Fabrication And Research Of Field Emission Array Cathode Based On Nanospheres Ligthography

The field emission array cathode(FEA)has the advantages of instant start,low power consumption,and room temperature operation.It can be used as the electron source of the X-ray tube to effectively reduce the size of the device and improve the performance of the device.Si-LaB6 composite FEA can effectively combine the mature micro-nano manufacturing process of silicon and the excellent field emission characteristics of LaB6 film.Thus it is a potential field emission cathode structure.Traditional Si-LaB6 FEA preparation generally uses micro-nano patterning technologies such as optical lithography and electron beam lithography(EBL),thus the integration is difficult to exceed 106tips/cm2,resulting in high cost and poor field emission performance.Nanosphere lithography(NSL)is a low-cost,high-yield,and highly integrated micro-nano patterning technology.The FEA prepared by NSL has an integration level of at least 107tips/cm2.It is expected to increase the field emission current density by increasing the array density and significantly reduce the cost of FEA preparation,which is helpful to the commercial application of FEA.This thesis uses NSL technology to prepare Si-LaB6 FEA for the first time,which provides a new idea for FEA preparation in the field of LaB6 field emission cathode to reduce costs and improve performance.The thesis has carried out a series of exploratory work around the process and parameters of using NSL technology to prepare Si-LaB6 FEA that meets the performance requirements,including:1.Theoretical design of Si-LaB6 FEA.The thesis selected the cylindrical emitter structure and the corresponding process plan;designed the FEA array density,and chose to use microspheres's diameter of 2?m in NSL technology;used Opera-3D to establish the Si-LaB6 FEA numerical model,and simulated the influence of height,diameter,and LaB6 thickness on the field emission performance.In this chapter,conclusions that have theoretical guiding significance for the experiment are drawn:(1)Si-LaB6 FEA mainly relies on the edge of the LaB6 film on the top of the Si column to generate field emission;(2)The diameter of ideal cathode emitter is 0.8?m,and the height is at least 1.7?m;(3)The thickness of LaB6 has little effect on the field emission performance.2.Using NSL technology to prepare Si-LaB6 FEA.The process plan was designed,and the appropriate process plan was selected according to the relevant pre-experimental results;the paper discussed each process step and some key process parameters,and finally prepared a Si-LaB6 FEA cathode with emitter diameter of about 0.8?m,height of about 2.2?m and the density of about 2.68×107 tips/cm2.Finally the surface morphology was characterized by SEM and EDS.3.Design and manufacture the field emission performance test system of the diode,and conduct the field emission performance test on the prepared Si-LaB6 FEA sample.The test results show that the Si-LaB6 FEA sample has a maximum field emission current density of 458mA/cm2 measured under a vacuum of 8×10-5 Pa,and the field enhancement factor calculated according to the FN characteristic curve is 4.64×104,which is much higher than the existing report using photolithography.