We describe how a direct combination of an axicon and a lens can represent a simple and efficient beam-shaping solution for laser material processing applications.We produce high-angle pseudo-Bessel micro-beams at 155...We describe how a direct combination of an axicon and a lens can represent a simple and efficient beam-shaping solution for laser material processing applications.We produce high-angle pseudo-Bessel micro-beams at 1550 nm,which would be difficult to produce by other methods.Combined with appropriate stretching of femtosecond pulses,we access optimized conditions inside semiconductors allowing us to develop high-aspect-ratio refractive-index writing methods.Using ultrafast microscopy techniques,we characterize the delivered local intensities and the triggered ionization dynamics inside silicon with 200-fs and 50-ps pulses.While similar plasma densities are produced in both cases,we show that repeated picosecond irradiation induces permanent modifications spontaneously growing shot-after-shot in the direction of the laser beam from front-surface damage to the back side of irradiated silicon wafers.The conditions for direct microexplosion and microchannel drilling similar to those today demonstrated for dielectrics still remain inaccessible.Nonetheless,this work evidences higher energy densities than those previously achieved in semiconductors and a novel percussion writing modality to create structures in silicon with aspect ratios exceeding~700 without any motion of the beam.The estimated transient change of conductivity and measured ionization fronts at near luminal speed along the observed microplasma channels support the vision of vertical electrical connections optically controllable at GHz repetition rates.The permanent silicon modifications obtained by percussion writing are light-guiding structures according to a measured positive refractive index change exceeding 10-2.These findings open the door to unique monolithic solutions for electrical and optical through-silicon-vias which are key elements for vertical interconnections in 3D chip stacks.展开更多
Through-silicon-via （TSV） to TSV crosstalk noise is one of the key factors affecting the signal integrity of three- dimensional integrated circuits （3D ICs）. Based on the frequency dependent equivalent electrical ...Through-silicon-via （TSV） to TSV crosstalk noise is one of the key factors affecting the signal integrity of three- dimensional integrated circuits （3D ICs）. Based on the frequency dependent equivalent electrical parameters for the TSV channel, an analytical crosstalk noise model is established to capture the TSV induced crosstalk noise. The impact of various design parameters including insulation dielectric, via pitch, via height, silicon conductivity, and terminal impedance on the crosstalk noise is analyzed with the proposed model. Two approaches are proposed to alleviate the TSV noise, namely, driver sizing and via shielding, and the SPICE results show 241 rnV and 379 mV reductions in the peak noise voltage, respectively.展开更多
This paper presents a blended analytical electrical–thermal model for steady state thermal analysis of through-silicon-via（TSV） in three-dimensional（3 D） integrated circuits. The proposed analytical model is vali...This paper presents a blended analytical electrical–thermal model for steady state thermal analysis of through-silicon-via（TSV） in three-dimensional（3 D） integrated circuits. The proposed analytical model is validated by the commercial FEM tool—COMSOL. The comparison between the results of the proposed analytical formulas and COMSOL shows that the proposed formulas have very high accuracy with a maximum error of 0.1%.Based on the analytical model, the temperature performance of TSV is studied. Design guide lines of TSV are also given as：（1） the radius of the TSV increases, the resistance decreases and the temperature can be increased;（2） the thicker the dielectric layer, the higher the temperature;（3） compared with carbon nanotube, the Cu enlarges the temperature by 34 K, and the W case enlarges the temperature by 41 K.展开更多
Vacuum-assisted spin-coating is an effective polymer filling technology for sidewall insulating of through-silicon-via(TSV).This paper investigated the flow mechanism of the vacuum-assisted polymer filling process bas...Vacuum-assisted spin-coating is an effective polymer filling technology for sidewall insulating of through-silicon-via(TSV).This paper investigated the flow mechanism of the vacuum-assisted polymer filling process based on experiments and numerical simulation,and studied the effect of vacuum pressure,viscosity of polymer and aspect-ratio of trench on the filling performance.A 2D axisymmetric model,consisting of polymer partially filled into the trench and void at the bottom of trench,was developed for the computational fluid dynamics(CFD)simulation.The simulation results indicate that the vacuum-assisted polymer filling process goes through four stages,including bubble formation,bubble burst,air elimination and polymer re-filling.Moreover,the simulation results suggest that the pressure significantly affects the bubble formation and the polymer re-filling procedure,and the polymer viscosity and the trench aspect-ratio influence the duration of air elimination.展开更多
基金conducted using LaMP facilities at LP3.The project received funding from the French National Research Agency(ANR-22-CE92-0057-0,KiSS project)and the European Union’s Horizon 2020 research and innovation program under grant agreements No.101034324(MSCA-COFUND)and No.724480(ERC).
