污染是一个非常严重的问题，可以引起:
腐蚀
对MFC的破坏
破坏阀门波纹管
污染物生成
污染过滤器
调节器控制的损坏
传感器的损坏
多种多样引起污染的原因包括:
空气混合在系统中
水分混合在系统中
连接错误的气瓶
气路有外漏
气路加热不正确
气路安装不正确
气路中的组件有污染
硅烷或硅烷气路
在一个清洁不当污染系统中安装 新的流量计。
正常使用也会导致很多气体残留污染。
注意事项:
更换气瓶时,CGA装置会暴露出来，残余的气体将与空气反应，这个污染将进入气路中并污染工艺腔体。
如果一个阀或流量计被拆下时发现有污染腐蚀迹象，那么气路中其它组件很可能也以同样的方式被污染腐蚀。
如果新的流量计安装到这个系统中，那么将马上会被污染，之前的工作将白费。
旧的过滤器常常有污染物，当清洗污染系时请更换过滤器。
如果你有一个系统清洗后仍有问题,你需要考虑更换过滤器
你总是需要仔细检查气瓶安装以确保它是正确的。
供气之前需要检漏 ，工作中也需检漏。
在打开气体之前，需要先吹扫整个从气瓶到工艺腔体的气路系统。
使用密封圈需要符合气体特性
使用MFC需要匹配气体
CONTAMINATION:
Contamination is a very serious issue and can cause:
Process problems
Corrosion
Damage to the MFC
Perforation of valve bellows and diaphragms
Particle generation
Destruction of filters
Loss of regulator control
Loss of sensors
Causes of contamination can be varied but may include:
Air in the gas system
Moisture in the gas system
Inadvertent connection of the wrong type of gas bottle
Corrupted gas in the bottle
Leaking fittings
Pinholes or micro cracks in valve diaphragms or bellows
Inadvertent opening of the gas system to atmosphere
Incorrect gas line heating
Incorrect gas line installation
Installation of components that were either improperly cleaned or not cleaned
Dusting of Silane or Silane based gas systems
Perforated flex lines
Installing new components in an improperly cleaned, contaminated system.
Normal use can also cause contamination as many gases leave residues.
Things to remember to prevent contamination:
When changing a gas bottle, the CGA fitting will be exposed to air and any
residual gas in that fitting will react and form a contaminate which will stay in
the system unless cleaned out or prevented. This contaminate will then enter
the gas stream and travel to the process chamber. The CGA fitting has a
bottle side as well.
If a component such as a valve or MFC is removed and it shows signs of
contamination, corrosion, etc. then the rest of the system is most likely also
contaminated the same way.
If new or refurbished components are installed in this system then they will
immediately become re-contaminated. Your work will be wasted.
Filters will trap contamination, when cleaning a contaminated
system…replace the filter .
If you have a system that is having flow problems after cleaning, did you
replace the filter ?
Always double check the gas bottle you are installing to ensure it is correct.
Never assume someone else has done something that was supposed to be
done, always check. Verify, Verify, Verify.
Always leak check a system prior to turning on the gas supply.
Always leak check a system after work is performed on the system.
Always purge and evacuate a gas system from the gas bottle to the chamber
prior to turning on the gas.
Use O-rings and seals that are compatible with the gas and the process.
Use MFC’s that are calibrated for the gas in use
