集成电路制造技术第五章-2(化学机械抛光)
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第八章 化学机械抛光 CMP (Chemical Mechanical Planarization)
化学机械抛光的重要性
（1） 铜比铝具有更佳的 导电率，是亚微米线宽的 电极布线的理想材料。
•铜湿法刻蚀钻刻严重。
• 铜的等离子体刻蚀很难 实现，且效果较差。
• CMP技术是实现大马士 革结构铜布线层关键工艺。
集成电路微细化的追求： 高集成度 更快的器件运行速度
在追求纳米级线宽与多层 布线的趋势中，存在几个 典型的技术难题。
(2)分辨率和焦深的折衷
R
k ,
NA
k
NA2
(3) 表面平坦化 减小台阶，提高镀膜
效果。
• 表面平坦化的问题
• 例子1
用0.25 mm工艺制作256 MB DRAM，在 运用两层铝金属导线的情况下，在存储 单元及外围电路部分，高台(存储单元) 和低地(外围电路)两者的高度将相差约1 mm，而此工艺的焦深只有约0.20 mm。 这对曝光机的聚焦效果将造成影响。 因此必须表面平坦化。
Application of CMP
Copper Deposited
CMP Copper and Tantalum
Chemical Mechanical Polishing System
• Polishing pad, Wafer carrier, Slurry dispenser
CMP process
• 0.25 mm pattern require roughness <200nm
• Only CMP can achieve this planarization
• When feature size > 0.35 mm, other methods can be used
Definition of Planarization
Disadvantage of CMP
• Introduce defects of its own • Need appropriate post-CMP cleaning
Application of CMP
• STI formation • Dielectric layer planarization • Tungsten plug formation • Copper interconnection (Damascene method
• Planarization is a process that removes the surface topologies, smoothes and flattens the surface
• The degree of planarization indicates the flatness and the smoothness of the surface
• The planarized surface eliminates sidewall thinning because of poor PVD step coverage
• Uniform thin film deposition
• Reduce defect density, improve yield
例子2
• Photolithography resolution R=K1/NA • To improve resolution, NA or • DOF=K2/2(NA)2, both approaches to
improve resolution reduce DOF
• Here we assumed K1=K2, =248 nm (DUV), and NA=0.6, Resolution for 0.25 mm DOF = 208 nm and 150 nm for 0.18 mm resolution
• Removes the used slurry
CMP Slurries Toothpaste
compressible at process temperature
– Soft pad: better within wafer uniformity, poorer topographical selectivity
– Hard pad: high removal rate, longer conformality range
CMP process2
Orbital Polishing
Wafer carrier
Polishing Pad Toothbrush
• Porous, flexible polymer materials • Pad directly affects quality of CMP • Pad materials: durable, reproducible,
• Global planarization is required for the feature size smaller than 0.35 mm, which can only be achieved by CMP.
Advantage of CMP
• Planarized surface allows higher resolution of photolithography process
• Process requirement: high topography selectivity to achieve surface planarization
Pad Conditioner
• Sweeps across the pad to increase the surface roughness required by planarization
Definition of Planarization
Definition of Planarization
Degrees of Planarization
Planarization
• Smoothing and local planarization can be achieved by thermal flow or etchback.
化学机械抛光的重要性
（1） 铜比铝具有更佳的 导电率，是亚微米线宽的 电极布线的理想材料。
•铜湿法刻蚀钻刻严重。
• 铜的等离子体刻蚀很难 实现，且效果较差。
• CMP技术是实现大马士 革结构铜布线层关键工艺。
集成电路微细化的追求： 高集成度 更快的器件运行速度
在追求纳米级线宽与多层 布线的趋势中，存在几个 典型的技术难题。
(2)分辨率和焦深的折衷
R
k ,
NA
k
NA2
(3) 表面平坦化 减小台阶，提高镀膜
效果。
• 表面平坦化的问题
• 例子1
用0.25 mm工艺制作256 MB DRAM，在 运用两层铝金属导线的情况下，在存储 单元及外围电路部分，高台(存储单元) 和低地(外围电路)两者的高度将相差约1 mm，而此工艺的焦深只有约0.20 mm。 这对曝光机的聚焦效果将造成影响。 因此必须表面平坦化。
Application of CMP
Copper Deposited
CMP Copper and Tantalum
Chemical Mechanical Polishing System
• Polishing pad, Wafer carrier, Slurry dispenser
CMP process
• 0.25 mm pattern require roughness <200nm
• Only CMP can achieve this planarization
• When feature size > 0.35 mm, other methods can be used
Definition of Planarization
Disadvantage of CMP
• Introduce defects of its own • Need appropriate post-CMP cleaning
Application of CMP
• STI formation • Dielectric layer planarization • Tungsten plug formation • Copper interconnection (Damascene method
• Planarization is a process that removes the surface topologies, smoothes and flattens the surface
• The degree of planarization indicates the flatness and the smoothness of the surface
• The planarized surface eliminates sidewall thinning because of poor PVD step coverage
• Uniform thin film deposition
• Reduce defect density, improve yield
例子2
• Photolithography resolution R=K1/NA • To improve resolution, NA or • DOF=K2/2(NA)2, both approaches to
improve resolution reduce DOF
• Here we assumed K1=K2, =248 nm (DUV), and NA=0.6, Resolution for 0.25 mm DOF = 208 nm and 150 nm for 0.18 mm resolution
• Removes the used slurry
CMP Slurries Toothpaste
compressible at process temperature
– Soft pad: better within wafer uniformity, poorer topographical selectivity
– Hard pad: high removal rate, longer conformality range
CMP process2
Orbital Polishing
Wafer carrier
Polishing Pad Toothbrush
• Porous, flexible polymer materials • Pad directly affects quality of CMP • Pad materials: durable, reproducible,
• Global planarization is required for the feature size smaller than 0.35 mm, which can only be achieved by CMP.
Advantage of CMP
• Planarized surface allows higher resolution of photolithography process
• Process requirement: high topography selectivity to achieve surface planarization
Pad Conditioner
• Sweeps across the pad to increase the surface roughness required by planarization
Definition of Planarization
Definition of Planarization
Degrees of Planarization
Planarization
• Smoothing and local planarization can be achieved by thermal flow or etchback.