Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32917—Plasma diagnostics
  • H01J37/32926—Software, data control or modelling
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32917—Plasma diagnostics
  • H01J37/32935—Monitoring and controlling tubes by information coming from the object and/or discharge
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32917—Plasma diagnostics
  • H01J37/3299—Feedback systems
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/32—Processing objects by plasma generation
  • H01J2237/327—Arrangements for generating the plasma

Definitions

• the invention relates to a signal processing system for determining and making available a data stream describing a plasma process. Furthermore, the invention relates to a power supply device with such a signal processing system.
• a constant load impedance (plasma impedance) that varies little is formed after the plasma has been ignited.
• An automatic impedance matching network compensates for this impedance and presents its nominal impedance to the generator, which generates the power to ignite and operate the plasma.
• the plasma burns unstably, be it due to unfavorable chamber geometry, process chemistry, arcing or similar, various stochastic processes cause the plasma impedance and thus the power coupled into the plasma to constantly vary.
• the amount of the mean reflected power is often used as an indicator for the quality of the adjustment process of an automatic matchbox and at the same time as a stability criterion for the plasma.
• transient and decay processes occur at the beginning and end of each pulse, which lead to reflected power despite a stable process and the best possible adjustment.
• a signal processing system for determining and making available a data stream describing a plasma process, having a) a detection device which is set up for detecting a signal curve which is repeated in a predetermined time interval and changes as a function of a plasma process state, b) a determination device that is set up to generate the data stream based on at least two signal curves recorded in a respective time interval, the data stream having a continuously determined stability index for the plasma process.
• a signal course means: the course of a signal proportional to an envelope curve, to an effective value curve, a root-mean-squared (RMS) curve, or to an extreme value curve of an MF or HF signal or the course of a DC signal that can change continuously.
• RMS root-mean-squared
• the stability index can depend on the reflected power, but it can also depend on other parameters, i.e. it cannot depend solely on the reflected power. Furthermore, the stability index can be independent of the reflected power and, in particular, can reach its maximum even if the reflected power is not equal to zero. With the stability index determined according to the invention, a higher statement can be made about the stability of the plasma.
• the data stream represents a continuous provision of constantly updated data, in particular stability indicators.
• the data stream can be designed in such a way that updated data of the stability index are always output after a predetermined data stream interval.
• the data stream interval may be independent of the predetermined time interval of the repeating waveform.
• TRUMPF Kunststofftinger GmbH + Co. KG DS15155-3263 vall can in particular be greater than the time interval of the repeating signal curve.
• the data flow interval can be approx. 1 ms up to approx. 1 s. It can be made available to a higher-level plasma process control unit.
• the higher-level plasma process control unit can be set up to include this stability index in its process improvement control and, for example, to adjust gas supply, gas mixture, pressure, electrical parameters such as frequency, power, voltage, current, modulation or pulse frequency so that the stability index is more favorable has value.
• the data stream can be generated by comparing the at least two signal profiles recorded in one time interval. This comparison can be a correlation or a subtraction, for example.
• An output value of the data stream can be based on a number of such comparisons with a number of recorded signal profiles.
• the stability index can be determined as a statistical value, e.g. an average or a maximum value from several such comparisons. Several data streams with several different stability indicators can be determined according to different statistical evaluations.
• the determined stability indicators can be used alone and/or in combination with other data for AI (artificial intelligence) applications and/or for machine learning, both as test and learning data, thus making the processes even more stable.
• the data stream can be generated in such a way that a time window used to determine the stability index is at least as long
• the stability index(es) can be used very advantageously to control the plasma process in a plasma process that has a basic instability, e.g. due to an unstable load or environmental conditions.
• a basic instability can thus be determined using the one or more stability index(es), and an attempt can be made to keep the process in this basic instability, and using the stability index(es) to recognize when the process enters an altered instability that deviates from the baseline instability, and if this altered instability is undesirable, to take action to come back to the baseline instability.
• the detection device can have an analog-to-digital converter (ADC) and store data in a memory. All the data from a time interval can be stored in a first memory section (array), and the data from a subsequent time interval can be stored in a further memory section. There may be more than two such memory sections. When the last intended memory section has been written to, the next memory section can be written to again and the data located there can be overwritten.
• ADC analog-to-digital converter
• the recording device can do all this.
• the detection device can have a hard-wired or programmable logic module, in particular an FPGA. This has the advantage that fast data processing is possible. The same routines can always be executed. Another advantage is the configurability of an FPGA.
• the determination device can be set up to have read access to the memory sections, in particular always to the memory sections that are currently not being written to by the detection device.
• the determination device can be designed as a microprocessor or have one.
• a microprocessor can be set up to carry out further tasks of a controller.
• the plasma process is preferably excited by an HF power signal.
• the signal course can repeat itself.
• the waveform can be repeated periodically with a waveform frequency.
• the signal curve can be repeated with the period duration of the time interval in normal operation, e.g. be a periodically modulated signal, or a periodically pulsed signal or a combination of these repeated signal curves.
