TEM sample preparation
In the preparation of TEM samples for FIB cross-sections, there are three methods:Pre-Thin, Lift-out, Omni-probeAs for the choice of FIB, it depends on the analysis requirements of the sample.
The preparation of samples using the pre-thinning method involves first grinding the samples to a thickness of 5-10 μm, and then further thinning them to a thickness of 0.1 μm suitable for TEM observation using FIB. The advantage of this method is that it can produce very large area (~50 μm) and uniformly thick TEM samples. Since the thin area is still held by the same material around it, there is no concern about deformation or curling of the thin sample. However, this method requires grinding followed by FIB cutting, making it more labor-intensive and time-consuming, and there is still a risk of grinding failure.
The probe extraction method involves using FIB to roughly cut the sample to about 1-2 μm and then depositing Pt with FIB to weld the probe to the sample. After that, the probe is moved to transfer the sample to the sample holder, where Pt is deposited with FIB to weld the sample to the holder. The probe is then cut away from the sample using FIB, and finally, the sample is finely polished with FIB to achieve a thickness suitable for TEM observation.
This is the most complex and time-consuming TEM sample preparation method, with a total working time of about 1.5 to 2 hours. However, this method allows for repeated entry and exit from the FIB for any necessary local adjustments to the sample thickness after TEM observation, ensuring zero errors and zero risks in TEM sample preparation. This method is usually adopted for very important sample analyses.
Record of each step in the TEM sample preparation process:
