Development of a viable 3D integrated circuit technology

Three-dimensional integrated circuit technology with transistors stacked on top of one an-other in multi-layer silicon film has always been a vision in the future technology direction. While the idea is simple, the technique to obtain high performance multi-layer transistors is extraordinarily diffi-cult. Not until recently does such technology become feasible. In this paper, the background and vari-ous techniques to form three-dimensional circuits will be reviewed. Recent development of a simple and promising technology to achieve three-dimensional integration using Metal-Induced-Lateral-Crystalliza-tion will be described. Preliminary results of 3D inverters will also be provided to demonstrate the viabil-ity for 3D integration.

An optimal stacking order for mid-bond testing cost reduction of 3D IC

In order to solve the problem that the testing cost of the three-dimensional integrated circuit(3D IC)is too high,an optimal stacking order scheme is proposed to reduce the mid-bond test cost.A new testing model is built with the general consideration of both the test time for automatic test equipment(ATE)and manufacturing failure factors.An algorithm for testing cost and testing order optimization is proposed,and the minimum testing cost and optimized stacking order can be carried out by taking testing bandwidth and testing power as constraints.To prove the influence of the optimal stacking order on testing costs,two baselines stacked in sequential either in pyramid type or in inverted pyramid type are compared.Based on the benchmarks from ITC 02,experimental results show that for a 5-layer 3D IC,under different constraints,the optimal stacking order can reduce the test costs on average by 13%and 62%,respectively,compared to the pyramid type and inverted pyramid type.Furthermore,with the increase of the stack size,the test costs of the optimized stack order can be decreased.

AIR-GAP-BASED RF COAXIAL TSV AND ITS CHARACTERISTIC ANALYSIS

Many 3D IC applications such as MEMS and RF systems require Through-Silicon Via （TSV） with operations for high-speed vertical communication. In this paper, we introduce a novel air-gap coaxial TSV that is suiTab, for such RF applications. Firstly, the detailed fabrication process is described to explain how to acquire such a structure. Then, an Resistor Inductance Conductance Capacitance （RLGC） model is developed to profile the transverse electromagnetic field effect of the proposed air-gap TSV. The model is further verified by a 3D field solver program through the S-parameter comparison. With reference to the numerically simulated results, this analytical model delivers a maximum deviation of less than 6%0, on the conditions of varying diameters, outer to inner radius ratios, and SU-8 central angles, etc. Taking advantages of scalability of the model, a number of air-gap-based TSV designs are simulated, providing 1.6-4.0 times higher bandwidth than the con- ventional coaxial TSVs and leading to an efficient high frequency vertical RF interconnection solution for 3D ICs.

Circuit modeling and performance analysis of SWCNT bundle 3D interconnects

Metallic carbon nanotubes （CNTs） have been proposed as a promising alternative to Cu interconnects in future integrated circuits （ICs） for their remarkable conductive, mechanical and thermal properties. Compact equiv alent circuit models for single-walled carbon nanotube （SWCNT） bundles are described, and the performance of SWCNT bundle interconnects is evaluated and compared with traditional Cu interconnects at different interconnect levels for through-silicon-via-based three dimensional （3D） ICs. It is shown that at a local level, CNT interconnects exhibit lower signal delay and smaller optimal wire size. At intermediate and global levels, the delay improvement becomes more significant with technology scaling and increasing wire lengths. For 1 mm intermediate and 10 mm global level interconnects, the delay of SWCNT bundles is only 49.49% and 52.82% that of the Cu wires, respec tively.