if you simply look at the cross section without polishing you are looking at the effect of the break on your material. if you want to see/measure the thickness, distribution of certain elements in your thin film, you need to embed your sample in an epoxy (suitable for SEM vacuum) and then cut and polish. This way you will be looking at the true cross section of your sample not the effect of the breaking or cutting...

As in most cases, I must ask you to provide more information about your experiment. What kind of thin film have you produced? And how did you obtain the cross section? If for example, the thin film has been deposited on a glass slide or an Si wafer, you would just break it apart. In that case it should be possible to analyse the cross section without any polishing (which might affect the microstructure of your film in a way that corrupts your results). Best way: Try to get access to a cross-beam microscope with a focused ion beam. Cleanest solution (expensive, though).

Thank you dear moseke

I have prepared thin films deposited on glass substrates.I deposited thin films  by spray pyrolysis method, and i dont obtain the cross section yet.

Okay, then just try the break-apart method (with the help of a glass cutter from the other side). With a little luck your film cross section should be suitable for SEM analysis.

I would use a diamond cutter to scratch a deep line at the back of the glass substrate before deposition. Use that to crack the coated substrate (after deposition) for cross-sectional SEM. Blow the cracked surface with N2 for removing any excess dust. Use conductive carbon or silver paste at the edges to enhace electrical conductivity.Once the ink is dry coat the sample with a thin evaporated graphite. In most of the cases (especially over brittle sustrates) polishing is not required for X-sectional SEM analysis. However, if you are looking at something very specific, then you may need polishing.

Good luck....

Polishing could be needed if you cannot produce a sufficiently smooth cross-section, which results in problems with focusing. With glass substrates with a thickness of 1 mm or less, it is usually not an issue. As Claus said, you'll need just a little luck while cleaving the sample.

if you simply look at the cross section without polishing you are looking at the effect of the break on your material. if you want to see/measure the thickness, distribution of certain elements in your thin film, you need to embed your sample in an epoxy (suitable for SEM vacuum) and then cut and polish. This way you will be looking at the true cross section of your sample not the effect of the breaking or cutting...

I think Thierry has got a point. Nevertheless, it may depend on the film, how big the effect of any cross-sectioning technique will be. I would try several methods and then compare. Maybe there's no difference at all.

yes i think a little polishing may be work.

Dear Amir! Sometimes necessary to investigate the cross-section of films. In this case the thin films are polishing by mechanically (3deg or 5deg) in special sample holder or by using undercuted Eraserhead, or by using argon ion etching.