Mn Alloy Films Research Articles

A Study on the Characteristics of Cu–Mn–Dy Alloy Resistive Thin Films

Cu–Mn–Dy resistive thin films were prepared on glass and Al2O3 substrates, which was achieved by co-sputtering the Cu–Mn alloy and dysprosium targets. The effects of the addition of dysprosium on the electrical properties and microstructures of annealed Cu–Mn alloy films were investigated. The composition, microstructural and phase evolution of Cu–Mn–Dy films were characterized using field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction. All Cu–Mn–Dy films showed an amorphous structure when the annealing temperature was set at 300 °C. After the annealing temperature was increased to 350 °C, the MnO and Cu phases had a significant presence in the Cu–Mn films. However, no MnO phases were observed in Cu–Mn–Dy films at 350 °C. Even Cu–Mn–Dy films annealed at 450 °C showed no MnO phases. This is because Dy addition can suppress MnO formation. Cu–Mn alloy films with 40% dysprosium addition that were annealed at 300 °C exhibited a higher resistivity of ~2100 μΩ·cm with a temperature coefficient of resistance of –85 ppm/°C.

Self-forming Mn-based diffusion barriers on low-k substrates

In this work, we report on a self-forming barrier process in Cu–Mn alloys. Cu–Mn alloy films were directly deposited onto low-k substrates by co-sputtering and then subjected to an annealing treatment at various temperatures. X-ray diffraction patterns obtained for the Cu–Mn alloys showed Cu(111), Cu(200), and Cu(220) peaks, while transmission electron microscopy images revealed that a uniform Mn-based interlayer self-formed at the Cu–Mn/low-k interface after annealing. In order to evaluate the barrier properties of the Mn-based interlayer, thermal stability measurements were carried out with the low-k dielectrics. The Cu–Mn alloy showed improved thermal stability when compared to a pure Cu reference sample. The chemical composition of the self-formed interlayers on the low-k substrates was ultimately investigated by X-ray photoelectron spectroscopy analysis. Our results show that the composition of the self-formed interlayers depends on the oxide and carbon concentrations in the low-k material.

Deposition of Cu–Mn alloy film from supercritical carbon dioxide for advanced interconnects

Cu–Mn alloy films for microelectronic interconnects were deposited by H2 reduction of bis(2,2,6,6-tetramethyl-3,5-heptanedionato)-copper(II) [Cu(tmhd)2] and bis(penta-methylcyclopentadienyl)-manganese [Mn(pmcp)2] in supercritical carbon dioxide (scCO2). 20-nm thick and continuous Cu–Mn films with a smooth surface were deposited at the temperature of 210 °C. Manganese was found to be segregated to film surface and its content on the surface increased with increasing Mn precursor concentration in scCO2. Mn addition by supercritical fluid deposition could improve surface quality of the Cu film. And electrical resistivity of the Cu–Mn films increased with the Mn contents in the film.

Structure and phase formation in Cu–Mn alloy thin films deposited at room temperature

Transmission electron microscopy characterization of Cu–Mn alloy thin films deposited by DC magnetron sputtering is applied to reveal the formation of phases throughout the composition range. Pure Cu and Mn films exhibit face-centred cubic (fcc) Cu and α-Mn phases, respectively. At room temperature the low Mn content films have fcc structure (γ-phase). Mn can substitute Cu in the fcc Cu lattice up to ∼35at.% Mn. The lattice parameter of fcc Cu–Mn alloy films follows a linear relationship of a0=aCu+0.322c (in Å), where aCu=3.615Å is the lattice parameter of Cu and c is the Mn atomic concentration. At high Mn content, above 50at.% Mn, a homogeneous one-phase structure is observed, possessing the short-range order of α-Mn. The incorporation of Cu into Mn suggests that this structure changes from crystalline α-Mn to disordered structure as the Cu content increases. A narrow two-phase region exists between 35 and 45at.% Mn. A grain size minimum of 2–3nm was observed in the 35–65at.% Mn region.

