Plasma display panel with Ne+N/sub 2/ gas-mixture discharges

The discharge characteristics of Ne+N/sub 2/ gas-mixtures were investigated for possible use in an AC Plasma Display Panel (PDP). The firing voltage increased with an increase in the N/sub 2/ concentration. When using a near ultra violet excited phosphor, (Ba,Sr)/sub 2/ SiO/sub 4/:Eu, the luminous efficiency of Ne+10% N/sub 2/ gas-mixture discharges under 400 torr was about 20% better than when using the conventional phosphor. The UV intensity emitted from the gas discharges was found to increase with an increased N/sub 2/ concentration. Furthermore, the UV efficiency increased with an increase in the N/sub 2/ partial pressure at a low N/sub 2/ concentration, yet became saturated at a high N/sub 2/ concentration.     

Metal-insulator-metal RF bypass capacitor using niobium oxide (Nb/sub 2/O/sub 5/) with HfO/sub 2//Al/sub 2/O/sub 3/ barriers

A high capacitance density (C/sub density/) metal-insulator-metal (MIM) capacitor with niobium pentoxide (Nb/sub 2/O/sub 5/) whose k value is higher than 40, is developed for integrated RF bypass or decoupling capacitor application. Nb/sub 2/O/sub 5/ MIM with HfO/sub 2//Al/sub 2/O/sub 3/ barriers delivers a high C/sub density/ of >17 fF//spl mu/m/sup 2/ with excellent RF properties, while maintaining comparable leakage current and reliability properties with other high-k dielectrics. The capacitance from the dielectric is shown to be stable up to 20 GHz, and resonant frequency of 4.2 GHz and Q of 50 (at 1 GHz) is demonstrated when the capacitor is integrated using Cu-BEOL process.     

La/sub 2/O/sub 3//Si/sub 0.3/Ge/sub 0.7/ p-MOSFETs with high hole mobility and good device characteristics

We have studied high-k La/sub 2/O/sub 3/ p-MOSFETs on Si/sub 0.3/Ge/sub 0.7/ substrate. Nearly identical gate oxide current, capacitance density, and time-dependent dielectric breakdown (TDDB) are obtained for La/sub 2/O/sub 3//Si and La/sub 2/O/sub 3//Si/sub 0.3/Ge/sub 0.7/ devices, indicating excellent Si/sub 0.3/Ge/sub 0.7/ quality without any side effects. The measured hole mobility in nitrided La/sub 2/O/sub 3//Si p-MOSFETs is 31 cm/sup 2//V-s and comparable with published data in nitrided HfO/sub 2//Si p-MOSFETs. In sharp contrast, a higher mobility of 55 cm/sup 2//V-s is measured in La/sub 2/O/sub 3//Si/sub 0.3/Ge/sub 0.7/ p-MOSFET, an improvement by 1.8 times compared with La/sub 2/O/sub 3//Si control devices. The high mobility in Si/sub 0.3/Ge/sub 0.7/ p-MOSFETs gives another step for integrating high-k gate dielectrics into the VLSI process.     

Successful enhancement of lifetime for SiO/sub 2/ on 4H-SiC by N/sub 2/O anneal

Time-dependent dielectric breakdown (TDDB) measurement by constant current stress has been performed to investigate the oxide (SiO/sub 2/) reliability grown on n-type 4H-SiC. At 300K, the intrinsic injected charge to breakdown (Q/sub BD/) of thermally grown SiO/sub 2/ in wet O/sub 2/ ambience is about 0.1 C/cm/sup 2/, whereas N/sub 2/O anneal after the thermal oxidation results in the drastic improvement of the reliability. The intrinsic Q/sub BD/ of N/sub 2/O annealed SiO/sub 2/ is found to be 10 C/cm/sup 2/, which is two orders of magnitude larger than that of the oxide without N/sub 2/O anneal, suggesting that the quality of SiO/sub 2/ and/or SiO/sub 2//SiC interface is improved. TDDB measurement has been also performed at high temperatures up to 423 K. The activation energy of oxide lifetime estimated from time to failure of 80% is 0.35 and 0.10 eV for the oxide with and without N/sub 2/O anneal, respectively.     

