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1.
Hot-carrier stressing was carried out on 1-μm n-type MOSFETs at 77 K with fixed drain voltage V d=5.5 V and gate voltage V g varying from 1.5 to 6.5 V. It was found that the maximum transconductance degradation ΔG m and threshold voltage shift ΔV t, do not occur at the same V g. As well, ΔK t is very small for the V g <V d stress regime, becomes significant at V g≈V d, and then increases rapidly with increasing V g, whereas ΔG m has its maximum maximum in the region of maximum substrate current. The behavior is explained by the localized nature of induced defects, which is also responsible for a distortion of the transconductance curves and even a slight temporary increase in the transconductance during stress 相似文献
2.
To investigate the highly boron-doped SiO2 film, p+ polysilicon-gate PMOSFETs and capacitors were fabricated using the same process as is used for surface-channel-type n+-gate devices, except for the gate-type doping. After the application of negatively biased Fowler-Nordheim (FN) stress, it was found that positive charges accumulate near the silicon/SiO2 interface and electrons accumulate near the polysilicon/SiO2 interface in p+-gate capacitors. DC hot carrier stress was applied to both PMOSFET gate types. The p+ gate's stress time dependence of I sub is smaller than that of the n+ gate, and the electric field near the drain in the p+ -gate PMOSFET was found to be more severe than that of the n+ -gate device. The subthreshold slope of the p+-gated PMOSFET was improved and then degraded during the hot carrier stressing, while that of the n+-gated device did not significantly change. The actual change of V th was larger than the value derived from Δgm using the channel-shortening concept. The idea of widely spreading and partially compensated electron distribution along with source-drain direction in the SiO2 film, which assumes the existence of trapped holes in the p+-gate PMOSFET, is proposed to explain these phenomena 相似文献
3.
A super-low-noise two-mode channel FET (TMT) with high- and plateau-shaped transconductance (gm) characteristics has been developed. It has two electron transport modes against the applied gate voltage (V gs). That is, the electrons mainly drift in a highly doped channel region at a shallow V gs. A plateau g m region and the maximum g m were achieved at a V gs range of -0.25~+0.5 V and 535 mS/mm, respectively. The minimum noise figure and associated gain for the TMT were superior in the low-drain-current (I ds) region and nearly equal in the middle and high I ds region to those of an AlGaAs/InGaAs pseudomorphic HEMT fabricated using the same wafer process and device geometry 相似文献
4.
A method of obtaining the spatial distribution of hot-carrier-induced trapped electrons in the gate oxide (N 0t(x )) of PMOSFETs is introduced with the aid of a two-dimensional simulator. The measured I ds versus V ds for various V gs for low drain bias and I ds versus V gs have been compared with data obtained from the simulation concerning the obtained spatial distribution of trapped electrons in the gate oxide. There exists a high degree of agreement between the measured current-voltage characteristics after hot-carrier stress and the simulation results concerning the newly obtained spatial distribution of trapped electrons in the gate oxide 相似文献
5.
Gate oxides grown with partial and complete oxidation in N2 O were studied in terms of hot-carrier stressing. The DC lifetime for 10% degradation in g m had a 15×improvement over control oxides not grown in a N2O atmosphere. Further improvement in g m degradation was observed in oxides that received partial oxidation as compared with control oxides. This improvement is due to the incorporation of nitrogen that reduces strained Si-O bonds at the Si/SiO2 interface, leading to lower interface state generation (ISG). Improvements were also observed in I g-V g characteristics, indicating a reduction of trap sites both at the Si/SiO2 interface and in the bulk oxide. Improved gate-induced drain leakage (GIDL) characteristics as a function of hot-carrier stressing for partial N2O oxides were observed over control oxides. However, severe drain leakage that masked GIDL was observed on pure N 2O oxides and is a subject for further study 相似文献
6.
