A kind of TEM sample preparation method

Abstract

In the TEM sample preparation method provided by the present invention, the sample is processed so that the distance between at least three surfaces and the target block inside the sample is 1 μm to 5 μm, and there are at least one pair of mutually parallel surfaces among the surfaces, and a pair of mutually parallel surfaces is optional, respectively. For the first surface and the second surface, the focused ion beam is incident to bombard the first surface and the second surface in a direction intersecting with the first surface, so that the first surface and the second surface have a depression with a parallelogram in cross section, And there is a target block exposed at the bottom of the depression. This method changes the emission angle of the focused ion beam when approaching the target block, regardless of whether the focused ion beam is incident in a direction perpendicular to the first surface or forming an acute angle with the first surface, the sample part around the target block can be preserved, only The thickness of the sample part where the target block is located is reduced, the thickness of the sample near the target block is increased, the problem of sample curling or cracking is reduced, and the success rate of sample preparation is improved.

Description

Technical field [0001] The invention relates to the field of transmission electron microscopy, in particular to a method for preparing TEM samples. Background technique [0002] Transmission Electron Microscope (TEM), abbreviated as Transmission Electron Microscope, is to project an accelerated and concentrated electron beam onto a very thin sample. The electrons collide with the atoms in the sample to change direction, resulting in solid angle scattering. The size of the scattering angle is related to the density and thickness of the sample, so images with different brightness and darkness can be formed. The images will be displayed on imaging devices (such as fluorescent screens, films or photosensitive coupling components) after being enlarged and focused. Nowadays, transmission electron microscopy has extremely wide and increasingly important applications in various fields including integrated circuit analysis, and FIB (Focused Ion beam) sample preparation is the most importa...

AI Technical Summary

Problems solved by technology

That is to say, this method is to cut a pit 3 in the middle of the sample 1 close to the target block 2, and the wall surface closest to the target block 2 in the pit 3 is the first wall surface 6, which is parallel to the first wall surface 6 The surface of the sample 1 is an outer surface close to the target block 2, that is, the first surface 7, and then the focus is emitted in a direction parallel to the first wall surface 6 and the first surface 7 (that is, the vertical downward direction) The ion beam 5 emits a current intensity between 300pA and 500pA, and the focused ion beam 5 will place the sample 1 on the two mutually parallel surfaces (ie, the first wall 6 and the first surface 7 ) within the emission range. Parts are all removed, so that although the above two parallel surfaces are closer to the target block 2, the part where the target block 2 is located will form a shape like Figure 4 The shown thickness is much smaller than the sample sheet 8 in other parts, and the distance between the first wall surface 6 and the first surface 7 is very close, that is, the sample sheet 8 in the area where the target block 2 is located is very thin, which will cause the sample sheet 8 to be thin. The mechanical strength is not enough, which causes the problem that the sample sheet 8 is prone to curling or cracking, which eventually leads to the failure of sample preparation

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