Highly Manufacturable Device Isolation Technology Using Laser-Induced Epitaxial Growth for Monolithic Stack Devices

A novel isolation technology using a laser-induced epitaxial growth (LEG) process is proposed to achieve monolithically stacked active silicon without additional thermal budget. The epitaxial behavior in the proposed LEG process can be completely understood by existing models regarding solidification of melted Si. Test devices for electrical characterization were fabricated based on an established 80-nm dynamic random access memory (DRAM) process. The characteristics of DRAM cell transistors with this LEG-processed active silicon are shown to be similar to those with conventional active silicon in terms of both device performances and distributions. Therefore, LEG process is believed to be a promising device isolation technology for monolithic multistack devices.