While measuring the thickness of polymer thin film on Silicon wafer using spectroscopic ellipsometry, I am getting a thickness of 50 nm at 65 deg, 120 nm at 70 deg and 125 nm at 75 degree, for the same measurement. Should I reconsider the model or should I exclude the angle 65 degree?
I suggest to restart the measurement at 60 deg if it is possible with your setup. It is possible that you problem is due to the Brewster angle : do you know the value of this angle for your polymer ?
Regards,
I agree with Jean-François: first thing to do is to check the measurements, particularly at 65°. In order to get a such a difference in thickness, I assume that the spectra must be very different, with much less maximums and minimums at 65°, which would be surprising if the measurement was done on the same spot. Does the polymer film visually look uniform? If not, you might expect some variation in thickness with the angle of incidence, due to a variation of the spot size on the sample.
What about the refractive index values? Are they different as well?
Which polymer have you measured, and which assumptions have you made/which model have you used to extract the thickness value?
Hi Jean-françois
I don't know the Brewster angle of my sample. From literature, it appears that it should be close to 70 deg
Daniel, you may be right. The sample is a polyelectrolyte multilayer. The film seems to be a little bit rough.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials Chemistry