真空获得俘获真空泵.ppt

Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空物理与技术真空物理与技术第5章真空获得（俘获泵）Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology低温泵低温泵Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology低温泵概述低温泵概述l俘获泵l低温抽气u20K以下，绝大多数气体蒸汽压可以忽略不计nHenH2u一个极冷的冰柜n20Kn液Hel极限压强最低、抽速最大Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology蒸汽特性蒸汽特性Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology抽气原理抽气原理lVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology蒸汽特性蒸汽特性l要达到10-8Torr以下压强，必须使用LH2或LHe冷却lLH2可以有效凝聚除He,Ne以及本身以外的一切气体u但LH2用途不广，爆炸lLN2可有效冷却H2O，CO2，但对Ar,O2无能为力lLHe成本限制了其使用，但是温度最低的冷剂300元/LVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology低温泵结构低温泵结构l低温抽气阵列u室温下，低温表面不能直接暴露气源u辐射热负荷冷凝热负荷u低温表面需要不透光具有中间温度的挡板Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology冷表面冷表面l二级冷表面二级冷表面lH2O蒸汽蒸汽u60KlHe和和H2抽除困难抽除困难u10 K(difficult)uHe/H2吸附量有限吸附量有限l注意保护第二级冷表面注意保护第二级冷表面u远离容易饱和气体u远离热负载u无油Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology冷却冷却l液Heu纯度（UltraPure)l压缩机lSimilar to a refrigerator cycle but differentVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyCapacityl抽气能力u低温泵到底能吸附多少气体？u取决于气体种类和泵的机械结构n9000Torr.LH2-alotbutnotinfiniten106Torr.LArn空气/水汽l抽速u与泵口分子入射率相关u取决于吸附与脱附的平衡Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology抽速抽速Ablackholeforwatervapor气体吸气表面入射率 逃逸率净抽速单位水蒸汽 1级表面15015L/sec.cm2N22级表面上11.98.93L/sec.cm2H22级表面内部45396L/sec.cm2Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology统计数据统计数据l10法兰盘低温泵u10,000 liter/second H2Ou1700 liters/second Aru4700 liters per second H2u2000 liters per second N2u抽速和分子入射率、气体分子种类密切相关抽速和分子入射率、气体分子种类密切相关Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology分类分类lLHe贮槽式u12LLHeS(H2)=4500L/s，200Dayu12LLHeS(H2)=27000L/s，200Dayl流程式u封闭循环（体积庞大，多用于空间模拟）lGHe闭环式uHe压缩机Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology低温泵小结低温泵小结l优点优点u干净干净 无油无油u不因突然漏气而损坏不因突然漏气而损坏u抽速大抽速大uHV，UHV 109Torru接近无限大的吸气能力接近无限大的吸气能力(除了除了He,H2)l缺点缺点u存储了大量的气体存储了大量的气体u热敏感热敏感u和部分气体反应和部分气体反应u压缩机压缩机Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology低温泵和涡轮分子泵比较低温泵和涡轮分子泵比较l干净干净 无油无油 高真空泵高真空泵l现代半导体工业中广泛应用现代半导体工业中广泛应用低温泵中等尺寸与气体反应贮存气体涡轮分子泵尺寸小与气体不反应抽除气体TypicallyineachapplicationsTypicallyinfilmdepositionapplicationsVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology典型的低温泵系统典型的低温泵系统Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology升华泵升华泵Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology化学清除化学清除lp=nkT，压强正比于气体分子浓度l化学清除u蒸发化学活性金属u与容器内气体发生化学反应，生成化合物l收气剂（消气剂）u蒸散式：依靠高温蒸散到别的元件上u非蒸散式：适当温度下工作（少量蒸发）Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology蒸散式收气剂蒸散式收气剂l小型电子管u抽空到某一真空度后，除气n玻璃除气温度(400-500C)下蒸汽压大的蒸发率：Ba,Ma层剥落l常见非蒸散式收气剂u锆n价格贵，可能引起爆炸n用锆铝合金代替u钛Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology升华泵升华泵lTi持续蒸发到冷壁上，构成相当抽气速率的泵u钛丝蒸发器n高温Ti机械强度太差n钛丝、钼丝缠绕，通电加热n空心钛钼合金球，内部白炽钨丝加热u比抽速nO2N2CO10L/cm2活性表面nH240L/cm2活性表面n不能抽除惰性气体u升华泵可提高真空度约2个数量级Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology离子泵离子泵Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology电清除电清除l电清除uuA在电场作用下被驱逐到负极被中和u新形成的气体分子被金属吸附而不再离开电极u实际上降低了空间分子浓度u离子泵Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology离子泵基本结构离子泵基本结构能吸附离子的表面：清洁的，冷的负电表面电子源（W热阴极）加速电子的阳极Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology离子泵偏压离子泵偏压Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology离子泵的限制离子泵的限制l超高真空设备u对活性气体和惰性气体同时起作用u表面足够大，没有漏气放气，极限压强很低u实际很快饱和（扩散的速率低于吸附的速率）u抽速慢，1L/sl操作u扩散泵将离子泵抽至10-5Pau泵体，电极烘烤除气u离子泵工作Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology离子蒸发泵离子蒸发泵l离子泵的限制u清洁表面：放电过程不断补充新的活性表面u对惰性气体抽除能力不强：吸附，没有反应l离子蒸发泵u利用离子泵抽气u利用收气金属不断蒸发形成新的表面u收气剂对离子作用远大于对分子作用u新鲜粒状表面，增强气体分子向内能徙动Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology结构结构l蒸发器u直热、电子束加热、阴极溅射l电离器u二极管、三极管、冷阴极磁放电、热阴极磁放电l蒸发金属uTi（钛泵）-不同与钛升华泵Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology冷钛泵（溅射离子泵）冷钛泵（溅射离子泵）l结构u阳极:不锈钢圆筒u阴极:钛板u磁场:平行与阳极筒u工作电压:3-7kV,潘宁放电l过程u预抽气到1Pau正离子溅射阴极TiuTi在阳极沉积l抽气u与Ti反应（化学）u扩散到Ti电极内（物理）u埋葬（物理）Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology抽气单元抽气单元l增加层积面积u单室抽气速率1-3L/su50单元l极限真空u10-9Pal抽速u选择性抽气u压强高:放电电流大,阳极电压降低;空间电荷u压强低:繁流初始电子太少u磁场Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology氩不稳定氩不稳定l惰性气体抽除能力不强？(物理吸附）u有效抽除He（离子埋葬）uAr抽速差，不稳定现象u三极式冷钛泵Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology应用应用lHVu10-4Torrn吸附泵u不需要前级泵（没有排气）l电源u5-7kVu大电流l寿命u气体负载uHV情况下5yearu溅射孔u氢化钛（机械形变）Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology离子泵小结离子泵小结l优点优点u干净干净 无油无油u安静安静u维护费用低（电）维护费用低（电）uUHV-10-11 torrl缺点u强磁场强磁场u溅射击穿溅射击穿Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology典型的离子泵组典型的离子泵组