Font Size: a A A

Study On Two-Dimension Electron Multiplier And New Technology

Posted on:2009-10-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y J GaoFull Text:PDF
GTID:1118360278950772Subject:Physical Electronics
Abstract/Summary:PDF Full Text Request
Low light level night vision technology to widen human visual range appeared since 1960s.With the continuous appearance of new conceptions,new ideas,new processes and new technologies,night vision devices and technology have rapidly developed.Becaues of the requirements of photoelectron technology,two demision electron multipliers are widely applied especially such as microchannel plates(MCP) and microphere plates(MSP).The MCP is two dimension electron multiplier that has the thin slice style honeycomb shape composition gathering through thousands and hundreds passageways.It is widely used in applications of imaging multiplication.Because response to nucleus particles and other short wave radiation,the MCP has found the important applications in the field of night vision in low-level light,high resolution kinescopes,oscilloscopes,photoelectronic multiplier tube,image photon counter,and detecting particle.So far the image multipliers have experienced for three generations in its development,and the MCP in the fourth generation become appeared.That also bring about a revolution in the MCP related to the image tube.The performances of MCP have been improved on and the related new technologies have emerged continuously.The work on MCP has a relatively high theoretical and practical value to studying the new MCP devices and improving on its performances.This paper is concerned with the theoretical and experimental study on new technologies including the advanced technology of MCP(AT-MCP),the microphere plates (MSP) and the micromachining for Si microchannel array.1.The development survey and the application background of the microchannel plates electron multiplier are introduced in this paper.And the new technologies of MCP are: researched.The main characteristics and the present research situation of MCP new technology are made a systematic description.2.Study on advanced technology of microchannel platesAdvanced technology of microchannel plates,AT-MCP,is a new technology of MCP process,which has many merits compared with the old process and had be believed to be a revolution in MCP process,proposed by Galileo Co.early in 1990s.Two key technologies of AT-MCP are the formation technology of silicon micropore deep-channel array and the manufacture technology of continuous dynode.By multiplex induction coupled plasma(ICP) etching,we carried out several experimental researches and process exploration for micromaching the silicon microchannel arrays.Some important process parameters,such as gas switching time,flow rate,etching rate,were analyzed.The study results reported here had demonstrated the mechanism of lateral etching,sidewall passivation and gas micro-transport in micromaching the microchannel arrays.We had prepared the first domestic sample of AT-MCP in laboratory,and tested its electronic gain and body resistance.We had carried out all the steps in the new process flow that was the formation of MCP's mask→wafer grinding and polishing→oxidization andd eposition→photolithography→etching mask→microchannel array etching→conducting layer→dynode layer→plating electrode→check and test,and proved the feasibility of AT-MCP.The footing effect and lag effect occurred in the ICP etching process were also systematically studied. These process problems had reappeared in the AT-MCP process though these problems had be solved in the field of integrated circuits process and microelectromechanical system (MEMS).The lag effect and the footing effect with process parameters were systematically studied in the ICP etching process.The method that platen power was moderately decreased in the process of high ratio deep-channel array can be influenced to decrease the footing effect.The continuous dynode was fabricated by LPCVD and sensitizing technology.The relationships between secondary emission coefficient and process parameters or between body resistance and process parameters were carefully studied.Our experiments and analysis results had led the author to believe that the deep pore structure with high aspect ratio and the deep trench differ greatly in etching process.The former is a closed structure for the gas transport,and the latter is a open structure,so the process of deep hole structure is a puzzle in micromaching and MEMS technology.3.Electrochemical etching for silicon microchannel arrayThe electrochemistry(EC) and photoelectrochemistry(PEC) of semicon-ductors has played an important role in the development of integrated circuit(IC) technology.Many of the processes used in IC manufacturing are based on electrochemical principles.So far Photoelectrochemical(PEC) etching researches were focus onⅢ-Ⅴsemiconductors electronic