Magneto-optic polar Kerr and Faraday effects in periodic multilayers

Magnetooptic (MO) effects in magnetic multilayers with periodically stratified regions are analyzed for the case of normal light wave incidence and polar magnetization (Faraday and polar Kerr effects). From the universal 4 x 4-matrix formalism simplified analytical representations restricted to terms linear in the off-diagonal permittivity tensor elements are obtained with no loss in accuracy. The MO effects are expressed as weighted sums of contributions from individual layers. Approximate expressions useful for the evaluation of trends in MO effects are given for periodic multilayers consisting of blocks with ultrathin magnetic films. The procedure is illustrated on periodic systems built of symmetric units. Limits on the ultrathin approximation are discussed

Characterization of organic low-dielectric-constant materials using optical spectroscopy

The dielectric function spectra of low dielectric constant (low-k) materials have been determined using high-precision four-zone null spectroscopic ellipsometry, near-normal incidence reflection spectrometry and Fourier transform infrared transmission spectroscopy. The optical functions over a wide spectral range from 0.03 to 5.4 eV (230 nm to 40.5 µm wavelength region) have been evaluated for representative low-k materials used in the semiconductor industry for interlayer dielectrics: (1) FLARE -- organic spin-on polymer, and (2) HOSP -- spin-on hybrid organic-siloxane polymer from the Honeywell Electronic Materials Company

Optical functions of low-k materials for interlayer dielectrics

The optical functions of low dielectric constant (low-k) materials have been determined using a high-precision four-zone null spectroscopic ellipsometer in the spectral range from 1.5 to 5.4 eV (230–840 nm wavelength region). The ellipsometric data were fitted simultaneously with near-normal incidence reflectivity spectra (ranging from 0.5 to 6.5 eV). A general method of simultaneous treatment of ellipsometric and reflectivity data is demonstrated on representative materials used in the semiconductor industry for interlayer dielectrics: (1) SiLK—organic dielectric resin from the Dow Chemical Company, (2) Nanoglass—nanoporous silica from the Honeywell Electronic Materials Company, and (3) tetra-ethyl-ortho-silicate (TEOS) (SiO2)—the standard dielectric material. The low-k materials (SiLK and Nanoglass) were prepared by a standard spin-coating process, while the SiO2 layer was prepared by thermal decomposition from TEOS onto single-crystal silicon wafers

Magneto-optic vector magnetometry for sensor applications

Influence of the magnetization components on the magneto-optic (MO) vector magnetometry and MO sensor applications is discussed for a general magnetization direction. Magneto-optic magnetometers are usually based on linear magneto-optic effects. We include also quadratic (second-order) and cubic (third-order) MO effects in description of a total magneto-optic response. The higher-order MO effects are generally anisotropic and exhibit high sensitivity to a crystal symmetry. Several advantages of magneto-optic sensor applications are presented

Magneto-optic polar Kerr and Faraday effects in magnetic superlattices

Magneto-optic (MO) effects in magnetic multilayers with periodic regions are discussed assuming normal incidence of polarized waves and polar magnetization (Faraday and polar Kerr effects). From the (4×4)-matrix formalism simplified analytical expressions linear in the off-diagonal permittivity tensor element are obtained with no loss in accuracy. The MO effects are expressed as weighted sums of contributions from individual layers. Approximate expressions are given for the case when the thickness of magnetic layers is much smaller than the radiation wavelength. The procedure is illustrated on superlattices consisting of symmetric sandwiches of ultrathin magnetic and non-magnetic metallic layers

Optical characterization of TiN/SiO2(1000 nm)/Si system by spectroscopic ellipsometry and reflectometry

Titanium nitride (TiN) films are used as diffusion barrier layers in the semiconductor industry. There is a need for accurate data on optical properties, because film thickness are usually monitored by optical methods. There are further needs to characterize TiN/(interlayer dielectrics)/Si system simultaneously. Thus, TiN(35, 60, 90 and 105 nm)/SiO2(1000 nm)/Si samples were prepared using sputtering from a TiN target in argon and nitrogen atmosphere. Those samples were characterized using simultaneous fits of multiple angle of incidence spectroscopic ellipsometry and normal incidence spectroscopic reflectivity. TiN films partially transmit light that interferes in the thick thermal silicon oxide, which gives more detailed information on the optical properties of TiN. Consequently optical dielectric function of TiN as well as two thickness of TiN and SiO2 were successfully determined simultaneously

Estimation of the dielectric properties of low-k materials using optical spectroscopy

The dielectric function spectra of low dielectric constant (low-k) materials have been determined using spectroscopic ellipsometry, near-normal incidence spectroscopic reflectometry, and Fourier transform infrared transmission spectrometry over a wide spectral range from 0.03 to 5.4 eV (230 nm to 40.5 µm wavelength region). The electronic and ionic contributions to the overall static dielectric constant were determined for representative materials used in the semiconductor industry for interlayer dielectrics: (1) FLARE—organic spin-on polymer, (2) HOSP—spin-on hybrid organic-siloxane polymer from the Honeywell Electronic Materials Company, and (3) SiLK—organic dielectric resin from the Dow Chemical Company. The main contributions to the static dielectric constant of the low-k materials studied were found to be the electronic and ionic absorptions

Magneto-optical ellipsometry of systems containing thick layers

A recurrent matrix method for description and modeling of light reflection and transmission by an anisotropic multilayer system consisting of thin and thick magneto-optic (MO) layers is proposed. Light interference in thin MO film is described by an amplitude-based Jones matrix formalism. For description of intensity summation in thick MO layers we propose using 4×4 coherence transforming matrices relating coherence vectors. The MO ellipsometry angles rotation and ellipticity are expressed in terms of the matrix components. Effects of partial coherence to reflection and transmission ellipsometry are discussed. Simplification of the general formalism is presented for the normal incidence polar MO geometry

Spectroellipsometric characterization of materials for multilayer coatings

The optical functions of titanium dioxide (TiO2), tantalum pentoxide (Ta2O5) and silicon dioxide (SiO2) have been determined in the spectral range from 1.5 to 5.4 eV (wavelength range from 230 to 840 nm). The ellipsometric spectra of 200 nm thick layers sputtered on a glass substrate were measured by a four-zone null spectroscopic ellipsometer. The data have been fitted by a Tauc–Lorentz model recently derived by Jellison and Modine for the optical functions of amorphous materials. The model dielectric function is based on a combination of the Tauc band edge and the Lorentz oscillator. The effects of the surface and interface layers and layer inhomogeneity on the measured data are discussed