Atom Lithography Based On Atoms Localized By Standing Wave Field

In the development of lithography,Abbe diffraction limit will limit the resolution of lithography,so many lithography methods have been proposed about resolution enhancement,such as the use of extremely short wavelength DUV or EUV light source,entangled photon pairs,multi-photon absorption media,electron beam,ion beam,etc.However,these methods not only improve the resolution but also bring many matters.For example,the high energy light source will cause damage to the substrate,and the light source or other materials are too complex to be realized at the current experimental level.In contrast,using atoms as photolithographic medium has the characteristics of lower energy,shorter de Broglie wave and higher resolution,and is relatively easy to implement in experiments.At present,the relatively mature methods of atomic lithography include the method of directly depositing atoms on the substrate by using the potential well of standing wave field and pumping atoms to metastable state to etch substrate.Their resolution is less than 100 nm.Other methods,such as using the trapped state of atom and multi-oscillations between energy levels,have only been experimentally confirmed and are still in the laboratory stage.The manipulation of atoms through light fields has evolved over the decades in fields such as laser cooling,Bose-Einstein condensation,and trapping neutral atom.In this paper,an atomic lithography method with adjustable resolution is proposed based on the manipulation of atoms by light field.The advantage is that the resolution is high and the required light field and atomic energy level are easy to achieve experimentally.The main research contents are as follows:1.The three-level Λ-type atomic system is coupled by a weak probe field and a strong standing wave field,and then the position distribution of excited atoms is calculated.The results show that some parameters of the system can affect the position distribution of excited atoms.We analyze the effect of two field detuning on the position distribution of excited atoms.Among them,it is observed that the position distribution period of excited atoms can reach λ/4(λ is the wavelength of standing wave field),and then the conditions of the generation of λ/4 period are explored,and the relationship between the system parameters and atomic distribution peak is obtained.By means of this relation,the position of the peak can be determined artificially by changing the system parameters.Using this property,we discuss its application in atomic lithography.Through theoretical calculation,the resolution of this method can be less than 0.02λ,contrast ratio is more than 95%.Then,for the realization of arbitrary two-dimensional atomic lithography,we propose to use the phase shift of the standing wave field for manipulation.2.In the same three-level Λ-type atomic system,we introduced additional standing wave fields in two directions,making the three fields orthogonal to each other for obtaining the distribution of atoms in three-dimensional space.We detect the absorption of the field to reflect the distribution of atoms in space.We investigate the influence of detecting field detuning on atomic spatial distribution and find two kinds of spatial distribution structures: stray shell structure and spherical structure.We explain why these two structures arise.The atomic distribution probability in unit space is plotted to explain the reason why the shell structure is double-layer when the probe absorption is taken as a fixed value.By observing the distribution of atoms in three-dimensional space from different angles,we conclude that the stray shell structure is more suitable for atom lithography,and the spherical structure is more suitable for atom localization.