AVS 50th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS-WeP

Paper PS-WeP8
Atomic Layer Etching of Silicon using a Low Angle Forward Reflected Ar Neutral Beam

Wednesday, November 5, 2003, 11:00 am, Room Hall A-C

Session: Poster Session
Presenter: S.D. Park, Sungkyunkwan University, Korea
Authors: S.D. Park, Sungkyunkwan University, Korea
D.H. Lee, Sungkyunkwan University, Korea
G.Y. Yeom, Sungkyunkwan University, Korea
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Atomic layer etching (ALE) is one of the important technologies for the fabrication of future nano-scale devices, because current dry etching techniques are not capable of etching with atomic layer resolution because of their high etch rates. In addition, relatively high energy of the ions can damage the crystal surface. Therefore, many studies on ALE of Si have been reported in recent years to develop a technique to etch materials layer-by-layer. But, these previous methods may show charging damage due to the charged particles such as positive ions and photons generated in the plasma. Therefore, in this study, ALE of Si was carried out using a sequential Cl@sub 2@ adsorption and an Ar neutral beam irradiation instead of ion beam. Low energy Ar neutral beam was generated by a low-angle forward reflected neutral beam technique. ALE of Si is a cyclic process consisting of 4 steps: (1) adsorption of Cl@sub 2@ on Si surface, (2) evacuation, (3) Ar neutral beam irradiation to the surface, (4) evacuation of etch products. The etch process parameters for optimizing the atomic layer etching of Si are Cl@sub 2@ gas exposure time, Ar neutral beam irradiation time, Ar neutral beam energy, etc. It is expected that the atomic layer etching of Si should be limited to 0.68 nm per cycle, which corresponds to the half mono-layer thickness of Si. The resulting step height and surface damage was estimated using transmission electron microscopy (TEM). The step height divided by the total number of ALE cycles yielded the etch rate per cycle. A scanning electron microscope (SEM) was used to observe as-etched Si profiles and an atomic force microscope (AFM) was used to analyze the surface topography.