Theory And Experimental Application Of Stress Characterization For Silicon-based Semiconductors Based On Raman Spectroscopy

Residual stress is one of the kernel factors influencing the efficiency,quality and reliability of the advanced semiconductor microelectronic devices.To develop experimental methods for stress characterizations of complex semiconductor device is a common demand of interdisciplinary research on mechanics,microelectronics and materials,and also an important fulcrum for mechanics to serve national strategic industries.Micro Raman spectroscopy is a new method of experimental mechanics developed in recent years.It has been successfully used in the investigations of semiconductor materials and devices.However,the traditional simplified/calibrated model of the Raman-mechanical measurement is widely used in the existing work,which is difficult to match the new requirements of experimental characterization of three-dimensional stress state and its distribution and evolution for heterogeneous material systems in the future development of semiconductor microelectronics.Therefore,this thesis presented the research on the theory and experimental application of stress characterization for silicon-based semiconductors based on Raman spectroscopy.The generalized model for arbitrary crystal plane of the Raman-mechanical measurement was presented based on the generalized Hooke's law,lattice dynamics and Raman selection rule around stress characterization for silicon-based semiconductors based on Raman spectroscopy.The stress-wavenumber factors of different crystal planes under typical stress states were derived.Based on the generalized model,the limitations of the traditional model were analyzed.The error range and influencing degree using the stress-wavenumber factors by the traditional model of the Ramanmechanical measurement was given.The results show that,the generalized model proposed in this work is a widely applicable experimental stress analysis of siliconbased semiconductors with complex structural feature at the microscale.The analytical methods and practical technology of stress components were developed to realize the quantitative analysis of each stress component under complex stress state in this work.The influences of all the stress components of complex stress states on the characteristic parameters of the Raman spectra were analyzed quantitatively.The mistakes induced by simplifying the stress state and neglecting the shear stress component in the traditional method were revised.After then,the analytical methods of stress components under the complex stress state,including explicit equation analysis,oblique backscattering measurement and implicit equation simplification,were developed based on the Raman characteristics of different crystal planes.Furthermore,a practical technology,namely iterative method,combining angleresolved Raman detection and fitting iteration process was proposed.The correctness of the proposed methods was confirmed by the verification experiments.Error analyses were carried out around the main error sources in the Raman-mechanical measurement.The results showed that the iterative method can effectively improve the confidence of spectral analysis and achieve accurate stress analysis.Based on the experimental theory analysis above,micro Raman spectroscopy was applied on the residual stress analyses on typical semiconductor microstructures.To analyze the complex residual stress in nano indentation,the stress-wavenumber relationship around the Berkovich nano-indentation on different crystal planes was established using the extended cavity model.The distributions of the stress components around the Berkovich nano-indentation were measured by Raman spectroscopy.For the multi-layer heterogeneous structure,the Raman-mechanical relationship of solidsolution Ge Si alloy was deduced by quantifying the effect of phonon confinement on the Raman shift.The distribution of residual stress along the depth direction was obtained by combining the micro Raman spectroscopy and multi-scale experiments.From these application results,the accuracy and applicability of experimental theory of internal stress in silicon-based semiconductors based on micro Raman spectroscopy were verified.