Abstract
This letter reports the enhancement of Raman signals from low-k dielectric materials in the Cu/low-k interconnects of nanoscale integrated circuit (IC) devices. The Cu nanostructure pattern of the IC device acted as an active substrate for light scattering by the surface plasmon effect, enhancing the Raman signals observed from the low-k dielectric material of the device. The enhancement of the Raman signal of the low-k material was found to be strongly dependent on the incident angle of the incident laser light. A maximally enhanced Raman intensity was achieved when this angle was approximately 45° relative to the surface normal. Our findings are significant to the characterization of low-k materials and the monitoring of low-k reliability in leading edge semiconductor technologies with nanometer-scale structures.
Highlights
With the scaling down of integrated circuit (IC) devices to nanometer-scale dimensions, Cu and low-k dielectric have been introduced into such devices to reduce their resistive– capacitive delay
The Cu nanostructure pattern of the IC device acted as an active substrate for light scattering by the surface plasmon effect, enhancing the Raman signals observed from the low-k dielectric material of the device
The low-k bands were assigned to a Si–O–Si symmetric stretch band at 470 cmÀ1, a Si–O–Si asymmetric stretch band at 940 cmÀ1, Si(CH)x stretch bands around 780 cmÀ1, a Si–H band at 2170 cmÀ1, and a C–Hx stretch band around 2920 cmÀ1.7 The Raman signals of low-k dielectrics showed a remarkable dependence on the polarization state of the incident beam, the maximum efficiency obtained when the polarization vector of the incident field was perpendicular to the direction of the comb nanostructures Cu lines
Summary
With the scaling down of integrated circuit (IC) devices to nanometer-scale dimensions, Cu and low-k dielectric have been introduced into such devices to reduce their resistive– capacitive delay. Raman and FTIR vibrational microscopies were successfully used to characterize the low-k dielectric properties of Cu/ low-k interconnects as well as their degradation behavior during reliability tests, and allowing us to clarify the low-k related reliability failure mechanism.. A concentrated surface plasmon electric field is responsible for this enhanced Raman scattering. The angle resolved enhanced Raman scattering via different nanostructures was studied in the literatures. The maximum enhancement Raman intensity appeared at approximately 45 relative to the surface normal. This behavior was qualitatively explained by a modified Greenler model by considering the anisotropic nature of the Ag nanorods.. The strongest enhanced Raman signals of the low-k IMD dielectrics were achieved using angle-resolved light scattering
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