Fabrication And Research Of Silicon Tip Arrays Based On Nanosphere Lithography

Compared to traditional hot cathodes,field emission is a form of cold electron emission that relies on an external electric field on the cathode surface and does not require any other energy to cause electrons to escape from the cathode surface.The field emission cathode vacuum device based on this principle has the advantages of fast starting speed,low power consumption,no heating,and long service life.The traditional silicon tip field emission arrays are usually prepared by optical lithography and electron beam lithography.The cost is high and the density of the prepared tip is about 106tips/cm2.The array density has a great impact on the field emission current.Nanosphere lithography（NSL）is a low-cost and material compatible micro-nano structure manufacturing technology,which can improve the field emission current by changing the array density.According to its microsphere assembly technology,the density of the field emission arrays prepared can reach 107 tips/cm2,which is at least an order of magnitude higher.The improvement of field emission current density is conducive to the wider application of field emission cathode vacuum devices.In this thesis,the material and structural parameters of the field emission silicon tip arrays are analyzed and optimized using the NSL technology and the Opera-3D simulation software.On this basis,the micro-nano processing process is designed,and the relevant parameters are studied and explored.Finally,the field emission performance of the prepared samples is tested.The main contents include:1.Structural design of silicon tip arrays based on nanosphere lithography technology.In this thesis,the Opera-3D simulation software is used to establish a local field emission silicon tip arrays model,determine the appropriate structure,cathode material and field emission parameters,and then analyze the influence of the height and curvature radius of the silicon tip on the field emission current through simulation.Select the theoretically optimal material and structural parameters as well as the height and radius of curvature of the silicon tip to guide the subsequent experimental preparation process.2.The silicon tip arrays were fabricated by NSL technology.Use diameter 2μm standard PS microspheres were self-assembled,the mask preparation process was designed,and the process parameters of magnetron sputtering,electron beam evaporation,reactive ion etching and thermal oxidation were optimized and studied,and the sample surface was characterized by scanning electron microscopy（SEM）.Finally,a silicon tip field emission cathode with good morphology and array density of 10⁷ tips/cm² was prepared.3.Field emission performance testing.Design and build a field launch testing platform.The test results show that under high vacuum(10^-5 Pa),the cathode anode spacing is about 0.1 mm,and the maximum anode voltage is 2400 V.The maximum field emission current density of the silicon cone array can reach 0.5 m A/cm².