Thermal deformation of Cu-SiCOH interconnect layer

The conventional dielectric material SiO₂ is going to be replaced by materials with low dielectric constants, such as SiCOH, in the demands of faster speed, lower power consumption and reduced cross-talk. Because of the decreasing dimensions and increasing complexity, it is important to verify Cu-SiCOH structure reliability experimentally. A novel experimental micromechanics technique SIEM (Speckle Interferometry with Electron Microscopy) was employed to examine the thermal deformation of Cu-SiCOH interconnect layer. SIEM is a micro-mechanics measurement technique that has a spatial resolution approaching to a few nanometers. It is able to perform the full field displacement mapping over a region of only several microns in diameter. An electronic chip, which was designed to test the Cu-SiCOH interconnect layer, was evaluated by SIEM. There are three layers in this electronic chip, SiCOH film (about 1 micron in thickness), copper wire and silicon die. The thermal deformation of these three layers in the cross-section of the chip was obtained at 15000x magnification with a temperature difference 188°C. And the Cu-SiCOH interconnect layer showed a good reliability.