Properties of thin LPCVD silicon oxynitride films

Thin, uniform silicon oxynitride films with films thicknesses of ≤ 10 nm were successfully deposited by low pressure chemical vapor deposition (LPCVD). The reactant gases were SiH₂Cl₂, N₂O, and NH₃. The compositional uniformity of these films as a function of depth was good. The structure of these oxynitride films was found to be dominated by the mixed matrix of Si, N, and 0, rather than a physical mixture of SiO₂ and Si₃N₄ clusters. N-H bonding was observed and the total amount of hydrogen in the as-deposited film was on the order of 5 x l0²⁰/cm³. No H-OH or Si-OH bonds were detected. Excellent dielectric breakdown distributions were found for oxynitride films with equivalent oxide film thicknesses as low as 7.5 nm. The conduction of Si-N-0 films depended on film composition. A small capacitor-voltage (C-V) window (< 0.1 V) was observed for the Si-N-O/Si structures. The midgap surface state density was on the order of 5 x 10¹⁰/cm² /eV. Either trapping of holes or the generation of positive states were found after high field stressing of the oxynitride films.     

Structural and electrical profiles for double damage layers in ion-implanted silicon

(111) Si specimens were implanted at room temperature with 5 × 1014 cm?2, 120 keVP+ ions, and annealed at 950°C. Transmission electron-microscope cross-section specimens revealed two discrete damage layers at depths of 95 and 190 nm. Electrical profiles showed decreases in carrier concentration and/or mobility at these two depths.     

Scalability and electrical properties of germanium oxynitride MOS dielectrics

In this letter, we present a fundamental study on the scalability and electrical properties of germanium oxynitride dielectrics for metal-oxide-semiconductor device applications. The nitrogen depth profile within the oxynitride dielectric layers was first monitored using angle-resolved x-ray photoemission spectroscopy and the dielectric permittivity variation was therefore identified. After thinning down the lower permittivity portion of these dielectrics, we successfully scaled down the capacitance-based equivalent SiO/sub 2/ thickness, in Ge MOS capacitors, to 1.9 nm without suffering from gate leakage. We have also investigated the effects of thermal annealing on various capacitor electrical properties. For instance, we measured a flat-band voltage shift of as much as -0.8 V from the ideal value on as-deposited capacitors and the recovery of the theoretical value, with acceptably small amount of oxide fixed charge, after subsequent thermal annealing. Lastly, we have benchmarked the performance of these oxynitride insulators with the advanced high-/spl kappa/ dielectrics on Ge and discussed the impacts on future scaling.     

Optical and electrical properties of thin wafers fabricated from nanocrystalline silicon powder

The infrared transmittance spectra and dark conductivity of wafers fabricated from nanocrystalline silicon powder (nc-Si) have been studied. The initial nc-Si powder is first synthesized by laser-induced silane dissociation, with the temperature of the surrounding buffer gas varied from 20 to 250°C, and then compacted at pressures from 10⁸ to 10⁹ Pa. It is found that compaction of the nc-Si powder results in formation of Si-H, Si-CH_x, and O_y-Si-H_x structures (x, y=1–3). The formed structures break down under annealing, with the Si-H and Si-CH_x complexes disintegrating at the lowest annealing temperature (t = 160°C). The dark conductivityof the nc-Si wafers is shown to increase along with the buffer gas temperature at which the starting powder was prepared. Two temperature regions are found in which the dark conductivity behaves in radically different ways. At wafer temperatures T ≥ 270 K, conductivity is mediated by free carriers, whereas, at lower temperatures, electron transport is governed by hopping conduction over localized states in the band gap.     