and photonic devices,silicon MEMS devices and silicon three-dimensional micromachining.In 1999,C.P.Beetz in Nanosciences Corporation of American proposed a new MCP process by EC and PEC techniques.Except that the EC or PEC etching was used to fabricate the microchannel arrays,the other.steps of new process were similar to the ones ofAT-MCP.The electrochemical etching system consisted of a potentiostat,a three electrodes electrolytic cell and a light exposure system.According to the electrochemical etching process flow that was wafer selection→grinding and polishing→oxidization→photolithography→pit precursor positioning→microchannel EC or PEC etching,several experiments for the silicon microchannel arrays were performed.The samples of silicon microchannel array with 3.0-4.0μm of pore diameters and more than 40 of aspect ratio were obtained by EC and PEC etching.We had made an attempt to deal with the structure, physical and chemical characteristics,and electrochemical properties in the interface of silicon and HF electrolyte,verify the principles of anodic corrosion in EC and PEC process, study the mechanism about nucleation and growth for macropore silicon with high aspect ratio theoretically.The obtained results were of great value in EC micromaching process design and theoretical researches.The creationary works about the new technologies in MCP process had been done in this paper,and summarized as follow:Two-dimension electron multiplier MCP's deep micropore array on silicon substrate was attained in the paper.Lots of very perfect two-dimension deep electron multiplier channels were gained by optimizing photo-electrochemical technics parameters,of which side length of square hole was 3.0-4.0μm and ratio of length to diameter of MCP-channel was more than 40 and this had no other internal report.According to Si/HF ethcing system,based on the local current burst theory,the authors had developed a variational method to explain the hole nucleation and growth in the process of electrochemical etching for silicon microchannel arrays.And firstly the process micromechanism of deep-channel array on p-type silicon was obtained by experimental verification.The process current density J is 0.58mA/cm~2 theoretically,but in this experiment the practical current density J is 0.60mA/cm~2 at the constant voltage of 1.85v. The consentaneous conclusion between theory and practical was obtained that the relative error is 3.4%and this had no oilier report.It is a key step to adjust the direction of the micropore array to the crystal orientation of Si substrate during the process of forming pre-determinate square patterns before PEC etching process.The electrochemical reaction strongly depends on the light intensity and HF concentration.These optimized experimental conditions were obtained and the three factors was very key to process deep-channel array on n-type silicon.It is demonstrated that these works were very valuable to further study and fabricate the deep micropore channel array of MCP.4.The development survey and the application background of the MSP electron multiplier are introduced in this paper.The main characteristics of MSP and the present research situation of process technology are made a systematic description.The MSP is a sintered plate of 20-60μm-diameter glass beads.The electron multiplicationprocess takes place in the interstices between these beads when a voltage is applied between the front and rear surfaces,which are covered with thin layers of nichrome. Despite the similarity in operating principle there are some significant differences between MCPs and MSPs.Advantages of MSPs are higher gain and less stringent vacuum requirements.The absence of long electron travel paths inside MSPs minimizes ionic feedback.A disadvantage of MSPs is lower spatial resolution due to the spreading out of the electron avalanche within the MSP,and also due to the randomness of the sphere stacking within the plate,as well as the larger unit sizea.Another disadvantage is the lower geometrical open area ratio than MCPs'.In this paper,we analyze thick cumulus,sintering phenomenon,dynamics and the law of mass transfer in the process of MSP body formation.Base on the theory of predecessor, we eatablish twin-ball mode of sintering speed rate and deduce rate equation of sintering.We make experiments MSP green body,manufacture MSP body and meet the demands basically. In the end,we analyse and discussed some phenomena in the course of experiment and the conclusion of the experiment.To the existing problem in the experiment,we put forward our idea and suggestion.The innovation point is that the process thoery of MSP is systematically analyzed and modified so that it is beneficial to the process technology of MSP.
Keywords/Search Tags:MicroChannel plate, Micromachining, Silicon electrochemistry, Macropore silicon, Deep-channel array, Microphere plate
PDF Full Text Request
Related items