High-Density Laser Linking Of Metal Interconnect

Laser programmed inter-level metal connections have been developed as a means to achieve high-density linking for customization in programmable gate arrays and for additive redundancy in restructurable integrated circuits. This work reports on the linking of 4 μmx 4 μm crossings of standard two-level metal interconnect lines and subsequent microstructural analyses aimed at understanding the mechanism of link formation. The links were formed by focusing a laser on metal 1 through an annular region of metal 2. The mechanism of link formation appears to be a physical connection made by a fracture of the dielectric layer due to the stress of thermal expansion of the metallization with molten metal 2 Ailing the crack.