In this paper differences in chemical composition of ultra-thin silicon oxynitride layers fabricated in planar rf plasma reactor are studied. The ultra-thin dielectric layers were obtained in the same reactor by two different methods: ultrashallow nitrogen implantation followed by plasma oxidation and plasma enhanced chemical vapour deposition (PECVD). Chemical composition of silicon oxynitride layers was investigated by means of X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The spectroscopic ellipsometry was used to determine both the thickness and refractive index of the obtained layers. The XPS measurements show considerable differences between the composition of the fabricated layers using each of the above mentioned methods. The SIMS analysis confirms XPS results and indicates differences in nitrogen distribution.

This work reports on changes in the properties of ultra-thin PECVD silicon oxynitride layers after high- temperature treatment. Possible changes in the structure, composition and electrophysical properties were investigated by means of spectroscopic ellipsometry, XPS, SIMS and electrical characterization methods (C-V, I-V and charge- pumping). The XPS measurements show that SiOxNy is the dominant phase in the ultra-thin layer and high-temperature annealing results in further increase of the oxynitride phase up to 70% of the whole layer. Despite comparable thickness, SIMS measurement indicates a densification of the annealed layer, because sputtering time is increased. It suggests complex changes of physical and chemical properties of the investigated layers taking place during high-temperature annealing. The C-V curves of annealed layers exhibit less frequency dispersion, their leakage and charge-pumping currents are lower when compared to those of as-deposited layers, proving improvement in the gate structure trapping properties due to the annealing process.

Experiments presented in this work are a summary of the study that examines the possibility of fabrication of oxynitride layers for Si structures by nitrogen implantation from rf plasma only or nitrogen implantation from rf plasma followed immediately by plasma oxidation process. The obtained layers were characterized by means of: ellipsometry, XPS and ULE-SIMS. The results of electrical characterization of NMOS Al-gate test structures fabricated with the investigated layers used as gate dielectric, are also discussed.

Efficient p‐type doping of zinc oxide (ZnO) is hindered on the one hand by the strong native n‐type doping of the ZnO, on the other hand, compensation effects (defect generation due to p‐doping) tend to preserve the n‐type doping. Incorporation of nitrogen is proposed as a promising method to achieve p‐type ZnO, because the ionic radii of nitrogen and oxygen are comparable. Therefore, nitrogen atoms can replace oxygen. Nevertheless, a reliable and stable p‐doping is still an unmatched challenge. This work will focus on the chemical nature of nitrogen implanted by ion irradiation into metal‐organic MBE grown ZnO layers on sapphire substrate. The incorporated nitrogen was investigated by photoelectron spectroscopy using synchrotron radiation (PES) and monochromatised Al Kα (mXPS), and near edge X‐ray absorption spectroscopy (NEXAFS). The preparation conditions were varied for preferential incorporation of the different nitrogen species. The three main N1s‐PES components were assigned to different nitrogen compounds (molecular N 2 , NO bonds and NZn bonds) with the help of NEXAFS data. In addition, the thermal stability of the nitrogen compounds were investigated. These results may lead to an optimisation of the nitrogen implantation process for a better doping efficiency.

Ultra-thin (5 and 6nm) silicon oxynitride layers have been fabricated by the plasma-enhanced chemical vapour deposition (PECVD) process. Split experiments with annealing of the deposited dielectric layers were performed using the RTP reactor and a standard furnace, both at 900°C. Possible changes in properties, structure and chemical composition of the obtained layers were investigated by means of spectroscopic ellipsometry, X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and electrical characterisation of manufactured test structures (metal–insulator–semiconductor (MIS) capacitors and MISFETs). The results achieved have shown that annealing at high temperature causes improvement of the properties of ultra-thin silicon oxynitride layers (e.g. lower interface traps density, lower leakage currents within the dielectric layer and lower charge-pumping currents of the MISFETs). The observed improvement in electro-physical properties can be attributed to the increase of the SiON phase. Moreover, comparison between the physical thickness and the equivalent oxide thickness (EOT) of the layers shows a decrease in physical thickness obtained by using the silicon oxynitride layer instead of the classical silicon dioxide. These findings are important for the consideration of chances of PECVD oxynitride layer application for CMOS technology.

