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EP-4035195-B1 - METHOD OF PLASMA PROCESSING A SUBSTRATE IN A PLASMA CHAMBER AND PLASMA PROCESSING SYSTEM

EP4035195B1EP 4035195 B1EP4035195 B1EP 4035195B1EP-4035195-B1

Inventors

  • GAJEWSKI, WOJCIECH
  • RUDA, KRZYSZTOF
  • SWIATNICKI, Jakub

Dates

Publication Date
20260513
Application Date
20200923

Claims (15)

  1. Method of plasma processing a substrate (10) in a plasma chamber (6), comprising the steps of a. supplying a power supply signal to electrodes (11, 12) arranged within the plasma chamber (6) in order to form a plasma (7) in the plasma chamber; b. monitoring at least one parameter related to the plasma processing; c. determining a feature related to the at least one monitored parameter; d. adjusting the power supply signal during the plasma processing to modify, in particular reduce, the feature, e. modification of the feature, in particular in order to eliminate and/or mitigate formation of crazing on the substrate (10), f. wherein the feature is indicative to crazing.
  2. Method according to claim 1, wherein the feature is a recurring event.
  3. Method according to claim 2, wherein the feature is a periodic event.
  4. Method according to any of the preceding claims, wherein the monitored parameter is different from the power supply signal that is adjusted.
  5. Method according to any of the preceding claims, wherein a machine learning and/or artificial intelligence algorithms are used to identify a parameter as an essential parameter related to an increased probability of crazing.
  6. Method according to any of the preceding claims, wherein the monitored parameter may be, but is not limited to, an electric potential between: a. the electrodes (11, 12) arranged within the plasma chamber, or b. one of the electrodes (11, 12) arranged within the plasma chamber and a reference electrode, or c. both electrodes (11, 12) arranged within the plasma chamber and a reference electrode, where the reference electrode may be grounded or floating.
  7. Method according to claim 3, wherein the power supply signal is periodical, in particular an AC signal, and the periodic event is with the period of the power supply signal.
  8. Method according to any of the preceding claims, wherein the method step d) to modify the feature is performed without interrupting the plasma processing.
  9. Method according to any of the preceding claims, wherein the relationship between the crazing and the feature is detectable.
  10. Method according to any of the preceding claims, wherein detecting a relationship between the crazing and the feature comprises the following steps: A) determine a probability of crazing with a predefined feature in a first shape; B) modify the feature compared to the 'feature' with the first shape; C) determine the probability of crazing with this modified feature; D) If the probability of crazing is lower with the modified feature, then detect this feature to be a feature indicative to crazing.
  11. Method according to any of the preceding claims, wherein adjusting the power supply signal comprises applying several sets of parameters to produce the power supply signal, determining the effect of a particular set of parameters on the feature, and selecting the parameter set leading to a more preferable level of the feature, in particular to reach its minimum or maximum level for further plasma processing.
  12. Method according to any of the preceding claims, wherein adjusting the power supply signal comprises at least one of a. modifying the amplitude of at least one power signal component, in particular of current and/or voltage, b. modifying the waveform of at least one power signal component, in particular of current and/or voltage, c. modifying the frequency of at least one power signal component, in particular of current and/or voltage.
  13. Method according to any of the preceding claims, wherein at least some of the method steps are performed in response to a user demand.
  14. Method according to any of the preceding claims, wherein at least some of the method steps are performed in response to detecting that at least one monitored parameter exceeds a threshold border (23).
  15. Plasma processing system (1) comprising a. a plasma chamber (6), b. at least one electrode (11, 12) located inside the plasma chamber (6), c. at least one power supply (2, 2a) supplying a power supply signal to the plasma chamber (6), d. at least one sensor for measuring at least one plasma process parameter such as an electric potential, e. at least one determination unit (4) configured to determine a feature related to the at least one monitored parameter, f. a control unit (13) for controlling the power supply in response to the feature, wherein the control unit is configured to adjust the power supply signal such that the feature is modified, in particular reduced, g. wherein the feature is indicative to crazing.

