摘要:

Perovskite CaZrO3gate dielectric thin films were prepared by the sol‐gel wet chemical technology, followed by post annealing in O2ambient at different temperatures from 550 to 700 °C. Based on our best knowledge, it is the first time in the literature to successfully prepare the CaZrO3thin films using wet chemical deposition methods, including sol‐gel and metallo‐organic decomposition (MOD) technique. These thin films were systematically characterized using differential thermal analysis (DTA), thermogravimetric analysis (TGA), X‐ray diffraction (XRD), scanning electron microscopy (SEM), Auger spectra (AES) and electrical and dielectric measurements. Using these techniques, the different reactions in various processing steps have been clarified. The dielectric constant of crystalline CaZrO3films is about 20 determined from the C‐f measurement and the thickness. The sol‐gel derived CaZrO3films exhibit stable dielectric properties nearly independent on the applied electrical field and frequency at room temperature. The leakage current density of the CaZrO3thin film annealed at 650 °C for 1 hour is approximately 9.5×10−8A/cm2at high applied electrical field 2.6 MV/cm. The high dielectric constant, low leakage current density and high breakdown strength suggest that the CaZrO3thin film is a promising candidate for gate applications. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622461

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

In this study, we use vacuum UV spectroscopic ellipsometry (VUVSE) to characterize new high dielectric materials. Indeed, all the candidates for high k dielectrics become strongly absorbent when the wavelength is reduced down to 140nm. So, the correlation between thickness and refractive index is reduced in the VUV range and much more precise structural information can be deduced. HfO2, Al2O3and mixed HfAlOxlayers have been studied with and without thin SiO2oxide at the interface. X‐ray reflectometry (XRR) has been used to measure precisely the layer thickness and roughness. The two techniques are included in the same automated metrology system dedicated to 300mm technology which is also presented. We show in particular that VUVSE can detect the crystalline character of the layers and their composition can be measured in addition to the layer thickness. Results are compared to those obtained by transmission electron microscopy (TEM), x‐ray fluorescence analysis (XRF) and x‐ray photoemission (XPS). © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622462

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Angle‐resolved X‐ray photoelectron spectroscopy (ARXPS) has been used to characterize non‐destructively silicon oxynitride and high‐k film samples. The ARXPS data have been processed to provide accurate and precise measurements of thickness of surface and interface layers. Concentration depth profiles have been reconstructed from the ARXPS data to provide elemental and chemical state distribution information. For silicon oxynitride samples, nitrogen doses have been calculated from the concentration profiles, thereby accounting for the distribution of the nitrogen within the oxynitride layer. A comparison of ARXPS with modeled single‐angle XPS experiments illustrate the potential errors in calculation of both thickness and dose using the latter technique. Sputter depth profiles are also shown to contain potentially misleading information when compared to reconstructed ARXPS depth profiles. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622463

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

This non‐contact high‐k monitoring technique is based on a differential quasistatic C‐V that is generated using time‐resolved metrology combining corona charging and contact potential difference (CPD) measurements. The technique incorporates transconductance corrections that enable measurements in the high field range (10MV/cm) required for extraction of large dielectric capacitance corresponding to ultra‐low equivalent electrical oxide thickness (EOT) down to the sub‐nanometer range. It also provides a means for monitoring the flat band voltage, VFB, the interface trap spectra, DIT, and the total dielectric charge, dQTOT. This technique is seen as a replacement for not only MOS C‐V measurements but also for mercury‐probe C‐V. EOT measurement by the differential corona C‐V has a major advantage over optical methods because it is not affected by water adsorption and molecular airborne contamination, MAC. These effects have been a problem for optical metrology of ultra‐thin dielectrics. The presented results illustrate the application of the technique to state of the art gate dielectrics, including Si‐O‐N and HfO2. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622464

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A new method for characterizing dielectric properties of high‐k films was investigated with an open‐circuit potential (OCP) measurement during etching of a film in a solution. The linear dependence of OCP on etching time was clearly observed. The areal density of the adsorbed ion charges on the film surface was estimated from the slope in the time dependence of OCP, and it was shown to be closely related to the electronegativity difference between the atoms on the film surface and etchant atoms in the solution. This finding implies that the time‐dependent OCP measurement is useful for evaluating the ionic characteristic of dielectric materials. The application of this technique to a depth‐profiling analysis of a multilayer dielectric film was also investigated. The transition of the etching surface from one layer to another one was clearly observed, which suggests that the depth‐dependent dielectric properties of high‐k films can be characterized with this method. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622465

