Signal processing system and power supply device having a signal processing system
A signal processing system includes an acquisition device configured to acquire a repeating signal trace in a specified time interval. The signal trace varies as a function of a plasma process state of a plasma process. The signal processing system further includes a determining device configured to generate a data stream describing the plasma process, based on at least two signal traces acquired in one time interval each. The data stream contains a continuously determined stability indicator for the plasma process.
1 . A signal processing system comprising
an acquisition device configured to acquire a repeating signal trace in a specified time interval, wherein the signal trace varies as a function of a plasma process state of a plasma process comprising a pulsed radio-frequency (RF) power signal,
a synchronization device configured to synchronize the acquisition device to a signal trace frequency such that the specified time interval is synchronized to a pulse of the pulsed RF power signal; and
a determining device configured to generate a data stream describing the plasma process, based on at least two signal traces acquired in one time interval each,
wherein the data stream contains a continuously determined stability indicator for the plasma process,
wherein the specified time interval of the repeating signal trace and/or a data stream interval are predetermined by process fluctuations of the plasma process,
wherein the data stream is generated based on a comparison of the at least two acquired signal traces,
wherein the determining device is configured to generate and output to a user the data stream including the stability indicator, and
wherein a value of the stability indicator is based on a distance of a respective signal trace of the at least two acquired signal traces in comparison to one of: a mean value, a maximum value, or a minimum value of an acquired signal trace of the at least two acquired signal traces acquired over a previous time interval.
2 . The signal processing system according to claim 1 , wherein the time interval is specified externally.
3 . The signal processing system according to claim 1 , wherein the time interval is determined internally by the signal processing system, using the acquisition device or the determining device.
4 . The signal processing system according to claim 1 , wherein the data stream is generated based on a comparison of the at least two signal traces of consecutive time intervals.
5 . The signal processing system according to claim 4 , wherein the stability indicator is determined based on a plurality of the comparisons with a plurality of acquired signal traces.
6 . The signal processing system according to claim 5 , wherein the stability indicator is determined as a mean value or a maximum value, from the plurality of comparisons.
7 . The signal processing system according to claim 1 , wherein the determining device is configured to generate multiple data streams with multiple different stability indicators determined according to different statistical evaluations.
8 . The signal processing system according to claim 7 , wherein the determined stability indicators are used alone or in combination with other data for machine learning, as test data and as training data.
9 . The signal processing system according to claim 1 , wherein, for generating the data stream, a time window used for determining the stability indicator is at least as long as a data stream interval.
10 . The signal processing system according to claim 1 , further comprising a memory device for recording the signal traces.
11 . The signal processing system according to claim 10 , wherein the memory device is configured as a ring buffer.
12 . The signal processing system according to claim 1 , further comprising a comparison device configured to compare recorded signal traces, and/or to compare values determined from the recorded signal traces, with one another or with a reference.
13 . The signal processing system according to claim 1 , wherein the determining device is configured to determine a mean signal trace over multiple time intervals.
14 . The signal processing system according to claim 1 , wherein the determining device is configured to determine a deviation of a sample of a signal trace from a mean signal trace.
15 . The signal processing system according to claim 1 , wherein the determining device is configured to determine an envelope, including minimum and maximum values of corresponding samples of multiple time intervals, and wherein the stability indicator is determined from the minimum and maximum values.
16 . A power supply device for generating a pulsed electrical high-frequency power signal for a plasma, comprising a power generator, an impedance matching arrangement connected to the power generator, and the signal processing system according to claim 1 .
17 . A process control arrangement for a plasma process, configured to use the stability indicator from the signal processing system of claim 1 for controlling the plasma process.