The Study Of Functional Electron-beam Resist And Its Device Applications

High-resolution functional nanostructures are widely used in many fields such as microelectronic device,plasmonic optics,biosensing and so on.It becomes more and more important to prepare the functional structures in nanoscale,which are the basis of these applications.Three steps are needed for preparing the functional structures:?1?high-resolution structures are firstly prepared in resist film by electorn beam lithography?EBL?;?2?functional materials are deposited on resist sample;?3?functional structures are acquired by pattern transfer process such as lift-off or etching process.As a mature preparation process,this technology can meet most of the application requirements in the laboratory.However,the technology is still needed to solve some problems including the lack of resolution,introduction of defects,the challenge of preparation of high-aspect-ratio structures and sub-10 nm lines.In order to solve the challenges,functional resist was provided for electron beam lithography process to define some functional nanostructure directly without the help of pattern transfer process.Based on the consideration,copper naphthenate solution and HAuCl₄/PVP compound solution are used as functional resist for e-beam lithography process to acquire high resolution conductive structure and transferrable gold nanoparticle arrays.At the same time,some traditional resist such as HSQ?Hydrogen silsequioxane?and PMMA?Polymethyl methacrylate?resist,will be transformed into high-resolution dielectric material and carbon structure with fluorescent property.These functional nanostructures have important device application value in optical and electrical aspects.?1?In most experiments,the conductive structures are usually fabricated by traditional lift-off technology.However,it is difficult for preparation of sub-10 nm structures.In our work,we use copper naphthenate as a functional resist to directly define line with 15 nm width.Then the sample was annealed in hydrogen atmosphere for acquiring graphene@copper line with about 7 nm width.The uniform structure has a high conductivity of 400 S cm^-1.Besides,the existence of graphene in sample lead to an ohmic contact between graphene and conductive structure.The copper naphthenate has some potential applications in electronic devices due to its low cost,simple fabrication process,high-resolution and high conductivity.?2?Due to its strong coupling effect of light,gold nanoparticles have been paid much attention in the field of plasmonic optics.And how to prepare transferrable crystalline gold nanoparticles is important for its applications.For this reason,we have developed HAuCl₄/PVP?polyvinyl pyrrolidone?compound resist.The compound resist can be patterned by electron beam lithography.Then an annealing process at 500?for 1 h was adopted to acquire crystalline gold nanoparticle arrays.It is convenient to transfer gold nanoparticles from substrate because of its hydrophobic properties.In our work,gold particle arrays were transferred to gold film decorated with monolayer crystal violet molecules.We find a huge Raman enhanced signal of crystalline molecules result from the coupling effect of gold nanoparticles and gold film.Abve all,the structure has potential applications in supersensitive detection.?3?Sensor is a very important tool for us to study the world.The controllable preparation of sensor is directly related to the accuracy of our understanding of the research objects.Fluorescence sensor is one of the typical sensors.The fluorescence materials have attracted extensive attention from researchers because it can be used to calibrate and analyze biochemical molecules.However,traditional fluorescence materials cannot precisely control the morphology and position in nanoscale,which poses a great obstacle to the high-precision material analysis.In this paper,the PMMA resist was irradiated by electron beam.Then the PMMA was transferred into graphene-like material containing oxygen and hydrogen atoms,which leads to a fluorescence property.The intensity and shape of fluorescence signal is sensitive for adsorption of external molecules such as NH₃?H₂O.Combining with its compatibility with other chemical molecules,we believe the fluorescence carbon material will have a huge application potential in the future.?4?Hydrogen silsesquioxane?HSQ?is a high-resolution negative resist with properties of high-aspect-ratio,low roughness,insulation characteristic after exposing.We define HSQ line with 20 nm width on the surface of CVD?chemical vapor deposition?MoS₂ sample.Then metal film was deposited by electron beam evaporation equipment.With the help of self-alignment technology,the channel length was directly defined by HSQ line.Many devices can be prepared in one substrate at the same time.No transfer process of semiconductor material was needed in whole fabrication flow.And it is useful to prepare short-channel device for system study of some new 2D materials,which is of great significance for the research of devices in the post-moore's law era.