The study examines the possibility of fabrication of pedestal oxynitride layers for high-k gate stacks by means of nitrogen implantation from r.f. plasma alone or followed immediately by the plasma oxidation process.The obtained layers were characterized by means of ellipsometry, X-ray photoelectron spectroscopy (XPS) and ultra low energy secondary ion mass spectrometry (ULE-SIMS). The results of electrical characterization of NMOS Al-gate test structures fabricated with the investigated layers used as a gate dielectric are also discussed.Presented results seem to be very promising and presented methods allow to form ultrathin pedestal oxynitride layers with good properties (e.g. breakdown behavior) and we believe that presented method-ultrashallow nitrogen plasma implantation with plasma oxidation may be seriously considered for future VLSI technologies. (C) 2008 Elsevier Ltd. All rights reserved.

Experiments presented in this work are a part of an extended study that examines the possibility of fabrication of oxynitride layers for future Si and SiC MOS structures by nitrogen implantation from RF plasma and subsequent plasma oxidation process. In order to avoid analysis of more complex SiC MOS devices, at this stage, the experiments were performed using silicon substrates. The obtained layers were characterized by means of ellipsometry, XPS and SIMS. The results of electrical characterization of MOS test structures fabricated with investigated layers used as gate dielectric, are also discussed.

We combine high-k dielectrics with wide band gap semiconductors for new possibilities for high frequency and high power applications. We investigate the dielectric properties of praseodymium based oxides by preparing MIS structures consisting of metal layer (M), PrO X (praseodymium oxide) as a high-k insulating layer (I), and silicon (Si) or silicon carbide (SiC) as semiconductor substrates (S). Our approach consists both, electrical measurements and spectroscopic characterization to analyze properties of the various interfaces within the stacks. For the electrical measurements we produce PrO X layers in the thickness range of 10nm to 240nm. We use capacitance-voltage analysis and determine permittivity values (ε r ) of 8 to 20 depending on physical thickness resulting in an equivalent oxide thickness (EOT) down to 5 nm. In order to prevent interface reactions and to improve the band alignment an interfacial layer is introduced into the stack between the semiconductor and the high-k material. We find aluminum oxynitride (AlON) as a suitable layer as revealed by XPS data. For AlON/PrO X stacks on Si we measured a mean interface state density of 5×10 11 /eVcm 2 and a leakage current (1 V above flat band) below 10 −5 A/cm 2 .

Thin films of oxynitrides are grown on 4H-SiC(0 0 0 1) surfaces to prepare these surfaces for further growth of gate dielectric layers. Our former investigation indicated two major problems by thermal treatment in N2O gas. First: even under optimised preparation conditions the nitrogen incorporation is very low (at the best around 7 at.%). And second: the preparation condition optimised for nitrogen incorporation (high temperature and low N2O pressure) leads to very thin layers (in the order of 1-2 monolayers only) and to graphite formation.Here we report on a surface pre-treatment to overcome these problems. The pre-treatment consists of the evaporation of Si onto the oxidised SiC surface. On the one hand the additional Si prevents the formation of the graphite by compensation of the loss of Si due to SiC decomposition and Si evaporation. On the other hand the excess Si improves the incorporation of N by acting as a sacrificial layer for the growth of oxynitride. Thereby the same high amount of N can be incorporated like observed on Si wafers (see P. Hoffmann et al., J. Non-Cryst. Solids 303 (2002) 6).The as prepared SiC surfaces and oxynitride layers were investigated by photoelectron spectroscopy to examine the chemical composition of both, the SiC surface (graphite formation) and the oxynitride layer (nitrogen incorporation). (c) 2005 Elsevier B.V. All rights reserved.