文摘We describe how a direct combination of an axicon and a lens can represent a simple and efficient beam-shaping solution for laser material processing applications.We produce high-angle pseudo-Bessel micro-beams at 1550 nm,which would be difficult to produce by other methods.Combined with appropriate stretching of femtosecond pulses,we access optimized conditions inside semiconductors allowing us to develop high-aspect-ratio refractive-index writing methods.Using ultrafast microscopy techniques,we characterize the delivered local intensities and the triggered ionization dynamics inside silicon with 200-fs and 50-ps pulses.While similar plasma densities are produced in both cases,we show that repeated picosecond irradiation induces permanent modifications spontaneously growing shot-after-shot in the direction of the laser beam from front-surface damage to the back side of irradiated silicon wafers.The conditions for direct microexplosion and microchannel drilling similar to those today demonstrated for dielectrics still remain inaccessible.Nonetheless,this work evidences higher energy densities than those previously achieved in semiconductors and a novel percussion writing modality to create structures in silicon with aspect ratios exceeding~700 without any motion of the beam.The estimated transient change of conductivity and measured ionization fronts at near luminal speed along the observed microplasma channels support the vision of vertical electrical connections optically controllable at GHz repetition rates.The permanent silicon modifications obtained by percussion writing are light-guiding structures according to a measured positive refractive index change exceeding 10-2.These findings open the door to unique monolithic solutions for electrical and optical through-silicon-vias which are key elements for vertical interconnections in 3D chip stacks.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61131001,61322405,61204044,61376039,and 61334003)
文摘Through-silicon-via （TSV） to TSV crosstalk noise is one of the key factors affecting the signal integrity of three- dimensional integrated circuits （3D ICs）. Based on the frequency dependent equivalent electrical parameters for the TSV channel, an analytical crosstalk noise model is established to capture the TSV induced crosstalk noise. The impact of various design parameters including insulation dielectric, via pitch, via height, silicon conductivity, and terminal impedance on the crosstalk noise is analyzed with the proposed model. Two approaches are proposed to alleviate the TSV noise, namely, driver sizing and via shielding, and the SPICE results show 241 rnV and 379 mV reductions in the peak noise voltage, respectively.
基金supported by the National Natural Science Foundation of China(Nos.61574106,61574104)the National Defense Pre-Research Foundation of China(No.9140A23060115DZ01062)the Key Science and Technology Special Project of Shaanxi Province(No.2015KTCQ01-5)
文摘This paper presents a blended analytical electrical–thermal model for steady state thermal analysis of through-silicon-via（TSV） in three-dimensional（3 D） integrated circuits. The proposed analytical model is validated by the commercial FEM tool—COMSOL. The comparison between the results of the proposed analytical formulas and COMSOL shows that the proposed formulas have very high accuracy with a maximum error of 0.1%.Based on the analytical model, the temperature performance of TSV is studied. Design guide lines of TSV are also given as：（1） the radius of the TSV increases, the resistance decreases and the temperature can be increased;（2） the thicker the dielectric layer, the higher the temperature;（3） compared with carbon nanotube, the Cu enlarges the temperature by 34 K, and the W case enlarges the temperature by 41 K.
文摘Vacuum-assisted spin-coating is an effective polymer filling technology for sidewall insulating of through-silicon-via(TSV).This paper investigated the flow mechanism of the vacuum-assisted polymer filling process based on experiments and numerical simulation,and studied the effect of vacuum pressure,viscosity of polymer and aspect-ratio of trench on the filling performance.A 2D axisymmetric model,consisting of polymer partially filled into the trench and void at the bottom of trench,was developed for the computational fluid dynamics(CFD)simulation.The simulation results indicate that the vacuum-assisted polymer filling process goes through four stages,including bubble formation,bubble burst,air elimination and polymer re-filling.Moreover,the simulation results suggest that the pressure significantly affects the bubble formation and the polymer re-filling procedure,and the polymer viscosity and the trench aspect-ratio influence the duration of air elimination.
