How hazardous is semiconductor etching?

[lifeson22]

Many of you may be annoyed by my question. I'm sorry in advance.

I've just finished my M.S. in Materials Science & Engineering, and have gotten an offer as a Semiconductor Process Engineer. The specialty is lithography and wet chemistry - including wet etching.

As an MSE student I learned to be horrified with Hydrofluoric Acid. I'm not a fan of other strong acids, but HF terrifies me. I imagine that I might be mixing acids, and some HF gets on my skin, or I breath it in. Or I might be dipping a wafer in an HF bath and splash some on me.

I know, there are safety procedures - splash goggles, protective clothing, respirator, etc. But I always make room for the one time I have an oversight, or when the gloves have a small cut, or the respirator isn't working right.

I'll be honest - I don't know very well how the etching is done, mostly because I've never seen it done. I don't know if specialized machines handle the acid for you, so that you're not directly exposed to it.

Am I worrying unnecessarily? How hazardous is etching engineering? Can some of you tell me how the whole process works - do you mix the acids manually, and dip the wafer manually during the R & D efforts? Or do machines handle the acid part for you?

One day I'll look at comments like this and, just like you, probably be very annoyed. But, as a pure newbie, I would love some kind answers. Thanks!

 

[Mapes]

I can tell you a little about R&D at MIT's Microsystems Technology Laboratories. All clean room workers wore a full clean room suit, latex gloves, and safety glasses; additionally, people working with acids, including HF, also wore a heavy apron, pull-on-plastic sleeves, heavy nitrile gloves, and a face shield, and they worked in fume hoods. It was routine to mix acids. However, it was very unusual to get any acid on your gloves, and it was nearly unthinkable to breath fumes. For etching wafers, we had a full set of plastic wafer and cassette holders so that dipping and rinsing would be done without getting near the containers of acid. Tweezers were discouraged, especially metal tweezers that would contaminate your process with Fe. pH-indicating strips and calcium gluconate (HF "antidote") were available next to the hood. All containers were emptied by aspiration and rinsed three times with DI water before removal from the hood.

Anyone violating these rules would get a stern lecture from anyone who saw that person. I always felt extremely safe.

I think it's appropriate and great that you're thinking about possible failure of safety devices. There should be multiple backups to prevent HF exposure. If you don't see these at your new company, don't process until your concerns are addressed.

 

[lifeson22]

Thanks Mapes, for the insightful answer. I'm very excited about semiconductor processing, but have my reservation because of the many hazards involved. Your answer puts me a bit more at ease with the acid hazards.