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    ABSTRACT: This year marks a major materials milestone in the makeup of silicon-based field-effect transistors: in the microprocessors produced by leading manufacturers, the SiO2 gate dielectric is being replaced by a hafnium-based dielectric. The incredible electronic properties of the SiO2/silicon interface are the reason that silicon has dominated the semiconductor industry and helped it grow to over $250 billion in annual sales, as reported by the Semiconductor Industry Association (SIA), San Jose, CA. The shrinkage of transistor dimensions (Moore's law) has led to tremendous improvements in circuit speed and computer performance. At the same time, however, it has also led to exponential growth in the static power consumption of transistors due to quantum mechanical tunneling through an ever-thinner SiO2 gate dielectric. This has spurred an intensive effort to find an alternative to SiO2 with a higher dielectric constant (K) to temper this exploding power consumption. This article reviews the high-K materials revolution that is enabling Moore's law to continue beyond SiO2.
    MRS Bulletin. 11/2008; 33(11).
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    ABSTRACT: A comparison of physical and electrical characteristics of lanthanum aluminate (LAO) dielectrics formed by atomic layer deposition (ALD) and molecular beam epitaxy (MBE) is investigated in this study. Physical characteristics of LAO deposited with these two deposition methods are compared using x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and secondary ion mass spectrometry (SIMS). Capacitors with TaN and TaSiN gate electrodes were fabricated to assess electrical properties of these LAO films. ALD LAO was deposited using La[N(SiMe3)2]3, Al(CH3)3 and water at 225–275 °C. ALD LAO is stable against Pt and TiN/W metal gates up to 800 °C. After annealing at 900 °C, interactions between metal gates and dielectrics are observed resulting in nonfunctional devices. MBE LAO film was deposited at room temperature or 200–400 °C in two ways: Using single element targets (La, Al) or a compound target. The LAO/TaN stack deposited with single element targets showed significant Si up diffusion from the substrate to the dielectric and the metal gate electrode. In addition, nitrogen diffusion from the metal gate into the dielectric was detected. The LAO/TaN stack deposited with a compound target showed improved thermal stability. No metal out-diffusion and only very slight Si out diffusion was detected after a 900 °C anneal. LAO capacitors show well-behaved capacitance-voltage and leakage current density-voltage characteristics. These results indicate that the method by which lanthanum aluminate films are deposited strongly influenced their thermal stability. Of all t- - he films examined, the most stable films are deposited by MBE using a compound target.
    Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society 01/2005; 23(6):2480-2485. · 1.36 Impact Factor
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    ABSTRACT: La aluminate (La2O3)x(Al2O3)1−x films were grown by atomic layer deposition method, for which the conduction band offset, valence band offset, and band gap were obtained by using x-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. The valence band offsets were nearly unchanged within the range from 2.23 to 2.37 eV with increasing Al content. The conduction band offsets were changed from 2.40 to 2.86 eV for the above dielectrics. Remarkably, the band gap could be engineered from 5.75 to 6.35 eV by increasing Al content. We also found that La aluminate films have symmetric band profiles.
    Applied Physics Letters 08/2008; 93(5). · 3.52 Impact Factor

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