New Modelling Off-state TDDB for 130nm to 28nm CMOS nodes

International audienceWe present a detailed analysis of Off-state Time Dependent Dielectric Breakdown (TDDB) under non-uniform field performed in MOSFET devices from 28nm FDSOI, 65nm SOI to 130nm nodes. Oxide breakdown in thin gate oxide is characterized under DC stress with different gate-length LG and as function of drain voltage VDS and temperature. We show that the leakage current is a better monitor for TDDB dependence under Off-mode stress whereas a new modeling is proposed. It is found that Weibull slopes β are higher in PFET due large amount of injected hot electrons than in NFET when hot holes are involved

Universal Dielectric Breakdown Modeling Under Off-State TDDB for Ultra-Scaled Device From 130nm to 28nm Nodes and Beyond

International audienceThis study investigates the commonality of TDDB under Off-state conditions across a range of CMOS nodes, from 130nm to ultra-scaled devices, i.e. 28nm fully-depleted silicon-on-insulator (FDSOI) CMOS. To achieve this, Off-mode gate-oxide breakdown is analyzed under non-uniform electric field to investigate the effects of stress induced leakage current, channel current, and lateral electric field in dielectric breakdown mechanism related to RF operations using ultra short channel devices. Oxide breakdown is characterized under DC stress with different gate-lengths LG as a function of drain voltage VDS and temperature. The study indicates that subthreshold leakage current is a critical factor in determining the Off-state time-dependent dielectric-breakdown (TDDB) degradation, which is caused by a combination of band-to-band tunneling mechanism, junction current and impact ionization phenomena. The proposed Off-state TDDB compact model confirms that the leakage current is a reliable indicator of TDDB dependence precursor to hard-breakdown. Additionally, the paper discusses potential causes of the higher form factor β value for PFET under Off-mode stressing, which may be attributed to high impact ionization, non-conducting hot-carrier effects, defect generation kinetics and a thinner defect cell size

Location of Oxide Breakdown Events under Off-state TDDB in 28nm N-MOSFETs dedicated to RF applications

International audienceA detailed analysis of Off-state gate-oxide breakdown (BD) mode and its location under non-uniform electric field is performed in 28nm fully-depleted silicon-on-insulator (FDSOI) N-MOSFET devices. We show that hard breakdown (HBD) occurs exclusively from the middle of the channel to the drain overlap extension for Off-state time-dependent dielectric-breakdown (TDDB). HBD is characterized under DC stress with different gate-length LG as a function of drain voltage VDS and temperature. We check that the leakage current is the better monitor for TDDB dependence precursor to HBD under Off-mode stress by using the proper modeling and discussing the different possible origin of the higher form factor B value under Off mode stressing

Integrated Test Circuit for Off-State Dynamic Drain Stress Evaluation

International audienceDynamic off-state stress for RF applications is investigated via integrated test circuits to enable GHz level testing. We have performed characterization of test circuits to ensure the dynamic stress signal waveform integrity, which is verified against model simulation data. We report a x2 gain on time-to-breakdown at 1GHz against DC TDDB off-state stress. Based on extraction of IDlin degradation, no frequency effect is observed from DC to 1GHz off-state stress conditions. Modeling of on-state and off-state interactions based on sum of degradations modes is then demonstrated and supported by experimental data.</p