Preparation method of transmission electron microscope sample

Abstract

The invention discloses a preparation method of a transmission electron microscope sample. The transmission electron microscope sample comprises a silicon substrate and an insulating layer, wherein a through-hole or groove type target structure is formed on the insulating layer. The preparation method comprises the following steps: firstly, depositing a metal conductive layer on the surface of the insulating layer; connecting the metal conductive layer with the silicon substrate, wherein the sample is directly arranged on a sample table in a focused ion beam system and the silicon substrate is grounded through the sample table; and then depositing a metal protective layer on a target structure part on the metal conductive layer. During sample cutting, electric charges generated by the metal protective layer can be conducted to the silicon substrate and then grounded through the sample table, so that the charge accumulation in the target structure is avoided and the problem that the target structure is damaged by electric breakdown is prevented; according to the method, the problems such as the charge accumulation in the target structure and the breakdown of the insulating layer are avoided during the sample cutting, so that real and intact information of the target structure is obtained.

Description

technical field [0001] The invention relates to the technical field of integrated circuit manufacturing, in particular to a method for preparing a semiconductor integrated circuit transmission electron microscope sample. Background technique [0002] In the production process of integrated circuits, it is necessary to use TEM (transmission electron microscope) to observe various structures, such as the morphology of the first metal layer after etching. The morphology refers to the through holes or trenches formed during etching. Groove and other structures, the observation of this structure needs to cut the sample, such as figure 1 , figure 1 A schematic diagram of the sample structure that needs to be cut and analyzed, figure 1 Among them, the surface of the silicon substrate 1 is an insulating layer 2, and the target structure 3 is etched on the insulating layer 2. The silicon substrate 1 is generally several hundred μm (micrometer) thick. If the ion beam is directly use...

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Problems solved by technology

[0004] However, it is clear to those skilled in the art that the current conventional method of using focused ion beams for TEM sample preparation sometimes causes electrical breakdown due to charge accumulation, such as figure 2 , figure 2 Schematic diagram of the structure of directly depositing a metal protective layer on the sample that needs to be cut and analyzed, figure 2 Among them, the surface of the silicon substrate 1 is an insulating layer 2, and a target structure 3 is etched on the insulating layer 2, the target structure 3 includes the bottom 4 of the target structure, and a metal protection layer 5 on the surface of the insulating layer is deposited at the target structure 3; but If a metal protective layer is directly deposited on the sample, when the ion beam cuts, the charge will accumulate at the bottom of the target structure and cause electrical breakdown, causing the sample to be destroyed and unable to be analyzed

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