5光刻与刻蚀工艺总结.ppt

PLASMA ETCH Etch dielectric Etch single crystal silicon Etch polysilicon Etch metal Dielectric Etch Etch oxide – Doped and undoped silicate glass – Contact (PSG or BPSG) – Via (USG, FSG or low-k dielectric) Etch nitride – STI（浅槽隔离） – Bonding pad（压焊点） Dielectric Etch Fluorine chemistry 4F + SiO2 ? SiF4 +2O CF4 is commonly used as fluorine source NF3 and SF6 have also been used 加入O2以提高刻蚀选择比，如图所示。 Single Crystal Silicon Etch Small amount O2 for sidewall passivation A little NF3 for preventing black silicon Polysilicon Etch Gates and local interconnections – Most critical etch process, smallest CD Capacitor electrodes for DRAM Require high selectivity over silicon dioxide Cl2 chemistry Polysilicon Etch Metal Etch For metal interconnection Metal stack: TiN/Al?Cu/Ti Cl2 as the main etchant BCl3, N2 are used for sidewall passivation O2 is used to improve selectivity to oxide Main challenges: etch profile and avoiding etch residue Metal Etch Chemistries Photoresist Dry Strip Etch Safety Corrosive and toxic gases – Cl2, BCl3, SiF4 and HBr – Could be fatal if inhalation at a high concentration (1000 ppm) RF power can cause electric shock --Can be lethal at high power Plasma Etch Trends 刻蚀总结 湿法刻蚀：化学刻蚀，各向同性，工艺简单，选择性高，粗线条， 干法刻蚀：物理和/或化学（三种工艺），各向异性，设备复杂，分辨率高，细线条 VLSI广泛使用干法刻蚀 针对不同的材料，其典型的湿法腐蚀液（配方）及干法腐蚀剂 Etch Polysilicon刻蚀多晶硅 Etch Polysilicon 继续 Strip Photoresist 光刻胶剥离 离子注入Ion Implantation 快速热退火Rapid Thermal Annealing 刻蚀术语 刻蚀速率 选择比 刻蚀均匀性 刻蚀剖面 湿法刻蚀 干法刻蚀 RIE：反应离子刻蚀 刻蚀速率 Δd = d0 - d1 (?) 厚度变化量；t 刻蚀时间 (min) PE-TEOS PSG薄膜, 1min 在6:1 BOE at 22 °C, 刻蚀前, t = 1.7 mm, 湿法刻蚀后, t = 1.1 mm 刻蚀选择比 选择性是指不同材料刻蚀速率之比 对底层的选择性，对光刻胶的选择性 举例 PE-TEOS PSG薄膜刻蚀速率 6000 ?/min, 硅刻蚀速率30 ?/min, PSG to silicon 刻蚀均匀性 圆片上和圆片间的重复性 Standard Deviation Non-uniformity标准偏差不均匀性 N points measurements Max-Min Uniformity 最大最小均匀性 刻蚀剖面 各向异性 各向同性 各向异性，锥形 各向异性，内切 刻蚀剖面 各向异性，脚印 各向异性，反脚印 各向异性，反锥形 各向异性，内切 湿法刻蚀 利用化学溶液溶解硅表面的材料 副产物是气体、液体或可溶于刻蚀溶液的固体 三个基本过程：刻蚀、漂洗、干燥 湿法刻蚀 纯化学腐蚀过程 特点：各向同性剖面 优点：工