An optical investigation of electronic excitations in the high temperature superconductors YBa/sub 2/Cu/sub 3/O/sub 7- delta / and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+ Delta /

The results of Raman scattering from superconducting gap excitations in the high T/sub c/ compounds YBa/sub 2/Cu/sub 3/O/sub 7- delta / and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+ Delta / are compared. In the normal state, both materials exhibit strong electronic interband scattering which manifests itself as a broad background continuum having both A/sub 1g/ and B/sub 1g/ symmetry components. At low temperatures a redistribution of this electronic scattering occurs, indicative of the formation of a superconducting gap in these compounds. The two symmetries exhibit distinct redistribution, however, denoting strong anisotropy. At temperatures well below T/sub c/, both compounds exhibit residual low-energy scattering, a feature suggestive of the coexistence of normal electrons and superconducting quasi-particles.<>     

Fully silicided NiSi gate on La/sub 2/O/sub 3/ MOSFETs

We have fabricated the fully silicided NiSi on La/sub 2/O/sub 3/ for n- and p-MOSFETs. For 900/spl deg/C fully silicided CoSi/sub 2/ on La/sub 2/O/sub 3/ gate dielectric with 1.5 nm EOT, the gate dielectric has large leakage current by possible excess Co diffusion at high silicidation temperature. In sharp contrast, very low gate leakage current density of 2/spl times/10/sup -4/ A/cm/sup 2/ at 1 V is measured for 400/spl deg/C formed fully silicided NiSi and comparable with Al gate. The extracted work function of NiSi was 4.42 eV, and the corresponding threshold voltages are 0.12 and -0.70 V for respective n- and p-MOSFETs. Electron and hole mobilities of 156 and 44 cm/sup 2//V-s are obtained for respective n- and p-MOSFETs, which are comparable with the HfO/sub 2/ MOSFETs without using H/sub 2/ annealing.     

MIM capacitors using atomic-layer-deposited high-/spl kappa/ (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ dielectrics

Metal-insulator-metal (MIM) capacitors with (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ high-/spl kappa/ dielectric films were investigated for the first time. The results show that both the capacitance density and voltage/temperature coefficients of capacitance (VCC/TCC) values decrease with increasing Al/sub 2/O/sub 3/ mole fraction. It was demonstrated that the (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ MIM capacitor with an Al/sub 2/O/sub 3/ mole fraction of 0.14 is optimized. It provides a high capacitance density (3.5 fF//spl mu/m/sup 2/) and low VCC values (/spl sim/140 ppm/V/sup 2/) at the same time. In addition, small frequency dependence, low loss tangent, and low leakage current are obtained. Also, no electrical degradation was observed for (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ MIM capacitors after N/sub 2/ annealing at 400/spl deg/C. These results show that the (HfO/sub 2/)/sub 0.86/(Al/sub 2/O/sub 3/)/sub 0.14/ MIM capacitor is very suitable for capacitor applications within the thermal budget of the back end of line process.     

GaN MOS device using SiO/sub 2/-Ga/sub 2/O/sub 3/ insulator grown by photoelectrochemical oxidation method

We report on a SiO/sub 2/-Ga/sub 2/O/sub 3/ gate insulator stack directly grown on n-type GaN by the photoelectrochemical oxidation method. The resultant MOS devices are fabricated using standard photolithography and liftoff techniques. The effect of annealing temperature on the SiO/sub 2/-Ga/sub 2/O/sub 3//n-type GaN MOS devices is investigated. The properties of high breakdown field, low gate leakage current, and low interface state density are investigated for the MOS devices.     

