214
T. Suga et al.
Fig. 8.11 SEM cross-sectional image of bump-less Cu–Cu bonded structure with 6 μm pitch [37]
Fig. 8.12 TEM images of
the Cu–Cu bonding interface
prepared by modified SAB
processes at 150 °C:
(a) modified diffusion
bonding using dry O 2 and
(b) vapor-assisted SAB using
humid N 2 gas [40, 41]
achieved by both methods. The bonded interconnects exhibit low resistances that
are only slightly higher than that obtained by using conventional SAB in UHV, as
compared in Fig. 8.13.