The key role of suppressor diffusion in defect-free filling of the through-silicon-via with high depth

et al. 2020

J. Electrochem. Soc.

In this study, by adding a single additive of Cetyltrimethyl Ammonium Bromide (CTAB) to the electrolyte, the bottom-up filling of micro via (Φ20 μm × 200 μm) was obtained with a fast filling rate. Accordingly, it was found that CTAB has a better diffusion performance and electrodeposition inhibition effect compared to a typical suppressor and leveler. Moreover, the filling results of the micro vias indicated that CTAB can be transported to the deep region of the micro via, successfully limiting the growth of Cu on the sidewall in these regions.

Section: Resultsmentioning

confidence: 99%

Communication—Fast Bottom-Up Filling of High Aspect Ratio Micro Vias Using a Single CTAB Additive

et al. 2020

J. Electrochem. Soc.

“…This causes the uniform deposition rate of plating. As shown in figure 9(c), at high current density conditions, the suppressor is depleted in the middle of via due to the consumption cannot be replenished in time by the diffusion [23,24]. Above the suppressor exhaustion depth, the accelerator coverage increases with the decreasing of the suppressor concentration.…”

Section: Tsv Filling Patterns Affected By the Current Densitymentioning

confidence: 95%

Experimental study of current density in copper filling process within deep through-silicon vias with high aspect ratio

J. Micromech. Microeng.

Liu

et al. 2019

Current density is one of the process parameters with the most significant effect on throughsilicon via (TSV) filling. However, the mechanism analysis of the influence of current density on TSV filling morphology lacks experimental demonstration. In this work, electrochemical deposition experiments and electrochemical analysis experiments were carried out to investigate the effect of current density on the copper filling within deep TSV with high aspect ratio. Three typical filling morphologies and corresponding evolution of the plating were observed. Additionally, the influence of current density on the competitive adsorption relationship between accelerator and suppressor was discussed based on the electrochemical measurement results. Furthermore, the diffusion time of additives was measured. The indirect effect of the current density on the local concentration of additives was discussed. Finally, three filling patterns were proposed to explain the effect current density on the filling process of deep TSV with high aspect ratio.

“…According to convection-dependent adsorption (CDA) effect, forced convection enhances the concentration of chloride ions on the cathode surface, thereby promoting the adsorption of suppressor [22], [23]. On the other hand, the limited diffusion of suppressor is the key factor causing the void defect of deep TSV filling [14]. Although forced convection cannot reach the bottom of the deep via, it increases the concentration gradient in the via and promotes the diffusion of the suppressor to the bottom of the via [24].…”

Section: Forced Convection Promotes the Adsorption Of Suppressormentioning

confidence: 99%

“…However, with the increase of TSV depth, the mass transfer of additives inside via is limited. Therefore, the consumption of additives cannot be replenished in time, resulting in defects [13], [14]. To promote the mass transfer of additives, pause pulse current and forced convection are often applied [15]- [21].…”

Section: Introductionmentioning

confidence: 99%

Effect of Stirring on the Defect-Free Filling of Deep Through-Silicon Vias

Liu

2020

IEEE Access

Self Cite

Through-silicon-via (TSV) is an advanced 3D electronic integration technology. In order to achieve the defect-free filling of deep TSV, forced convection is commonly applied during TSV filling process. In this study, the interaction effect of forced convection and current density on deep TSV filling process is systemically investigated. The filling morphology of TSV electrodeposited with different stirring rate and different current density were observed by the scanning electron microscope (SEM). The phenomenon that forced convection reduces the TSV filling ratio at low current density but promotes the TSV filling ratio at high current density was discovered. Additionally, the influence of stirring rate on the TSV filling results was researched. In order to study the mechanism of forced convection at different current densities, electrochemical analysis and particle size measurement were carried out. The volt-ampere characteristic curves of the plating solution stirred at different speeds were analyzed. Furthermore, the effects of forced convection and current density on the crystal size of deposited copper were studied separately. Based on the experimental results, the mass transfer of additives and crystal nucleation of deposited copper were discussed to explain the interaction effect of forced convection and current density on deep TSV filling process. INDEX TERMS Deep TSV filling, forced convection, mass transfer, crystal size.