Characterization method and application of silicon carbide radiation damage defect

Abstract

The invention belongs to the technical field of silicon carbide defect detection, and particularly discloses a characterization method and application of a silicon carbide radiation damage defect, and the characterization method comprises the following steps: firstly, respectively placing a to-be-detected sample A which is not irradiated and a to-be-detected sample B which is irradiated on an objective table, and carrying out Raman spectrum collection; then, carrying out spectrum pretreatment; and finally, analyzing vibration information: comparing the low-frequency vibration information of the silicon carbide sample A and the silicon carbide sample B, and combining the theoretical Raman spectrum calculation result of the silicon carbide wafer to obtain the change information of intermolecular interaction and lattice vibration after silicon carbide irradiation. The silicon carbide radiation damage defect characterization method and application have the advantages of being simple, free of damage and free of marks, have important application prospects in the aspects of silicon carbide quality control and rapid detection, and provide an effective means for crystal radiation damage detection in the fields of chips, aerospace, national defense and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide defect detection, and in particular to a method for characterizing radiation damage defects in silicon carbide and its application. Background Art

[0002] Silicon carbide's excellent physical and chemical properties have led to an ever-expanding range of applications in semiconductor devices, optoelectronics, aerospace, and other fields. However, radiation is one of the most detrimental environmental factors affecting silicon carbide devices in space. High-energy particles entering the material can introduce defects such as vacancies and interstitial atoms. These defects can significantly impact the electrical performance of silicon carbide devices, reducing their operating lifespan and even leading to functional failure, resulting in significant losses. Therefore, characterizing and detecting the radiation damage properties of silicon carbide is a crucial foundation for further research into the material's internal damage mechanisms.

[0003] In the existing technology, the methods for characterizing radiation damage to silicon carbide mainly use microscope observation, wafer defect analyzers, X-ray diffractometers and other equipment to detect and count defects and distribution in wafers. However, these detection methods are insufficient in characterizing information such as molecular interactions and lattice vibrations after radiation damage to silicon carbide. In addition, some detection methods are expensive, some detection methods are time-consuming and the detection process is cumbersome, and there are often cases of misjudgment of defects. Therefore, there is a need for more accurate and intuitive methods to characterize the radiation damage characteristics of silicon carbide, and then to clarify the mechanism of its differences, which is of great significance for comprehensively and systematically ensuring the reliability of silicon carbide devices in space radiation environments. Summary of the Invention

[0004] The purpose of the present invention is to provide a characterization method and application of silicon carbide radiation damage defects, which has the advantages of being simple, non-destructive and label-free. It has important application prospects in silicon carbide quality control and rapid detection, and provides an effective means for crystal radiation damage detection in the fields of chips, aerospace, national defense, etc.

[0005] To achieve the above object, the present invention provides a method for characterizing radiation damage defects in silicon carbide, comprising the following steps:

[0006] S1. Preparation of irradiated samples: taking an unirradiated silicon carbide wafer as the test sample A, placing the silicon carbide wafer in a proton irradiation device for irradiation to obtain the test sample B;

[0007] S2, Raman spectrum acquisition: Place the sample A and sample B obtained in S1 on the stage respectively, and use the Raman spectroscopy system to acquire Raman spectra;

[0008] S3. Spectral preprocessing: Preprocessing the Raman spectra of the sample A and the sample B to be tested respectively to obtain the scattering spectrum of the silicon carbide sample A and the scattering spectrum of the silicon carbide sample B;

[0009] S4. Vibration information analysis: Compare the low-frequency vibration information of silicon carbide sample A and silicon carbide sample B, and combine the theoretical Raman spectrum calculation results of silicon carbide wafers to obtain information on changes in intermolecular interactions and lattice vibrations after silicon carbide irradiation.

[0010] Preferably, in S2, the sample A and the sample B to be tested are placed on the stage, the excitation wavelength of the Raman spectroscopy system is 785 nm, the laser power is 90 mW, the integration time is 20 s, the accumulation times is 3 times, and the spectral resolution is adjusted by the slit and the grating.

[0011] Preferably, the slit is 100 μm and the grating is 1200 groove / mm.