The use of low dielectric constant materials in the on-chip interconnect process reduces interconnect delay, power dissipation and crosstalk noise. To achieve the requirements of the ITRS for 2007-2009 minimal sidewall damage from etch, ash or cleans is required. In chemical vapor deposited (CVD) organo-silicate glass (OSG) which are used as intermetal dielectric (IMD) materials the substitution of oxygen in SiO2 by methyl groups (-CH3) reduces the permittivity significantly (from 4.0 in SiO2 to 2.6-3.3 in the OSG), since the electronic polarizability is lower for Si-C bonds than for Si-O bonds.However, plasma processing for resist stripping, trench etching and post-etch cleaning removes C and H containing molecular groups from the near-surface layer of OSG. Therefore, compositional analysis and chemical bonding characterization of structured IMD films with nanometer resolution is necessary for process optimization.OSG thin films as-deposited and after plasma treatment are studied using x-ray absorption spectroscopy (XAS) and electron energy loss spectroscopy (EELS). In both techniques, the fine structure near the C1s absorption or energy loss edge, respectively, allows to identify C-H, C-C, and C-O bonds. This gives the opportunity to differentiate between individual low-k materials and their modifications. The O1s signal is less selective to individual bonds. XAS spectra have been recorded for non-patterned films and EELS spectra for patterned structures. The chemical bonding is compared for as-deposited and plasma-treated low-k materials. The Fluorescence Yield (FY) and the Total Electron Yield (TEY) recorded while XAS measurement are compared. Examination of the C1s near-edge structures reveal a modified bonding of the remaining C atoms in the plasma-treated sample regions.

Presented in this work experiments are a part of a broader study that examines the possibility of fabrication of pedestal oxynitride layers for high-K gate stacks by nitrogen implantation from r.f. plasma. The aim of this work was to study the influence of type of nitrogen gas source of nitrogen, r.f. power, temperature and implantation time on the oxynitride layer properties. The obtained layers were characterized by means of: ellipsometry, XPS and SIMS. In order to obtain dielectric layers suitable for electrical characterization methods, the plasma nitridation was followed by plasma oxidation process. The results of electrical characterization of test structures fabricated with investigated layers used as gate dielectric, are also discussed.

Changing local electronic polarizability and chemical bonding in OSG in such a way that the effective permittivity - and consequently the electrical performance of the Cu/low-k structure - deteriorates only slightly and that adhesion and stiffness are improved significantly is an extremely challenging task [1], [2]. As the interconnect line spacings continue to shrink, optimization of the electrical and mechanical properties of the ILD material becomes increasingly important for Cu/low-k integration since the effect of thin regions that have been modified by special treatments on the effective material properties, e. g. keff, increases. Composition and chemical bonding, changed by plasma or beam treatments, effect the materials properties significantly. Plasma processes for resist stripping, trench etching and post-etch cleaning remove C and H containing molecular groups from the near-surface layer of OSG. Electron-beam interaction with OSG changes the chemical bonding in the low-k material. In this paper, the effect of chemical bonding on permittivity and elastic modulus is studied. Compositional analysis and chemical bonding characterization of structured ILD films with nanometer resolution is done with electron energy loss spectroscopy (EELS). The fine structure near the C-K electron energy loss edge, allows to differentiate between C-H, C-C, and C-O bonds, and consequently, between individual low-k materials and their modifications. Dielectric permittivity changes are studied based on VEELS (valence EELS) measurements and subsequent Kramers-Kronig analysis. The elastic modulus is determined with atomic force microscopy (AFM) in force modulation (FM) mode. Nanoindentation was applied as a complementary technique to obtain reference data.

We elaborate the possibility of combining high-k dielectrics with wide band gap semiconductors, i.e. Pr2O3 on SiC. The thermal stability of interfacial aluminum oxynitride (AlON) layers between Pr-oxide and SiC has been investigated by synchrotron radiation photoemission spectroscopy (SRPES). The interface of Pr2O3 with SiC is reactive. Such reaction is successfully prevented by utilizing a stable interlayer derived from AlON. No elemental carbon is observed in detectable amount after Pr-Oxide deposition on AlON covered 3C-SiC and subsequent vacuum annealing. After vacuum annealing at 500°C AlON transformed to AlN and Pr-aluminate with a small amount of CN close to the SiC surface which were thermally stable even at 900°C. AlON hence provides a good diffusion barrier between Pr-oxide dielectric and 3C-SiC.