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We determined the optical constants of silicon oxynitride (SiOxNy) thin films using a vacuum ultraviolet spectroscopic ellipsometer. The SiOxNylayers with a nominal thickness of 25 nm ∼ 35 nm were grown on silicon substrates by using plasma enhanced chemical vapor deposition (PECVD). The precursor gases were nitrous oxide (N2O) and silane (SiH4). The ratiorof N2O flow rate to SiH4one in the deposition process was controlled from 1.16 to 3.05. The ellipsometric measurements were performed at the angle of incidence 75° for the spectral range from 0.75 eV to 8.75 eV. The complex refractive indices, optical band gaps, and thicknesses of the SiOxNylayers were determined by using Tauc‐Lorentz dispersion model. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622466

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Hafnium oxide thin films deposited by MOCVD were annealed in nitrogen at various temperatures. The as‐deposited films and annealed films were characterized using Auger electron spectroscopy (AES), atomic force microscopy (AFM), X‐ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The films were found to be slightly oxygen deficient. Angle‐resolved XPS revealed oxygen to be residing in two different chemical states, that of oxygen in hafnium oxide, and possibly, a hafnium silicate. Auger depth profiling revealed nitrogen enrichment in an interfacial layer at the film‐substrate interface, which could be the result of an ammonia pre‐treatment prior to deposition. The thickness of this interfacial layer was determined to be ∼ 15 A from TEM. Progressively larger grains were found from AFM measurements with increasing annealing temperature. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622467

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

In this report we use vacuum ultraviolet spectroscopic ellipsometry (VUV‐SE) to determine the optical as well as structural properties of high‐k metal oxides, in particular, of hafnium aluminates and titanium aluminates grown by jet‐vapor deposition. In our opinion, the adapted approach employed in this study can be applied in most other high‐k dielectric thin films which are of great interest in developing a new material replacement for the SiO2gate dielectric in CMOS and other IC devices. Specifically, VUV spectroscopic ellipsometry measurements were performed on a commercial ellipsometer with spectral range from 1.0 eV (1240 nm) to 8.7 eV (143 nm). The Generalized Tauc‐Lorentz (GTL) dispersion was used to determine the dielectric functions of these films. An ellipsometric model consisting of two layers of different film densities was found to be in excellent agreement with the experimental data. For the TiAlO films, only one film was needed in the model to fit the data. The optical bandgaps are seen to increase, while the relative film densities decrease, with increasing Al in the films. In addition, the optical dielectric functions shift to higher energy and decrease in magnitude as the films become more insulating. As a result, the Al appears to be mixed at the atomic level instead of forming a phase separation between HfO2and Al2O3. For TiAlO, we observed similar results except that the fundamental optical bandgap was not strongly affected by the amount of Al incorporated in the films. In our opinion, the adapted approach employed in this study can be applied in most other high‐k dielectric thin films which are of great interest in developing a new material replacement for SiO2in CMOS and other IC devices. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622468

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

With the silicon interface becoming increasingly scrutinized in high dielectric constant materials for SiO2replacement, fine distinctions in the quality of silicon cleaning can have a large impact on MOS parameters. One of the cleaning schemes that have potential to replace the industry standard RCA clean with HF/H2O etch is a modified version of the Shiraki clean. The evolution of Si (100) surface cleaned by the modified Shiraki method has been investigated by a conventional, single‐wave length ellipsometer. Using Low Energy Electron Diffraction (LEED), we have calibrated the ellipsometric measurement for the as‐cleaned silicon surface. It was found that a lower baseline of 0.7∼0.9 nm from ellipsometric measurements could be established as equivalent to a clean, hydrogen passivated surface. To verify the effect of the interfacial oxide thickness on the dielectric constant of the high‐k gate stack, thickness of the thin‐oxide grown under high vacuum condition was measured and correlated with the dielectric constant of the HfO2gate dielectric layer. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622469

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Submillimeter‐wavelength, linear‐absorption spectroscopy has been applied as a chemical diagnostic of a reactive‐ion etching plasma in a modified capacitively coupled Gaseous Electronics Conference (GEC) reactor. Approximately 1 mW of narrow‐band (< 10 kHz) submillimeter radiation between 450 GHz and 750 GHz is produced using a backward‐wave oscillator (BWO). The submillimeter method offers high sensitivity for the ≈ 1 MHz linewidth, Doppler‐broadened absorption lines typical of gas‐phase molecules at a total pressure of less than 133 Pa (1 Torr). A large variety of molecules can be detected, limited primarily by the need for a permanent electric dipole moment and for accurate line frequency predictions, which are often available in the literature. The capabilities of the diagnostic method have been demonstrated by the following three applications: 1) the measurement of water‐vapor contamination in the reactor and in the precursor gas; 2) the assessment of progress in the cleaning of the reactor; and 3) the determination of the endpoint in the etching of a SiO2thin film on silicon. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622470

出版商:AIP    

年代:1903

数据来源: AIP