Analysis Of The Distribution Of Doped Elements In FinFET With Atom Probe Tomography

With the size and structure of semiconductor devices becoming smaller and more complex,the characterization of semiconductor devices is becoming more and more difficult,especially the distribution of doping elements,which has been widely concerned by industry.Atom probe topography is gradually showing its great potential in semiconductor device analysis with its advantages of high resolution in three-dimensional direction,but it still faces many challenges in the research of FinFET devices.The samples used in this study include 6 samples doped with B,P and As respectively before annealing and after rapid annealing at 1100?for 30 s.The sample preparation method is using focused ion beam(FIB)from two directions:transverse and longitudinal.The experimental results show that:(1)In order to improve the success rate and quality of data,when using APT to characterize semiconductor materials,it is recommended to use experimental parameters of small laser energy,higher temperature,low pulse frequency and use SEM/TEM to assist data reconstruction.Separating extraction of lightly doped elements by mass spectrometry analysis of the region of interest can improve the quality of data analysis;(2)When APT is used to analyze the semiconductor materials with components with large differences in their evaporation fields,the ananlysis may suffer with local amplification effect and track overlaps.The influence of these two effects on APT data reconstruction can be effectively avoided by carefully selecting sampling direction during sampe preparation by using FIB;(3)After rapid annealing at 1100?for 30 s,two doping elements P and As diffuse towards the fin structure from Si O₂ later,and the diffusion depths of the two elements are different.P atom can diffuse to 11 nm region from the interface of the Si O₂ layer and fin structure,and As atom can diffuse to 2 nm region from the interface,but the diffusion of B atom is not obvious after annealing,and it is mainly distributed in the Si O₂ layer.In this study,we discussed how to improve the success rate and data quality of APT characterization of FinFET devices from the perspective of sample preparation and analysis methods,compared the data quality of APT under different sample preparation methods,and revealed the influence of rapid annealing on the distribution of light doping elements in FinFET devices.