CN-121978146-A - Scanning electron microscope sample preparation method applied to wafer sample with poor conductivity

Abstract

The invention belongs to the technical field of scanning electron microscope, and in particular relates to a scanning electron microscope sample preparation method applied to a wafer sample with poor conductivity, which comprises the following steps of cleaning the wafer sample; fixing the cleaned wafer sample on a carrying disc of a spin coater, then dripping conductive adhesive on the surface of the wafer sample, spin-coating the conductive adhesive on the surface of the wafer sample by the spin coater to obtain a sample for scanning electron microscope observation, wherein the conductive adhesive is polyaniline solution. The method can effectively eliminate the 'charge effect' on the surface of the non-conductive wafer, so that the non-conductive wafer has clear surface morphology under a scanning electron microscope, and the initial state of the wafer sample can be restored after the test is finished, and the original components and the original properties of the sample are not changed, so that the subsequent process and the test link are not influenced. In addition, the method has smaller shielding effect on the CL light output of the wafer sample and has a gain effect in the cathode fluorescence test link of the wafer sample.

Inventors

• WANG YELIANG
• HE CHAO
• LIU LIWEI
• HUANG YUAN
• GUO ZIHAO

Assignees

• 北京理工大学

Dates

Publication Date

20260505

Application Date

20251212

Claims (6)

1. 1. A scanning electron microscope sample preparation method applied to a wafer sample with poor conductivity is characterized by comprising the following steps: Cleaning the wafer sample; Fixing the cleaned wafer sample on a carrying disc of a spin coater, then dripping conductive adhesive on the surface of the wafer sample, spin-coating the conductive adhesive on the surface of the wafer sample by the spin coater to obtain a sample for scanning electron microscope observation, wherein the conductive adhesive is polyaniline solution.
2. 2. The scanning electron microscope sample preparation method applied to the wafer sample with poor conductivity according to claim 1, wherein the mass content of polyaniline in the polyaniline solution is 1.5-2.5%.
3. 3. A scanning electron microscope sampling method applied to a wafer sample with poor conductivity according to claim 1 or 2, wherein the cleaning process comprises: s1, placing a wafer sample in acetone, and performing ultrasonic oscillation for a period of time; s2, taking out the wafer sample from acetone, drying, placing in isopropanol, and performing ultrasonic oscillation for a period of time; s3, taking out the wafer sample from isopropanol, drying, then placing in deionized water, and performing ultrasonic oscillation for a period of time; and S4, taking the wafer sample out of the deionized water and drying.
4. 4. The scanning electron microscope sample preparation method applied to the wafer sample with poor conductivity according to claim 1or2, wherein when the wafer sample is 2 inches, the volume of the dropped conductive adhesive is 700-800 uL; When the wafer sample is 3 inches, the volume of the dropwise added conductive adhesive is 1.5-2.0 mL; When the wafer sample is 4 inches, the volume of the dropwise added conductive adhesive is 2.5-3.5 mL.
5. 5. The scanning electron microscope sample preparation method for the wafer sample with poor conductivity according to claim 1 or 2, wherein the spin coating of the spin coater is performed for 4-6 seconds under the condition of 400-600 revolutions per minute, then for 50-70 seconds under the condition of 5000-7000 revolutions per minute, and finally for 4-6 seconds under the condition of 400-600 revolutions per minute.
6. 6. Use of the scanning electron microscope sampling method according to any one of claims 1 to 5 in scanning electron microscope-cathode fluorescence testing.

Description

Scanning electron microscope sample preparation method applied to wafer sample with poor conductivity Technical Field The invention belongs to the technical field of scanning electron microscope, and particularly relates to a scanning electron microscope sample preparation method applied to a wafer sample with poor conductivity. Background Scanning electron microscope, SEM (Scanning Electron Microscope) for short, is a high resolution electron microscope for observing and analyzing the surface morphology and microstructure of materials. Scanning electron microscope scans the sample surface through electron beam, and signals such as secondary electron, back scattered electron, cathode fluorescence are excited, and the signals are collected and analyzed through different detectors, so that images and data can be obtained. The scanning electron microscope has wide application in the fields of material science, biology, geology and the like, and can be used for material characterization, basic research and the like. Cathode fluorescence (Cathodoluminescence, CL) refers to photon signals with wavelengths in ultraviolet, infrared or visible light bands excited by electron beam bombardment on the surface of a substance, and detection and processing of fluorescent signals excited by the electron beam are usually combined with a scanning electron microscope, so that morphology observation, structure and component analysis and combination research of fluorescent spectrum excited by the electron beam can be realized. The basic principle of the scanning electron microscope is that the scanning electron microscope scans the surface of a sample through electron beams and interacts with the sample, so that the first precondition of the scanning electron microscope for the sample is that the sample needs to have good conductivity, otherwise, a large amount of injected electrons can be gathered on the surface of the sample locally or in a large area and cannot be led away from the sample, and the large amount of the electrons can influence the electrostatic field of the area so as to influence the detection imaging of secondary electrons, which is reflected in that the brightness difference is very large on an electron microscope image, and the bright area fluctuates severely along with the adjustment of the magnification, and in addition, the phenomenon of drift can be observed under the larger magnification. This imaging problem, which is due to poor conductivity of the sample, is called "charge effect". To eliminate the effect of "charge effect", it is necessary to increase the conductivity of the sample in principle so that the injected electrons can form a path away from the surface of the sample. It is conventional practice in the industry to plate a gold or carbon film on the surface of the sample, both of which have good electrical conductivity, and to cover the surface of the poorly conductive sample to help conduct electrons away from the sample surface. However, the conductive layer formed in this way is difficult to remove from the surface of the sample, and is almost an "irreversible" sample preparation method, especially in the semiconductor industry, the production and processing of wafers has a series of complicated procedures, and for some substrate materials with poor conductivity, the manner of coating the film can affect the subsequent process and testing procedure of the sample. In addition, the gold film or the carbon film can shield the CL signal, and the accuracy and the actual effect of the CL detection link are affected. Disclosure of Invention The invention aims to provide a scanning electron microscope sample preparation method applied to a wafer sample with poor conductivity, by using the method, the 'charge effect' on the surface of a non-conductive wafer can be effectively eliminated, so that the wafer sample has clear surface morphology under the scanning electron microscope, and the initial state of the wafer sample can be restored after the test is finished, the original components and the original properties of the sample are not changed, and thus, the influence on the subsequent process and test links is avoided. In addition, in a scanning electron microscope-cathode fluorescence (SEM-CL) test, compared with a traditional film plating method, the method has smaller shielding effect on the light output quantity of the wafer sample CL and has a gain effect in a cathode fluorescence test link of the wafer sample. Specifically, the invention provides the following technical scheme: a scanning electron microscope sample preparation method applied to a wafer sample with poor conductivity comprises the following steps: Cleaning the wafer sample; Fixing the cleaned wafer sample on a carrying disc of a spin coater, then dripping conductive adhesive on the surface of the wafer sample, spin-coating the conductive adhesive on the surface of the wafer sample by the spin coater to obtain a sample for s