• the RF power signal may have a frequency significantly higher than the waveform frequency, typically a frequency higher by a factor of 4, 10, 50, 100 or more.
• the HF power signal can be at frequencies greater than or equal to 4 MHz, in particular at frequencies that are also less than or equal to 80 MHz, in particular in the frequency range from 10 to 50 MHz, particularly preferably at 13.56 MHz.
• the frequency of the repetitive waveform can be at frequencies greater than or equal to 10 kHz.
• the frequency of the repetitive signal curve can be at frequencies less than or equal to 500 kHz. It can be caused by modulated or pulsed operation of the HF power signal. It can be caused by modulated or pulsed operation of another power supply that is also connected to the plasma process, e.g. a bias power supply. It can be caused by a periodic change in an impedance matching arrangement. It can be caused by a periodic change in the plasma process. This can be a movement of the substrate in the plasma process, e.g. advancing the substrate, or the movement of several substrates on a turntable.
• the waveform may be a substantially constant value.
• a constant HF power signal from the power generator can be applied to a plasma process with a previously described turntable at a rotational speed
• the predetermined time interval of the repeating signal curve and/or the data stream interval can be predetermined by process fluctuations in the plasma process.
• process fluctuations can be caused by one or more gaps between several substrates, e.g. in a continuous coating system or in a system with rotating targets or rotating substrates due to bumps or irregularities in these devices.
• Systems of this type and reasons for such process fluctuations are described, for example, in WO2020/152097 A1 entitled "Method for compensating for process fluctuations in a plasma process and controller for a power generator for supplying a plasma process".
• the signal processing system can be set up so that the time interval can be specified externally, e.g. by a power generator, an impedance matching arrangement or by another unit influencing the plasma process, such as a low-frequency, modulated or pulsed additional power supply connected to the plasma process, in particular a bias power supply.
• the time interval can also be specified by the advance or the rotational speed of the substrate in the plasma or in the plasma chamber.
• the signal processing system can be set up to determine the time interval itself, in particular by means of the detection device or the determination device. This can be done, for example, by autocorrelation, e.g. by correlating the signal curve with the signal curve itself at an earlier point in time. Alternatively, the time interval could be determined using frequency analysis, e.g. by searching for frequencies unequal, in particular lower than the excitation frequency of the plasma process.
• the signal processing system can be set up so that the data stream is generated on the basis of a comparison of two signal profiles at successive time intervals.
• the consecutive time intervals do not necessarily have to be directly consecutive time intervals.
• a number of first signal profiles from a number of first time intervals can also be compared with a signal profile from a subsequent time interval and used to generate the data stream.
• a mean value curve or a maximum value curve can be formed from a number of first signal curves from a number of first time intervals and used for the same comparison.
• the signal processing system can have a storage device for recording the signal curves. This makes it possible to compare signal curves and/or values determined from them with one another. Averaging is also possible. Envelopes can also be generated. Extreme values of the signal curve can be determined and saved for each time interval.
• the memory device can be in the form of a ring memory.
• a synchronization device for synchronizing the detection device to the waveform frequency may be provided. This makes it possible for entire signal curves, pulses or the start of pulses to be recorded and compared. Alternatively, multiple process starts and ignition events could be recorded. This is particularly beneficial when a process tends not to fire or go into a "bad" state on startup.
• a comparison device can be provided which is set up to compare recorded signal curves and/or values determined from them with one another or with a reference.
• the determination device can be set up to determine an average signal profile over a number of time intervals. This allows an average signal course to be determined. Each new signal curve is weighted accordingly in the middle signal curve.
• the determination device can be designed
• TRUMPF Kunststofftinger GmbH + Co. KG DS15155-3263 be, in particular at the same time, to determine how far the new signal curve deviates from the mean signal curve, in particular to determine a deviation of a sample of a signal curve from a mean signal curve.
• the maximum of this deviation or its mean value can then serve as a measure of the (in)stability.
• This value is recorded for the N time intervals and the maximum value of this or the mean value is output. Without recording, an extreme value could also be used, which decays with each new time interval until it arrives at zero after N time intervals.
• the determination device can be set up to determine an envelope curve, in particular of the minimum and maximum values of the corresponding samples of a plurality of time intervals, and to determine a stability index therefrom.
• N pulses can be recorded.
• the oldest is overwritten again (ring buffer).
• the maximum and minimum values for each sample are determined for all of these pulses in the ring buffer.
• An envelope of maximum and minimum values is created.
• a measure of the instability can also be determined by taking the mean distance from the maximum and minimum values.
• not every waveform has to be recorded in a time interval. Individual time intervals can also be omitted during the determination.
• the invention relates to a power supply device for generating an electrical high-frequency power signal (HF power signal) for a plasma, having a power generator, an impedance matching arrangement connected to the power generator, and having a signal processing system according to the invention.
• the signal processing system can be arranged in the power supply device. Alternatively, it can be arranged in the impedance matching arrangement. Furthermore, it is conceivable that it is arranged externally, ie neither in the power supply device nor in the impedance matching arrangement.