[0012] Preferably, in S2, the acquisition times are 5 times, and the acquisition wave number range is 0-4000cm -1 .

[0013] Preferably, in S3, the preprocessing process is as follows: the Raman spectra of silicon carbide samples A and B are respectively subjected to cosmic ray removal processing, baseline removal processing and noise removal processing to obtain the scattering spectrum of silicon carbide sample A and the scattering spectrum of silicon carbide sample B.

[0014] Preferably, the baseline removal process uses a polynomial fitting method.

[0015] Preferably, the denoising process adopts the Saviztky-Golay method.

[0016] Preferably, in S4, the low-frequency vibration information includes characteristic peak position, characteristic peak intensity and characteristic peak shape.

[0017] The present invention also provides a method for characterizing silicon carbide radiation damage defects and its application in the chip field, aerospace field, and national defense field.

[0018] Therefore, the present invention adopts the above-mentioned method for characterizing radiation damage defects in silicon carbide and its application, and the beneficial effects are as follows:

[0019] (1) In view of the problem that the existing technology is insufficient in characterizing the information such as molecular interactions and lattice vibration after silicon carbide radiation damage, the present invention measures the Raman spectrum of silicon carbide wafers before and after radiation based on the Raman scattering spectrum that reflects the low-frequency vibration spectrum of matter. The Raman characteristics of silicon carbide wafers before and after radiation are characterized from a molecular perspective. By analyzing the changes in the position, intensity, and shape characteristics of the Raman characteristic peaks of silicon carbide lenses before and after radiation, the 0-4000cm -1 The information on the changes in the internal structure and molecular interactions of the crystal before and after radiation in the wavenumber range is much better than that of the traditional 500-2000cm -1 The Raman spectrum detection of different wavenumbers has realized the detection of radiation damage to silicon carbide in a wider wavenumber range; through theoretical calculation of the Raman spectrum of silicon carbide crystal, it is found that the Raman spectrum detection results of silicon carbide crystal are consistent with the theoretical calculation results. By analyzing the attribution and source of the Raman characteristic peaks, theoretical guidance is provided for clarifying the mechanism of the difference in Raman spectrum of silicon carbide before and after radiation and the characterization of the changes in lattice properties.

[0020] (2) The characterization method of the present invention has the advantages of being simple, non-destructive, and label-free. By setting the excitation wavelength of the Raman spectroscopy system to 785 nm, the influence of the fluorescence effect on the Raman scattering spectrum is effectively suppressed, while having high detection sensitivity and fast detection speed. By setting the laser power of the Raman spectroscopy system to 90 mW, it is ensured that there is no damage to the wafer, and rapid, non-destructive, and label-free detection of wafer damage characteristics is achieved. It has important application prospects in silicon carbide quality control and rapid detection, and provides an effective means for crystal radiation damage detection in the fields of chips, aerospace, and national defense. The technical solution of the present invention is further described in detail below through the accompanying drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention provides a method for characterizing radiation damage defects in silicon carbide and calculation results of theoretical Raman spectra of silicon carbide wafers according to an embodiment of the present invention;

[0022] Figure 2 is a scattering spectrum of a silicon carbide sample A in a method for characterizing radiation damage defects in silicon carbide and an application example of the present invention;

[0023] Figure 3 This is a scattering spectrum of a silicon carbide sample B in a method for characterizing radiation damage defects in silicon carbide and an application example of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0025] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0026] Example 1

[0027] A method for characterizing radiation damage defects in silicon carbide comprises the following steps:

[0028] S1. Preparation of irradiated samples: Take an unirradiated silicon carbide wafer as the sample A to be tested, and place the silicon carbide wafer in a proton irradiation device for irradiation to obtain the sample B to be tested.

[0029] The irradiation process of the proton irradiation device is as follows: the silicon carbide wafer is placed in the proton irradiation device and the wafer is irradiated with protons at room temperature. The proton irradiation energy is 17.8 MeV and the irradiation dose is 5×10 11 p / cm 2 .

[0030] S2. Raman spectrum acquisition: Place the sample A and the sample B to be tested directly on the stage, and use the Raman spectroscopy system to collect Raman spectra.

