Fabrication of nanoscale step height structure using atomic layer deposition combined with wet etching

The current techniques used for the fabrication of nanosteps are normally done by layer growth and then ion beam thinning. There are also extra films grown on the step surfaces in order to reduce the roughness. So the whole process is time consuming. In this paper, a nanoscale step height structure is fabricated by atomic layer deposition (ALD) and wet etching techniques. According to the traceable of the step height value, the fabrication process is controllable. Because ALD technology can grow a variety of materials, aluminum oxide (Al₂O₃) is used to fabricate the nanostep. There are three steps of Al₂O₃ in this structure including 8 nm, 18 nm and 44 nm. The thickness of Al₂O₃ film and the height of the step are measured by anellipsometer. The experimental results show that the thickness of Al₂O₃ film is consistent with the height of the step. The height of the step is measured by AFM. The measurement results show that the height is related to the number of cycles of ALD and the wet etching time. The bottom and the sidewall surface roughness are related to the wet etching time. The step height is calibrated by Physikalisch-Technische Bundesanstalt (PTB) and the results were 7.5(1.5 nm, 15.5(2.0 nm and 41.8(2.1 nm, respectively. This research provides a method for the fabrication of step height at nanoscale and the nanostep fabricated is potential used for standard references.