• FIG. 1 shows a schematic representation of a power supply device
• FIG. 2 shows a diagram to clarify a first procedure for determining a data stream with a stability index
• FIG. 3 shows a diagram to clarify a second procedure for determining a data stream with a stability index.
• Figure 1 shows a power supply device 1 for generating a particularly pulsed electrical high-frequency power signal for generating a plasma in a plasma chamber 4.
• the power supply device 1 comprises a power generator 2 and an impedance matching arrangement 6 connected to the power generator 2, via which the power generator 2 is connected to the plasma chamber 4 is connected.
• a detection device 10 is set up to detect a signal curve which is repeated in a predetermined time interval and changes as a function of the plasma process state.
• the detection device 10 is arranged between the power generator 2 and the impedance matching arrangement 6 . It can be designed, for example, as a measuring device for measuring current and/or voltage, or as a directional coupler in order to record a power.
• a detection device 12, 14 can be arranged in the power generator 2 or the impedance matching arrangement 6 (two detection devices 12, 14 are shown, but one is sufficient). It is also conceivable that the determination device 12, 14 is arranged at a different location. It is set up to generate a data stream based on at least one signal profile recorded in a time interval, the data stream having a continuously determined stability index for the plasma process.
• the signal curves detected by the detection device 10 can be stored in a storage device 16 and made available from there to the determination device 12, 14.
• the memory device 16 can be designed as a ring memory.
• the comparison of the recorded signal curves and/or values determined therefrom with one another or with reference values can be carried out by a comparison device 20 . Based on the comparison, a data stream that has a stability index can be generated and output, in particular displayed to a user.
• the signal curves can be recorded in a synchronized manner.
• a synchronization device 18 is provided for synchronizing the detection of the signal curves, which device can be connected both to the detection device 10 and to a controller 22 .
• the controller 22 can control both the power generator 2 and the synchronization device 18 .
• FIG. 2 shows a first signal curve 100, which corresponds to a pulsed high-frequency power and is supplied by the power generator 2, and a second signal curve 101, which corresponds to a reflected power.
• Fig. 2 shows a pulsed RF signal, a pulsed DC bias signal or similar signal.
• the envelope of the pulse signal can be seen. This can be a frequency of, for example, 10 kHz up to 500 kHz.
• An HF signal that is pulsed with this pulse shape has a significantly higher frequency, eg 10 MHz or more. It is not shown in FIG.
• the signal curves 100, 101 are normal.
• the time interval T5 there is a discontinuity in the form of a pulse dropout or an undesired event.
• the time intervals T6-T8 correspond to a recovery phase.
• time intervals T1...T8 are synchronized to the rising edge of a pulse of the HF power signal, i.e. the detection of the signal curves 100, 101 is carried out by the synchronization device 18 synchronized to the pulse signal that the pulsing of the HF -Power signal causes.
• the determining device 12, 14 forms, for example, the sliding mean value of the signal curve 100 over n time intervals, so that a mean signal curve is produced. Each new time interval is weighted accordingly in the mean signal curve. Furthermore, it is determined how far each sample of the new time interval deviates from the mean signal curve. The maximum of this deviation or its mean value can then serve as a measure of the stability of the plasma process. Alternatively, the cross-correlation between the new time interval and the mean value formed can be used. This stability index can be recorded for the n time intervals and the maximum value or the mean value can be output. This represents the data stream described above.
• sampling points samples
• a maximum value can be stored. This maximum value decays at each new time interval, unless a discontinuity occurs, until it arrives at zero after N time intervals.
• a stability index would be determined and output for the time intervals T1-T4, which would be associated with a high level of stability, since the samples deviate little from an average signal curve, while a stability index would be determined and possibly output for the time intervals T5-T8, which would be assigned to low stability.
• the signal curve 101 is shown again.
• a maximum value and a minimum value is formed for each sample over the time intervals, so that an envelope 103 can be generated.
• a stability index can be determined, for example, from the mean value, from the maximum and minimum values of corresponding samples of the time intervals. Accordingly, when the envelope 103 is close to the waveform 101, as in the intervals T11-T13, there is great stability. Accordingly, a stability index would be determined and output for the time intervals T11-T13, which would be assigned to a high degree of stability. If the envelope has a large distance to the signal curve 101, as in the interval T14, there is little stability. Accordingly, a stability index would be determined and output for the time interval T14, which would be associated with a lower stability.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Plasma Technology (AREA)
• Drying Of Semiconductors (AREA)

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• 2021
  • 2021-06-16 DE DE202021103238.3U patent/DE202021103238U1/de active Active
• 2022
  • 2022-06-03 CN CN202280042869.5A patent/CN117501403A/zh active Pending
  • 2022-06-03 WO PCT/EP2022/065203 patent/WO2022263209A1/de active Application Filing
  • 2022-06-03 KR KR1020247001237A patent/KR20240017403A/ko unknown
  • 2022-06-03 EP EP22734524.6A patent/EP4356415A1/de active Pending
• 2023
  • 2023-12-08 US US18/533,220 patent/US20240105431A1/en active Pending

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