第三章 氧化.pptVIP

第 三 章 Oxidation 氧化 Oxidation氧化 简介 氧化膜的应用 氧化机理 氧化工艺 氧化设备 RTO快速热氧化 简介 硅与O2直接反应可得； SiO2性能稳定； 氧化工艺在半导体制造中广泛使用 Oxidation 氧化膜的应用 掺杂阻挡层 表面钝化(保护) – Screen oxide, pad oxide, barrier oxide 隔离层 – Field oxide and LOCOS 栅氧化层 掺杂阻挡氧化层 Much lower B and P diffusion rates in SiO2 than that in Si SiO2 can be used as diffusion mask 表面钝化(保护)氧化层 Pad Oxide衬垫氧化层, Screen Oxide屏蔽氧化层 Sacrificial Oxide牺牲氧化层, Barrier Oxide阻挡氧化层 Screen Oxide Pad and Barrier Oxides in STI Process Application, Pad Oxide Relieve strong tensile stress of the nitride Prevent stress induced silicon defects 牺牲氧化层 Sacrificial Oxide Defects removal from silicon surface 器件隔离氧化层 临近器件的绝缘隔离 Blanket field oxide Local oxidation of silicon (LOCOS) Thick oxide, usually 3,000 to 10,000 ? Blanket Field Oxide Isolation LOCOS Process LOCOS Compare with blanket field oxide – Better isolation更好的隔离 – Lower step height更低台阶高度 – Less steep sidewall侧墙不很陡峭 Disadvantage缺点 – rough surface topography粗糙的表面形貌 – Bird’s beak鸟嘴 被浅的管沟(STI)所取代 栅氧化层 Gate oxide: thinnest and most critical layer Capacitor dielectric 氧化膜(层)应用 Silicon Dioxide Grown on ImproperlyCleaned Silicon Surface 表面未清洗硅片的热氧化层 热氧化生长的SiO2层是无定形的 SiO2分子间趋于交联形成晶体 未清洗硅片表面的缺陷和微粒会成为SiO2的成核点 这种SiO2层的阻挡作用很差 氧化前需要清洗硅片表面 氧化前圆片清洗 颗粒 有机粘污 无机粘污 本征氧化层 RCA清洗 Developed by Kern and Puotinen in 1960 at RCA Most commonly used clean processes in IC fabs (1号液)－NH4OH:H2O2:H2O with 1:1:5 to 1:2:8 ratio at 70 to 80℃ to remove organic . (2号液)-- HCl:H2O2:H2Owith 1:1:6 to 1:2:8 ratio at 70 to 80 ℃ to remove inorganic contaminates ，DI water rinse HF dip or HF vapor etch to remove native oxide. Pre-oxidation Wafer Clean Particulate Removal High purity deionized (DI) water or H2SO4:H2O2 followed by DI H2O rinse. 高压清洗或者放在清洗液中加热漂洗，最后烘干High pressure scrub or immersion in heated dunk tank followed by rinse, spin dry and/or dry bake (100 to 125 °C). 被氧化的硅片上有机物的清除 强氧化剂清除有机污垢 H2SO4:H2O2 or NH3OH:H2O2 followed by DI H2O rinse. High pressure scrub or immersion in heated dunk tank followed