SiC dislocation detection method

SiC dislocation detection method

In order to grow high-quality SiC crystals, it is necessary to determine the dislocation density and distribution of seed crystals to screen out high-quality seed crystals. In addition, studying the changes of dislocations during the crystal growth process is also conducive to the optimization of the growth process. Mastering the dislocation density and distribution of the substrate is also very important for the study of defects in the epitaxial layer. Therefore, it is necessary to characterize and analyze the crystallization quality and defects of SiC crystals through reasonable techniques to accelerate the production and preparation of high-quality and large-sized SiC. The detection methods for SiC defects can be classified into destructive methods and non-destructive methods. Destructive methods include wet etching and transmission electron microscopy (TEM). Non-destructive methods include non-destructive characterization by cathodic fluorescence (CL), X-ray profiling (XRT) technology, photoluminescence (PL), photostress technology, Raman spectroscopy, etc.

Wet corrosion is the most common method for studying dislocations. Due to the need to carry out corrosion in high-temperature molten alkali, this method is highly destructive. When the corroded SiC wafers are observed under a microscope, corrosion pits of different shapes and sizes can be seen. Generally, there are three shapes of corrosion pits on the Si surface: nearly circular, hexagonal, and shell-shaped. Corresponding to TEDs, TSDs and BPDs defects respectively, Figure 1 shows the morphology of the corrosion pit. With the development of detection equipment, the lattice distortion detector, laser confocal microscope, dislocation detector and other devices developed can comprehensively and intuitively detect the dislocation density and distribution of the corrosion plate. Transmission electron microscopy can observe the subsurface structure of samples at the nanoscale and also detect crystal defects such as BPDs, TEDs and SFs in SiC. As shown in Figure 2, it is a TEM image of dislocations at the interface between seed crystals and growing crystals. CL and PL can non-destructively detect defects on the subsurface of crystals, as shown in Figures 3 and 4. However, compared with PL, CL has a wider measurable band range, and wide bandgap semiconductor materials can be effectively excited.

Fig. 2 TEM of dislocations at the interface between seed crystals and growing crystals under different diffraction vectors

Fig. 3 The principle of dislocations in CL images

X-ray topography is a powerful non-destructive technique that can characterize crystal defects through the width of diffraction peaks. synchrotron monochromatic beam X-ray topography (SMBXT) uses highly perfect reference crystal reflection to obtain monochromatic X-rays, and a series of topography maps are taken at different parts of the reflection curve of the sample. Different regions show different diffraction intensities, thus enabling the measurement of lattice parameters and lattice orientations in different regions. The imaging results of dislocations play an important role in studying the formation of dislocations. As shown in Figure 5(b) and (c), they are the X-ray topography diagrams of dislocations. Optical stress technology can be used for non-destructive testing of the distribution of defects in wafers. Figure 6 shows the characterization of SiC single crystal substrates by optical stress technology. Raman spectroscopy is also a non-destructive subsurface detection method. Feng et al. discovered by Raman scattering method that the sensitive peak positions of MP, TSDs and TEDs are at ~796cm-1, as shown in Figure 7.

Fig. 7 Detection of dislocation by PL method.

(a) The PL spectra measured by TSD, TMD, TED and dislocation-free regions of 4H-SiC;

(b),(c),(d) Optical microscope images of TED, TSD, and TMD and PL intensity mapping maps;

(e) PL image of BPDs

ZMSH offers ultra-large-sized monocrystalline silicon and columnar polycrystalline silicon, and can also customize the processing of various types of silicon components, silicon ingots, silicon rods, silicon rings, silicon focusing rings, silicon cylinders, and silicon exhaust rings.

As a global leader in silicon carbide materials, ZMSH provides a comprehensive portfolio of high-quality SiC products, including 4H/6H-N type, 4H/6H-SEMI insulating type, and 3C-SiC polytypes, with wafer sizes ranging from 2 to 12 inches and customizable voltage ratings from 650V to 3300V. Leveraging proprietary crystal growth technology and precision processing techniques, we have achieved stable mass production with ultra-low defect density (<100/cm²) and nanoscale surface roughness (Ra <0.2nm), maintaining a monthly production capacity of 10,000 wafers. ZMSH offers end-to-end solutions spanning substrates, epitaxy, and device processing, serving over 50 global clients across new energy vehicles, 5G communications, and industrial power applications. Moving forward, we will continue to invest in large-diameter SiC R&D to drive wide-bandgap semiconductor industry advancement and support carbon neutrality goals.

The following is the SiC substrate 4H-N,SEMI,3C-N type and SiC seed wafer of ZMSH:

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