High-performance Pt/SrBi/sub 2/Ta/sub 2/O/sub 9//HfO/sub 2//Si structure for nondestructive readout memory

Metal-ferroelectric-insulator-semiconductor (MFIS) capacitors with 390-nm-thick SrBi/sub 2/Ta/sub 2/O/sub 9/ (SBT) ferroelectric film and 8-nm-thick hafnium oxide (HfO/sub 2/) layer on silicon substrate have been fabricated and characterized. It is demonstrated for the first time that the MFIS stack exhibits a large memory window of around 1.08 V at an operation voltage of 3.5 V. Moreover, the MFIS memory structure suffers only 18% degradation in the memory window after 10/sup 9/ switching cycles. The excellent performance is attributed to the formation of well-crystallized SBT perovskite thin film on top of the HfO/sub 2/ buffer layer, as evidenced by the distinctive sharp peaks in X-ray diffraction (XRD) spectra. In addition to its relatively high /spl kappa/ value, HfO/sub 2/ also serves as a good seed layer for SBT crystallization, making the proposed Pt/SrBi/sub 2/Ta/sub 2/O/sub 9//HfO/sub 2//Si structure ideally suitable for low-voltage and high-performance ferroelectric memories.     

Electrical and reliability characteristics of an ultrathin TaO/sub x/N/sub y/ gate dielectric prepared by ND/sub 3/ annealing of Ta/sub 2/O/sub 5/

This letter describes a unique process for the preparation of high quality tantalum oxynitride (TaO/sub x/N/sub y/) via the ND/sub 3/ annealing of Ta/sub 2/O/sub 5/, for use in gate dielectric applications. Compared with tantalum oxide (Ta/sub 2/O/sub 5/), a significant improvement in the dielectric constant was obtained by the ammonia treatment followed by light reoxidation in a wet ambient. We were able to confirm nitrogen incorporation in the tantalum oxynitride (TaO/sub x/N/sub y/) by Auger electron spectroscopy. Compared with NH/sub 3/ nitridation, tantalum oxynitride prepared by nitridation in ND/sub 3/ shows less charge trapping and larger charge-to-breakdown characteristics.     

High-performance MIM capacitor using ALD high-k HfO/sub 2/-Al/sub 2/O/sub 3/ laminate dielectrics

For the first time, we successfully fabricated and demonstrated high performance metal-insulator-metal (MIM) capacitors with HfO/sub 2/-Al/sub 2/O/sub 3/ laminate dielectric using atomic layer deposition (ALD) technique. Our data indicates that the laminate MIM capacitor can provide high capacitance density of 12.8 fF//spl mu/m/sup 2/ from 10 kHz up to 20 GHz, very low leakage current of 3.2 /spl times/ 10/sup -8/ A/cm/sup 2/ at 3.3 V, small linear voltage coefficient of capacitance of 240 ppm/V together with quadratic one of 1830 ppm/V/sup 2/, temperature coefficient of capacitance of 182 ppm//spl deg/C, and high breakdown field of /spl sim/6 MV/cm as well as promising reliability. As a result, the HfO/sub 2/-Al/sub 2/O/sub 3/ laminate is a very promising candidate for next generation MIM capacitor for radio frequency and mixed signal integrated circuit applications.     

Effect of Mg doping on the superconducting properties of Cu/sub 1-x/Tl/sub x/Ba/sub 2/Ca/sub 3-y/Mg/sub y/Cu/sub 4/O/sub 12-/spl delta//

Superconducting properties of Cu/sub 1-x/Tl/sub x/Ba/sub 2/Ca/sub 3-y/Mg/sub y/Cu/sub 4/O/sub 12-/spl delta// (Cu/sub 1-x/Tl/sub x/Mg/sub y/-1234) material have been studied in the composition range y=0,1.5,2.25. The zero resistivity critical temperature [T/sub c/(R=0)] was found to increase with the increased concentration of Mg in the unit cell; for y=1.5 [T/sub c/(R=0)]=131 K was achieved which is hitherto highest in Cu/sub 1-x/Tl/sub x/-based superconductors. The X-ray diffraction analyses have shown the formation of a predominant single phase of Cu/sub 0.5/Tl/sub 0.5/Ba/sub 2/Ca/sub 3-y/Mg/sub y/Cu/sub 4/O/sub 12-/spl delta// superconductor with an inclusion of impurity phase. It is observed from the convex shape of the resistivity versus temperature measurements that our as-prepared material was in the region of carrier over-doping, and the number of carriers was optimized by postannealing experiments in air at 400/spl deg/C, 500/spl deg/C, and 600/spl deg/C. The T/sub c/(R=0) was found to increase with postannealing and the best postannealing temperature was found to be 600/spl deg/C. The mechanism of increased T/sub c/(R=0) is understood by carrying out infrared absorption measurements. It was observed through softening of Cu(2)-O/sub A/-Tl apical oxygen mode that improved interplane coupling was a possible source of enhancement of T/sub c/(R=0) to 131 K.     

