The nanomechanical responses and interface adhesion of electrochemically plated copper ͑Cu͒ film have been investigated for the evaluation of interconnect reliability. The hardness and elastic modulus of the Cu film were measured by nanoindentation test as about 2.1 and 120 GPa, respectively. A dislocation burst phenomenon was observed and revealed the initiation of plastic deformation of the Cu film. The converted true stress-strain curve provided a stress criterion of 9.3 GPa for the plastic yielding of the Cu film. Besides, the creep behavior was also analyzed under nanoindentation test and showed a power law expression with a creep stress exponent of about 22. Moreover, the interfacial adhesion strength and delamination behavior between the Cu film and silicon carbide ͑SiC͒ etch stop layer have been studied using a four-point bending test. During delamination, cracks irregularly propagated along the Cu/SiC interface with blocking by the ductile Cu film. The fracture energy release rate for the delamination of Cu/SiC interface was measured as around 2-10 J/m 2 , affected by SiC deposition condition and testing parameter.Copper ͑Cu͒ with low electrical resistivity and high thermal conductivity has been widely adopted as multilevel interconnects in ultralarge-scale integrated ͑ULSI͒ circuits to reduce the problem of serious resistance-capacitance delay. 1 Copper metallization, mainly performed by electrochemical plating, has the advantages of low processing temperature, low cost, high throughput, good quality, and gap-filling capability, thus becoming attractive in the generation of 90 nm semiconductor manufacturing. 1-5 However, mechanical damages of the Cu films, such as film deformation and interface delamination caused by thermal stresses, chemical-mechanical polishing, or even wire bonding during chip packaging, severely suppress the processing yield and application reliability of microelectronic devices. 6-10 Film deformation and interface delamination detrimentally affect the performance of integrated circuits ͑ICs͒, especially with increasing integration density of ICs and thus increasing the amount of layer interface in the interconnect structures. A high resistance of the Cu films to the mechanical damages is thus strongly demanded to fit the strict requirements of next-generation semiconductor manufacturing. The true mechanical properties of the Cu films, including film strength and interface adhesion, therefore need to be clarified for the evaluation of the reliability of multilevel interconnects.However, due to the limit of conventional measurement equipment, the mechanical properties of nanoscale Cu thin films used in finely patterned interconnect structures have not been well studied. Nanomechanical analyses are required for further investigation of the true mechanical responses and deformation mechanisms of these thin films. An instrumented nanoindentation test has been widely applied for measurement of the hardness and elastic modulus of thin films and provides reliable results. 11,12 However, o...
In this study, the interface chemistry and adhesion strengths between Cu and SiCN etch stop layers have been investigated under different plasma treatments. From the examination of interface microstructures and the analyses of chemical compositions and bonding configurations, an oxide layer was found to exist at the untreated
Cu∕SiCN
interface. After
H2
and
NnormalH3
treatments, the amount of oxides was effectively reduced. Some Cu silicides formed during SiCN deposition, and Cu nitrides even formed under
NnormalH3
plasma treatment. The adhesion strengths of the
Cu∕SiCN
interfaces were measured by nanoindentation and nanoscratch tests under which interface delamination occurred around indented regions. The adhesion energy of the untreated
Cu∕SiCN
interface was obtained as about 4.98 and
0.98J∕normalm2
, respectively, by nanoindentation and nanoscratch tests. After
H2
and
NnormalH3
plasma treatments, the adhesion energy was effectively improved to 5.90 and
5.99J∕normalm2
by nanoindentation test, and to 1.74 and
2.58J∕normalm2
by nanoscratch test, respectively, because of the removing of oxides and the formation of Cu silicides and nitrides at the
Cu∕SiCN
interfaces.
In this study, amorphous Ni-P films were deposited by electroless plating under different pH values. Their mechanical properties and deformation behavior were then investigated by instrumented nanoindentation. With increasing pH value of the plating solution from 3.75 to 6.0, the hardness and elastic modulus of the obtained Ni-P films increased from 6.1 GPa and 146 GPa to 8.2 GPa and 168 GPa respectively. From the load-indentation depth curve, the Ni-P films were found to yield at an indentation depth of 8 nm. By microstructural examination around the indented regions, early-stage plastic deformation of the amorphous Ni-P films was verified through the formation and extension of shear bands with a spacing of several tens of nanometers. Within the shear bands, flow dilatationinduced intense shear localization was expected and resulted in crystallization in the amorphous matrix. The critical shear stress and energy release rate required for the initiation of early-stage plastic yielding of the Ni-P films were calculated to be about 1.4 GPa and 3.0 J/m(2) respectively, both of which increased with pH values
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