Plasma-enhanced atomic layer deposition of Cu–Mn films with formation of a MnSixOy barrier layer

Conformal Cu–Mn seed layers were deposited by plasma enhanced atomic layer deposition (PEALD) at low temperature (120°C), and the Mn content in the Cu–Mn alloys were controlled form 0 to approximately 10 atomic percent with various Mn precursor feeding times. Resistivity of the Cu–Mn alloy films decreased by annealing due to out-diffusion of Mn atoms. Out-diffused Mn atoms were segregated to the surface of the film and interface between a Cu–Mn alloy and SiO2, resulting in self-formed MnOx and MnSixOy, respectively. The adhesion between Cu and SiO2 was enhanced by the formation of MnSixOy. Continuous and conductive Cu–Mn seed layers were deposited with PEALD into 24nm SiO2 trench, enabling a low temperature process, and the trench was perfectly filled using electrochemical plating under conventional conditions.

Structural and magnetic phase diagrams of epitaxial Cr–Mn alloy thin films

We report here a systematic study of Cr–Mn alloy films that have been epitaxially stabilized on GaSb (100) using molecular beam epitaxy. The crystal structural transition between the α-Cr-type and the α-Mn-type for the Cr–Mn alloy films is observed along with changes in growth temperature, film thickness, and the ratio of Cr to Mn. Ferrimagnetism is observed in the Cr–Mn films containing the α-Mn-type phase based on the magnetic field-dependent anomalous Hall effect hysteresis and is corroborated by the magnetization hysteresis. The α-Mn-type CrMn phase at the expanded lattice parameter induces the observed ferrimagnetic ordering. The magnetic moments of Cr–Mn films can be tuned by adjusting the growth temperature, film thickness, and the ratio of Cr to Mn. Eventually, new structural and magnetic phase diagrams of the epitaxial Cr–Mn alloy films are established. The results of this study can prove helpful in both forming a comprehensive understanding of Cr–Mn alloys and in finding new applications for it in spintronic devices.

Resistivity reduction by external oxidation of Cu–Mn alloy films for semiconductor interconnect application

A self-forming barrier process using Cu–Mn alloy has been reported to exhibit excellent reliability for interconnect lines in advanced semiconductor devices. However, Mn increases resistivity. In this work, the authors investigated optimum annealing conditions to remove Mn from the Cu–Mn alloy by forming an external Mn oxide and to reduce resistivity to a level of pure Cu. The results were interpreted by an external oxidation mechanism of Mn atoms.

Phase identification of self-forming Cu–Mn based diffusion barriers on p-SiOC:H and SiO2 dielectrics using x-ray absorption fine structure

X-ray absorption fine structure spectroscopy has been used to study the chemical and structural properties of self-forming diffusion barrier layers from Cu-8 at. % Mn alloy films on porous low-k and thermally grown SiO2 dielectrics. For the porous low-k/Cu(Mn) system, we provide evidence that the interface is composed of MnSiO3 and MnO with near complete Mn segregation from the alloy film; however, we find that the self-forming process does not go to full completion on thermally grown SiO2 substrates.

Electrochemical preparation of Fe–Mn alloy film in organic bath

Fe–Mn alloy films have been prepared by electrodeposition in an organic bath containing FeCl 2 + MnCl 2 in dimethyl formamide. The electroreduction of Mn(II) was irreversible and the diffusion coefficient of Mn(II) was calculated to be 8.0 × 10 − 11 m 2 s − 1 at 298 K. An amorphous film of Fe–Mn was obtained by potentiostatic electrolysis. The Mn content varied from 4.8 at.% to 72.3 at.% with increase in the applied cathodic potential. Scanning electron microscope investigation showed that the deposited film was homogeneous and consisted of spherical particles. Nano-sized pores were observed in the surface of these particles. After heat treatment at 773 K, large crystal grains formed and X-ray diffraction patterns indicate that solid solution of Mn in γ-Fe occurred. The alloying temperature of the Fe–Mn film was determined to be 1013 K using differential thermal analysis.

