Clarification of Stress Field Measured by Multiwavelength Micro-Raman Spectroscopy in the Surrounding Silicon of Copper-Filled Through-Silicon Vias

Recently, micro-Raman spectroscopy has become popular in the near-surface silicon stress measurement around copper-filled through-silicon vias. Because the stress σ_Raman measured by the micro-Raman spectroscopy is a combined result of all of the stress components, interpretation of this stress becomes obscure. Ryu et al. has claimed that σ_Raman is approximately biaxial and hence it is proportional to σ_r + σ_θ. On the other hand, Wilson et al. has claimed that σ_r + σ_θ should be close to zero and hence σ_Raman is directly proportional to σ_z. In view of the dilemma as proposed by different research groups, this paper aims to provide insight into the origin of this stress so that it can be understood and used properly.