Plasma processing apparatus and plasma processing method
The present invention provides a plasma processing apparatus having a radio frequency power supply supplying time-modulated radio frequency power which is controllable widely with high precision, and a plasma processing method using the plasma processing apparatus. The plasma processing apparatus includes: a vacuum chamber; a first radio frequency power supply for generating plasma in the vacuum chamber; a sample holder disposed in the vacuum chamber, on which a sample is placed; and a second radio frequency power supply supplying radio frequency power to the sample holder, wherein at least one of the first radio frequency power supply and the second radio frequency power supply supplies time-modulated radio frequency power, one of parameters of controlling the time-modulation has two or more different control ranges, and one of the control ranges is a control range for a high-precision control.
1. A plasma processing apparatus, comprising:
a vacuum chamber in which a sample is plasma processed;
a first radio frequency power supply supplying a first radio frequency power to generate plasma in the vacuum chamber;
a sample holder on which the sample is placed; a second radio frequency power supply supplying a second radio frequency power to the sample holder,
a D/A converter converting a digital signal into an analog signal;
an A/D converter converting an analog signal into a digital signal;
wherein the D/A converter converts a set parameter for time modulation of the first radio frequency power into a first analog value corresponding to the set parameter and being a value relating to a first frequency band and a second analog value corresponding to the set parameter and being a value relating to a second frequency band wider than the first frequency band;
a signal processor configured to select a first digital value that the first analog value is converted by the A/D converter or a second digital value that the second analog value is converted by the A/D converter, based on a signal to select the first frequency band or the second frequency band; and
a pulse generator generating a pulse waveform for time modulation of the first radio frequency power based on the first digital value or the second digital value selected by the signal processor
wherein a range of an analog voltage value of the first analog value is the same as a range of an analog voltage value of the second analog value.
2. The plasma processing apparatus according to claim 1 , wherein:
the parameter is a duty ratio, and
the pulse waveform is a pulse waveform of the duty ratio corresponding to the first digital value or the second digital value selected by the signal processor.
3. The plasma processing apparatus according to claim 1 , wherein the signal processor selects the first digital value that the first analog value is converted by the A/D converter or the second digital value that the second analog value is converted by the A/D converter by synchronizing a timing and a signal reception according to the signal.
4. A plasma processing apparatus comprising:
a vacuum chamber in which a sample is plasma processed;
a first radio frequency power supply supplying a first radio frequency power to generate plasma in the vacuum chamber;
a sample holder on which the sample is placed;
a second radio frequency power supply supplying a second radio frequency power to the sample holder;
a D/A converter converting a digital signal into an analog signal;
an A/D converter converting an analog signal into a digital signal;
wherein the D/A converter converts a set parameter for time modulation of the second radio frequency power into a first analog value corresponding to the set parameter and being a value relating to a first frequency band and a second analog value corresponding to the set parameter and being a value relating to a second frequency band wider than the first frequency band;
a signal processor configured to select a first digital value that the first analog value is converted by the A/D converter or a second digital value that the second analog value is converted by the A/D converter based on a signal to select the first frequency band or the second frequency band; and
a pulse generator generating a pulse waveform for time modulation of the second radio frequency power based on the first digital value or the second digital value selected by the signal processor
wherein a range of an analog voltage value of the first analog value is the same as a range of an analog voltage value of the second analog value.
5. The plasma processing apparatus according to claim 4 , wherein:
the parameter is a duty ratio, and
the pulse waveform is a pulse waveform of the duty ratio corresponding to the first digital value or the second digital value selected by the signal processor.
6. The plasma processing apparatus according to claim 4 , wherein the signal processor selects the first digital value that the first analog value is converted by the A/D converter or the second digital value that the second analog value is converted by the A/D converter by synchronizing a timing and a signal reception according to the signal.
7. A plasma processing apparatus, comprising:
a vacuum chamber in which the sample is plasma processed;
a first radio frequency power supply supplying a first radio frequency power to generate plasma in the vacuum chamber;
a sample holder on which the sample is placed;
a second radio frequency power supply supplying a second radio frequency power to the sample holder,
a control device comprising an input section, a microcomputer, and a D/A converter converting a digital signal into an analog signal,
wherein the D/A converter converts a set parameter for time modulation of the first radio frequency power into a first analog value corresponding to the set parameter and being a value of a first frequency band and a second analog value corresponding to the set parameter and being a value of a second frequency band wider than the first frequency band;
an A/D converter having a plurality of output ports thereon, the A/D converter configured to receive the first analog value and the second analog value, and to convert the first analog value and the second analog value transmitted by the control device to a first digital signal and a second digital signal respectively, wherein the A/D converter is further configured to output the first digital signal on the first output port and to output the second digital signal on the second output port;
a signal processor configured to select the first output port on which is output the first digital signal converted by the A/D converter or the second output port on which is output the second digital signal converted by the A/D converter based on a signal received by the signal processor from the control device, wherein the signal corresponds to the first and second digital signals, and wherein the signal is based on the first radio-frequency power;
a pulse generator generating a pulse waveform for time modulation of the first radio frequency power based on the first digital signal or the second digital signal selected by the signal processor, and
wherein a range of an analog voltage value of the first analog value is the same as a range of an analog voltage value of the second analog value.
8. The plasma processing apparatus according to claim 7 ,
wherein the signal processor selects the first digital signal that the first analog value is converted by the A/D converter or the second digital signal that the second analog value is converted by the A/D converter by synchronizing a timing and a signal reception according to the signal.