Structural and magnetic properties of a chemically ordered face-centered-cubic (111) Mn alloy film

A 4 ML Ni∕W(110) substrate is used to establish a (111) face-centered-cubic (fcc) template upon which 3 ML of Fe is deposited and annealed to 580K to form a substrate with very good short and long range fcc (111) order, that is Fe rich at the surface. Mn alloy films are formed by annealing a subsequent Mn deposit of 0.3–1.6 ML. Low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), and directional AES show that an ordered alloy is not formed until an annealing temperature of 580K, upon which a multilayer alloy with a P(23×23)R30° LEED pattern is created. The alloy films formed from 0.3 to 0.5 ML of Mn have magnetic properties similar to the FeNi substrate. Hysteresis loops and ac-susceptibility curves measured using the Kerr effect give square loops with a ferromagnetic moment along the in-plane fcc [-211] direction and a Curie temperature TC of about 460K. There is an increase in coercive field likely due to the inhomogeneities introduced by the Mn. Alloy films formed from 0.8 to 1.6 ML of Mn show a marked increase in the width of the susceptibility peak, and a decrease in the peak temperature. The hysteresis loop becomes slanted with a reduced coercive field. The measurements are consistent with a paramagnetic or antiferromagnetic Mn alloy forming an uneven interface within the FeNi film, so that the remaining FeNi film has a wide distribution in TC.

Sputtering growth and optical properties of [100]-oriented tetragonal SnO2 and its Mn alloy films

SnO 2 and its Mn alloy thin films have been grown on Al2O3(0001) substrates by reactive radio-frequency magnetron sputtering performed in the presence of O2 gas. The prepared films showed preferred orientation in the [100] direction of the rutile structure of SnO2. The O2/Ar gas-flow ratio maintained during the sputtering was found to significantly affect the crystalline quality and stoichiometry of the films. The optical constants of the SnO2 and Sn1−xMnxO2 (x⩽0.27) films were measured by spectroscopic ellipsometry in the 2–5 eV photon energy region. The band-gap energy of SnO2 is determined to be 3.86 eV and that of Sn1−xMnxO2 increases for x⩽0.11 and then decreases for the higher x, exhibiting a negative bowing. The initial increase of the band-gap energy is attributable to the hybridization between localized Mn d states located near the band gap and O p-like valence bands. The decrease of the band-gap energy is interpreted as due to the SnO2–MnO2 alloying effects.

Magnetic and Magnetooptical Properties of Mn(Sb-Bi) Thin Films Fabricated by the Interdiffusion Method

NiAs-type Mn(SbBi) alloy films, with c-axes oriented perpendicular to the film surface, were obtained in the composition range 45 ≪ Mn ≪ 65 at%, Bi ≪ 10 at% by first forming an oriented SbBi layer by vapor deposition and annealing, then depositing an Mn layer onto this SbBi layer at an appropriate substrate temperature, and finally annealing at temperatures up to 500°C. Several different phases appeared in these films, the matrix of which was the NiAs type Mn (SbBi) phase. It was found that the phases and lattice constants of Mn(SbBi) change on increasing the annealing temperature. Systematic experiments on the magnetic anisotropy constant Ku and Kerr rotation angle ? K were carried out for the Mn(SbBi) films. As a result, substitution of Bi for Sb led to 1) an increasing K u value, and 2) a change in the wavelength dependence of ? K . The maximum observed values of K u and ? K were 4.5 × 106 erg/cm3 and 0.5° at H ex = 7 kOe.

Formation of amorphous AlCr and AlMn alloy films by rf sputtering

A new type of amorphous alloy, formed in the limited composition range of about 80–90 at.% Al (AlCr) and 70–90 at.% Al (AlMn) was produced by fr sputtering under Ar atmosphere. The existence of the amorphous phase was confirmed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The formation of the amorphous phase is discussed in association with the intermetallic compounds (CrAl 7, Mn 4Al 11, MnAl 6, etc.) having crystallographically complex structure, which have nearly the same composition as the amorphous phase. A weak X-ray scattering halo is observed at the diffraction angle lower than of the strongest halo which characterizes the amorphous structure. The weak scattering halo, which is generated by an X-ray interference effect, is considered to be correlated to the small clusters in which a transition metal atom coordinates several Al atoms. The crystallization temperatures of the amorphous alloys are about 400 and 370°C for AlCr and AlMn samples, respectively.

