A method for simulating Atomic Force Microscope nanolithography in the Level Set framework

During the last decades it has been shown that the Atomic Force Microscope (AFM) can be used in non-contact mode as an efficient lithographic technique capable of manufacturing nanometer sized devices on the surface of a silicon wafer. The AFM nanooxidation approach is based on generating a potential difference between a cantilever needle tip and a silicon wafer. A water meniscus builds up between the tip and the wafer, resulting in a medium for oxyions to move due to the high electric field in the region. A simulator for nanooxidation with a non-contact AFM, implemented in a Level Set environment, was developed. The presented simulator implements the growth of thicker oxides by analyzing the potential, electric field, and ion concentrations at the ambient/oxide and oxide/silicon interfaces, while the growth of thin oxides assumes a single liquid/silicon interface, which is modeled as an infinitely long conducting plane. The nanodot shapes have been shown to follow the electric field and hence the surface charge distribution shape; therefore, a Monte Carlo particle distribution for the surface charge density is generated for two-dimensional and three-dimensional topography simulations in a Level Set framework.

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► A local oxidation nanolithography simulator is created in the Level Set framework.
► 3D simulations include oxide–ambient, oxide–silicon, and trapping layer interfaces.
► Potential and electric field between the needle tip and the substrate is calculated.
► Nanodot shape generated to follow the surface charge density at the silicon surface.
► Monte Carlo particle distribution for surface charge density is calculated.