Impact of Electrode Composition and Processing on the Low-Frequency Noise in SrTio3 MIM Capacitors

Strontium titanate (STO) has been proposed as dielectric material in metal-insulator-metal (MIM) capacitors for future DRAM generations due to its higher dielectric constant and corresponding lower equivalent oxide thickness. In this letter, we show for the first time the impact of electrode composition and processing on the low-frequency noise (LFN), hence on the device material defectiveness, in large area (1000 μm × 1000 μm) MIM capacitors with STO dielectric (EOT is ~0.4nm, physical thickness is ~8.5nm) and Ru/TiN or TiN as metal electrodes. LFN measurements show that the power spectral density (S_IG) associated with gate current (I_G) fluctuations follows a 1/f shape and that SIG αI^α_G with α measured between 1.6 and 1.9. In particular, it is shown that PVD processing for top electrode Ru in place of chemical vapor deposition processing results in a significant (more than three decades) noise reduction (lower trap density) according to the observed lower gate leakage (<; 10^-7A/cm² at ±1 V).