Anodically-bondable LTCC substrates with novel nano-structured electrical interconnection for MEMS packaging

Abstract

In this study, anodically-bondable LTCC (low temperature cofired ceramic) substrates are proposed to provide electrical connective packaging by using novel nano-structured gold. On-chip MEMS compatible fabrication of nanoporous gold (NPG) was developed and its porous structure offers sponge-like functions which forms electrical contacts as well during anodic bonding. A MEMS integrated Si substrate is mechanically sealed to a metal feedthrough LTCC substrate by anodic bonding and its electrical connection is formed by the nanoporous structured pads simultaneously

Low-temperature gold-gold bonding using selective formation of nanoporous powders for bump interconnects

“…The ligament sizes of the sheet surface increased with increasing temperature. These results indicated that metal diffusions of Au and Ag occurred even at low temperature because of the high reactive surface of the powders [7,8]. Figure 7 shows the bonding strengths measured by tensile tests.…”

“…The use of nanoporous structures on the surface is one of the efficient methods, due to sponge-like flexible features and highly reactive surface of the nano-or mesoscale structures. Since nanoporous structures have a large surface-to-volume ratio, they have been widely used in various applications in sensors, actuators, and clean-energy devices [6,7]. For example, the electrical connective packaging by using nanoporous gold pads was reported [7].…”

“…Since nanoporous structures have a large surface-to-volume ratio, they have been widely used in various applications in sensors, actuators, and clean-energy devices [6,7]. For example, the electrical connective packaging by using nanoporous gold pads was reported [7]. However, the formation of a nanoporous bump structure on the substrate involves many steps of sputtering, lithography, evaporation, and etching.…”

Fabrication and packaging process of silicon resonators capable of the integration of LSI for application of timing device

“…The process for packaging using LTCC with the metal feed-through offers great potential to reduce cost and improve reliability. The simple and versatile technology for hermetic packaging of RF MEMS fabricated by standard anodic bonding process has been reported [7][8]. Fabrication of a silicon diaphragm capacitive pressure sensor for high temperature application using LTCC substrate has been developed [9].…”