AZO透明导电薄膜的结构与光电性能

采用射频溅射工艺制备了Zn1-xAlxO透明导电薄膜。通过XRD、UV透射和电学性能测试等分析手段,研究了Al浓度对薄膜的组织结构和光电性能的影响规律。结果表明:薄膜具有c轴择优取向,随着Al浓度的增加,(002)衍射峰向高角度移动,峰强度逐渐减弱,x(Al)为15%掺杂极限浓度。x(Al)为2%时,薄膜电阻率是3.4×10–4Ω.cm。随着掺杂量x(Al)从0增加到20%,薄膜的禁带宽度从3.34 eV增加到4.0 eV。     

Structural and electrical properties of stable ni/cr thin films

The electrical and structural properties of nickel-chrome (NiCr) thin film resistors were studied for the effect of post-deposition annealing on stability. The temperature coefficient of resistance (TCR) of sheet resistivities in the range of 100 to 200 Ω/□ could be improved by both air and vacuum annealing to achieve 5 ± 5 ppm/°C over the temperature range of -180° C to +100° C. With stability tests, air annealing proved to be more favorable for stable TCR. Studies via SIMS and ESCA identified surface segregation of Cr whereas TEM micrographs revealed correlating structural transformation of the films upon annealing. An intentional impurity, Si, played an important role in achieving a low TCR.     

Effect of fast annealing on the electrical properties of SiO2/Si structures with thin layers of anodic silicon oxide

Effects of fast annealing on the properties of SiO₂/Si structures with thin, ～10 nm, layers of anodic silicon oxide formed on single-crystal Si substrates are studied in relation to the semiconducting properties of the silicon support and to the duration, temperature, and environment of thermal treatment. The optimal duration of high-temperature annealing of structures in an inert atmosphere for their application in the technology of nanosize MOS integrated circuits is determined.     

Structural and electrical properties of co-evaporated In,Garich CIGS thin films

The CIGS thin trims are prepared by co-evaporation of elemental In, Ga and Se on the substrates of Mo-coated glasses at 400℃ followed by co-evaporation of elemental Cu and Se at 550℃. We study the structural and electrical properties using XRD, XRF and Hall effect measurements. In general, Cu（In,Ga）sSes phase exists when Cu/（In＋Ga） ratio is from 0.17 to 0.27, Cu（In,Ga）3Se5 phase exists for Cu/（In＋Ga） ratio between 0.27 and 0.41, Cu2（in,Ga）4Se7 and Cu（In,Ga）2Se3.5 phases exist for Cu/0n＋Ga） ratio between 0.41 and 0.61, and OVC（or ODC） and CuIn0.7Ga0.3Se2 phases exist when Cu/（In＋Ga） ratio is from 0.61 to 0.88. With the increase of Cu/（In＋Ga） ratio, the carrier concentrations of the films gradually increase, but the electrical resistivity gradually decreases.     

Structural and electrical properties of co-evaporated In, Ga-rich CIGS thin films

The CIGS thin films are prepared by co-evaporation of elemental In, Ga and Se on the substrates of Mo-coated glasses at400℃ followed by co-evaporation of elemental Cu and Se at 550℃. We study the structural and electrical properties usingXRD, XRF and Hall effect measurements. In general, Cu(In,Cra)5Se8 phase exists when Cu/(In Ga) ratio is from 0.17 to0.27, Cu(In,Ga)3Se5 phase exists for Cu/(In Ga) ratio between 0.27 and 0.41, Cu2(In,Ga)4Se7 and Cu(In,Ga)2Se3.5 phasesexist for Cu/(In Ga) ratio between 0.41 and 0.61, and OVC(or ODC) and CuIn0.7Ga0.3 Se2 phases exist when Cu/(In Ga)ratio is from 0.61 to 0.88. With the increase of Cu/(In Ga) ratio, the carrier concentrations of the films gradually increase,but the electrical resistivity gradually decreases.     

