Method for preparing a tem sample

A method for preparing a transmission electron microscope (TEM) sample, comprising a plurality of steps:

• step 1:
• providing a thin-film pre-sample, and selecting a target region for forming the TEM sample in the thin-film pre-sample, wherein the thin-film pre-sample has voids;
• step 2:
• performing a first cutting to form a first front surface and a first back surface of the TEM sample in the target region of the thin-film pre-sample by applying a first focused ion beam (FIB);
• wherein the TEM sample after the first cutting comprises a first thickness between the first front surface and the first back surface, wherein the voids are exposed from the first front surface or the first back surface of the TEM sample, and wherein the first thickness meets a preset condition;
• step 3:
• forming a first material layer to fill the voids in the TEM sample by applying an atomic layer deposition (ALD) process, wherein the preset condition of the first thickness enables filling of the voids;
• step 4:
• performing a second cutting to form a second front surface and a second back surface of the TEM sample in the target region of the thin-film pre-sample by applying a second FIB;
• wherein the TEM sample after the second cutting comprises a second thickness between the second front surface and the second back surface, and wherein the second thickness is thinner than the first thickness, and wherein the second thickness is a target thickness of the TEM sample.