AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS-MoP

Paper PS-MoP31
Atomic Layer Etching of Silicon using a Low Angle Forward Reflected Ar Neutral Beam

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: S.D Park, Sungkyunkwan University, South Korea
Authors: S.D Park, Sungkyunkwan University, South Korea
D.H. Lee, Sungkyunkwan University, South Korea
G.Y. Yeom, Sungkyunkwan University, South Korea
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Atomic layer etching (ALE) is expected to be a very important process for the fabrication of future nano-scale devices, because current dry etching techniques could not strictly control the etch depth in nono-scale 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 Cl2 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 Cl2 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 Cl2 gas exposure time, Ar neutral beam irradiation time, Ar neutral beam energy, etc. It is expected that the etch rate per cycle increased with the chlorine supplying time and saturated to a constant value of about 1.36â"« per cycle which corresponds to the one mono-layer thickness of Si. The 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.