Characteristics of oxidized CuMn alloy films

Characteristics of oxidized CuMn alloy films

二層膜拡散法により作成したＭｎ（ＳｂＢｉ）薄膜の磁気および磁気光学特性

NiAs-type Mn(SbBi) alloy films, whose c-axes were oriented perpendicular to the film surface, were obtained in the composition range, 45 < Mn < 65 at.%, Bi < 10 at.% by the following method. The first step was the formation of oriented SbBi layer annealing, the second step was the deposition of the Mn layer onto this SbBi layer at appropriate substrate temperature and the last step was the annealing of this film up to 500°C The several phases appeared in these films. Matrix of the films was NiAs-type Mn(SbBi) phase. It was found that the phases and lattice constant for Mn(SbBi) changes by increasing the annealing temperature. Systematic experimental of magnetic anisotropy constant, Ku, and Kerr rotation angle, θk, was carried out for Mn(SbBi) films. As a result, a substitution of Bi for Sb led to 1) increasing Ku value and 2) change of the wave length dependence of θk. It was observed that the maximum values of Ku and θk were 4.5 × 106 erg/cm3 and 0.5° at Hex = 7 kOe.

Magnetic and Magneto-Optical Properties of Mn(Sb1-xBix) Thin Films

Mn(Sb-Bi) alloy films with an NiAs-type structure were prepared by successive deposition of Mn layers onto Sb-Bi alloy layers, followed by annealing at temperatures up to 500oC. A single NiAs-type phase was obtained over the wide composition range 52≦Mn≦62 at%, 35≦Sb≦48 at%, 0≦Bi≦5 at%. Systematic experimental investigations of the magnetic and magneto-optical properties of these films were carried out. These investigations clarified (1) the dependences of M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> , H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> and K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</sub> on composition, and (2) the dependence of θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</sub> on the composition and the wavelength λ (0.4 to 1.1 μm). The magnitudes of M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> and θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</sub> were found to depend on the Mn content. Maximum values of M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> and θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</sub> were 600 emu/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and 0.7° (at λ=0.633 μm) respectively for films containing 52 at% Mn. The maximum (positive) value of K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</sub> (=1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> erg/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) was obtained for films containing about 62 at% Mn.

Ｍｎ（Ｓｂ１−ｘＢｉｘ）薄膜の磁気及び磁気光学特性

Mn(Sb-Bi) alloy films with NiAs-type structure were prepared by successive deposition of Mn layer onto Sb-Bi alloy layer, followed by annealing up to 500°C The single phase of NiAs-type was obtained in the wide composition range, 52≤Mn≤62 at.%, 35≤Sb≤48 at.%, 0≤Bi≤5 at.%. Systematic experimental investigation for the magnetic and magnetooptical properties was carried out for these films. As a result, (1) the dependences of Ms, Hc and Ku on composition and, (2) the dependence of θK on composition and also on λ (0.4∼1.1 μm) were systematically clarified. The magnitudes of Ms and θk were dependent on Mn composition. Maximum values of Ms and θK were 600 emu/cm3 and 0.7° (λ=0.633 μm), respectively for films with around 52 at.%Mn. The positive maximum value of Ku (nearly equals 1×106 erg/cm3 was obtained for films with about 62 at.%Mn.

Crystallization process and new crystals in some non-crystalline Mn alloy films prepared by vacuum codeposition

Crystallization process and new crystals in some non-crystalline Mn alloy films prepared by vacuum codeposition

Inelastic Scattering and Spin Scattering Times in Metallic Thin Films

Inelastic scattering time τ e and spin scattering time τ s are studied in Bi, Cu–Mn alloy and noble metal films through the analyses of their magnetoconductivity. Inelastic scattering time in Bi films is found to be proportional to T -1 and to the sheet conductivity below 1.5 K, and to depend on T more strongly at higher temperature. These features are consistent with recent theories on τ e due to electron-electron interaction in two-dimensional disordered systems. In Cu–Mn alloy films with various concentration of Mn, systematic change of the magnetoconductivity is mainly ascribed to the variation of τ s , which is caused by Mn atoms. In noble metal films, the temperature dependence of the magnetoconductivity indicates that both scattering times are of a comparable order of magnitude at low temperature.