Interconnects and Interposer in Porous Anodic Aluminum Oxide: The Fabrication Technology and Process Integration

Abstract

Porous anodic aluminum oxide (AAO) features its interesting nanoporous structure which is capable of being used as a template for nanopatterning, highly anisotropic nanowire fabrication, and MEMs devices fabrication. In this work, AAO was demonstrated to be an interposer substrate for 2.5/3D packaging technology in microelectronics exploiting the unique etching characteristic of nanopores. Not only the high density vertical through via was fabricated but also metallized with Cu as void-less interconnect simply by using wet chemicals. Passive devices like inductors were embedded in AAO film after via metallization and re-distribution layer Cu electroplating which provide multifunctionalities to proposed AAO interposer. AAO with the special structural and etching properties plus its low electrical loss, thermal stability, and mechanical robustness, is a promising material for heterogeneous integration and advanced microelectronic packaging technology.

Porous Anodic Aluminum Oxide Interposer: Fabrication, Characterization, and Evaluation

“…Previously, however, fabrication works has been done to create through AAO interconnects taking advantage of the anisotropic structural and etch properties 22 of vertically self-aligned nanopores. [23][24][25] Reasons behind considering AAO as a potential substrate for interconnects and integrated passive devices (IPDs) are AAO's good electrical property, mechanical toughness, unique nanoporous structures, easiness in fabrication and customization, and so on. Patterning Al foil to leave a frame underneath AAO could serve the purpose of handling which offers additional option to carry AAO interposer in high volume manufacturing environment.…”

Direct Metal Layer Forming with Good Adhesion on Porous AAO Films by Electroless Cu Plating

“…One promising material in particular, anodized aluminum oxide (AAO), has been explored for potential use in microelectronic applications. [1][2][3] While AAO material shows promise as a microelectronic material, a significant limitation is in metalizing the surface at low cost.…”

“…These unique properz E-mail: melonmj0219@gmail.com ties have attracted research and work in porous AAO films for applications in nanowire fabrication, biomedical devices, [13][14][15] microelectromechanical systems (MEMs), microelectronics, interposers, and RF substrates. [1][2][3][16][17][18][19] In most cases, PVD has been used for depositing metal layers on the surfaces of AAO films. 1,[5][6][7]16 Metal layers on the surfaces of AAO are used for forming electrical traces, structural features, or etch masks.…”