Cross-sectional Transmission Electron Microscopy (TEM) and Secondary Ion Mass Spectroscopy (SIMS) of syndes devices Lot 96AA & 94AE.

Transmission Electron Microscopy (TEM) cross sections and Secondary Ion Mass Spectroscopy (SIMS) have been used to examine device lot 96AA MOS desynchronizer. A thin layer of silicon dioxide, about 20angstroms thick was found between two layers of polysilicon. This thin layer of oxide serves as a diffusion barrier which leads to high gate threshold voltages. A thin layer of oxide was also found at the interface between the aluminum metallization and polysilicon at the source and drain contact window structure. This has led to high contact resistance. Cracks have also been found in TaSi(2) at every step of the polycide runner which also contribute to high resistivity between contacts.