Cheng-Tung Huang

On the Origin of Gate-Induced Floating-Body Effect in PD SOI p-MOSFETs

This letter systematically investigates the origin of gate-induced floating-body effect (GIFBE) in partially depleted silicon-on-insulator p-type MOSFETs. The experimental results indicate that GIFBE causes a reduction in the electrical oxide field, leading to an underestimate of negative-bias temperature instability degradation. This can be partially attributed to the electrons tunneling from the process-induced partial n+ polygate. However, based on different operation conditions, we found that the dominant origin of electrons was strongly dependent on holes in the inversion layer under source/drain grounding. This suggests that the mechanism of GIFBE at higher voltages is dominated by the proposed anode electron injection model, rather than the electron valence band tunneling widely accepted as the mechanism for n-MOSFETs.

Charge trapping induced drain-induced-barrier-lowering in HfO2/TiN p-channel metal-oxide-semiconductor-field-effect-transistors under hot carrier stress

This letter studies the channel hot carrier stress (CHCS) behaviors on high dielectric constant insulator and metal gate HfO2/TiN p-channel metal-oxide-semiconductor field effect transistors. It can be found that the degradation is associated with electron trapping, resulting in Gm decrease and positive Vth shift. However, Vth under saturation region shows an insignificant degradation during stress. To compare that, the CHC-induced electron trapping induced DIBL is proposed to demonstrate the different behavior of Vth between linear and saturation region. The devices with different channel length are used to evidence the trapping-induced DIBL behavior.

Investigation of an anomalous hump in gate current after negative-bias temperature- instability in HfO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors

This Letter investigates a hump in gate current after negative-bias temperature-instability (NBTI) in HfO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors. Measuring gate current at initial through body floating and source/drain floating shows that hole current flows from source/drain. The fitting of gate current (Ig)-gate voltage (Vg) characteristic curves demonstrates that the Frenkel-Poole mechanism dominates the conduction. Next, by fitting the gate current after NBTI, in the order of Frenkel-Poole then tunneling, the Frenkel-Poole mechanism can be confirmed. These phenomena can be attributed to hole trapping in high-k bulk and the electric field formula Ehigh-k ehigh-k = Q + Esio2esio2.

Investigation of abnormal negative threshold voltage shift under positive bias stress in input/output n-channel metal-oxide-semiconductor field-effect transistors with TiN/HfO2 structure using fast I-V measurement

This letter investigates abnormal negative threshold voltage shifts under positive bias stress in input/output (I/O) TiN/HfO2 n-channel metal-oxide-semiconductor field-effect transistors using fast I-V measurement. This phenomenon is attributed to a reversible charge/discharge effect in pre-existing bulk traps. Moreover, in standard performance devices, threshold-voltage (Vt) shifts positively during fast I-V double sweep measurement. However, in I/O devices, Vt shifts negatively since electrons escape from bulk traps to metal gate rather than channel electrons injecting to bulk traps. Consequently, decreasing pre-existing bulk traps in I/O devices, which can be achieved by adopting HfxZr1−xO2 as gate oxide, can reduce the charge/discharge effect.

High-k shallow traps observed by charge pumping with varying discharging times

In this paper, we investigate the influence of falling time and base level time on high-k bulk shallow traps measured by charge pumping technique in n-channel metal-oxide-semiconductor field-effect transistors with HfO2/metal gate stacks. NT-Vhigh level characteristic curves with different duty ratios indicate that the electron detrapping time dominates the value of NT for extra contribution of Icp traps. NT is the number of traps, and Icp is charge pumping current. By fitting discharge formula at different temperatures, the results show that extra contribution of Icp traps at high voltage are in fact high-k bulk shallow traps. This is also verified through a comparison of different interlayer thicknesses and different TixN1−x metal gate concentrations. Next, NT-Vhigh level characteristic curves with different falling times (tfalling time) and base level times (tbase level) show that extra contribution of Icp traps decrease with an increase in tfalling time. By fitting discharge formula for different tfal...

Abnormal sub-threshold swing degradation under dynamic hot carrier stress in HfO2/TiN n-channel metal-oxide-semiconductor field-effect-transistors

This work finds abnormal sub-threshold swing (S.S.) degradation under dynamic hot carrier stress (HCS) in n-channel metal-oxide-semiconductor field-effect-transistors with high-k gate dielectric. Results indicate that there is no change in S.S. after dynamic HCS due to band-to-band hot hole injection at the drain side which acts to diminish the stress field. Moreover, the impaired stress field causes the interface states to mainly distribute in shallow states. This results in ON state current and transconductance decreases, whereas S.S. degradation is insignificant after dynamic HCS. The proposed model is confirmed by one-side charge pumping measurement and gate-to-drain capacitance at varying frequencies.

Hole injection-reduced hot carrier degradation in n-channel metal-oxide-semiconductor field-effect-transistors with high-k gate dielectric

This work finds a significant difference in degradation under hot carrier stress (HCS) due to additional hole injection in n-channel metal-oxide-semiconductor field-effect-transistors with high-k gate dielectric. A comparison performed on degradation of input/output (I/O) and standard performance (SP) devices showed that performance degradation of the I/O device is worse than the SP device under HCS. For the SP device, both channel-electrons and hot holes can inject into gate dielectric, in which hole acts to diminish the stress field. However, I/O device shows only electron injection. The proposed model is confirmed by gate induced drain leakage current and simulation tool.

Analysis of an anomalous hump in gate current after dynamic negative bias stress in HfxZr1-xO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors

This letter investigates a hump in gate current after dynamic negative bias stress (NBS) in HfxZr1-xO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors. By measuring gate current under initial through body floating and source/drain floating, it shows that hole current flows from source/drain. The fitting of gate current-gate voltage characteristic curve demonstrates that Frenkel-Poole mechanism dominates the conduction. Next, by fitting the gate current after dynamic NBS, in the order of Frenkel-Poole then tunneling, the Frenkel-Poole mechanism can be confirmed. These phenomena can be attributed to hole trapping in high-k bulk and the electric field formula Ehigh-k ehigh-k = Q + Esio2esio2.

Analysis of anomalous traps measured by charge pumping technique in HfO2/metal gate n-channel metal-oxide-semiconductor field-effect transistors

This letter investigates anomalous traps measured by charge pumping technique in high voltage in HfO2/metal gate n-channel metal-oxide-semiconductor field-effect transistors. N-Vhigh level characteristic curves with different duty ratios indicate that the electron discharge time dominates the value of N for extra traps. By fitting ln (N (tbase level = 2.5μs)-N (tbase level))-Δtbase level at different temperatures and computing the equation t = τ0 exp (αe,SiO2d SiO2 + αe,HfO2d HfO2,trap), results show that these extra traps measured by the charge pumping technique at high voltage can be attributed to high-k bulk shallow traps.

Abnormal interface state generation under positive bias stress in TiN/HfO2 p-channel metal-oxide-semiconductor field effect transistors

This Letter studies positive bias stress-induced abnormal interface state on TiN/HfO2 p-channel metal-oxide-semiconductor field effect transistors. It can be found that the degradation is associated with electron trapping, resulting in Vth shift but without subthreshold slope degradation. However, charge pumping current (ICP) shows a significant degradation after stress. Accordingly, the impact ionization-induced Nit located HfO2/SiO2 is proposed to demonstrate the ICP degradation. The AC stress with several frequencies is used to evidence the occurrence of impact ionization. Further, the device with additional pre-existing Nit located SiO2/Si has insignificant degradation due to reduction in stress electric field.