When more than one dies are stacked vertically in 3-D integrated circuits (3DICs), the overall system yield degrades significantly. While each die can be tested before stacking, failures in 3DIC interconnects could jeopardize the entire system. In this paper, a dual-mode transceiver is proposed as a built-in-self-test/repair solution to improve the yield of direct face-to-face copper thermocompression bonding (Cu-Cu bonding). The proposed transceiver could improve the Cu-Cu bonding-based interconnect reliability with the introduction of two operation modes: the ohmic mode when Cu-Cu bonding presents low resistance and the capacitive coupling mode when Cu-Cu bonding is showing any sign of failure with high resistance at the bonding interface. Such mode sensing is self-contained in the transceiver itself with the help of the proposed resistance sensor. In this paper, we discuss the modeling of Cu-Cu bonding and the proposed transceiver design with power, latency, jitter, and crosstalk simulations followed by the design guideline for the practical implementation with yield analysis.

3D physical design needs accurate device model of through-silicon vias (TSVs). In this paper, physics-based electrical-thermal model is introduced for both signal and dummy thermal TSVs with the consideration of nonlinear electrical-thermal dependence. Taking thermal-reliable 3D clock-tree synthesis as a case-study to verify the effectiveness of the proposed TSV model, one nonlinear programming-based clock-skew reduction problem is formulated to allocate thermal TSVs for clock-skew reduction under non-uniform temperature distribution. With a number of 3D clock-tree benchmarks, experiments show that under the nonlinear electrical-thermal TSV model, insertion of thermal TSVs can effectively reduce temperature-gradient introduced clock-skew by 58.4% on average, and has 11.6% higher clock-skew reduction than the result under linear electrical-thermal model.

A robust physical design of 3-D IC requires investigation on through-silicon via (TSV). The large temperatures and stress gradients can severely affect TSV delay with large variation. The traditional physical model treats TSV as a resistor with linear electrical-thermal dependence, which ignores the fundamental device physics. In this paper, a physics-based electrical-thermal–mechanical delay model is developed for signal TSVs in 3-D IC. With consideration of liner material and also stress, a nonlinear model is established between electrical delay with temperature and stress. Moreover, sensitivity analysis is performed to relate the reduction of temperature and stress gradients with respect to dummy TSVs insertion. Taking the design of 3-D clock tree as a case study, we have formulated a nonlinear optimization problem for clock-skew reduction. By allocating dummy TSVs to reduce the temperature and stress gradients, the clock skew introduced by signal TSVs and drivers can be minimized. A number of 3-D clock-tree benchmarks are utilized in experiments. We have observed that with the use of dummy TSV insertion, clock skew can be reduced by 61.3% on average when the accurate nonlinear electrical-thermal–mechanical delay model is applied.

We present an overview of a new monolithic fabrication technology known as three-dimensional integration. 3D integration refers to any process by which multiple conventional device layers may be stacked and electrically interconnected. By combining state-of-the-art single-wafer integration with a high-density inter-wafer interconnect, our 3D integration process is capable of providing improved circuit performance in terms of metrics such as wire length, area, timing, and energy consumption. In this paper, we will discuss the overall 3D integration process flow, as well as specific technological challenges and the issues they present to circuit designers. We will also describe how these issues may be tackled during the placement, routing, and layout stages of physical design. Finally, we will present some performance results that may be obtained by integrating circuits in three dimensions.