[0031] The process of Raman spectrum acquisition is as follows:

[0032] Samples A and B were placed on the stage, the excitation wavelength of the Raman spectroscopy system was 785 nm, and the measurement wavenumber range of the Raman spectrum was set to 0-4000 cm -1 , the laser power is 90 mW, the integration time is 20 s, the cumulative number of times is 3, the slit is 100 μm, and the number of measurements for both sample A and sample B is 5 times.

[0033] S3. Spectrum preprocessing: preprocessing the Raman spectra of the sample A and the sample B to be tested respectively to obtain the scattering spectrum of the silicon carbide sample A and the scattering spectrum of the silicon carbide sample B.

[0034] The preprocessing process is as follows:

[0035] The Raman spectra of the sample A and the sample B to be tested are processed by removing cosmic rays, removing baselines and removing noises in turn to obtain the scattering spectrum of the silicon carbide sample A, as shown in Figure 2 As shown, the scattering spectrum of silicon carbide sample B is obtained, as shown in Figure 3 shown.

[0036] The polynomial fitting method was used for baseline removal, and the Saviztky-Golay method was used for denoising.

[0037] The process of removing cosmic ray interference is as follows: by comparing the adjacent data points, the cosmic ray interference peak with high-frequency noise characteristics is detected, and the high-frequency noise is filtered out from the Raman spectrum by using a low-pass filtering method, thereby achieving the removal of cosmic ray interference.

[0038] The baseline removal process is as follows: a polynomial fitting is performed on the non-peak data in the Raman spectrum data after cosmic rays are removed, and the original spectrum data is corrected based on the fitting curve, thereby achieving Raman spectrum baseline removal.

[0039] The denoising process is as follows: the Saviztky-Golay method is used for denoising, and a moving window with local polynomial fitting is used to perform least squares fitting on the spectrum in the window to achieve smoothing filtering of the spectrum. During denoising, the filter window and fitting order are 31 and 3, respectively, thereby achieving denoising of Raman spectral data.

[0040] S4. Vibration information analysis: First, the theoretical Raman spectrum of the silicon carbide wafer is calculated. The calculation results are as follows: Figure 1 Then, perform low-frequency vibration information analysis:

[0041] By comparing the scattering spectra of silicon carbide sample A and silicon carbide sample B before and after radiation, and combining the theoretical Raman spectrum calculation results, the low-frequency vibration information of the silicon carbide samples before and after radiation is analyzed, as shown in Table 1.

[0042] Determination of spectral characteristic peaks: Figure 1 It can be seen that in 0-1000cm -1 Within the range, the theoretical Raman spectrum calculation results of silicon carbide wafers have a total of 5 Raman characteristic peaks, and the characteristic peak positions are: 199.0cm -1 、256.2cm -1 、601.5cm -1 、776.4cm -1 、964.2cm -1 .Depend on Figure 2 It can be seen that in 0-4000cm -1 Within the range, the unirradiated silicon carbide sample A has 7 Raman characteristic peaks, and the characteristic peak positions are: 202.8cm -1 、608.5cm -1 、776.2cm -1 、964.1cm -1 、2351.7cm -1 、2571.2cm -1 .Depend on Figure 3 It can be seen that in 0-4000cm -1 Within the range, the irradiated silicon carbide sample B has two Raman characteristic peaks, and the characteristic peak positions are: 1843.5cm-1 、2143.6cm -1 .

[0043] Table 1 Statistics of low-frequency vibration information results

[0044]

[0045] Table 1 shows the changes in intermolecular interactions and lattice vibrations of silicon carbide after irradiation: The Raman characteristic peaks calculated from the theoretical Raman spectrum of silicon carbide wafers are 199.0 cm -1 、256.2cm -1 、601.5cm -1 、776.4cm -1 、964.2cm -1 , of which 199.0cm -1 and 256.2cm -1 The Raman characteristic peak at 601.5 cm corresponds to the transverse acoustic phonon vibration E2(TA), -1 The Raman characteristic peak at 776.2 cm corresponds to the longitudinal acoustic phonon vibration A1 (LA). -1 The Raman characteristic peak corresponds to the transverse optical phonon vibration E2(TO), 964.2cm -1 The Raman characteristic peak corresponds to the longitudinal optical phonon vibration A1 (LO). Comparing the scattering spectrum test results of the unirradiated silicon carbide sample A with the theoretical Raman spectrum calculation results, it can be seen that the 202.8cm -1 、608.5cm -1 、776.2cm -1 、964.1cm -1 These four Raman characteristic peaks are basically consistent with the theoretical calculation results.