The fabrication of 0.8-μm MOSFETs using 7.7-nm-thick nitrided oxides reoxidized by rapid thermal processing at 900-1150°C for 15-200 s is described. The hot-carrier-induced degradation was studied in terms of subthreshold swing, threshold voltage V T, and transconductance g m voltage characteristics. Results indicate that rapid reoxidation markedly improves hot-carrier immunity; lifetimes reaching 30-mV V T shift and 10 percent g m degradation are improved by 3 and 1.5 orders of magnitude compared with those for thermal oxides, respectively. A degradation characteristic inherent to the (reoxidized) nitrided-oxide system is found, based on the gate-voltage dependence of g m degradation 相似文献
7.
N-channel MOSFETs with different gate dielectrics, such as silicon dioxide, silicon dioxide annealed in nitrous oxide (NO), and reoxidized nitrided oxide (ONO), were first hot-carrier (HC) stressed and then irradiated to a total dose of 1.5 Mrd. For equal substrate current stressing NO devices have the least degradation, whereas the threshold voltage (V t) shift due to irradiation is maximum for these devices. For all three types of gate dielectrics the V t shift due to irradiation of HC stressed devices was higher than that of the unstressed device. However, for ONO devices the V t shift due to irradiation of the hot-electron stressed (stressing with V d=V g=6.5 V) device was less than that of the unstressed device 相似文献
8.
The mechanisms of channel hot-carrier-induced degradation in short n-channel MOSFETs with reoxidized nitrided oxide as the gate dielectric are discussed. Charge pumping measurements, supported by observations on the gate voltage dependence of degradation and the power law dependence of Δg m on stress time, demonstrate that virtually no interface trap generation occurs in reoxidized nitrided oxides and that electron trapping is the dominant degradation mechanism. Although electron trapping can be enhanced in these dielectrics, this mechanism is not as important for device degradation as interface trap generation, and the net effect is substantially improved resistance to hot-carrier stress. A three-orders-of-magnitude improvement in device lifetime (versus conventional oxide) is demonstrated 相似文献
9.
Busta H.H. Pogemiller J.E. Zimmerman B.J. 《Electron Devices, IEEE Transactions on》1993,40(8):1537-1542
The field at the tip of a field emitter triode can be expressed by E =βV g+γV c, where V g and V c the gate and collector voltages, respectively. For small gate diameters and tips below or in the plane of the gate and/or large tip-to-collector distances, γV c<<βV g. The-device is operated in the gate-induced field emission mode and the corresponding I -V c curves are pentode-like. By increasing the gate diameter and/or recessing the gates from the tips, collector-assisted operation can be achieved at reasonable collector voltages. Results are presented for two devices with gate diameters of 3.6 and 2.0 μm. By obtaining γ at different emitter-to-collector distances, I -V c and transconductance g m-V g curves are calculated and compared with experimental results. It is shown that as a consequence of collector-assisted operation, the transconductance of a device can be increased significantly 相似文献
10.
A technique has been developed to differentiate between interface states and oxide trapped charges in conventional n-channel MOS transistors. The gate current is measured before and after stress damage using the floating-gate technique. It is shown that the change in the I g-V g characteristics following the creation and filling of oxide traps by low gate voltage stress shows distinct differences when compared to that which occurs for interface trap creation at mid gate voltage stress conditions, permitting the identification of hot-carrier damage through the I g- V g characteristics. The difference is explained in terms of the changes in occupancy of the created interface traps as a function of gate voltage during the I g-V g measurements 相似文献
11.
