Researches On The Characteristics Of Laser-assisted Discharge Z Pinch Plasma

Extreme ultraviolet lithography is the most promising lithography technology for making chips with characteristic sizes smaller than 22nm,and Extreme ultraviolet source is an important part of extreme ultraviolet lithography technology.Laser assisted discharge plasma extreme ultraviolet source is a method to obtain Extreme ultraviolet source.It can use any traditional solid material as the required material for discharge plasma.It has the advantages of simple device structure,high power of extreme ultraviolet source and high conversion efficiency,so it has a broad application prospect.Theoretically,the physical characteristics of laser ablation plasma in the laser trigger phase,the z-pinch process of plasma in the discharge phase,and the plasma output extreme ultraviolet radiation are analyzed.Experimentally,Firstly,we designed and built an experimental setup of laser assisted discharge plasma.The effects of different electrode polarity on Z-pinch plasma were investigated.By comparing the time evolution process of discharge plasma and the extreme ultraviolet radiation when the target material is anode and cathode,respectively.We can know that the target material as cathode is benefit to generate discharge z-pinch plasma and extreme ultraviolet emission.Secondly,the plasma dynamics in the initial stage of laser assisted discharge Z-pinch plasma was studied.In the experiment,we found that there are two peak signals before main discharge current starts to rise.By using the paper to block the two electrodes,we obtained that the two signal come from cathode and anode of the electrode,respectively.In addition,we also measured the expansion plasma velocity of1×10~5m/sduring discharge.Finally,the plasma dynamics in pinch stage of laser assisted discharge Z-pinch plasma was studied.The effects of discharge parameters(discharge current and electrode separation)and laser parameters(laser energy and laser focused spot size)on the characteristics of Z-pinch plasma were investigated.The results are as follows:when initial supply direct-current voltage is 7kV,electrode separation is 5mm,laser focus is 50mm from the target surface,and the laser energy is 90mJ,the quality of pinch plasma is better and extreme ultraviolet emission is the stronger.