Investigation of degradation and recovery characteristics of NBTI in 28-nm high-k metal gate process

Degradation induced by the negative bias temperature instability(NBTI)can be attributed to three mutually uncoupled physical mechanisms,i.e.,the generation of interface traps(ΔV_(IT)),hole trapping in pre-existing gate oxide defects(ΔV_(HT)),and the generation of gate oxide defects(ΔV_(OT)).In this work,the characteristic of NBTI for p-type MOSFET fabricated by using a 28-nm high-k metal gate(HKMG)process is thoroughly studied.The experimental results show that the degradation is enhanced at a larger stress bias and higher temperature.The effects of the three underlying subcomponents are evaluated by using the comprehensive models.It is found that the generation of interface traps dominates the NBTI degradation during long-time NBTI stress.Moreover,the NBTI parameters of the power-law time exponent and temperature activation energy as well as the gate oxide field acceleration are extracted.The dependence of operating lifetime on stress bias and temperature is also discussed.It is observed that NBTI lifetime significantly decreases as the stress increases.Furthermore,the decrease of charges related to interface traps and hole detrapping in pre-existing gate oxide defects are used to explain the recovery mechanism after stress.

Single-event-transient effect in nanotube tunnel field-effect transistor with bias-induced electron–hole bilayer

The single event transient(SET)effect in nanotube tunneling field-effect transistor with bias-induced electron–hole bilayer(EHBNT-TFET)is investigated by 3-D TCAD simulation for the first time.The effects of linear energy transfer(LET),characteristic radius,strike angle,electrode bias and hit location on SET response are evaluated in detail.The simulation results show that the peak value of transient drain current is up to 0.08 m A for heavy ion irradiation with characteristic radius of 50 nm and LET of 10 Me V·cm^(2)/mg,which is much higher than the on-state current of EHBNTTFET.The SET response of EHBNT-TFET presents an obvious dependence on LET,strike angle,drain bias and hit location.As LET increases from 2 Me V·cm^(2)/mg to 10 Me V·cm^(2)/mg,the peak drain current increases monotonically from 0.015 mA to 0.08 mA.The strike angle has an greater impact on peak drain current especially for the smaller characteristic radius.The peak drain current and collected charge increase by 0.014 mA and 0.06 fC,respectively,as the drain bias increases from 0.1 V to 0.9 V.Whether from the horizontal or the vertical direction,the most sensitive hit location is related to wt.The underlying physical mechanism is explored and discussed.

A comparison of surgical efficacy between a 1.8-mm microincision and 3.2-mm and 5.5-mm incisions for phacoemulsification

Phacoemulsification is a commonly used surgical method in cataract surgery. This paper observes and compares the surgical efficacy of three incisions of different length for phacoemulsification to identify the optimal method for cataract surgery. Ninety patients were enrolled in the present study and divided into three groups. The 1.8-mm group received Bausch ＆ Lomb MI60 foldable intraocular lens （IOL） implantation （n=30）, 3.2-mm group received Bausch ＆ Lomb Akreos AO foldable lens implantation （n=30）, and 5.5-mm group received Alcon TYPE 05 rigid IOL implantation （n=30）. Visual acuity, Oculyzer-based anterior segment analysis, and corneal endothelial cell count before surgery, and 3, 7, 30, and 90d after surgery were recorded and compared. Pseudophakic accommodation three days, one week, one month, and three months after surgery was determined. Intraoperative ultrasound time and ultrasonic energy were recorded. It was finally concluded that for phacoemulsification with the same phaco tip, a 1.8-mm microincision can lead to quicker recovery of visual acuity, more stable astigmatism, and higher pseudophakic accommodation than conventional incision.