Scherrer D. Kruse J. Laskar J. Feng M. Wada M. Takano C. Kasahara J. 《Electron Device Letters, IEEE》1993,14(9):428-430
The low-power microwave performance of an enhancement-mode ion-implanted GaAs JFET is reported. A 0.5-μm×100-μm E-JFET with a threshold voltage of V th=0.3 V achieved a maximum DC transconductance of g m=489 mS/mm at V ds=1.5 V and I ds=18 mA. Operating at 0.5 mW of power with V ds=0.5 V and I ds =1 mA, the best device on a 3-in wafer achieved a noise figure of 0.8 dB with an associated gain of 9.6 dB measured at 4 GHz. Across a 3-in wafer the average noise figure was F min=1.2 dB and the average associated gain was G a=9.8 dB for 15 devices measured. These results demonstrate that the E-JFET is an excellent choice for low-power personal communication applications 相似文献
12.
Vuillaume D. Marchetaux J.-C. Lippens P.-E. Bravaix A. Boudou A. 《Electron Devices, IEEE Transactions on》1993,40(4):773-781
The creation of defects by hot-carrier effect in submicrometer (0.85-μm) LDD n-MOSFETs is analyzed by the floating-gate and the charge-pumping techniques. It is emphasized that the floating-gate technique is an attractive tool for characterizing the oxide traps located in the drain-gate overlap region, near the oxide spacer of the LDD structures. This work gives new insight into the creation of acceptorlike oxide traps which are electrically active only after electron injection phases. These defects are generated in the whole stress gate bias range (from V d/8 to V d) by hot-hole and/or hot-electron injections, and their generation rates (10-9 and 10-2 for electron and hole injections, respectively) are one decade greater than for the interface state generation. Two-dimensional simulations show that they are mainly responsible for the I d-V g degradation of the LDD MOSFETs, and that the trap concentrations deduced from charge-pumping experiments are consistent with the I d-V g degradation 相似文献
13.
Threshold voltage model for deep-submicrometer MOSFETs 总被引:9,自引:0,他引:9
Liu Z.-H. Hu C. Huang J.-H. Chan T.-Y. Jeng M.-C. Ko P.K. Cheng Y.C. 《Electron Devices, IEEE Transactions on》1993,40(1):86-95
The threshold voltage, V th, of lightly doped drain (LDD) and non-LDD MOSFETs with effective channel lengths down to the deep-submicrometer range has been investigated. Experimental data show that in the very-short-channel-length range, the previously reported exponential dependence on channel length and the linear dependence on drain voltage no longer hold true. A simple quasi-two-dimensional model is used, taking into account the effects of gate oxide thickness, source/drain junction depth, and channel doping, to describe the accelerated V th on channel length due to their lower drain-substrate junction built-in potentials. LDD devices also show less V th dependence on drain voltage because the LDD region reduces the effective drain voltage. Based on consideration of the short-channel effects, the minimum acceptable length is determined 相似文献
14.
Deep submicrometer CMOSFETs with re-annealed nitride-oxide gate dielectrics have been demonstrated to satisfy 3.3-V operation, unlike conventional oxide FETs. The 1/4-μm re-annealed nitrided-oxide CMOS devices achieve (1) an improved saturation transconductance g m of ~250 μS/μm for n-FETs together with acceptably small degradation in p-FET g m resulting in a CMOS gate delay time of 55 ps/stage comparable or superior to the device/circuit performance of oxide FETs, and (2) device lifetimes improved by ~100 times to exceed 10 years with respect to both ON- and OFF-state hot-carrier reliability for n-FETs as well as gate-dielectric integrity together with unchanged p-FET hot-carrier reliability, all at 3.3-V operation. To achieve these CMOS performance/reliability improvements, both a light nitridation and subsequent re-annealing in O 2 (reoxidation) or in N2 (inert-annealing) are found to be crucial 相似文献
15.
