Scan chain design for three-dimensional integrated circuits (3D ICs)

Scan chains are widely used to improve the testability of IC designs. In traditional 2D IC designs, various design techniques on the construction of scan chains have been proposed to facilitate DFT (Design-For-Test). Recently, three-dimensional (3D) technologies have been proposed as a promising solution to continue technology scaling. In this paper, we study the scan chain construction for 3D ICs, examining the impact of 3D technologies on scan chain ordering. Three different 3D scan chain design approaches (namely, VIA3D, MAP3D, and OPT3D) are proposed and compared, with the experimental results for ISCAS89 benchmark circuits. The advantages as well as disadvantages for each approach are discussed. The results show that both MAP3D and VIA3D approaches require no changes of 2D scan chain algorithms, but OPT3D can achieve the best wire length reduction for the scan chain design. The average scan chain wire length of six ISCAS89 benchmarks obtained from OPT3D has 46.0% reduction compared to the 2D scan chain design. To the best of our knowledge, this is the first study on scan chain design for 3D integrated circuits.