Mariko Takagi

A highly reliable metal-to-metal antifuse for high-speed field programmable gate arrays

This paper describes a novel metal-to-metal antifuse technology for field programmable gate arrays which achieves very high performance and reliability while maintaining full CMOS compatibility. Plasma-CVD SiN with Si/N=1 and Al covered with TiN are used as an antifuse dielectric and electrodes, respectively. This structure allows a desirable characteristics for high-speed FPGAs with off-state reliability of 1.7/spl times/10/sup 5/ years.<<ETX>>

A novel 0.15 /spl mu/m CMOS technology using W/WNx/polysilicon gate electrode and Ti silicided source/drain diffusions

A 0.15 /spl mu/m CMOS technology integrating W/WNx/polysilicon gate electrodes and Ti silicided source/drain diffusions is presented in this paper. Gate electrodes with sheet resistance as low as 1.6 /spl Omega//sq. and Ti silicided source/drain diffusions of 3.6 /spl Omega//sq. are realized. As a result, both the gate RC delay and parasitic source/drain resistance are minimized and high circuit performance is achieved.

Relation between stress-induced leakage current and dielectric breakdown in SiN-based antifuses

Degradation process of metal-to-metal antifuses which use thin silicon nitride as dielectric layer under high field stress is studied in detail. Prior to dielectric breakdown, leakage current at stress voltage increases with large and complex fluctuations for any sample. So-called stress-induced leakage current at low voltages in current-voltage characteristics is also observed and it increases as the stress continues. It is shown that the stress-induced leakage current and the pre-breakdown leakage current with fluctuations are identical phenomena, and that the stress-induced leakage current strongly relates to the dielectric breakdown. Therefore,it is important to understand the mechanism of the stress-induced leakage current in order to improve antifuse reliabilities. Discrete two-step fluctuations on the stress-induced leakage currents at low voltages are found and the stress-induced leakage current is not proportional to antifuse areas. Considering these findings, it is concluded that the stress-induced leakage current flows through local spots. The conduction mechanism of the stress-induced leakage currents is also studied. The main conduction process in SiN films appears to be Frenkel-Poole conduction. We also find that as the stress continues, the barrier height between an electrode and a SiN film becomes lower and the dielectric constant becomes larger. It is also found that the appearance of the stress-induced leakage current in the I-V characteristics depends on the thickness of the barrier metal. Dielectric breakdown electric field and TDDB lifetime also show the same dependence. Considering the experimental results, the stress-leakage current is related to the electrode material.<<ETX>>

Relation between Stress-Induced Leakage Current and Dielectric Breakdown in SiN-Based Antifuses

We report on the degradation process of metal-to-metal antifuses that use thin silicon nitride film as the dielectric layer under high electric field stress. Stress-induced leakage current was observed in all samples, and it flows through local spots. Two-level fluctuations were found on the leakage current well below the stress voltage, and large and complex fluctuations were observed near the stress voltage. The conduction mechanism of the stress-induced leakage current was the Poole-Frenkel type. It was found that the dielectric constant of the path became large and that the breakdown and the anomalous current depended on the barrier metal thickness. Considering these results, the stress-induced leakage current and the breakdown are thought to be caused by electromigration of electrode material to the SiN film.