High-rate Magnetron Sputtering Research Articles

Planarization of aluminum alloy film during high rate sputtering

Planar Al-1%Si and Al-4%Cu films have been deposited over periodic oxide lines 1μm thick and valleys of 2 μm pitch. This was accomplished during high rate magnetron sputtering in a 60 –70 s deposition time. The planarizing effect is mostly thermally driven and achieved using a combination of substrate heating (480–510°C range) and r.f. bias (−150 to −250 V self-bias) during sputtering. It was found that depositing a 0.1 μm thick underlayer of TaSi 2.4 just prior to the aluminium alloy deposition significantly improves the reliability of the planarization effect.

Magnetic granular Fe-(SiO2) solids

We have synthesized a series of granular Fe-SiO2 solids consisting of Fe metal granules of nanometer sizes embedded in an insulating SiO2 matrix. The ultrafine microstructures, revealed by TEM, are achieved by using a high-rate magnetron sputtering system. The magnetic properties of such solids are determined by the granular size and the metal volume fraction. Below the percolation threshold, isolated single-domain particles having large magnetic coercivity in the blocked state exhibit superparamagnetic relaxation, which has been studied by using SQUID magnetometry and Mössbauer spectroscopy. Above the percolation threshold, magnetic coercivity drops dramatically and the magnetic properties approach that of pure Fe. The anisotropy energy of the magnetic granules, much larger than that due to magnetocrystalline anisotropy, has been determined.

Amorphous Cores Produced by High Rate Sputtering

In attempts to obtain new amorphous materials for use in magnetic cores, high-rate magnetron sputtering was used to grow Co-Zr-Mo-Ni amorphous films on glass substrates, which were annealed at temperatures above the Curie point T c but below the crystallization temperature T x . Although the annealing was effective in reducing the anisotropy, it did not totally eliminate it. Ring cores with excellent frequency characteristics were also obtained.

Electromigration in aluminum films prepared with a high rate magnetron sputtering cathode

Electromigration has been studied in pure aluminum films prepared by high rate magnetron sputtering. Deposition was performed under various bias and wafer preheat conditions, including those producing planarization of the aluminum. Film structure was determined by transmission electron microscopy (TEM) and x-ray diffraction (XRD). Films prepared with high bias power exhibited a relatively narrow grain size distribution; those prepared without bias had a bimodal grain size distribution. Annealing under normal alloying conditions led to the development of small voids in the latter, and the behavior of these during electromigration was ascertained.

Influences of D.C. bias on aluminum films prepared with a high rate magnetron sputtering cathode

A high rate high efficiency sputtering cathode which produces a relatively high bias current has been developed. This cathode was used to prepare Al-1%Si films with substrate bias voltages in the range 0–150 V d.c. The step coverage, microstructure, texture, sheet resistance and reflectivity of the films were examined, and the results were related to the bias conditions. Primarily it was shown that a substantial redistribution of material could be achieved with the new target configuration, while maintaining a practical bias voltage; excellent step coverage was obtained over a perpendicular step with a 1 μm wall separation.

A sputtering wind

A directional pressure probe extending from a capacitance manometer and rotatable over 360 deg of orientation was inserted at midlength near a high-rate magnetron sputtering source. Actuating the cathode at currents up to 12 A gave rise to a pressure difference between probe orientations facing toward and away from the source. The greater pressure was observed when facing away. The difference was as large as 10% of the base pressure and varied systematically with the base pressure and the cathode current. It appears that energetic particles emanating from the source collide with the ambient gas, pumping it preferentially toward the ends of the cylindrical magnetron and driving opposed toroidal circulation cells that return the gas to the cathode at midlength. A freewheeling fanblade was installed and observed to rotate when the sputtering source was on. Blocking the direct incidence of condensible particles with a shutter caused the direction of rotation to reverse. This counter-rotation was in accord with the gas circulation model and confirmed the existence of a brisk ‘‘sputtering wind.’’

CoCr thin films prepared by high rate magnetron sputtering

CoCr thin films for perpendicular recording have been prepared by magnetron sputtering from 6 mm to 8 mm thick targets with deposition rates up to 12 nm/s. From hysteresis loops and x-ray diffraction patterns it was concluded that the films have a perpendicular magnetic anisotropy and a hcp-texture with c-axis normal to the film plane. The coercivity H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\perp</tex> ) ranged from 20 kA/m to 140 kA/m.

