Yield of key integrated circuits such as DRAM, mixed signal and linear ICs out of the fab is usually very small. Attempts to tighten process control to improve the yield in the front-end of the wafer fab prove to be expensive and a better approach is to design in redundancy/repairability. Redundancy, repairability and post-fabrication programmability can be designed into a die to reduce manufacturing costs in the front end and a back-end process can be used to improve the yields coming out of the factory. This paper discusses various options available to the designer and focuses on the application of a laser to repair the die. The need for repair and selection of a repair technique is motivated through a discussion on the economics of the process. This is followed by a description of the physics of the process itself, along with tools to aid in the analysis and synthesis of repair elements on the die.
© 2004 Optical Society of AmericaPDF Article