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Nucleation and growth of dielectric films on III-V semiconductors during atomic layer deposition.

机译：原子层沉积过程中III-V半导体上介电膜的形核和生长。

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摘要

In order to continue with metal-oxide-semiconductors (CMOS) transistor scaling and to reduce the power density, the channel should be replaced with a material having a higher electron mobility, such as a III-V semiconductor. However, the integration of III-V's is a challenge because these materials oxidize rapidly when exposed to air and the native oxide produced is characterized by a high density of defects. Deposition of high-k materials on III-V semiconductors using Atomic Layer Deposition (ALD) reduces the thickness of these oxides, improving the semiconductor/oxide interface quality and the transistor electrical characteristics. In this work, ALD is used to deposit two dielectrics, Al 2O3 and TiO2, on two III-V materials, GaAs and InGaAs, and in-situ X-ray photoelectron spectroscopy (XPS) and in-situ thermal programmed desorption (TPD) are used for interface characterization.;Hydrofluoric acid (HF) etching of GaAs(100) and brief reoxidation in air produces a 9.0 ±1.6 Å-thick oxide overlayer containing 86% As oxides. The oxides are removed by 1 s pulses of trimethylaluminum (TMA) or TiCl4. TMA removes the oxide overlayer while depositing a 7.5 ± 1.6 Å thick aluminum oxide. The reaction follows a ligand exchange mechanism producing nonvolatile Al–O species that remain on the surface. TiCl4 exposure removes the oxide overlayer in the temperature range 89°C to 300°C, depositing approximately 0.04 monolayer of titanium oxide for deposition temperatures from 89°C to 135°C, but no titanium oxide is present from 170 °C to 230 °C. TiCl4 forms a volatile oxychloride product and removes O from the surface while leaving Cl atoms adsorbed to an elemental As layer, chemically passivating the surface. The native oxide of In0.53Ga0.47As(100) is removed using liquid HF and gas phase HF before deposition of Al2O3 using TMA and H2O at 170 °C. An aluminium oxide film with a thickness of 7.2 ± 1.2 Å and 7.3 ± 1.2 Å is deposited during the first pulse of TMA on liquid and gas phase HF treated samples, respectively. After three complete ALD cycles the thickness of the aluminum oxide film is 10.0 ± 1.2 Å on liquid HF treated and 6.6 ± 1.2 Å on gas phase HF treated surfaces. Samples treated with gas phase HF inhibit growth. Inhibition is caused by residual F atoms that passivate the surface and by surface poisoning due to the thicker carbon film deposited during the first pulse of TMA. On InGaAs covered by native oxide, the first TMA pulse deposits 9 Å of aluminum oxide, and reaches saturation at 13 Å after 15 pulses of TMA. The film grows by scavenging oxygen from the substrate oxides. Substrate oxides are reduced by the first pulse of TMA even at 0°C. At 0°C, on a 9 Å thick Ga-rich oxide surface, 1 pulse of TMA mainly physisorbs and a limited amount of aluminum oxide is deposited. At 0°C, 110°C, and 170°C, more aluminum oxide is deposited on surfaces initially containing As oxide, and larger binding energy (BE) shifts of the O 1s peak are observed compared to surfaces that contain Ga oxides only, showing that As oxides improve the nucleation of Al2O 3.
机译：为了继续进行金属氧化物半导体（CMOS）晶体管缩放并降低功率密度，应使用具有较高电子迁移率的材料（例如III-V半导体）代替沟道。但是，III-V's的集成是一个挑战，因为这些材料在暴露于空气时会迅速氧化，并且生成的天然氧化物的特征是缺陷密度高。使用原子层沉积（ALD）在III-V半导体上沉积高k材料可以减小这些氧化物的厚度，从而改善半导体/氧化物界面质量和晶体管的电气特性。在这项工作中，ALD用于在两种III-V材料GaAs和InGaAs以及原位X射线光电子能谱（XPS）和原位热程序解吸（TPD）上沉积两种电介质Al 2O3和TiO2。 GaAs（100）的氢氟酸（HF）蚀刻和空气中的短暂再氧化会产生9.0±1.6Å厚的氧化层，其中含有86％的As氧化物。通过1 s的三甲基铝（TMA）或TiCl4脉冲除去氧化物。 TMA去除氧化物覆盖层，同时沉积7.5±1.6Å厚的氧化铝。反应遵循配体交换机制，产生残留在表面的非挥发性Al-O物质。 TiCl4暴露可在89°C至300°C的温度范围内去除氧化物覆盖层，在89°C至135°C的沉积温度下沉积约0.04的二氧化钛单层，但170°C至230°C的氧化钛不存在C。 TiCl4形成挥发性的氯氧化物产物，并从表面除去O，同时使Cl原子吸附到元素As层上，从而使表面化学钝化。使用液态HF和气相HF去除In0.53Ga0.47As（100）的天然氧化物，然后使用TMA和H2O在170°C沉积Al2O3。在TMA的第一个脉冲期间，分别在液相和气相HF处理的样品上沉积厚度为7.2±1.2Å和7.3±1.2Å的氧化铝膜。经过三个完整的ALD循环后，液态HF处理的氧化铝膜的厚度为10.0±1.2Å，气相HF处理的表面的氧化铝膜的厚度为6.6±1.2Å。气相HF处理的样品会抑制生长。抑制作用是由于钝化表面的残留F原子以及在TMA的第一个脉冲期间沉积的较厚的碳膜而引起的表面中毒所致。在被天然氧化物覆盖的InGaAs上，第一个TMA脉冲沉积9Å氧化铝，并在15个TMA脉冲后达到13Å饱和。该膜通过从基底氧化物中清除氧气来生长。即使在0°C，TMA的第一个脉冲也会还原衬底氧化物。在0°C时，在9 thick厚的富Ga氧化物表面上，主要发生1个TMA脉冲的物理吸附，并沉积了少量的氧化铝。在0°C，110°C和170°C下，更多的氧化铝沉积在最初包含As氧化物的表面上，与仅包含Ga氧化物的表面相比，观察到O 1s峰的结合能（BE）位移更大，表明As氧化物改善了Al2O 3的成核作用。

著录项

  • 作者

    Granados Alpizar, Bernal.;

  • 作者单位

    The University of Arizona.;

  • 授予单位 The University of Arizona.;
  • 学科 Engineering Chemical.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 122 p.
  • 总页数 122
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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