A new metal-ferroelectric (PbZr/sub 0.53/Ti/sub 0.47/O/sub 3/)-insulator (Dy/sub 2/O/sub 3/)-semiconductor (MFIS) FET for nonvolatile memory applications

Metal-ferroelectric-insulator-semiconductor (MFIS) field-effect transistors with Pb(Zr/sub 0.53/,Ti/sub 0.47/)O/sub 3/ ferroelectric layer and dysprosium oxide Dy/sub 2/O/sub 3/ insulator layer were fabricated. The out-diffusion of atoms between Dy/sub 2/O/sub 3/ and silicon was examined by secondary ion mass spectrometry profiles. The size of the memory windows was investigated. The memory windows measured from capacitance-voltage curves of MFIS capacitors and I/sub DS/-V/sub GS/ curves of MFIS transistors are consistent. The nonvolatile operation of MFIS transistors was demonstrated by applying positive/negative writing pulses. A high driving current of 9 /spl mu/A//spl mu/m was obtained even for long-channel devices with a channel length of 20 /spl mu/m. The electron mobility is 181 cm/sup 2//V/spl middot/s. The retention properties of MFIS transistors were also measured.     

Modeling of tunneling currents through HfO/sub 2/ and (HfO/sub 2/)/sub x/(Al/sub 2/O/sub 3/)/sub 1-x/ gate stacks

We present a physical modeling of tunneling currents through ultrathin high-/spl kappa/ gate stacks, which includes an ultrathin interface layer, both electron and hole quantization in the substrate and gate electrode, and energy band offsets between high-/spl kappa/ dielectrics and Si determined from high-resolution XPS. Excellent agreements between simulated and experimentally measured tunneling currents have been obtained for chemical vapor deposited and physical vapor deposited HfO/sub 2/ with and without NH/sub 3/-based interface layers, and ALD Al/sub 2/O/sub 3/ gate stacks with different EOT and bias polarities. This model is applied to more thermally stable (HfO/sub 2/)/sub x/(Al/sub 2/O/sub 3/)/sub 1-x/ gate stacks in order to project their scalability for future CMOS applications.     

Evidence and understanding of ALD HfO/sub 2/-Al/sub 2/O/sub 3/ laminate MIM capacitors outperforming sandwich counterparts

Metal-insulator-metal capacitors with atomic-layer-deposited HfO/sub 2/-Al/sub 2/O/sub 3/ laminated and sandwiched dielectrics have been compared, for the first time, for analog circuit applications. The experimental results indicate that significant improvements can be obtained using the laminated dielectrics, including an extremely low leakage current of 1/spl times/10/sup -9/ A/cm/sup 2/ at 3.3V and 125/spl deg/C, a high breakdown electric field of /spl sim/3.3MV/cm at 125/spl deg/C, good polarity-independent electrical characteristics, while retaining relatively high capacitance density of 3.13 fF//spl mu/m/sup 2/ as well as voltage coefficients of capacitance as low as -80 ppm/V and 100 ppm/V/sup 2/ at 100 kHz. The underlying mechanism is likely due to alternate insertions of Al/sub 2/O/sub 3/ layers that reduce the thickness of each HfO/sub 2/ layer, hereby efficiently inhibiting HfO/sub 2/ crystallization, and blocking extensions of grain boundary channels from top to bottom as well as to achieve good interfacial quality.     

Long-wavelength InAlGaAs VCSELs with Al/sub 2/O/sub 3/ embedded current-confinement apertures

Long-wavelength InAlGaAs VCSELs with Al/sub 2/O/sub 3/ embedded current-confinement structures are reported. Using atomic layer deposition, the current confinement structures are fabricated by depositing Al/sub 2/O/sub 3/ on airgap surfaces of undercut apertures, which are formed by laterally etching the active region. 1.57 /spl mu/m VCSELs showing an output power of over 1 mW and direct modulation characteristics at 4 Gbit/s are reported using these current-confinement apertures.     

