Opticalin situprobing method for laser antifuse linking

Abstract

In circuit restructuration, it is often needed to create antifuse links, consisting in the formation of a connection between two adjacent metallic layers. These can be created by focusing a laser at a relatively high intensity to ensure efficient link creation. In order to minimize the optical power delivered in the chip from the pump laser, we have developed a novel optical in situ technique consisting of probing the link formation with a second laser beam. A sudden increase in the probe reflectance signal occurs when the metal fills the gap. By slowly increasing the pump laser beam power, it is possible to stop the intervention just after the link creation, thus minimizing the optical power delivered to the chip during the laser linking process.