Fuse processing using dielectric planarization pillars

Abstract

An electrical fuse structure comprises a semiconductor substrate; at least one electrically insulating layer over the semiconductor substrate having a portion thereof containing electrical wiring and another, adjacent portion thereof substantially free of electrical wiring; optionally, a further electrically insulating layer over the at least one electrically insulating layer. The electrically insulating layer(s) have a depression formed over the portion substantially free of electrical wiring, with the depression having a lower surface level than an adjacent portion of the electrically insulating layer. The fuse structure also includes a fuse insulator disposed over the depression and a fuse over the fuse insulator. Preferably, the fuse insulator is disposed only in the depression to elevate the fuse to the same level as the adjacent portion of the electrically insulating layer. The fuse structure may have a single layer or comprise alternating layers having different degrees of reflectivity to a laser beam, such as alternating layers of silicon oxide and silicon nitride. The preferred fuse structure comprises an electrically and thermally resistive fuse insulator in the depression, such that the fuse insulator substantially prevents heat of an energy beam directed at the fuse from being transmitted to the semiconductor substrate. More preferably, the fuse formed has a width less that that of the fuse insulator. The fuse structure may further include additional wiring over the electrical insulating layer at the same level as the fuse.