Influence of Anodization Parameters on Film Thickness and Volume Expansion of Thick and Large-Sized Anodic Aluminum Oxide Film

Anodic aluminum oxide (AAO) film with a thickness ranging from 20 to100 μm was prepared by using a large-sized Al plate (4 cm × 10 cm) to investigate the anodization parameter effect on the film thickness and volume expansion factor. A corrosion treatment (voltage = 0 V) was performed to investigate the film dissolution caused by acid. The actual anode surface temperature was also measured to confirm the field-assisted nature of AAO dissolution. The film thickness increases exponentially with temperature, and increases approximately linearly with voltage, duration or concentration. The volume expansion factor gives a first rising and then falling trend with temperature or duration, while it has a nearly linear trend with voltage or concentration. The volume expansion factor increases with the intensified electric field, while its decrease is attributed to the Joule heat-enhanced dissolution. In the case of large film thickness (> 20 μm), the pore confinement effect may be one of the reasons for the change of volume expansion factor. In addition to the conventional parameters, the heat transfer-related parameters such as sample size also greatly affect the AAO film growth.

Improvement of Plasma Resistance of Anodic Aluminum-Oxide Film in Sulfuric Acid Containing Cerium(IV) Ion

The parts of equipment in a process chamber for semiconductors are protected with an anodic aluminum-oxide (AAO) film to prevent plasma corrosion. We added cerium(IV) ions to sulfuric acid in the anodizing of an AAO film to improve the plasma corrosion resistance, and confirmed that the AAO film thickness increased by up to ~20% when using 3 mM cerium(IV) ions compared with general anodizing. The α-Al2O3 phase increased with increasing cerium(IV) ion concentration. The breakdown voltage and etching rate improved to ~35% and 40%, respectively. The film’s performance regarding the generation of contamination particles reduced by ~50%.

A Modified Interposer Fabrication Process by Copper Nano-Pillars Filled in Anodic Aluminum Oxide Film for 3D Electronic Package

Though copper nano-pillars (CNPs) filled in anodic aluminum oxide (AAO) film has been developed for many years, the high pore-filling percentage in AAO is still a bottleneck. We have demonstrated a new electrodeposition method to fill CNPs in AAO without the seed layer which is required in the traditional electrodeposition process. CNPs with uniform heights were obtained and the pore-filling percentage reached up to 97.5%. Low current density is beneficial for the high pore-filling percentage due to the uniform growing rate in different nanoscale pores. The high temperature increased the diffusion velocity of ions and enhanced the pore filling percentage but also corroded the AAO film simultaneously. Results showed that CNPs grains with <220> orientation were fabricated. Electrodeposition with low electric current could contribute to the forming of CNPs with (220) preferred orientation due to the promotion of dehydration reduction processes. The thermal conductivities of Cu-AAO interposers reaches 92.34 W/(m·K) and 3.19 W/(m·K) in vertical and horizontal directions, respectively.

Express-Method for the Study of Electrolyte Anion Profiles in the Bulk of Dense Anodic Alumina Films

ABSTRACTThe procedure proposed is the express method for the study of anion distribution profiles in the anodic aluminum oxide film. The method consists in measuring the variation of the steady-state electrode potential during the oxide etching. It allows the influence of the initial aluminum composition, the electrolyte composition, anodization regimes, etc. on the characteristics of dense anodic alumina films to be studied. The method developed can be used to study a chemical evolution in anodic alumina formed to correlate with modelling and simulations across materials science disciplines.

Challenges to Fabricate Large Size-Controllable Submicron-Structured Anodic-Aluminum-Oxide Film

Anodic aluminum oxide (AAO) is well known for its unique controllable structure and functional contributions in research and developments. However, before AAO can be widely used in the industry, some engineering problems should be overcome. In this study, we designed a novel electrochemical mold, which can resolve the exothermal problem for large-size aluminum sheets during high-voltage anodization process. AAO film with a large sample size of 11 x 11 cm2 in area, 148 μm in thickness and 450 nm in average pore diameter, decorated with ordered-pattern structure, was successfully obtained through a 200 V anodization process. It was noticed that the local heat was generated with increasing the anodizing voltage, resulting in undesired pits and burr defects on the AAO surface. In order to retain AAO’s quality and reduce the producing cost of the anodization process, a mass producing system combining with an overhead conveyor was proposed. The convenient anodization system, novel electrochemical mold and bath may help to fabricate high-quality AAO films efficiently.