High rate magnetron sputtering of ferromagnetic SmCo, Fe and CoCr thin films

Ferromagnetic thin films have been sputtered from a modified conventional magnetron cathode (3" diameter). The targets (5 to 6 mm thick) were stainless steel, demagnetized SmCo <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> and CoCr(15-18 at% Cr). The deposition rate was 6 nm/s at a power density of 15 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Increasing the power rates up to 12 nm/s could be achieved. The saturation magnetization ranged from 0.4 to 1,5 Tesla. The films sputtered from stainless steel had a magnetization only 30 % smaller than the magnetization of Fe. The coercive force varied from 0.8 to 75 kA/m.

Performance characteristics of a new high rate magnetron sputtering cathode

The coating characteristics of an extended magnetron sputtering cathode which allows for the transfer of sputtered material from the target to the substrate with an improved efficiency are described in this paper. The cathode allows for the holding of target bars such that the sputtering surface forms a V-shaped trough which, coupled with a small (1.75 cm) separation between the target and the substrate, allows for very efficient transport of material from the target to the substrate. A further aspect of the shape is a narrow deposition zone (7 cm) compared with that of|planar magnetron|sources. Thez.sfnc;cathode achieves aluminum deposition rates of 1.75 μm min −1 in this narrow deposition zone. Furthermore, the appropriate placement of electron capture electrodes permits the achievement of these rates at relatively low substrate heat fluxes. The combined high rate and narrow deposition zone result in a substantially high productivity of the sputtering machine, which is quantitatively described in this paper.

Investigation of high rate magnetron sputtering of niobium films for Josephson integrated circuits

High rate Dc-magnetron sputtering of 30 nm niobium thin films is shown to be a very good technique to achieve reproducible and stable ground plane, tunnel junctions electrodes, control lines and even resistors for Josepson Integrated Circuits. Pure niobium films have low residual resistivity (ρ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</inf> k <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\simeq 2\mu \Omega</tex> cm), low stresses, and are no longer in the "dirty limit". High quality ratio ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R_{J}/R_{N} \simeq 20</tex> at 4 K). Josephson Junctions were performed with niobium base electrode. Critical temperatures either below 4.2K used for resistors or between 4.2K and 16K can be controlled accurately by reactive magnetron sputtering in an argon-nitrogen plasma. Homogeneous low critical temperature can be also selectively obtained by liquid cathodization or by RF plasma post-treatments on a pure niobium film through a photoresist mask. Nb, Nb(N), Nb(O) and Nb (H) films are studied by TEM and X ray diffraction. The critical temperature change obtained can be explained by lattice BCC structure dilatation or distorsion and by impurities inclusion.

Nb3Ge Prepared by High Rate Sputtering in a Container Cooled by Liquid N2

Nb3Ge has been prepared by high rate magnetron sputtering followed by quenching just after deposition. A superconducting onset temperature (Ton) above 21∼22 K was obtained over a wide band of a substrate temperature (TD) 600°∼750°C and that of Ar pressure (Pr) from 0.1 Torr to 0.5 Torr. The highest Ton, Tc (the midpoint of transition) and the transition width were 22.5 K, 21.5 K and 1.5 K respectively. The preparation of a uniform and reproducible sample has become very easy. Associated physical properties of a film are described.

High Rate Magnetron Sputtering with Coaxial, Cylindrical Electrode Configuration

High Rate Magnetron Sputtering with Coaxial, Cylindrical Electrode Configuration

Application of high rate magnetron sputtering to the fabrication of A-15 compounds

High quality Nb 3 Sn films have been fabricated using a recently developed magnetron sputtering process capable of deposition rates approaching 1 μm/min. at sputtering voltages less than 500 V and power levels of about 5 KW. Low sputtering voltages allow more complete thermalization at lower pressures of the material condensing on the substrate which can improve long range order. Transition temperatures of up to 18.3 ° K, J c (O)'s of 15 × 106A/cm2and Hc 2 as high as 240 kOe have been achieved in 1-3 μm films deposited from a Nb 3 Sn reacted powder target with substrate temperatures between 600 and 800°C. The films exhibit smooth surfaces and, generally, a preferred orientation. The growth of the film is columnar in nature. The sputtering parameters, substrate material and temperature will be related to film structure, T c and J c (H,T) and the Nb/Sn ratio as determined by Rutherford backscattering.

High rate magnetron sputtering for metallizing semiconductor devices : Vance Hoffman. Solid St. Technol. p. 57 (Dec. 1977)

High rate magnetron sputtering for metallizing semiconductor devices : Vance Hoffman. Solid St. Technol. p. 57 (Dec. 1977)