Structural,opto-thermal and electrical properties of ZnO:Mo sprayed thin films

Zinc oxide (ZnO) thin films doped with molybdenum (Mo) have been prepared by the spray pyrolysis technique. X-ray analysis shows that ZnO:Mo thin films crystallize in hexagonal structure with a preferred orientation of the crystallites along (002) direction. The surface topography of these films was performed by the atomic force microscopy. The dispersion of the refractive index was discussed in terms of the single oscillator model proposed by Wemple and DiDomenico. The single oscillator energy (E₀) as well as the dispersion energy (E_d) were therefore calculated. Finally, the electric conductivity was investigated depending on the effect of temperature. The activation energy (E_a) was found to range from 0.63 to 0.94 eV; the electrical behavior can be correlated with Mo-doping.     

Effect of si—h and n—h bonds on electrical properties of plasma deposited silicon nitride and oxynitride films

Strong correlations were observed between the improvement in the metal-insulator-semiconductor (MIS) (aluminum-nitride-semiconductor) electrical properties of plasma deposited silicon nitride and oxynitride films and their (Si—H/N—H) bonding ratios in the film bulk. Total hydrogen concentration and spin density of all deposited films decreased with post-deposition annealing. Films with more Si—H bonds and stable (Si—H/ N—H) ratios generally have lowerV _fb shift, less positive trap charge and higher breakdown dielectric strength. Silicon oxynitride films with refractive indices of 1.75-1.80, as-deposited and after annealing in forming gas (10% H₂ + 90% N₂) at various temperatures, were found to have stable (Si—H/N—H) bonding ratios, lower silicon dangling bond density, and better MIS electrical properties compared to other plasma deposited nitride and oxynitride films.     

Cathodoluminescence and photoluminescence of amorphous silicon oxynitride

The cathodoluminescence and photoluminescence of amorphous silicon oxynitride (a-SiO_xN_y) films with different compositions were measured for the first time in the near infrared to visible–ultraviolet range. The red band with energy at 1.8–1.9 eV, blue band with energy 2.7 eV, ultraviolet bands with energies 3.1, 3.4–3.6, 4.4–4.7, and 5.4 eV were observed in a-SiO_xN_y. The 1.8–1.9 eV band is attributed to the oxygen and nitrogen atoms with unpaired electrons and the 2.7 eV band is attributed to twofold coordinated silicon atoms with two electrons. The 5.4 eV shoulder is due to the peroxy radicals and other ultraviolet bands are supposed to be due to the Si–Si bonds.     

Structural, electrical and optical properties of ZnO thin films deposited by sol-gel method

Thin films of intrinsic and Al-doped ZnO were prepared by the sol-gel technique associated with spin coating onto glass substrates. Zinc acetate dehydrate, ethanol and monoethanolamine were used as a starting material, solvent and stabiliser, respectively. Structural, electrical and optical characterizations of the films have been carried out. All films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction 〈0 0 2〉. The four-points technique was used to characterize thin films electrically. All films exhibit a transmittance above 80-90% along the visible range up to 650 nm and a sharp absorption onset about 375 nm corresponding to the fundamental absorption edge 3.3 eV. Intense UV photoluminescence is observed for undoped and 1% Al-doped ZnO films.     

Structural and electrical properties of plasma-deposited silicon nitride from SiH4-N2 gas mixture

Plasma-deposited silicon nitride films were produced from SiH₄-N₂ gas mixture. Their composition, chemical bonds, and electrical properties were investigated by varying the deposition conditions. The silicon nitride films from SiH₄-N₂ gas mixture exhibit (i) less hydrogen, (ii) higher thermal endurance, (iii) higher density, and (iv) smaller etching rate than those of the films deposited from SiH₄, and NH₃ gas mixture. These results can be partly attributed to lower hydrogen concentration. As the Si/N ratio approaches the stoichiometric value, 0.75, the resistivity and the breakdown strength are increased. They are 10¹⁵Ωcm and 9MV/cm, respectively, at Si/N≃0.85. Interface state density between silicon and silicon nitride layers is as low as 1& #x223C; 5xl0¹¹cm⁻² eV⁻¹. On leave from The Northwest Telecommunication Engineering Institute, Xi’an, The People’s Republic of China.     

