Issue



Sematech achieves low-K plus coppers


01/01/1998







Sematech achieves low-k plus copper

SEMATECH`s interconnect program has integrated spin-on low-k dielectric materials into its copper metal process some two months ahead of schedule, and an exploration of CVD low-k materials is set to begin.

Citing competitive reasons, the consortium has not identified the insulating materials; however Jon Dahm, director of interconnect at SEMATECH, said the consortium has narrowed the choices down to three spin-on materials, from an original 150 possibilities. Tokyo Electron is providing the spin-on equipment, and Novellus is providing a CVD capping material. Allied Signal, Dow Chemical, DuPont, Schumacher, and W.L. Gore and Assoc. are also involved as dielectric suppliers, he said.

The low-k dielectrics being used by SEMATECH have a constant of 2.7, providing a 33% reduction in crosstalk compared to silicon dioxide`s constant of 4.0. "We`ve eliminated a tremendous amount of duplication of effort (for our member companies)," Dahm said. "We also know what the tricks are to making (the materials) work with copper." The next round of effort will focus on low-k CVD materials, and dielectrics with a constant of between 2 and 2.5, Dahm said.

In 1997, SEMATECH announced that it had used a damascene PVD/electroplating process to produce a copper metal layer on wafers, though the process used silicon dioxide as the insulator. At the time, a copper-plus-low-k process was not anticipated until year`s end. However, researchers achieved their goal on Oct. 31, said Dahm.

IBM and Motorola followed the announcement with their own plans to use six-layer copper interconnect processes in the coming year. Both advances pointed to silicon dioxide as a dielectric, at least initially.

SEMATECH`s latest work brings the needed dielectric materials into its own copper metallization development work and that of member companies. Dahm said SEMATECH`s development work is intended to give member companies a 6-12 month lead in advancing the move to copper metallization. - P.N.D.