New Connectivity

An etched circuit that shows the conductors and vias, which provide signal connections

Millions of transistors, circuits and other chip devices—after being defined by lithography and created by physical and chemical processing—must be connected to each other through several levels in order to create a functioning semiconductor. This process, called interconnect, defines one of the most difficult areas of semiconductor engineering. In fact, about 50% of the structure and fabrication cost of today's advanced integrated circuits are in interconnects, with that percentage growing for each new technology generation.

The International Technology Roadmap for Semiconductors (ITRS) identifies five difficult challenges for interconnect between now and 2009:

Introduction of new materials to meet conductivity requirements and reduce current leakage
Manufacturable interconnect structures that are compatible with new materials and processes
Achievement of necessary reliability
Three-dimensional (3D) control of interconnect features to achieve circuit performance and reliability
Manufacturability and defect management to meet cost/performance requirements

An important new approach in this field is 3D interconnect, in which chips are physically stacked and their circuits physically connected through microscopic avenues called "vias." Another advanced method is heterogeneous integration, which combines established interconnect schemes with advanced ones at selected places within a chip. These and other emerging interconnect technologies are being contemplated by engineers and scientists within the AMRC.