| The extreme micro and nano fabrication methods directly determine the degree of integrated devices,and the degree of integrated devices is directly related to the development of the national science and technology level.In the fabrication of micro and nano structures below 10 nm,the traditional lithography technology has been difficult to achieve the resolution requirements.There are only three direct lithography techniques with high resolution of micro and nano fabrication: electron beam direct writing,ion beam direct writing,and proton beam direct writing.All of these direct lithography techniques are difficult to achieve the required dose of micro-nano structure formation due to the low deposition dose of individual particles,and micro-nano structures are fabricated by increasing the number of particles exposed.Exposure of multiple particles will introduced errors in the incident position resulting in low resolution.Exposure of a single heavy ion may directly meet the dose required for nanostructure formation,reducing the positional errors introduced by multiple particles and thus producing higher resolution micro and nano structures.In this thesis,the theory of micro-nano fabrication based on single heavy ion exposure was established,the fabrication of nanowires and various nanopores was developed,and the transport behavior of DNA molecules in polymer nanopores was studied based on the biconical nanopore.These works have great scientific significance and application value in the theoretical basis of single ion micro and nano fabrication and extending the application of heavy ion beams.Firstly,the energy deposition mechanism of individual heavy ions in materials is investigated.Based on the energy deposition model,the individual ion radial dose distribution model was established.A single heavy ion exposure can reach the critical value of lithographic dose in the nanometer scale around the tracks,which provides theoretical support for the application of the single heavy ion exposure in nanostructure preparation.Sub-5 nm nanowire structures were successfully prepared by single-ion exposure in the collaborative study.The single-ion radial dose distribution model combined with heavy-ion linear energy transfer(LET)was used to establish the relationship between heavy-ion exposure parameters and the dose required for the formation of nanostructures.The resolution of the nanowire structures formed by the exposure far exceeds that of other direct lithography methods.It has been demonstrated high-energy heavy ion exposure has the capability of extreme fabrication for nanostructure.Then we fabricated individual polymer nanopores and individual graphene/polymer nanopores and investigated their etched states.We successfully accelerated the etching rate of polymer nanopores by controlling the applied voltage.The PMMA/graphene structure was also used to transfer graphene to polymer nanopores to verify the feasibility of heavy ions to prepare graphene/polymer composite nanopores.Finally,graphene/polymer nanopores were successfully prepared,providing an experimental basis for the preparation of multiple types of nanopores by the individual heavy ion.Finally,the application of track etched nanopores in molecule detection was studied.In comparison with single conical nanopore,the double conical polymer nanopores not only enhance the etching rate,but also protect the tip nanopore and extend the service life of polymer nanopores.We have successfully measured the DNA molecule signal and analyzed its translocation events by the biconical polymer nanopore for DNA molecule detection.In this study,the application of single polymer nanopores prepared by single heavy ion is extended,and the application system of polymer nanopores prepared by heavy ion track etching is improved. |
