Space charge and anomalous discharge currents in crosslinkedpolyethylene

Transient currents in cross-linked polyethylene (XLPE) have been investigated by using different parameters: temperature T, electrical field E_p and hydrostatic pressure P. Anomalous discharging currents flowing in the same direction as charging currents were observed from T=30 to 70°C, P=0.1 to 30 MPa and E_p=13 to 33 kV/mm. The space charge was measured using the pressure wave propagation method (PWP). Theoretical calculation revealed that this anomalous behavior can result from charge migration under a partial blocking condition at the electrodes. We discuss theoretical results which are in reasonable agreement with our discharge current measurements     

Interface states characterization in heterojunction solar cells from CV-GV measurements and modeling

A new method is proposed to extract interface states density D_it at the hydrogenated amorphous/crystalline silicon interfaces (aSi:H/cSi) of heterojunction solar cells - HET. This technique based on CV and GV measurements consists in adapting standard electrical D_it models for MOS structures to the specific case of HET solar cells. In particular, a parasitic conductance is introduced to account for the high leakage current of the diode in the forward regime. The relevance and accuracy of such an analytical model is then demonstrated by comparison with experimental results and with more complex numerical approaches. Finally, this technique enables us to demonstrate the high quality of the interface of HET solar cells which exhibit D_it levels below 10¹¹ defects per cm².     

Performance and reliability of advanced High-K/Metal gate stacks (Invited Paper)

This paper provides a systematic study of mobility performance and Bias Temperature Instabilities (BTI) reliability in advanced dielectrics stacks. By studying a large variety of dielectric stacks we clearly demonstrate that mobility performance, interface defects Nit and Negative BTI reliability are strongly correlated. All are affected by nitrogen species N which is clearly identified as the main mobility killer when it reaches unintentionally the Si interface during the deposition of nitrided gates or the nitridation steps.     

Ageing and reliability testing and monitoring of power cables:diagnosis for insulation systems: the ARTEMIS program

The ARTEMIS BRITE-EURAM program has been presented in this paper. Its main objective is to develop a diagnostic methodology to assess i) the susceptibility of polymeric cable insulation to electrical ageing; and ii) the state of the insulation at any chosen time in order to evaluate the remaining life-time of operating power cables. The ARTEMIS partners include cable manufacturers, material suppliers, electricity distributors and a number of universities throughout Europe     

Initial and PBTI-induced traps and charges in Hf-based oxides/TiN stacks

Positive voltage instabilities are studied for Nmos transistors with hafnium-based high-κ gate stacks. Using an optimized dedicated fast measurement setup, dynamic transient measurements of drain current are performed over more than ten decades of time. The two main phenomena involved, a reversible one known as hysteresis and a nonreversible one known as PBTI are clearly experimentally separated and studied in detail. A physical model is presented, explaining the dynamic behaviour and leading to precise traps physical characteristics and profiles inside the HfO₂ layer. PBTI defects in HfO₂ are shown to be of a different nature than hysteresis traps. A turn-around effect is evidenced for PBTI above which physical mechanisms seem to change; it has important implications on lifetime determination methodology. Finally, HfSiON experiments are presented for both hysteresis and PBTI and they show that this material is much less critical than HfO₂.     

SiON and SiO2/HfSiON gate oxides time dependent dielectric breakdown measurements at nanoscale in ultra high vacuum

Time dependent dielectric breakdown (TDDB) measurements on a nano-scale using an AFM tip under ultra high vacuum as upper electrode are systematically compared to device measurements in this paper. Both studies were performed on the same SiON or SiO₂/HfSiON gate oxides. The shape factor of the TDDB distribution and the acceleration factor are compared at both scales.     

Process dependence of BTI reliability in advanced HK MG stacks

Bias temperature instabilities (BTI) reliability is investigated in advanced dielectric stacks. We show that mobility performance and NBTI reliability are strongly correlated and that they are affected by the diffusion of nitrogen species N at the Si interface. PBTI, more sensitive to bulk oxide traps, is strongly reduced in very thin dielectric films. Reducing the metal gate thickness favors the reduction of mobility degradations and NBTI, but, also strongly enhances PBTI, due to a complex set of reactions in the gate oxide. Trade off must be found to obtain a great trade off between device performance and reliability requirements.