Electrical characteristics of nMOSFETs fabricated on hybrid orientation substrate with amorphization/templated recrystallization method

The use of hybrid orientation technology (HOT) with direct silicon bond (DSB) wafers consisting of a (1 1 0) crystal orientation layer bonded to a bulk (1 0 0) handle wafer provides promising opportunities for easier migration of bulk CMOS designs to higher performance materials. However, the material quality of nMOSFETs regions, which has been undergone amorphization/templated recrystallization (ATR) process for transforming the Si surface into (1 0 0) orientation, is still a concern because the ATR-induced defects (i.e., dislocation loops or threads) at the recrystallization layer, could degrade gate oxide integrity. In this paper, we report an investigation of charge pumping and low-frequency (1/f) noise in HOT nMOSFETs. Devices with the increased anneal time brought out a significant reduction in the charge pumping current and 1/f noise, which indicates ATR-induced defects were suppressed and consequently the “low-trap-density” of the Si/SiO₂ interface. Finally, for the first time, the behavior of 1/f noise for HOT nMOSFETs was investigated, and could be described by a unified model, i.e. a combination of carrier-number fluctuations and mobility fluctuations.     

PMOSFET Reliability Study for Direct Silicon Bond (DSB) Hybrid Orientation Technology (HOT)

The use of hybrid orientation technology with direct silicon bond wafers consisting of a (110) crystal orientation layer bonded to a bulk (100) handle wafer provides exciting opportunities for easier migration of bulk CMOS designs to higher performance materials, particularly (110) Si for PMOSFETs for higher hole mobility. In this letter, a 3times mobility improvement and 36% drive current gain were achieved for PMOSFETs on (110) substrates. A systematic investigation of PMOSFET reliability was conducted, and significant degradation of negative bias temperature instability lifetime on (110) orientation was observed due to higher density of dangling bonds. We also report the crystal orientation dependence on ultrathin nitrided gate oxide time-dependent dielectric breakdown.     

Synthesis and characterization of Nd doped LiMn2O4 cathode for Li-ion rechargeable batteries

Spinel powders of LiMn_1.99Nd_0.01O₄ have been synthesized by chemical synthesis route to prepare cathodes for Li-ion coin cells. The structural and electrochemical properties of these cathodes were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, cyclic voltammetry, and charge-discharge studies. The cyclic voltammetry of the cathodes revealed the reversible nature of Li-ion intercalation and deintercalation in the electrochemical cell. The charge-discharge characteristics for LiMn_1.99Nd_0.01O₄ cathode materials were obtained in 3.4–4.3 V voltage range and the initial discharge capacity of this material were found to be about 149 mAh g⁻¹. The coin cells were tested for up to 25 charge-discharge cycles. The results show that by doping with small concentration of rare-earth element Nd, the capacity fading is considerably reduced as compared to the pure LiMn₂O₄ cathodes, making it suitable for Li-ion battery applications.     

Charge trapping induced frequency-dependence degradation in n-MOSFETs with high-k/metal gate stacks

This letter investigates the reliability issues of HfO₂/Ti_{1 − x}N_x metal-oxide-semiconductor field effect transistor in terms of static and dynamic stress. The results indicate threshold voltage (V_th) instability under dynamic stress is more serious than that under static stress, owning to transient charge trapping within high-k dielectric. Capacitance–voltage techniques verified that electron trapping under dynamic stress was located in high-k dielectric near the source/drain (S/D) overlap region, rather than the overall dielectric. Furthermore, the V_th shift clearly increases with an increase in dynamic stress operation frequency. This phenomenon can be attributed to the fact that electrons injecting to the S/D overlap region have insufficient time to de-trap from high-k dielectric. We further investigated the impact of different Ti_{1 − x}N_x composition of metal-gate electrode on charge trapping characteristics, and observed that V_th shift decreases significantly with an increase in the ratio of nitride. This is because the nitride atoms diffusing from the metal gate fill up oxygen vacancies and reduce the concentration of traps in high-k dielectric.