Correction Algorithm Research And EDA Software Development For Electron Beam Lithography Based On SaaS And Parallel Computing

Electron beam lithography and its electronic design automation(EDA)software affect the development of integrated circuits,micro electron mechanical systems processing and other fields.Electron beam lithography has the characteristics of high resolution,but the proximity effect and fogging effect in the process of electron beam lithography hinder the improvement of fabrication precision.With the inclusion of electron beam lithography software in the Wassenaar Arrangement,and more and more science and technology enterprises and universities in China have been included in the"Entity List"by the United States Department of Commerce,electron beam lithography related technologies and EDA software have been further intervened or even prohibited from being exported to China.In order to prevent the related technologies of electron beam lithography from being restricted,it is very important to independently study the correction algorithm of electron beam lithography and develop domestic EDA software.With the feature size keep shrinking,it is necessary to realize more accurate simulation and correction of electron beam lithography.Therefore,the simulation algorithm of electron beam exposure process is studied in this paper,Monte Carlo method is used to simulate the scattering of electron beam,and the calculation result is fitted into point spread function(PSF)by high robust genetic algorithm,and Open Multi-Processing(Open MP)is used to accelerate it.Then,algorithms of layout information processing,results of exposure and electron beam lithography correction are studied,and the fast Fourier transform(FFT)is used to reduce the time complexity of convolution operation from O(N~2)to O(Nlog(N)).Finally,a complete process and algorithm of highly robust electron beam lithography correction is explored.There is a large amount of calculation to complete the whole process of electron beam lithography correction,and it is costly and time-consuming for software users to build local clusters,so this paper adopts the software as a service(SaaS)software delivery model,and develops an EDA software which can realize large-scale parallel,large-scale layout calculation and small feature size correction.The algorithm and software implementation of this paper uses C++,Python and other programming languages,a total of more than 20000 lines of code.In order to further simulate and analyze the result after electron beam exposure,this paper studies the simulation algorithm of the resist development process,as well as a variety of indicators and calculation processes for analyzing the correction result of electron beam lithography.First of all,through calculation and comparison,it is found that the corrected energy deposition density distribution pattern is more uniform and the development pattern is more complete.Then,this paper also studies the edge placement error(EPE),the line edge roughness(LER),the line width roughness(LWR)and the critical dimensions(CD)to quantitatively analyze and locally evaluate the correction result.By calculation and comparison,it is found that the calculated value of EPE is reduced from 26.5nm to 1.64nm after correction.It means that the corrected development pattern is closer to the target pattern,and the edge of the corrected development pattern is smoother,and the line width is closer to the target value.According to the calculation results of the above analysis indexes,the correction algorithm described in this paper greatly improves the resolution of electron beam lithography.