A novel high-/spl kappa/ SONOS memory using TaN/Al/sub 2/O/sub 3//Ta/sub 2/O/sub 5//HfO/sub 2//Si structure for fast speed and long retention operation

A novel high-/spl kappa/ silicon-oxide-nitride-oxide-silicon (SONOS)-type memory using TaN/Al/sub 2/O/sub 3//Ta/sub 2/O/sub 5//HfO/sub 2//Si (MATHS) structure is reported for the first time. Such MATHS devices can keep the advantages of our previously reported TaN/HfO/sub 2//Ta/sub 2/O/sub 5//HfO/sub 2//Si device structure to obtain a better tradeoff between long retention and fast programming as compared to traditional SONOS devices. While at the same time by replacing hafnium oxide (HfO/sub 2/) with aluminum oxide (Al/sub 2/O/sub 3/) for the top blocking layer, better blocking efficiency can be achieved due to Al/sub 2/O/sub 3/'s much larger barrier height, resulting in greatly improved memory window and faster programming. The fabricated devices exhibit a fast program and erase speed, excellent ten-year retention and superior endurance up to 10/sup 5/ stress cycles at a tunnel oxide of only 9.5 /spl Aring/ equivalent oxide thickness.     

Preparation and growth of thin film Pb/sub 2/Sr/sub 2/Ca/sub 0.5/Y/sub 0.5/Cu/sub 3/O/sub 8+ delta / superconductors by laser ablation

For the first time, the preparation of thin films of superconducting Pb/sub 2/Sr/sub 2/Y/sub 0.5/Ca/sub 0.5/Cu/sub 3/O/sub 8+ delta / material using standard bulk target preparation conditions and the laser ablation technique is reported. In common with much of the bulk characteristics, it is found that the width of the superconducting transition is large, extending from T/sub c,onset/ between 70-83 K and T/sub c,zero/ between 16-20 K.<>     

A novel strained Si/sub 0.7/Ge/sub 0.3/ surface-channel pMOSFET with an ALD TiN/Al/sub 2/O/sub 3//HfAlO/sub x//Al/sub 2/O/sub 3/ gate stack

Proof-of-concept pMOSFETs with a strained-Si/sub 0.7/Ge/sub 0.3/ surface-channel deposited by selective epitaxy and a TiN/Al/sub 2/O/sub 3//HfAlO/sub x//Al/sub 2/O/sub 3/ gate stack grown by atomic layer chemical vapor deposition (ALD) techniques were fabricated. The Si/sub 0.7/Ge/sub 0.3/ pMOSFETs exhibited more than 30% higher current drive and peak transconductance than reference Si pMOSFETs with the same gate stack. The effective mobility for the Si reference coincided with the universal hole mobility curve for Si. The presence of a relatively low density of interface states, determined as 3.3 /spl times/ 10/sup 11/ cm/sup -2/ eV/sup -1/, yielded a subthreshold slope of 75 mV/dec. for the Si reference. For the Si/sub 0.7/Ge/sub 0.3/ pMOSFETs, these values were 1.6 /spl times/ 10/sup 12/ cm/sup -2/ eV/sup -1/ and 110 mV/dec., respectively.     

Very high density RF MIM capacitors (17 fF//spl mu/m/sup 2/) using high-/spl kappa/ Al/sub 2/O/sub 3/ doped Ta/sub 2/O/sub 5/ dielectrics

Using high-/spl kappa/ Al/sub 2/O/sub 3/ doped Ta/sub 2/O/sub 5/ dielectric, we have obtained record high MIM capacitance density of 17 fF//spl mu/m/sup 2/ at 100 kHz, small 5% capacitance reduction to RF frequency range, and low leakage current density of 8.9/spl times/10/sup -7/ A/cm/sup 2/. In combination of both high capacitor density and low leakage current density, a very low leakage current of 5.2/spl times/10/sup -12/ A is calculated for a typical large 10 pF capacitor used in RF IC that is even smaller than that of a deep sub-/spl mu/m MOSFET. This very high capacitance density with good MIM capacitor characteristics can significantly reduce the chip size of RF ICs.