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Plasma-assisted Atomic Layer Deposition

The aim of the project is to study the extension of the presently very relevant atomic layer deposition (ALD) technique with plasma processes. It is expected that this plasma-assisted ALD technique will open up new routes in thin film growth such that the typical ALD advantages such as ultimate growth control, extremely high conformality and good uniformity, will be extended with new advantages such as an increased choice in materials and precursors, higher throughput processing, and processing at reduced substrate temperatures. This will lead to a broader range of ALD-like processes which will form a better alternative for the "traditional" chemical and physical vapor thin film synthesis methods. The application of ALD-like processes yield solutions to several key technological problems in newly emerging technologies which more and more require ultimate control of film growth.

One of those emerging technologies is the deposition of thin seed and barrier layers in copper interconnect structures. At the moment, the most researched material for application in barrier layers is tantalum (Ta) and its nitride (TaN). Although these materials can be readily deposited using physical vapor deposition (PVD), the continuing downscaling requires a step towards ALD. With "traditional" ALD only TaN can be deposited, for the deposition of single metal element layers like Ta, one has to resort to plasma-assisted ALD. Another material of interest is Al2O3 which has applications as high-k dielectric in gate stacks and high-density capacitors but also as moisture diffusion barrier for OLED displays and surface passivation layers for crystalline silicon solar cells. Besides these applications many new applications are emerging due to the miniaturization trend which is prevalent in microelectronics and related technologies.

A more thorough overview of (plasma-assisted) ALD can be found in the following ECS transactions paper. For a description in Dutch read this NEVAC article. For a short overview in Dutch, read this NEVAC abstract.

  • the development of plasma-assisted ALD processes for metal oxides (Al2O3, HfO2, TiO2, Ta2O5, Er2O3, SrTiO3, Co3O4, PtO2, etc.), metal nitrides (TiN, TaN, Ta3N5, etc.) and metals (Ru, Pt, Co, etc.),
  • the development of related processing hardware (deposition tools, precursor injection, online process diagnostics),
  • mechanistic studies of plasma-assisted ALD using a combination of diagnostics (in situ spectroscopic ellipsometry, quartz crystal microbalance measurements, quadrupole mass spectrometry, optical emission spectroscopy, infrared spectroscopy),
  • application of ALD films in a broad range of technologies:
    - 3D integration and system-in-package
    - Gate stacks
    - High density capacitors
    - OLEDs/plastic electronics
    - Solar cells
    Solid state batteries
    - Adhesion and protective coatings
    - Etc.

At the moment the following remote plasma ALD reactors are in operation in our group at the TU/e:

  • ALD-I (homebuilt reactor)
  • FlexAL (Oxford Instruments load-locked ALD reactor)
  • OpAL (Oxford Instruments open-load ALD reactor)

Staff member involved:

Collaboration with:

Funded by: