Detecting an arc occuring during supplying power to a plasma process
Methods, apparatus and systems for detecting an arc during supplying a plasma process in a plasma chamber with a power are provided. An example plasma power supply includes: a DC source, an output signal generator, a first signal sequence measurement device for measuring a first signal sequence present between the DC source and the output signal generator, a second signal sequence measurement device for measuring a second signal sequence present at an output of the output signal generator, and a controller configured to generate a reference signal sequence based on one of the first and second signal sequences, to compare the reference signal sequence and the other of the first and second signal sequences that has not been used to determine the reference signal sequence, and to generate a detection signal if the reference signal sequence and the other of the first and second signal sequences cross.
1. A method of detecting an arc occurring during supplying power to a plasma process in a plasma chamber, comprising:
determining a first signal sequence present between a DC source and an output signal generator, wherein the output signal generator comprises an input connected to the DC source and an output connected to the plasma chamber;
determining a second signal sequence present at the output of the output signal generator;
determining a reference signal sequence based on one of the first and second signal sequences;
comparing the reference signal sequence with the other of the first and second signal sequences; and
detecting an arc by determining if the reference signal sequence and the other of the first and second signal sequences cross.
2. The method of claim 1 , wherein at least one of the first signal sequence, the second signal sequence and the reference signal sequence, is digitized in a digital domain.
3. The method of claim 1 , wherein the reference signal sequence is determined in periodic intervals.
4. The method of claim 1 , wherein at least one of the first signal sequence and the second signal sequence comprises one of a current, a voltage, and a power.
5. The method of claim 1 , wherein at least one of the first signal sequence and the second signal sequence comprises one of an average value, an effective value, and a maximum value.
6. The method of claim 1 , comprising:
measuring a time elapsed after determining the crossing of the other of the first and second signal sequences and the reference signal sequence; and
determining that an arc is detected if the other of the first and second signal sequences and the reference signal sequence do not cross again within the measured elapsed time being no smaller than a predetermined time interval.
7. The method of claim 1 , further comprising:
generating an arc detection signal in response to determining that the arc is detected.
8. The method of claim 1 , wherein determining a reference signal sequence comprises determining the reference signal sequence to be one of:
the one of the first and second signal sequences minus a first given value, and
the one of the first and second signal sequences multiplied by a second given value.
9. A plasma power supply for supplying a plasma process in a plasma chamber with a power, the plasma power supply comprising:
a DC source;
an output signal generator comprising an input connected to the DC source and an output connected to the plasma chamber;
a first signal sequence measurement device for measuring a first signal sequence present between the DC source and the output signal generator;
a second signal sequence measurement device for measuring a second signal sequence present at the output of the output signal generator; and
a controller connected to the first and second signal sequence measurement devices and configured to receive the first signal sequence and the second signal sequence, the controller comprising:
a reference signal sequence generator configured to generate a reference signal sequence based on one of the first and second signal sequences, and
a comparator configured to compare the reference signal sequence and the other of the first and second signal sequences that has not been used to determine the reference signal sequence, and to generate a detection signal if the reference signal sequence and the other of the first and second signal sequences cross.
10. The plasma power supply of claim 9 , wherein the controller is a digital controller configured to be clocked with a given time interval.
11. The plasma power supply of claim 9 , wherein the controller comprises a counter configured to measure a time elapsed after the other of the first and second signal sequences and the reference signal sequence cross.
12. The plasma power supply of claim 9 , wherein the controller comprises an arc detection device configured to generate an arc detection signal based on the detection of the crossing of the reference signal reference and the other of the first and second signal sequence.
13. The plasma power supply of claim 12 , wherein the arc detection device is configured to generate the arc detection signal if the reference signal sequence and the other of the first and second signal sequences do not cross again within a given time interval elapsed after the crossing of the reference signal sequence and the other of the first and second signal sequences.
14. The plasma power supply of claim 12 , wherein the output signal generator comprises an extinguisher connected to the arc detection device and configured to extinguish an arc.
15. The plasma power supply of claim 9 , wherein the output signal generator comprises at least one of:
a DC-signal source,
a bridge inverter, and
a pluser.
16. The plasma power supply of claim 9 , further comprising an effective value generator configured to generate at least one of:
an effective value of the first signal sequence, and
an effective value of the second signal sequence.
17. The plasma power supply of claim 9 , further comprising a maximum value generator configured to generate at least one of:
a maximum value of the first signal sequence within a first given time interval, and
a maximum value of the second signal sequence within a second given time interval.
18. The plasma power supply of claim 9 , wherein the reference signal sequence generator is configured to determine the reference signal sequence to be one of:
the one of the first and second signal sequences minus a first given value, and
the one of the first and second signal sequences multiplied by a second given value.
19. A device for a plasma power supply for supplying a plasma process in a plasma chamber with a power, the device comprising:
a reference signal sequence generator configured to generate a reference signal sequence based on one of a first signal sequence present between a DC source and an input of an output signal generator that is connected to the DC source and a second signal sequence present at an output of the output signal generator that is connected to the plasma chamber, the plasma power supply including the DC source and the output signal generator; and
a comparator configured to:
compare the reference signal sequence and the other of the first and second signal sequences which has not been used to determine the reference signal sequence, and
generate a detection signal if the reference signal sequence and the other of the first and second signal sequences cross.
20. The device of claim 18 , further comprising an arc detection device configured to generate an arc detection signal by
determining that the reference signal sequence and the other of the first and second signal sequence cross, and
determining that the reference signal sequence and the other of the first and second signal sequences do not cross again within a given time interval elapsed after the crossing of the reference signal sequence and the other of the first and second signal sequences.