[0046] In addition, there are 2351.7cm -1 、2571.2cm -1 Two broad characteristic peaks. Comparing the scattering spectra of unirradiated silicon carbide sample A and irradiated silicon carbide sample B, we can see that 202.8cm -1 、608.5cm -1 、776.2cm -1 、964.1cm -1 These four Raman characteristic peaks disappear after radiation, while 2351.7cm -1 、2571.2cm -1 The two broader characteristic peaks changed to 1843.5 cm after irradiation. -1 、2143.6cm -1There are two relatively broad characteristic peaks, and the characteristic peak intensities are quite different, indicating that radiation causes significant damage to the internal lattice structure, lattice vibration mode, and crystal properties of the silicon carbide wafer. Raman spectroscopy can effectively characterize radiation damage defects in silicon carbide.

[0047] Therefore, the present invention adopts the above-mentioned method and application of characterizing silicon carbide radiation damage defects, which has the advantages of simplicity, non-destructiveness and no labeling, and has important application prospects in silicon carbide quality control and rapid detection, and provides an effective means for crystal radiation damage detection in the fields of chips, aerospace, national defense, etc.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for characterizing radiation damage defects in silicon carbide, characterized in that: The steps include: S1. Preparation of irradiated samples: taking an unirradiated silicon carbide wafer as the test sample A, placing the silicon carbide wafer in a proton irradiation device for irradiation to obtain the test sample B; S2, Raman spectrum acquisition: Place the sample A and sample B obtained in S1 on the stage respectively, and use the Raman spectroscopy system to acquire Raman spectra; S3. Spectral preprocessing: Preprocessing the Raman spectra of the sample A and the sample B to be tested respectively to obtain the scattering spectrum of the silicon carbide sample A and the scattering spectrum of the silicon carbide sample B; S4. Vibration information analysis: Compare the low-frequency vibration information of silicon carbide sample A and silicon carbide sample B, and combine the theoretical Raman spectrum calculation results of silicon carbide wafers to obtain information on changes in intermolecular interactions and lattice vibrations after silicon carbide irradiation.

2. The method for characterizing radiation damage defects in silicon carbide according to claim 1, characterized in that: In S2, the sample A and the sample B to be tested are placed on the stage. The excitation wavelength of the Raman spectroscopy system is 785 nm, the laser power is 90 mW, the integration time is 20 s, the accumulation times is 3 times, and the spectral resolution is adjusted by the slit and the grating.

3. The method for characterizing radiation damage defects in silicon carbide according to claim 2, wherein: The slit is 100 μm, and the grating is 1200 groove / mm.

4. The method for characterizing radiation damage defects in silicon carbide according to claim 1, wherein: In S2, the acquisition times are 5 times, and the acquisition wave number range is 0-4000cm -1 .

5. The method for characterizing radiation damage defects in silicon carbide according to claim 1, wherein: In S3, the preprocessing process is as follows: the Raman spectra of silicon carbide samples A and B are sequentially subjected to cosmic ray removal processing, baseline removal processing, and noise removal processing to obtain the scattering spectrum of silicon carbide sample A and the scattering spectrum of silicon carbide sample B.

6. The method for characterizing radiation damage defects in silicon carbide according to claim 5, characterized in that: The baseline removal process uses a polynomial fitting method.

7. The method for characterizing radiation damage defects in silicon carbide according to claim 5, characterized in that: The denoising process adopts the Saviztky-Golay method.

8. The method for characterizing radiation damage defects in silicon carbide according to claim 1, wherein: In S4, the low-frequency vibration information includes characteristic peak position, characteristic peak intensity and characteristic peak shape.

9. Application of the method for characterizing radiation damage defects in silicon carbide according to any one of claims 1 to 8 in the fields of chips, aerospace, and national defense.

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