Fujitsu Sets Ground for 32-nm Logic LSI Devices with Multi-Layer Interconnect Technology

Fujitsu announced that they have developed a new technology to offer high-reliability multi-layer interconnects for logic LSIs for 32nm generation and the next-generation nodes to come. This technological breakthrough uses copper with manganese additives coated with a microscopic film that acts like a metal barrier.

According to the company, the new technology reduces the linear resistance inside the interconnects and increases the electro-migration resistance, the main factor that leads to LSI degradation over time. The technology tries to answer the strong demand of high-performance, logic LSI devices to feature higher levels of integration and to consume less power, a target that can be achieved only by developing finer interconnects to be used in LSI devices.

The 32nm generation of logic LSIs that Fujitsu is currently working on will feature 50-nanometer wide pure-copper interconnects, but this requires a low electric resistance in the interconnects. The old 45-nanometer technology used copper interconnects shielded by a metal barrier that would act like a protective shield against age and humidity degradation. Moreover, the same barrier did not allow copper to diffuse into the insulating film, which would ultimately oxidize copper. While thickness was not a problem at the 45-nanometer scale, the 32-nm technology can not afford it, since it would take up a disproportionate amount of space.

Fujitsu came with a viable solution to fix the insulating film shortcoming. The company succeeded in reducing the line resistance by forming copper with manganese additives on an ultra-thin film barrier metal. The multi-layer interconnect technique allows the production of thinner and lower-resistance interconnects. Increasing electro-migration resistance would result in lower degradation over time. This technological breakthrough may open the gates for multi-layer interconnect technology applicable for logic LSIs for the 32nm generation and the company is planning to further develop the technology for even better integration with the LSI.