Cutting silicon samples with plastic thin films

I'm measuring thicknesses of ~15 $\mu$m nickel thin films electroplated on a silicon substrate. I only have access to a SEM for this task. I need to cut the samples to get a side view of the film. However, the nickel film is plastic and the silicon undergoes a brittle fracture. As a result the nickel film often detaches from the substrate near the fracture point before I have the chance to cut it, making imaging impossible.

How could I cut through both the plastic thin film and the brittle silicon simultaneously? I'm getting access to liquid nitrogen in a week or so with the intention of freezing the sample. Is there a ~room temperature process which would allow me to prepare samples meanwhile?

1 Answer

Liquid nitrogen performed poorly in this case. The change in temperature and tension popped the relatively thick film straight off the substrate!

The best results were achieved with encasing the small square samples in epoxy. It allowed the samples to be cut with a diamond saw without even fracturing the silicon. Tool marks were apparent and the film suffered, but in this case it was enough to estimate the thickness of the film.

• Since you mentioned tool marks, I have to ask: did you try grinding and polishing the observed sample face? That should eliminate tool marks quite handily without degrading the coating. Feb 3, 2017 at 0:34
• No, I felt that it was unnecessary here. Feb 3, 2017 at 8:28