| Summary: | 碩士 === 國立交通大學 === 電子物理系所 === 101 === Metal Induced Lateral Crystallization (MILC) technique has been purposed due to metal can be used to cause crystallization at controlled locations with low temperature. In 1992 Hayzelden et al. found nickel shows two advantages. One is fast migration property. The other is small lattice constant mismatch between NiSi_2 and crystal silicon (c-Si). So nickel is common used as MILC source in experiments now. Large crystal grain size can reduce defects and enhance carriers mobility, many research focus on how to increase grain size. But boron enhanced nickel crystallization is a controversial issue. The support groups think boron can reduce 〖NiSi〗_2 formation energy and modify lattice constant mismatch between crystal silicon and 〖NiSi〗_2 resulting in 〖NiSi〗_2 faster migration, longer metal induced lateral crystallization (MILC) length and larger grain size. However, the opposite groups think boron atoms are interrupt factor for crystallization. They believe doping boron with MILC process would block nickel crystallization causing short MILC length and small grain size.
Weather boron enhance or reduce nickel diffusion is what we curious. So the experiments are designed by different boron doping concentration (〖5*10〗^14 〖cm〗^(-2),〖1*10〗^15 〖cm〗^(-2)) samples with MILC crystallization on SONOS memories. We discuss this effect in physical and electrical parts, including XRD analysis, conductance measurement, program/erase speed, source/drain resistance extraction, GIDL current, retention and endurance researches.
The boron enhanced nickel diffusion effect is successfully proved in SONOS memories. We also found with double difference of boron doping concentration (〖5*10〗^14 〖cm〗^(-2),〖1*10〗^15 〖cm〗^(-2)) leading to double difference of grain size. Therefore, T. Ma et al. found MILC length double increase effect between boron dosages 〖3*10〗^14 〖cm〗^(-2) and 〖3*10〗^15 〖cm〗^(-2) can be modified to 〖1*10〗^15 〖cm〗^(-2) in SONOS memories. In addition, the high boron doping device shows better performance presenting large grain size, small variation, high mobility, fast program/erase speed, low resistance and long retention time. In this thesis, we gradually examine and verify boron enhanced nickel diffusion phenomenon which can promote SONOS memories physical and electrical characteristics.
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