This paper presents a new electrostatic discharge (ESD) protection design for input/output (I/O) cells with embedded silicon-controlled rectifier (SCR) structure as power-rail ESD clamp device in a 130-nm CMOS process. Two new embedded SCR structures without latchup danger are proposed to be placed between the input (or output) pMOS and nMOS devices of the I/O cells. Furthermore, the turn-on efficiency of embedded SCR can be significantly increased by substrate-triggered technique. Experimental results have verified that the human-body-model (HBM) ESD level of this new proposed I/O cells can be greater than 5 kV in a 130-nm fully salicided CMOS process. By including the efficient power-rail ESD clamp device into each I/O cell, whole-chip ESD protection scheme can be successfully achieved within a small silicon area of the I/O cell.