Decoupling analysis of stress components on monocrystalline silicon using angle-resolved oblique backscattering Raman spectroscopy

Stress is a key to controlling the electro-optical properties of semiconductor devices based on strain engineering. Micro-Raman spectroscopy is regarded as an effective technique of non-destructive measurement for the stress in semiconductor material. What the results using traditional Raman methods, however, are usually the sum of in-plane principal stress, or some form of equivalent stress, on a specific crystal plane. It is regarded far from possible to detect any stress components using Raman on a random crystal plane. This work presented a method of stress analysis based on angle-resolved oblique backscattering micro-Raman spectroscopy. A general physical-mechanical model was proposed by solving the equation of lattice dynamics in the sample coordinate system and then performing Raman selection in the eigenvector coordinate system. Using this model and considering the factors including refraction, polarization diversion, and numerical aperture (NA), this work established the analytic relationship between the increment of polarized Raman shift and all the stress components on a random crystal plane (taking {100} plane of monocrystalline silicon as an example) under any stress state. The stress component results of verification experiments quite agreed with their corresponding theoretical resolutions. It proved that the proposed method based on angle-resolved oblique backscattering micro-Raman spectroscopy, including both the model and the device, solved the widely recognized problem that the stress components of monocrystalline silicon, especially on {100} crystal plane, could not be decoupled by Raman.