High-speed CMOS: Si light emitters for on-chip optical interconnects

TLDR: In this paper, the speed of operation of a reverse biased pn junction has been evaluated using a streak camera, and the results clearly indicate that optical interconnects are a viable option for the future IC technologies.

Abstract: The delays and power requirements associated with long metal lines for 70nm and beyond technologies make on-chip optical interconnects an attractive option. The semiconductor industry has not enthusiastically responded to on-chip optical interconnects due to the difficulties associated with fabrication of optical emitters on Silicon substrate. Most emitters being researched use materials other than Silicon technologies - not compatible with conventional Si fabrication process. Hence, an optical inter-connect incorporating Si light emitter that can be fabricated shows excellent promise. A reverse biased Si-based p-n junction is known to emit broadband visible and infrared light emission in the range of 400-900 nm. Due to indirect band-gap in Si, the speed of operation and power requirement of Si based light emitting diodes has been considered to be non feasible for VLSI implementation. In this paper, the speed of operation of a reverse biased pn junction has evaluated using a streak camera. Power requirement for optical interconnects has been calculated using the experimental value of quantum efficiency. Results from the experiments clearly show that Si-based diodes are capable of operating in minimum of 10's of GHz and will require power less than conventional global metal interconnects on an IC. These results clearly indicate that optical interconnects are a viable option for the future IC technologies.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.