I. INTERCONNECT TRENDS AND CHALLENGESThe driving force behind the impressive advancement of the VLSI circuit technology has been the rapid scaling of the feature size, i.e., the minimum dimension of the transistor. Table I lists the main characteristics of each technology generation in the NTRS. Such rapid scaling has two profound impacts. First, it enables much higher degree of on-chip integration. The number of transistors per chip will increase by more than 2 per generation to reach 800 millions in the© ¢ m technology. Second, it implies that the circuit performance will be increasingly determined by the interconnect performance. The interconnect design will play the most critical role in achieving the projected clock frequencies in the NTRS. This paper presents the trends and challenges of interconnect design in current and future technologies and discusses the available solutions.In order to better understand the significance of interconnect design in the future technology generations, we performed a number of experiments based on the interconnect parameters provided in the NTRS as shown in the bold face in Table II global interconnects, we also derived the interconnect parameters for the M4 layer,c which are also shown in Table II. Furthermore, we derived a set of device parameters as shown in Table III based on the data on processes and device in the NTRS. Using these sets of parameters, we carried out extensive simulations using HSPICE to quantitatively measure the interconnect performance and reliability in future technology generations and obtained the following results:(1) Interconnect delay is clearly the dominating factor in determincWe assume that the minimum width and spacing of M4 is 2.5 times those of M1. The aspect ratios 7 6 8 and 7 6 A @ are used to determine the metal thickness and the dielectric thickness for all layers. For M1, we assume that the substrate and M2 are the ground planes; and for M4, we assume that M3 and M5 are the ground planes. The total capacitance, including the area capacitance, fringing capacitance, and coupling capacitance components, are obtained using the 3D field solver FastCap [2]. Based on these assumptions, our capacitance values for M1 closely match those given in the NTRS.

Abstract-This paper presents a set of interconnect performance estimation models for design planning with consideration of various effective interconnect layout optimization techniques, including optimal wire sizing, simultaneous driver and wire sizing, and simultaneous buffer insertion/sizing and wire sizing. These models are extremely efficient, yet provide high degree of accuracy. They have been tested on a wide range of parameters and shown to have over 90% accuracy on average compared to running best-available interconnect layout optimization algorithms directly. As a result, these fast yet accurate models can be used efficiently during high-level design space exploration, interconnect-driven design planning/synthesis, and timing-driven placement to ensure design convergence for deep submicrometer designs.Index Terms-Buffer insertion and sizing, design planning, driver sizing, interconnect estimation, wire sizing.

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In this paper, we develop a multi-level physical hierarchy generation (mPG) algorithm integrated with fast incremental global routing for directly updating and optimizing congestion cost during placement. The fast global routing is achieved by using a fast twobend routing and incremental A-tree algorithm. The routing congestion is modeled by the wire usage estimated by the fast global router. A hierarchical area density control is also developed for placing objects with significant size variations. Experimental results show that, compared to GORDIAN-L , the wire length driven mPG is ¿ times faster and generates slightly better wire length for test circuits larger than 100K cells. Moreover, the congestion driven mPG improves ¼± wiring overflow with ± larger bounding box wire length but ¿ ± shorter routing wire length measured by graph based A-tree.

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