Nguyen L.D. Schaff W.J. Tasker P.J. Lepore A.N. Palmateer L.F. Foisy M.C. Eastman L.F. 《Electron Devices, IEEE Transactions on》1988,35(2):139-144
The authors describe a study of charge control in conjunction with DC and RF performance of 0.35-μm-gate-length pseudomorphic AlGaAs/InGaAs MODFETs. Using C -V measurements, they estimate that a two-dimensional electron gas (2DEG) with density as high as 1.0×1012 cm-2 can be accumulated in the InGaAs channel at 77 K before the gate begins to modulate parasitic charges in the AlGaAs. This improvement in charge control of about 10-30% over a typical AlGaAs/GaAs MODFET may partially be responsible for the superior DC and RF performance of the AlGaAs/InGaAs MODFET. At room temperature, the devices give a maximum DC voltage gain g m/g d of 32 and a current gain cutoff frequency f T of 46 GHz. These results are state of the art for MODFETs of similar gate length 相似文献
16.
Ng G.I. Pavlidis D. Tutt M. Weiss R.M. Marsh P. 《Electron Devices, IEEE Transactions on》1992,39(3):523-532
Extensive bias-dependent and temperature-dependent low-frequency (LF) noise measurements were performed on lattice-matched and strained In0.52Al0.48As/InxGa1-x As(0.53<x <0.70) HEMTs. The input-noise voltage spectra density is insensitive to V DS bias and shows a minimum at V GS corresponding to the peak g m condition. The corresponding output-noise voltage spectral density, which depends strongly on the gain of the devices, increases with V DS. The input noise was rather insensitive to indium (In) content. Temperature-dependent low-frequency noise measurements on these devices reveal shallow traps with energies of 0.11, 0.15, and 0.18 eV for 60%, 65%, and 70% In HEMTs. Noise transition frequencies for these devices were on the order of 200-300 MHz and remain almost the same for different channel In content and V DS bias 相似文献
17.
An analytical expression for the recombination current in a forward-biased p-n junction is derived and it is shown that formulas given for the recombination current in most textbooks overestimate the recombination current by a large factor of the order of (V bi-V )/V th where V bi is the built-in voltage, V is the applied forward-bias voltage, and V th is the thermal voltage 相似文献
18.
The effects of hot-carrier stress on gate-induced drain leakage (GIDL) current in n-channel MOSFETs with thin gate oxides are studied. It is found that the effects of generated interface traps (ΔD it) and oxide trapped charge on the GIDL current enhancement are very different. Specifically, it is shown that the oxide trapped charge only shifts the flat-band voltage, unlike ΔD it. Besides band-to-band (B-B) tunneling, ΔD it introduces an additional trap-assisted leakage current component. Evidence for this extra component is provided by hole injection. While trapped-charge induced leakage current can be eliminated by a hole injection subsequent to stress, such injection does not suppress interface-trap-induced leakage current 相似文献
19.
Chen Ih-Chin Choi Jeong Yeol Hu Chenming 《Electron Devices, IEEE Transactions on》1988,35(12):2253-2258
The correlation between channel hot-carrier stressing and gate-oxide integrity is studied. It is found that channel hot carriers have no detectable effect on gate-oxide integrity even when other parameters (e.g., ΔV T and ΔI D) have become intolerably degraded. In the extreme cases of stressing at V G≈V T with measurable hole injection current, however, the oxide charge to breakdown decreases linearly with the amount of hole fluence injected during the channel hot-hole stressing. This may limit the endurance of a nonvolatile memory using hot holes for erasing. This can also explain the gate-to-drain breakdown of a device biased in the snap-back region, since snap-back at low gate voltage is favorable for hole injection. Snap-back-induced oxide breakdown could be an ESD (electrostatic discharge) failure mechanism 相似文献
20.
A simple method is proposed for extracting the electrical parameters of a silicon-on-insulator (SOI) material from a depletion-mode MOSFET. It is based on an analysis of static input current-voltage I D(V G) and transconductance-voltage g m(V G) characteristics in the linear region. Functions varying linearly with gate voltage are constructed from I D(V G) and g m(V G) functions. These new functions allow a straightforward determination of the parameters usually obtained from a capacitance-voltage measurement (doping level, oxide charge, etc.) and also the bulk-layer and accumulation-layer carrier mobility 相似文献