF power supply unit is first operated in the continuous mode with RF power supply at a power level lower than a predetermined power level, until a certain time point after the first RF power supply unit starts RF power supply, then the second RF power supply unit increases RF power after the certain time point, and then the second RF power supply unit is switched into the power modulation mode.
3. The plasma etching apparatus according to claim 2 , wherein the RF controller is preset to perform control such that the first RF power supply unit also increases RF power after the certain time point.
4. The plasma etching apparatus according to claim 1 , wherein the apparatus further comprises a variable DC power supply configured to apply a DC voltage to the first electrode, and the control system is preset to control the variable DC power supply to start voltage application when the first RF power supply unit starts RF power supply.
5. The plasma etching apparatus according to claim 4 , wherein the control system is preset to control the variable DC power supply to gradually increase voltage when starting the voltage application.
6. The plasma etching apparatus according to claim 1 , wherein the apparatus further comprises a variable DC power supply configured to apply a DC voltage to the first electrode.
7. The plasma etching apparatus according to claim 1 , wherein the first RF power has a frequency of 27 to 100 MHz.
8. The plasma etching apparatus according to claim 1 , wherein the second RF power has a frequency of 400 kHz to 13.56 MHz.
9. The plasma etching apparatus according to claim 1 , wherein the first power is set to be within a range of 10 to 500 W and the second power is set to be within a range of 100 to 5,000 W in the power modulation mode of the second RF power supply unit.
10. The plasma etching apparatus according to claim 1 , wherein a power modulation frequency is within a range of 0.25 to 100 Hz in the power modulation mode of the second RF power supply unit.
11. The plasma etching apparatus according to claim 1 , wherein a power modulation duty ratio (second power time/one cycle total time) is within a range of 1 to 99% in the power modulation mode of the second RF power supply unit.
12. The plasma etching apparatus according to claim 1 , wherein the RF controller is preset to control the first RF power supply unit to operation in a power modulation mode that executes modulation of the first RF power between a third power and a fourth power larger than the third power in synchronism with the power modulation mode of the second RF power supply unit.
13. The plasma etching apparatus according to claim 1 , wherein the first power is non-zero value.
14. A plasma etching apparatus comprising:
a process container configured to be vacuum-exhausted;
a first electrode disposed inside the process container;
a second electrode disposed opposite to the first electrode and configured to support a target substrate thereon;
a first radio frequency (RF) power supply unit connected to the first electrode or the second electrode and configured to apply a first RF power for plasma generation to the first electrode or the second electrode;
a second RF power supply unit connected to the second electrode and configured to apply a second RF power for providing a bias for ion attraction to the second electrode;
a process gas supply unit configured to supply a process gas into the process container; and
a control system including and an RF controller configured to control the first and second RF power supply units, wherein
the RF controller is configured to switch the second RF power supply unit between a continuous mode that executes continuous supply of the second RF power at a constant power level and a power modulation mode that executes modulation of the second RF power between a first power and a second power larger than the first power,
the RF controller is preset to control the second RF power supply unit such that the second RF power supply unit is first operated in the continuous mode for plasma ignition and then is switched into the power modulation mode, and
the RF controller is preset to control the second RF power supply unit to gradually increase power during a period longer than a period of one cycle including a period of the first power and a period of the second power in the power modulation mode when switching into the power modulation mode from the continuous mode.
15. The plasma etching apparatus according to claim 14 , wherein the first power is non-zero value.