Development Of Electron Beam Lithography EDA Tool For Proximity Effect Correction

The complete electron beam lithography process is complicated with long cycle times and interference factors such as proximity effects in the actual lithography environment.Experimenters need to simulate the electron beam lithography exposure process to improve the lithography accuracy and exposure success rate.In recent years,the U.S.Export Administration Regulations(EAR)and the Wassenaar Arrangement(WA)have both strictly controlled the export of computational lithography software to China,which is typical"stuck neck"technology.With this starting point,this thesis studies the Electronic Design Automation(EDA)software for electron beam lithography from scratch.First,this thesis introduces the research background and current situation of EDA software for computational lithography at home and abroad,and introduces the theoretical basis of the electron beam lithography process and its simulation physical model.The thesis analyzes the energy deposition distribution model of the electron beam lithography exposure process,selects the Monte Carlo to simulate the electron scattering process,and uses the approximation function to calculate the energy deposition density after exposure.Since the electron scattering process causes proximity effect and thus reduces the lithography accuracy,the exposure dose correction technology is recommended after studying different proximity effect correction methods in this thesis.Specifically,the exposure dose can be adjusted by“SPECTRE”,and at the same time,fast Fourier transform(FFT)is used to accelerate the convolution process in dose correction.It reduces its computational time complexity from O(N~2)to O(Nlog(N)).In this thesis,we use the threshold development model to obtain the post-exposure graph and use the edge placement error to represent the error between the graph before and after exposure.Second,this thesis proposes the software for simulating and optimizing electron beam lithography-HNU-EBL,writes about 29,000 lines of code,completes the development of functional modules such as Monte Carlo calculation,point spread function fitting,proximity effect correction,edge placement error and energy deposition distribution,and offers an easy-to-operate Graphical User Interface(GUI),and according to business logic,the modules are arranged into a directed acyclic graph without cyclic dependencies between modules,ensuring high cohesion within modules and low coupling between modules.In addition,this thesis also analyzes the structure of Geometry Data Standard Ⅱ(GDSⅡ)files for electron-beam lithography and preprocesses each of the six pixel data:"BOUNDARY","PATH","CIRCLE","SREF","AREF"and"TEXT".In the analysis and processing of graphical data,this thesis proposes a geometric visualization algorithm for polyline to complex polygon and completes the triangulation of arbitrary complex polygons,and uses the Vertex Buffer Object(VBO)drawing mode to realize the high-speed display of graphical information in GDSⅡ files.Finally,this thesis analyzes the computational performance of HNU-EBL and compares it with the mature commercial EBL software-Nano PECS.The results show that the computational speed of HNU-EBL is on average 1～2 orders of magnitude faster than that of NanoPECS.In this thesis,we analyzed the test strategy and determined the system test plan,and conducted complete system tests under 20 different test environments,which all completed the expected functions normally and fully met the software development requirements.This thesis provides a full-featured,good computing speed with high ease of use and high compatibility EDA software for electron beam lithography simulation and calculation,and the software has been released on http://www.ebeam.com.cn/and used by Huawei Technologies,Chinese Academy of Sciences,Fudan University and other institutions.