The electrical properties of phosphorus doped silicon layers obtained by ion implantation through a passivating oxide

The electrical properties of phosphorus doped silicon layers obtained by ion implantation through a passivating oxide are studied. The quality of the fabricated n⁺p diodes is investigated. The influence of the process parameters and of the crystal orientation on the sheet resistance of the n⁺ layers is studied. It is shown that sheet resistances higher than 1 kΩ/□ with a good linearity and a very low temperature coefficient can easily be obtained in a reproducible way.     

多孔硅薄膜的纵向均匀性及其光学特性研究

多孔硅样品使用脉冲电化学腐蚀法经过不同的腐蚀时间制备完成,使用反射光谱、光致发光光谱和SEM对多孔硅薄膜的纵向均匀性以及其光学特性进行了研究,还详细研究了随腐蚀深度变化的折射率和光学厚度(n*d)等光学参数。实验表明：随着腐蚀深度的增加,多孔硅薄膜的平均折射率n降低,即多孔度变大;多孔硅薄膜的光学厚度的形成速度减小;同时,反射光谱表现更弱的干涉性,表明薄膜的均匀性和界面的平整性变差;另外,光致发光谱的强度微弱变强。     

Enhanced dielectric properties of Zr−Sn−Ti oxynitride thin films

Zr_0.26Sn_0.23Ti_0.51O_xO_y (ZSTON) and Zr_0.26Sn_0.23Ti_0.51O_2σ (ZSTO) films have been prepared on Pt coated silicon substrates by pulsed laser deposition technique using a Zr−Sn−Ti oxide target at a substrate temperature of 650°C in N₂ and O₂ ambient, respectively. TEM observation showed that both kinds of films are amorphous. XPS analysis showed that the N/O ratio in ZSTON is 0.08/0.92. With the help of a comparative study of the dielectric properties of ZSTON and ZSTO films, it has been found that incorporation of nitrogen can increase the dielectric coefficient and decrease the dielectric loss of the multicomponent oxide films remarkably. Optical transmittance measurements showed that incorporation of nitrogen can slightly decrease the width of the bandgap and increase the refractive index of the films. It is proposed that amorphous Zr−Sn−Ti oxynitride stable at 650°C is a potential dielectric material for DRAM applications.     

Downward uniformity and optical properties of porous silicon layers

Porous silicon (PS) samples were fabricated by pulse current etching using different times. The downward uniformity and optical properties of the PS layers have been investigated using reflectance spectroscopy, photoluminescence spectroscopy, and scanning electron microscopy (SEM). The relationship between the refractive index and the optical thickness of PS samples and the etching depth has been analyzed in detail. As the etching depth increases, the average refractive index decreases, indicating that the porosity becomes higher, and the formation rate of the optical thickness decreases. Meanwhile, the reflectance spectra exhibit less intense interference oscillations,which mean the uniformity and interface smoothness of the PS layers become worse. In addition, the intensity of PL emission spectra is slightly increased.     

Metallurgical and electrical properties of chromium silicon interfaces

The effect of annealing treatment up to 500°C on CrSi contacts was studied from physico-chemical and electrical view points. The solid-solid reactions between a 1000 Å thick Cr layer and a 〈111〉N single crystal of silicon, were studied by the He⁺ ion backscattering method, X-ray diffraction and transmission electron microscopy. We first observed a growth in the Cr grains and then the nucleation and growth of the disilicide CrSi₂. For annealing temperatures greater than 415°C, the growth is linear in time with an activation energy of 1.5±0.1 eV and for lower temperatures it becomes superlinear. The growth mechanism is discussed in terms of growth limiting phenomena. The variations of the electrical parameters (ideality factor n and barrier height 0_Bn) as a function of 15 min anneals between 300 and 500°C were correlated to the physico chemical observations. We establish, firstly, an optimal temperature annealing range in order to obtain good Schottky CrSi diodes and, secondly, a low limit of Cr thickness which must be deposited to obtain acceptable Schottky CrSi₂  Si diodes after annealing.