A 150-200°C atomic layer deposition (ALD) process has been developed for advanced gap and tunnel junction applications for thin films heads. The primary advantage of the ALD process is the near 100% step coverage with properties that are uniform along the sidewall. This process provides smooth false(Rnormala≃2Åfalse), pure (impurities <2 atom %), AlOx films with excellent breakdown strength (9-10 MV/cm). The process uses trimethylaluminum (TMA) as the aluminum source and water as the oxidant. The optimal precursor/oxidant delivery methods for high breakdown strengths were found to be vapor draw for the TMA and a bubbler for the water. For both reagents, a sweep gas is used to reduce the transit time to the wafer. The ALD AlOx films are continuous and exhibit excellent insulating characteristics even down to 5-10 Å making them a potential candidate for tunnel barriers for magnetic tunnel junctions. By plasma annealing the films in situ every 25-50 Å, the as-deposited tensile stress becomes slightly compressive and the breakdown field exceeds 10 MV/cm. ALD provides a relatively low deposition rate of 0.8 Å/cycle. A small chamber volume that allows the cycle time of 5 s is the key to meeting production throughput requirements of 4-6 w h−1 for a 100 Å film. © 2001 The Electrochemical Society. All rights reserved.
Titanium nitride (TiN) has been widely used in the semiconductor industry for its diffusion barrier and seed layer properties. However, it has seen limited adoption in other industries in which low temperature (<200 °C) deposition is a requirement. Examples of applications which require low temperature deposition are seed layers for magnetic materials in the data storage (DS) industry and seed and diffusion barrier layers for through-silicon-vias (TSV) in the MEMS industry. This paper describes a low temperature TiN process with appropriate electrical, chemical, and structural properties based on plasma enhanced atomic layer deposition method that is suitable for the DS and MEMS industries. It uses tetrakis-(dimethylamino)-titanium as an organometallic precursor and hydrogen (H2) as co-reactant. This process was developed in a Veeco NEXUS™ chemical vapor deposition tool. The tool uses a substrate rf-biased configuration with a grounded gas shower head. In this paper, the complimentary and self-limiting character of this process is demonstrated. The effects of key processing parameters including temperature, pulse time, and plasma power are investigated in terms of growth rate, stress, crystal morphology, chemical, electrical, and optical properties. Stoichiometric thin films with growth rates of 0.4–0.5 Å/cycle were achieved. Low electrical resistivity (<300 μΩ cm), high mass density (>4 g/cm3), low stress (<250 MPa), and >85% step coverage for aspect ratio of 10:1 were realized. Wet chemical etch data show robust chemical stability of the film. The properties of the film have been optimized to satisfy industrial viability as a Ruthenium (Ru) preseed liner in potential data storage and TSV applications.
A granular magnetic material, Co–Fe–Hf–O, has been developed-using dc pulsed magnetron reactive sputtering. The deposition rate is as high as 1.3nm∕s. The electrical and magnetic properties of Co–Fe–Hf–O film can be tuned by changing O2 during deposition. A highly resistive, magnetically soft film has been achieved in a small range of the O2∕(Ar+O2) gas flow ratio. The origin of the dependence of magnetic and electrical properties of this material is studied and explained by monitoring the evolution of the film microstructure, using x-ray diffraction and transmission electron microscopy.
FeCo films and their lamination with ultrathin NiFe layers down to 5 Å were deposited using dc magnetron sputtering techniques. Soft magnetic FeCo films were obtained at an optimal target power of 500 W and an optimal deposition pressure of 2 mTorr with high saturation flux density, B sat Ͼ 2.4 T, and low easy-axis coercivity, H ce ഛ 15 Oe, and hard-axis coercivity, H ch ഛ 3 Oe, at a film thickness of 2000 Å. While the magnetostriction remains at ϳ4 ϫ 10 −6 the stress was further optimized by applying substrate bias at a controlled level ഛ50 V without sacrificing film magnetic softness.
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