Fabrication of High-Density Wiring Interposer for 10 GHz 3D Packaging Using a Photosensitive Multiblock Copolymerized Polyimide

Abstract

We have developed a high-density wiring interposer for 10 GHz 3D packaging using a photosensitive multiblock copolymerized polyimide. This new polyimide can realize micron-sized fine patterns without pattern shrinkage because of the nonrequirement of high-temperature thermal curing. The polyimide has good electric properties such as high breakdown voltage and low dielectric constant. Therefore, it is considered that by introducing this photosensitive polyimide as an insulator of the interposer, a high-performance interposer for LSI packaging can be realized. We confirmed experimentally that the high-density wiring interposer can be fabricated using the polyimide and gold. We optimized the basic properties of the photosensitive polyimide film for the fabrication of the interposer. Fine metal wirings were smoothly covered by the polyimide, as confirmed by scanning electron microscopy (SEM) of the cross section of the fabricated balance pair strip line structure. From the time domain reflectometry (TDR) measurement, it was determined that the characteristic impedance of the strip line is within 55.2 Ω ± 11.5% at the center of the interposer chip.

Electron Tomography of Pencil-Shaped GaN/(In,Ga)N Core-Shell Nanowires

“…The ongoing process of miniaturization of optoelectronic devices has given rise to the development of complex, three-dimensional (3D) nanostructures. In this respect, nanowires (NWs) are promising candidates to realize high-quality quantum well or quantum dot (QD) structures due to their large surface-to-volume ratio associated with an efficient strain relaxation in axial or radial NW heterostructures [1–3]. Recent improvements in selective area growth (SAG) by molecular beam epitaxy (MBE) on GaN-on-sapphire templates has led to the fabrication of ordered and uniform GaN NW arrays with either flat- or pencil-shaped top [4, 5].…”

Development of silicon and carbon foam low mass interposers

“…Passive devices known as interposers are widely used in the BGA packaging sector to fan out the contacts of an integrated circuit (IC) to a larger BGA pitch, or to convert between different pitch devices [1]. In the context of vertical integration of IC's for system on package (SoP) and system in package (SiP) applications [2], interposer devices find new uses to minimize stress on the IC, provide higher speed signal paths than possible on chip [3], allow vertical integration of IC's with different pinouts or pitch, support embedded passive components, implement tests prior to vertical integration, handle and monitor stacked DRAM's, etc. Finally, in the context of intelligent trackers, a new application of interposers would be to provide physical separation between two coupled measurement layers [4].…”

“…We investigate two fabrication methods described in the sections below. The carbon foams used have a density of g/cm 3 and thermal expansion coefficient close to silicon (≤ 2 ppm/ • C, but not yet precisely measured). The mechanical attachment to silicon is done using a commercial high temperature adhesive specified to maintain cured properties up to 300 • C [7].…”

Interconnection of Multi-Pad Electrodes by "Controlled Anisotropic Extraneous (CAEx) Deposition" of Electroless NiB Film

“…Currently, several methods including wire bonding, TAB, and flip-chip bonding are being used widely. Especially, the method of flip-chip bonding with small metal bumps is used more widely than other methods for fine-pitch bonding, as the former technology is more compatible with a higher packaging density with a shorter electrical path because of the use of a fine-bump array with a fine-pitch 4 . However, insufficient alignment-accuracy in the chip-tosubstrate bonding is becoming a serious problem in dealing with finer bumps 1 .…”