Through-chip electrodes with high aspect ratios can offer the shortest interconnection and reduce signal delay. Copper has been selected as that electrode material because of its good compatibility to conventional multilayer interconnection in large-scale integration and back end-of-line processes. In this paper, filling vias with higher aspect ratio, 10 m 2 and 70 m depth, used for through-chip electrodes is reported. Removing overhang at via tops is important to achieve perfect via filling. Upon testing a series of electrodeposition conditions, conformal electrodeposits were obtained. With those conformal electrodeposits, seams and voids always remained at the via center. Perfect via filling was achieved by the pulse reverse plating method and by increasing Janus Green B concentration up to 20 mg/L in the plating bath.

The national project of “Ultra High-Density Electronic System Integration” was initiated in 1999. This is the first project to focus on a niche area between electronic devices and systems. It aims to develop technologies for overcoming the problems in terms of performance of electronic systems. Three-dimensional (3D) LSI chip stacking, optoelectronics hybrid integration, and optimum circuit design are the technology categories. For the 3D stacking technology, a chip-based stacking technology is under extensive development that includes wafer preparation for chip stacking, wafer thinning, chip stacking, and inspection and testing. In this paper, the current development status of the 3D stacking technology, called V-STACK technology, is introduced.

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Fluorocarbon films with low dielectric constants and high thermal resistance have been developed by plasmaenhanced chemical vapor deposition (PECVD) using gas mixtures of fluorocarbons (e.g., C4F,), hydrocarbons (e.g., C2H,), and/or hydrogen. A conventional parallel plate electrode PECVD system was used as the reactor. We report dielectric constants lower than 2.4 with these fluorinated films. The thermal decomposition temperature was higher than 400°C and the glass transition temperature (Tg) was also higher than 450°C. This enables the use of organic films with very low dielectric constant in actual devices.

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