Praseodymium (Pr) silicate dielectric layers were prepared by oxidation and subsequent N2 annealing of thin Pr metal layers on SiO2∕Si(100) substrates. Transmission electron microscopy studies reveal that the resulting dielectric has a bilayer structure. Nondestructive depth profiling by using synchrotron radiation x-ray photoelectron spectroscopy shows that, starting from the substrate, the dielectric stack is composed of a SiO2-rich and a SiO2-poor Pr silicate phase. Valence and conduction band offsets of about 2.9 and 1.6eV, respectively, between the dielectric and the Si(100) substrate bands were deduced. Pr silicate films with an equivalent oxide thickness of 1.8nm show approximately three orders of magnitude lower leakage currents than silicon oxynitride references. Capacitance versus voltage measurements of the Pr silicate/Si(100) system report a flat band voltage shift of 0.22V, an effective dielectric constant of about 11 and a reasonably good interface quality with an interface state density on the order of 1011cm−2. Experimental results are supplemented by ab initio considerations which review the most probable mechanisms of fixed charge formation in the Pr silicate layers.

It will be reported on the growth of oxynitride ultra-thin layers (< 2 nm) on (0001)-oriented 4H-SiC surfaces. The oxynitride layers were grown by a thermal treatment of the samples in low pressure (up to 1000 Pa) N2O ambient. By varying the growth conditions (N2O pressure, sample temperature, growth time) different layers were made. The highest nitrogen incorporation was found to be at high temperatures and low NO pressures.The grown layers were investigated by photoelectron spectroscopy (XPS) for chemical analysis. Concerning the chemical analysis, the general nitrogen content of the samples is compared at different preparation conditions. The films are found to consist mainly of SiO2 and small fraction of silicon nitride. Only a tenth of the nitrogen was incorporated as oxynitride. The results obtained for oxynitride thin films on 4H-SiC are compared to similarly prepared oxynitride layers on Si(1 1 1) investigated in the past. Furthermore, an additional source of nitrogen due to dopand diffusion in the SiC single crystal is reported. (c) 2005 Elsevier B.V. All rights reserved.

Synchrotron radiation x-ray photoelectron spectroscopy was applied to study the solid state reaction between praseodymium and thin silicon dioxide layers on Si(100). Nondestructive depth profiling studies by variation of the incident photon energy indicate after praseodymium deposition at room temperature the reaction of the upper silicon dioxide to praseodymium oxide and silicide. High-temperature annealing of films with an appropriate praseodymium / silicon dioxide ratio results in homogeneous praseodymium silicate films with an atomically abrupt interface. Ab initio calculations corroborate the results of the photoemission study.

The "ITRS Roadmap" suggests the necessity of working out the processing methods allowing formation of ultrathin dielectric layers with higher values of the dielectric permittivity than for silicon dioxide. The silicon oxynitride layers (SiOx,N-y) seem to be the most natural compromise. But still none of high temperature methods used for its formation can be seriously considered as final solution for future ULSI-CMOS ICs production due to the inevitable formation of nitride monolayers just at the silicon-insulator interface. The main scope of this investigation is to check if this is true.The oxynitride layers were produced by PECVD method. The process has already been optimised in order to allow repeatable and reliable formation of ultrathin layers (< 10 nm). These layers were investigated by photoelectron spectroscopy (PES) using variable excitation energy. This results in a variable escape depth of the photo electrons and thus the depth structure of the sample can be concluded. Due to the combination of chemical information and depth information this method is a unique tool for investigating the hidden nitride layers. In this work, we present a comparing study of oxynitride layers with different oxygen-to-nitrogen ratios and different post-deposition annealing temperatures investigated by the above described method. It will be shown that the main difference between certain preparation conditions is the SiO2- and the nitride-content and that nitride and oxynitride is distributed nearly homogeneously. (C) 2004 Elsevier B.V. All rights reserved.