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