Wafer-level sensor structure for measurements of the ion energy distribution function and the ion angle distribution function in low-pressure plasmas

• Applicants: Professor Dr.-Ing. Thomas Mussenbrock; Dr.-Ing. Sven Zimmermann
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2017 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 335529250

• Final Report Year: 2022

Final Report Abstract

For the first time, the ion angle distribution function (IADF) of a plasma could be analyzed by means of microelectromechanical systems (MEMS). The measurement method is based on a piezoelectrically actuated, perforated plate, which is tilted to select the ion incidence angles. In order to cover typical ion angle distribution functions in their entire width, the MEMS element is operated resonantly in the kilohertz range, since only angles < 1° could be covered in quasi-static operation. The ion currents are measured time-averaged over several periods. As a result, the ion angle distribution is not directly accessible, but must be determined iteratively via parameter variation of the assumed ion angle distribution function. The corresponding plasmas of the measurements were simulated numerically and ion trajectories through the lattice stack were calculated. This novel measurement principle is disruptive compared to previous sensor concepts in terms of geometric dimensions, resolution and degrees of freedom of the measurement. This opens up new possibilities for the measurement of IADF in basic research as well as from a application perspective, not least because the sensor can also be manufactured completely from CMOS-compatible materials. In plasma reactors, such as those used in microelectronics production, it has not yet been possible to obtain measurement data due to the strong coupling of interference signals into the sensor system. Follow-up investigations should give appropriate weighting to the aspect of electromagnetic shielding of the sensor system, also together with cooperation partners. Furthermore, the combination of the grid stacks for the measurement of the ion energy distribution function with the ion angle sensor, which are produced by means of silicon technology and researched in the project, is open. Further undesired effects such as electrical charging can be analyzed by simulations. In an industrial cooperation, the silicon grids will be examined from 06/2022 onwards with regard to their concrete applications in measuring systems for low-pressure plasmas. The industrial partner has also shown interest in the sensors for measuring the ion angle distribution function. This cooperation will be continued after patenting of the measurement principle by the participating universities.

Publications

• MEMS based IEDF/IADF sensing: Kinetic analysis of the ion dynamics inside the sensor". In: APS Annual Gaseous Electronics Meeting Abstracts. APS Meeting Abstracts. 2018, GT1.050
  K. Roessel, B. Berger, T. Mussenbrock, M. Melzer, C. Stoeckel und S. Zimmermann
  
• Observation of the generation of multiple electron beams during a single sheath expansion phase in capacitive RF plasmas. Plasma Sources Science and Technology, 27(12), 12LT02.
  Berger, B.; You, K.; Lee, H.-C.; Mussenbrock, T.; Awakowicz, P. & Schulze, J.
  
• A generic method for equipping arbitrary rf discharge simulation frameworks with external lumped element circuits. Journal of Applied Physics, 125(17).
  Schmidt, Frederik; Trieschmann, Jan; Gergs, Tobias & Mussenbrock, Thomas
  
• Sensing IEDFs and IADFs in radio-frequency discharges using a MEMS-based sensor stack". In: DPG-Frühjahrstagung der Sektion Materie und Kosmos (SMuK). 2019
  K. Roessel, B. Berger, T. Mussenbrock, M. Melzer, C. Stoeckel und S. Zimmermann
  
• Voltage waveform tailoring in radio frequency plasmas for surface charge neutralization inside etch trenches. Plasma Sources Science and Technology, 28(7), 075017.
  Krüger, Florian; Wilczek, Sebastian; Mussenbrock, Thomas & Schulze, Julian
  
• Charged particle dynamics and distribution functions in low pressure dual-frequency capacitively coupled plasmas operated at low frequencies and high voltages. Plasma Sources Science and Technology, 29(7), 075014.
  Hartmann, P.; Wang, L.; Nösges, K.; Berger, B.; Wilczek, S.; Brinkmann, R. P.; Mussenbrock, T.; Juhasz, Z.; Donkó, Z.; Derzsi, A.; Lee, Eunwoo & Schulze, J.
  
• Electron dynamics in low pressure capacitively coupled radio frequency discharges. Journal of Applied Physics, 127(18).
  Wilczek, S.; Schulze, J.; Brinkmann, R. P.; Donkó, Z.; Trieschmann, J. & Mussenbrock, T.
  
• Control of electron velocity distributions at the wafer by tailored voltage waveforms in capacitively coupled plasmas to compensate surface charging in high-aspect ratio etch features. Journal of Physics D: Applied Physics, 54(25), 255202.
  Hartmann, P.; Wang, L.; Nösges, K.; Berger, B.; Wilczek, S.; Brinkmann, R. P.; Mussenbrock, T.; Juhasz, Z.; Donkó, Z.; Derzsi, A.; Lee, Eunwoo & Schulze, J.
  
• Ion dynamics in capacitively coupled argon–xenon discharges. Plasma Sources Science and Technology, 30(6), 065019.
  Klich, M.; Wilczek, S.; Janssen, J. F. J.; Brinkmann, R. P.; Mussenbrock, T. & Trieschmann, J.
  
• Static High Voltage Actuation of Piezoelectric AlN and AlScN Based Scanning Micromirrors. Micromachines, 13(4), 625.
  Stoeckel, Chris; Meinel, Katja; Melzer, Marcel; Žukauskaitė, Agnė; Zimmermann, Sven; Forke, Roman; Hiller, Karla & Kuhn, Harald
  
• Validation of the smooth step model by particle-in-cell/Monte Carlo collisions simulations. Plasma Sources Science and Technology, 31(4), 045014.
  Klich, Maximilian; Löwer, Jan; Wilczek, Sebastian; Mussenbrock, Thomas & Brinkmann, Ralf Peter