A physicochemical model for electroplating copper in through-silicon vias (TSVs) is proposed to investigate the filling mechanism. Finite element method (FEM) and multifrontal massively parallel sparse direct solver (MUMPS) are employed to solve the numerical model. The motion of the fluid/solid interface (electrolyte/metal interface) is tracking using the Arbitrary Lagrange-Eulerian (ALE) method. Compared to other models, the diffusion, adsorption, desorption and incorporation of the additives (accelerator and suppressor) and ions (cupric ion and chloride ion) are included in this model. Simultaneously, the deactivation of the accelerator and the process parameters for copper deposition are also considered in the model. Numerical simulations are performed for filling the Ø 40 μm × 140 μm blind vias. The “Δ”, “V”, “8”, and extreme bottom-up filling models are achieved by verifying the component of plating baths. A good match is achieved qualitatively between the simulated profiles and the real-world filling experiments.
The impurities incorporated in the electrodeposited 40 nm Cu lines as well as in blanket Cu films were studied. Two different levelers were used in the study. While the impurity in the blanket films were found highly dependent on the leveler and its concentration, the leveler had no impact on the impurity in the narrow lines. Furthermore, the concentrations of suppressor and chloride showed little to no impact on the impurity in the narrow lines. An increase of accelerator concentration resulted in higher S and Cl contents in the lines. The increase in S incorporation was also observed for blanket wafers plated with incremental concentrations of accelerator. In addition, the impurity in the narrow lines was also found to increase with the increase of the applied plating current density. A correlation between a slow Cu grain growth and high impurity content was established by using Cu blanket films plated with different leveler concentrations or Cu films ion-implanted with different doses of impurities.
Conventional engineered surfaces for fluid manipulation are hindered by the set wettability, and thus they can only achieve spontaneous transport of single‐phase fluid, namely liquid or gas. Moreover, fluid transport systems that are robust to path defects have yet to be fully explored. Here, unprecedentedly, a universal wettability switching strategy is developed for achieving programmable directional transport of both droplets and subaqueous bubbles on a dumbbell‐patterned functional surface (DPFS), featuring in strong robustness, high efficiency, and effective cost. By tuning the superwettability of DPFS through octadecyltrichlorosilane treatment and ultraviolet‐C selective irradiation, the transport fluid can alternate between liquid and gas. The material's switchable superwettability regulates the fluid directed dynamics within the confined pattern, in which the sustaining fluid propelling relies on the surface energy difference between the starting and terminal sites. This enables the construction of multiple channels, which works synergistically with ultralow‐volume‐loss transport to impart the fluidic system with strong robustness against path defects. Underlying the completion of complex microfluidics tasks, spatially‐selective cooling devices and subaqueous gas microreactors are successfully demonstrated. This energy‐consumption‐free fluid transport system opens a new avenue for on‐chip programmable fluid manipulation, promoting innovative applications requiring rational control of two‐phase fluid transport.
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