Description

The invention relates to a method of plasma processing a substrate in a plasma chamber, comprising the steps of supplying a power supply signal to the plasma chamber in order to form a plasma in the plasma chamber and monitoring at least one parameter related to the plasma processing. Furthermore, the invention relates to a plasma processing system, in particular, in which the inventive method is implemented. Crazing defects were first identified in large-area sputtering processes driven by AC power supplies. The defects occur on the substrate and lead to damaging the substrate such as architectural glass as described in more detail e.g. in US 2018/0040461 A1. Crazing occurs depending on the power supply used (medium frequency (MF) power supply or DC bipolar power supply, also called bipolar power supply, both a form of AC power supplies). If the occurrence of crazing is detected, different actions can be taken, for example thorough mechanical cleaning of the vacuum chamber components, grounding/insulation of rollers, careful treatment of the glass edges, covering rollers with a synthetic fibre, use of an auxiliary anode biased positively with respect to ground level, or changing the coater geometry. Proper cleanliness of the vacuum chamber is mentioned as one of the most important issues. The system cleanliness, which is deteriorating during the deposition process, was given as an example for crazing observed during deposition of metal layers such as Ag or Ni-Cr. Grounding/insulation of glass rollers and covering rollers with synthetic fibre is used to keep the glass and all layers of the coating which are already deposited on it, on a floating potential. This has an influence on the behaviour of plasma and floating potential dynamics in the system. Few glass manufacturers claim a special treatment to the glass edge to considerably reduce crazing probability. It has been qualitatively shown that a small rounding of the glass pane edge has a potential to eliminate crazing. This method is, however, limited by the thickness of the glass. Processing of glass with a thickness from 4 to 10 mm showed that as the glass thickness increases the edge rounding becomes less successful in crazing prevention. Other manufacturers have shown that the influence of glass thickness can be eliminated by a controlled change of the target to glass distance. None of the methods mentioned above are effective enough to eliminate the occurrence of crazing. The object of the present invention is to provide a method and a system which eliminate or at least dramatically decrease the occurrence of crazing. According to a first aspect the invention relates to a method of plasma processing a substrate in a plasma chamber, comprising the steps of a. supplying a power supply signal to electrodes arranged within the plasma chamber in order to form a plasma in the plasma chamber;b. monitoring at least one parameter related to the plasma processing;c. determining a feature related to the at least one monitored parameter;d. adjusting the power supply signal during the plasma processing to modify, in particular to reduce, the feature,e. modification of the feature, in particular in order to eliminate and/or mitigate formation of crazing on the substrate,f. wherein the feature is indicative to crazing. Whereas known methods only react to the occurrence of crazing and then perform method steps in order to reduce the crazing, the inventive method is applied before crazing even occurs. Therefore, it is possible to eliminate or at least dramatically decrease the damage of the substrate due to crazing. The power supply may be designed to deliver AC power with more than 500 W, in particular more than 5 kW and typically more than 50 kW. The power supply may be designed to deliver AC power in a frequency range between 1 kHz and 200 kHz, in particular between 5 kHz and 100 kHz. The output power of the power supply may be connected to two targets in the plasma chamber, so that both targets may be driven as cathodes and anodes alternately. The power supply signal that is adjusted may be a current-, a voltage-, or a power-controlled signal. Advantageously it is a current-controlled signal. The monitored parameter can be for example voltage, current, power, reflected waves (at a basic frequency or other frequency) and/or, or a combination of the aforementioned as, for example, the impedance of the plasma process. The monitored parameter may be different from the power supply signal that is adjusted. For example: If the power supply signal is a current-controlled signal, the monitored parameter may be a voltage. Or, if the power supply signal is a voltage- or power-controlled signal, the monitored parameter may be a current. The monitored parameter can be the voltage of one of the targets against the potential of the plasma chamber, which may be ground or earth. The monitored parameter can additionally be the voltage of the other target against the potential o