Ieee Std P1838: Dft Standard-Under-Development For 2.5d-, 3d-, And 5.5d-Sics

For stacked integrated circuits, effective test access requires the design-for-test (DfT) features in the various dies to operate in a concerted way to transport test stimuli and responses from and to the external I/Os up and down through the stack. This 3D-DfT can be proprietary if all dies in the stack are made by a single company. However, in the likely case that the various dies in the stack originate from different companies, standardized 3D-DfT is required to guarantee inter-operability. IEEE Std P1838 is a standard-under-development that addresses exactly this issue. This paper presents a status report of P1838 and describes its three main hardware components: a serial control mechanism, a die wrapper register, and a flexible parallel port.