PR in NMOS fabrication

[4electros]

I was trying to know about NMOS fabrication steps though this link:

**broken link removed**

i didn't understand what PR actually is? what PR stands for?
what about these terms: etching, PR developed, i need to have a clue .

thanks in advance!

 

[dknguyen]

Resist is used to protect areas of copper that you want to keep. PR = photo-resist which means that the resist is UV-light cured (uncured resist covered areas of copper will still be "etched" away).

Etching is the process of dissolving away the copper that you dont want (the copper not covered by cured-resist).

Ahhh, I just noticed you were talking about NMOS fabrication and not PCB farication...

well, its still pretty much the same thing instead of copper, its with P and N-doped silicon...I think...
Etching is the part of laying down certain types of silicon on the parts you want through a mask which protects other areas from getting the silicon deposited on it. I think PR still means photo-resist...but I am not sure exactly. Sorry.

 

[Papabravo]

The site itself refers to photoresist. It is exposed to UV rather than visible light. Etching solutions in silicon processing are much nastier than anything used on copper PC boards.

Don't try this at home and don't put your lips on it.

 

[RadioRon]

Now you've caught my interest with that comment. Why would anyone want to "put your lips on it"? Is it because you did this once?

 

[dknguyen]

Hehe, that's exactly what I was thinking when I read the post.

 

[Papabravo]

No, but it's been an engineering in joke for as long as I can remember. In 1970 I worked for a company that aspired to be a vertically integrated manufacturer of data entry terminals. Those terminals had keyboards, displays, cassette tape drives, and a power supply all inside a single package. We had a guy who designed the display electronics and there was a high voltage section that drove the CRT. Since we had to assemble and disassemble those early prototypes to do our work we were mindful of the advice which he profered, not to put our lips on the high voltage.

Seemed like good advice, then and now.

ROFL