Recovery of the MOSFET and circuit functionality after the dielectric breakdown of ultra-thin high-k gate stacks

The reversibility of the gate dielectric breakdown in ultra-thin high-k dielectric stacks is reported and analyzed. The electrical performance of MOSFETs after the dielectric recovery is modeled and introduced in a circuit simulator. The simulation of several digital circuits shows that their functionality can be restored after the BD recovery

Reliability Analysis of Hafnium Oxide Dielectric Based Nanoelectronics

With the physical dimensions ever scaling down, the increasing level of sophistication in nano-electronics requires a comprehensive and multidisciplinary reliability investigation. A kind of nano-devices, HfO2-based high-k dielectric films, are studied in the statistical aspect of reliability as well as electrical and physical aspects of reliability characterization, including charge trapping and degradation mechanisms, breakdown modes and bathtub failure rate estimation. This research characterizes charge trapping and investigates degradation mechanisms in high-k dielectrics. Positive charges trapped in both bulk and interface contribute to the interface state generation and flat band voltage shift when electrons are injected from the gate under a negative gate bias condition.A negligible number of defects are generated until the stress voltage increases to a certain level. As results of hot electrons and positive charges trapped in the interface region, the difference in the breakdown sequence is attributed to the physical thickness of the bulk high-k layer and the structure of the interface layer. Time-to-breakdown data collected in the accelerated life tests are modeled with a bathtub failure rate curve by a 3-step Bayesian approach. Rather than individually considering each stress level in accelerating life tests (ALT), this approach derives the change point and the priors for Bayesian analysis from the time-to-failure data under neighborhood stresses, based on the relationship between the lifetime and stress voltage. This method can provide a fast and reliable estimation of failure rate for burn-in optimization when only a small sample of data is available

Resistive switching like-behavior in MOSFETs with ultra-thin HfSiON dielectric gate stack : pMOS and nMOS comparison and reliability implications

In this work, the Resistive Switching (RS) phenomenon in n and pMOSFETs with ultrathin Hf based high-k dielectric is studied. Two different conductive levels, a high (HRS) and a low (LRS) resistance states can be distinguished in the dielectric. The influence of the voltage polarities applied to reach the HRS and the LRS on the RS phenomenology is analyzed. The drain current-drain voltage and drain current-gate voltage transistor characteristics during the HRS have also been analyzed in those cases where the RS has been observed. The results can be useful to understand the effect of the RS on the MOSFETs performance from a reliability point of view

Reversible dielectric breakdown in ultra Hf based high-k stacks under current limited stresses

The effects of a current-limited breakdown (BD) on the post-BD current of MOS capacitors with a thin high-k dielectric stack have been analysed. A strong current reduction after BD and, consequently, a partial recovery of the insulating properties of the dielectric stack is observed. The similarities with the Resistive Switching phenomenon observed in MIM structures for memory applications are discussed

Resistive switching-like behavior of the dielectric breakdown in ultra-thin Hf based gate stacks in MOSFETs

The gate dielectric breakdown (BD) reversibility in MOSFETs with ultra-thin hafnium based high-k dielectric is studied. The phenomenology is analyzed in detail and the similarities with the resistive switching phenomenon emphasized. The results suggest that the conductive path in the dielectric after BD can be 'opened' and 'closed' many times and that the BD recovery partially restores not only the current through the gate, but also the MOSFET channel related electrical characteristics

Injected charge to recovery as a parameter to characterize the breakdown reversibility of ultrathin HfSiON gate dielectric

The injected charge to recovery (QR) is presented as a parameter to characterize the dielectric breakdown (BD)reversibility in MOSFETs with ultrathin high-k hafnium based gate dielectric. The procedure to recover the dielectric is explained and the dependences of QR with the current limit during BD, the polarity of the BD-recovery stresses and the number of stress cycles are analyzed

Dielectric breakdown in ultra-thin Hf based gate stacks : a resistive switching phenomenon

In this work, the temperature dependence of the resistive switching-related currents (gate and drain) in MOSFETs with ultra-thin Hf based high-k dielectric has been analyzed, for the two dielectric conductivity states. The two different conductive states of the resistive switching have been associated to the breakdown (BD) and BD recovery of the dielectric. The results about the temperature dependence of the post-BD gate current are in agreement with those obtained from the study of the injected charge to recovery, a useful parameter to analyze the switch from the high to the low conductivity state. The drain current in the MOSFETs, for the two conductivity states, for different locations of the BD path along the channel (source and drain) and several temperatures has also been studied. The results are a contribution for a better understanding of the resistive switching phenomenon in ultra-thin gate dielectrics, which could be useful for the developing of models to describe BD reversibility