Modeling remote inductively coupled plasmas for plasma-enhanced atomic layer deposition

Abstract

Remote inductively coupled plasmas (ICPs) are utilized in atomic precision processing as they provide the requisite flux of reactive and energetic species. Their remote nature helps mitigate damage to the substrate by energetic ions and photons produced in the plasma. However, the attributes of these plasma sources are not well characterized, particularly in the spatial afterglow where the growth substrate is located. This work focuses on modeling a commercially available remote ICP source with a 2D hybrid plasma model in pure Ar. The results of the model are benchmarked against spatially resolved Langmuir probe measurements in Ar and achieve good agreement with the measurements in the afterglow for a variety of operating conditions. The benchmarked results provide confidence in the model, which can then be used to better understand the physics in the spatial afterglow. In the remote ICP system, capacitive power coupling plays a large role in determining the plasma properties in the spatial afterglow, where a small amount of capacitive power coupling is responsible for elevated electron density, plasma potential, and electron temperature. These results are discussed in the context of atomic layer deposition (ALD). While this work discusses pure Ar plasmas, capacitive power coupling in the afterglow will affect mixtures with molecular gases used in ALD.