Growth of high permittivity dielectrics by high pressure sputtering from metallic targets

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Universidad Complutense de Madrid
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The integrated circuit based on complementary metal-oxide-semiconductor (CMOS) devices is currently the dominant technology in the microelectronic industry. Their success is based on their low static power consumption and their high integration density. The metal-oxide-semiconductor field effect transistors (MOSFETs) are the main component of this technology. Their dimensions have been decreasing during the last years following the Moore’s law. This downscaling has made possible their continuous performance improvement. However, the size shrinking produced an excessive increase in the leakage current density that made this technology to face several challenges. The introduction of high permittivity (κ) dielectrics permits the use of a thicker insulator film (thus, reducing the leakage current) but with a lower equivalent SiO2 thickness (EOT). Besides, the introduction of these materials also required a change in the poly-Si electrode, that became a pure metal. The main objective of this thesis was the fabrication of metal-insulator-semiconductor (MIS) structures using high κ dielectrics grown from metallic targets. This was performed by means of high pressure sputtering (HPS). The advantage introduced by this system is that, due to the high working pressure, the particles suffer many collisions (because their mean free path is much lower than the target-substrate distance) and get thermalized before reaching the substrate in a pure diffusion process. This way, the semiconductor surface damage is preserved. The key novelty of this work consisted on the fabrication process using metallic targets. A two-step deposition process was developed: first, a thin metallic film is sputtered in an Ar atmosphere and, afterwards, this film was in situ oxidized...
Los circuitos integrados basados en los dispositivos CMOS (complementary metal-oxide-semiconductor) son en la actualidad la tecnología dominante de la industria microelectrónica. Su éxito se basa en su bajo consumo de potencia estática y en su alta capacidad de integración. Esto ha hecho que las dimensiones de los transistores de efecto campo metal-óxido-semiconductor (MOSFET, metal-oxide-semiconductor field effect transistor), que es el dispositivo principal de dicha tecnología, se hayan ido reduciendo durante los últimos años de acuerdo a la ley de Moore. A medida que los tamaños se fueron reduciendo, proceso habitualmente denominado escalado, las prestaciones de los transistores mejoraban. Sin embargo, esta continua reducción de los transistores lleva asociada una excesiva corriente de fugas que hace que los transistores dejen de funcionar de una manera óptima. Por tanto, los dieléctricos de alta permitividad (κ) se introdujeron para permitir emplear aislantes de mayor espesor físico (y así reducir las fugas), pero con un menor espesor de óxido de silicio equivalente (EOT, equivalent oxide thickness). El cambio en el material aislante de la puerta lleva asociado también un cambio en el electrodo metálico...
Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Departamento de Física Aplicada III (Electricidad y Electrónica), leída el 07/07/2016
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