Abstract
Laser-assisted device alteration (LADA) is an established technique used to identify critical speed paths in integrated circuit. In this paper, the characterization of continuous wave 1340nm laser induced currents and the LADA failure rate show that a two photon absorption explanation for the LADA effect is not plausible. The following sections confirm the results of a 28nm-node nMOS transistor using a 2.45NA solid immersion lens. The effects of global heating to that of local laser heating are then compared. The paper shows that the LADA response time to approximately 1300nm irradiation is << 100ns. It explains LADA at approximately 1300nm, free carrier absorption in the silicon and in the local silicide layers, and presents selected 1320nm LADA images on 28nm-node devices. Finally, it shows 1064nm LADA images on the same structure that indicate that 1064nm interaction with transistors is related to free carrier absorption, rather than electron-hole pair creation.
