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.