Special session 4C: Hot topic 3D-IC design and test

Three-dimensional (3D) integration using through silicon via (TSV) is a promising approach to coping with the challenges faced by the current 2D technology. A TSV-based 3D IC is implemented by stacking multiple dies which are vertically connected by TSVs. This may shorten the global interconnects of a 3D IC and greatly improve its performance and power consumption. High bandwidth is achieved by the increase of IO channels provided by the TSVs, which also reduce the unnecessary waste of energy during data movement. In addition, the 3D integration technology shows other advantages over 2D technology, such as high functionality, heterogeneous integration, small form factor, etc. However, there are still challenges that need to be tackled before volume production of 3D ICs using TSV becomes possible, including technology scalability, quality and reliability, yield, thermal management, equipment and infrastructure, and costs. To demonstrate the feasibility of 3D-IC technologies, many academic and industrial institutes have been working on various test vehicles, especially in recent years. An increasing attention also has been attracted around the world in the semiconductor industry by the development of related technologies. In this special session, we will discuss the evolutionary efforts toward the realization of 3-D ICs. As memory dies need to be integrated in most 3D-IC system, we will also address the challenges in the design and test of 3D memories against cross-layer process, voltage and temperature variations while suppressing thermal effect and power consumption, etc. We will share our experiences and show results from some of the test vehicles we have worked on, including processor/memory stacks, analog/logic stacks, logic/logic stacks, etc. We will show a 1,024-bit wide bus chip-to-chip interconnection using 40×40 fine-pitch TSVs to demonstrate ultra-low-power operation. For memories, we will present a 3D-RAM structure using small voltage-swing TSVs, vertical-device-stacking nonvolatile-SRAM and ReRAM, and a 3D vertical-gate NAND flash. To address the challenge of reliability and yield, we will also discuss important test techniques. Demonstration of benefits provided by 3D integration technology will also be shown. Last but not least, we will describe our development plan regarding various types of die stacking using heterogeneous process integration, especially processor/memory stacking that is widely believed to be a key technology in future generations of smart handheld devices.