A 55nm Ultra Low Leakage Deeply Depleted Channel technology optimized for energy minimization in subthreshold SRAM and logic

This paper presents an Ultra-Low Leakage (ULL) 55nm Deeply Depleted Channel (DDC) process technology for low power Internet of Things (IoT) applications. The DDC ULL devices provide 67% reduction in threshold (VT) variation due to Random Dopant Fluctuation (RDF). Circuit techniques such as subthreshold operation and reverse body biasing (RBB) are co-designed with the technology to maximize the energy/power saving. A test chip implements a 1Kb 6T SRAM, an FIR filter, and a 51-stage RO to showcase how the technology works with circuit techniques to minimize energy. The 6T SRAM array operates reliably down to 200mV with a reduced leakage power of 7nW (85% lower compared to non-DDC devices). The FIR filter consumes just 4.5pJ/cycle operating at 0.36V at 200 KHz.