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Effects of the conventional bath additives ͓chloride ions ͑Cl − ͒, poly͑ethylene glycol͒ ͑PEG͒, bis͑3-sulfopropyl͒disulfide ͑SPS͒, and Janus green B ͑JGB͔͒ used in the damascene process on the filling of submicrometer trenches with electrodeposited copper were investigated by electrochemical polarization measurement and cross-sectional microscopy. The combination of Cl − and PEG inhibited copper deposition in the areas of opening of the trenches, while SPS accelerated it at the bottom. Polarization curves showed that the degree of acceleration of copper deposition by SPS increases with the concentration of SPS. This SPS concentration-dependent acceleration accounts for the observed bottom-up growth. The addition of JGB inhibited copper deposition at the later stages of the filling process, leading to the suppression of the overfill phenomenon, although the bottom-up growth was also inhibited at high JGB concentrations. Bath agitation significantly enhanced the inhibition effect of JGB on the overfill phenomenon, without disturbing the bottom-up growth.

By designing advantageous cellular geometries and combining the material size effects at the nanometer scale, lightweight hybrid microarchitectured materials with tailored structural properties are achieved. Prior studies reported the mechanical properties of high strength cellular ceramic composites, obtained by atomic layer deposition. However, few studies have examined the properties of similar structures with metal coatings. To determine the mechanical performance of polymer cellular structures reinforced with a metal coating, 3D laser lithography and electroless deposition of an amorphous layer of nickel-boron (NiB) is used for the first time to produce metal/polymer hybrid structures. In this work, the mechanical response of microarchitectured structures is investigated with an emphasis on the effects of the architecture and the amorphous NiB thickness on their deformation mechanisms and energy absorption capability. Microcompression experiments show an enhancement of the mechanical properties with the NiB thickness, suggesting that the deformation mechanism and the buckling behavior are controlled by the brittle-to-ductile transition in the NiB layer. In addition, the energy absorption properties demonstrate the possibility of tuning the energy absorption efficiency with adequate designs. These findings suggest that microarchitectured metal/polymer hybrid structures are effective in producing materials with unique property combinations.

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Articles you may be interested inA low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock Rev. Sci. Instrum. 85, 094709 (2014); 10.1063/1.4896043 Exploring Ramsey-coherent population trapping atomic clock realized with pulsed microwave modulated laser J. Appl. Phys. 115, 093109 (2014); 10.1063/1.4867915 Quasi-bichromatic laser for a lin⊥lin coherent population trapping clock produced by vertical-cavity surfaceemitting lasers Rev. Sci. Instrum. 83, 093111 (2012);We report the characterization of dark line resonances observed in Cs vapor microcells filled with a unique neon ͑Ne͒ buffer gas. The impact on the coherent population trapping ͑CPT͒ resonance of some critical external parameters such as laser intensity, cell temperature, and microwave power is studied. We show the suppression of the first-order light shift by proper choice of the microwave power. The temperature dependence of the Cs ground state hyperfine resonance frequency is shown to be canceled in the 77-80°C range for various Ne buffer gas pressures. The necessity to adjust the Ne buffer gas pressure or the cell dimensions to optimize the CPT signal height at the frequency inversion temperature is pointed out. Based on such Cs-Ne microcells, we preliminary demonstrate a 852 nm vertical cavity surface emitted laser ͑VCSEL͒-modulated based CPT atomic clock exhibiting a short term fractional frequency instability y ͑͒ = 1.5ϫ 10 −10 −1/2 until 30 s. These results, similar to those published in the literature by others groups, prove the potential of our original microcell technology in view of the development of high-performance chip scale atomic clocks.

Void-free copper filling of trenches for ultralarge scale integrated interconnect structure was demonstrated by electroless deposition technique using polyethylene glycol as an inhibiting bath additive. With this electroless plating bath, the authors succeeded in demonstrating superfilling. Of particular interest is that the deposition at trench opening was nil during the filling process, while that at the bottom was very fast. This letter presents a demonstration and a proof of superfilling of trenches by electroless copper deposition.