>i wanna know the depth of layers.
>i have 4 multi layer(silicon dioxide, silicon nitride, poly-silicon,
>silicon nitride) wafer. but i don't know the way to measure the depth
>of each layer during etching.
>but i can't make a step.
>because right now i can't use dry etch.
>so i wanna use an ellipsometer.
>if you have info about it let me know.
>thanks in advance.

I use an ellipsometer made by a company called Sopra (www.sopra-sa.com).
They are very helpful.  Try contacting them and see if they will measure
your sample for you.

Justin Mansell  |       "Only a risk tests the reality of a belief"
Ginzton Laboratory      |                       - C. S. Lewis
445 Via Palou St.       |
Stanford, CA 94305      |