Interfacial reaction and thermal stability of Ta2O5/TiN for metal electrode capacitors

High dielectric constant (k) materials are being considered as a replacement for SiO₂ and SiN in capacitors for DRAM and RF circuits as critical dimensions of ICs continue to decrease. The transition to a nonsilicon-based dielectric in these applications is not simply a change in materials. It also represents a fundamental change in processing toward deposited dielectrics and away from those that can be thermally grown on bulk or polycrystalline silicon. Dielectrics formed by thermal growth on a similar material have many advantages, including good step coverage, thickness uniformity, and control of interfacial properties. To retain these advantages with deposited materials, one must have good control of interfacial growth properties, such as with epitaxial film growth. We discuss here the importance of the high-k dielectric/metal interface in deciding electrical properties of deposited metal oxide thin films.