Fabrication Of X-ray Zone Plates With Large Aspect Ratio

X-ray microscopic imaging technology is widely used in microelectronics,life sciences,materials science and other fields because of its high resolution,high penetration,various image mechanisms and environmental friendly.Zone Plate is the key component in the X-ray microscopy imaging system.The outermost zone width is important for the resolution of imaging.A sufficient thickness(or height)of zone plate is required to obtain high diffraction efficiency under high energy density.But,it is complicated and expensive by traditional process.In this thesis,X-ray zone plate have been prepared through atomic layer deposition and focus ion beam cutting technique.The main works of this thesis can be summarized as follows:(1)The relationship between the height of zone plate,X-ray energy and diffraction efficiency have been calculated.We have simulated the X-ray zone plate diffraction efficiency for different materials(HfO2/Al2O3,HfO2/SiO2,Ir/Al2O3,Au/air)under different X-ray energies(5keV,8keV,10keV,15keV,20keV,24keV).Based on the results,the X-ray zone plate structure parameters and the preparation processes have been decided.(2)The preparation of Al2O3 and HfO2 films through atomic layer deposition(ALD)technique have been investigated.The growth rates,atomic ratio and surface roughness of Al2O3 and HfO2 films at the substrates temperatures of 100℃-300℃ have been evaluated.(3)The control precision of the Al2O3 and HfO2 film thickness on silicon and tungsten substrates have been investigated through ALD technique.The multilayer films of Al2O3 and HfO2 have been prepared on a 30 μm-diameter electrochemically polished tungsten filament using ALD.And then,the sample was cut through focused ion beam(FIB)technique.As a results,we have obtained the X-ray zone plate with a height of 10μm(the height is not limited),an outermost ring width of 10 nm and an aspect ratio of 1000.It shows that X-ray zone plate with large aspect ratio can be fabricated by this way.