I. The Materials Science Foundation of Silicon Carbide Chips

A. The Basic Physical and Chemical Properties of Silicon Carbide

Silicon carbide (SiC), as the core material of the third-generation semiconductors, holds revolutionary significance in the electronics industry due to its unique material properties.

1. Wide bandgap width (3.26 eV) and the resulting high breakdown electric field capability
Silicon carbide boasts a much wider band gap—far exceeding the 1.12 eV of conventional silicon (Si). This exceptional property endows SiC with an extraordinarily high breakdown electric field strength, reaching up to 3.0 MV/cm, making it particularly well-suited for high-voltage and high-power applications. For instance, SiC power devices can withstand significantly higher electric fields while simultaneously minimizing power losses, which makes them an ideal choice for advanced high-voltage electrical systems.

2. High thermal conductivity and electron saturation velocity
SiC's thermal conductivity (4.9 W/cm·K) is significantly higher than silicon's (1.5 W/cm·K), effectively reducing heat buildup in power devices and thereby enhancing reliability. Moreover, SiC boasts an electron saturation drift velocity as high as 2 × 10⁷ cm/s—twice that of silicon—making it exceptionally well-suited for high-frequency applications.

3. Chemical Inertness and Radiation Resistance
Silicon carbide boasts exceptional chemical stability, maintaining consistent performance even in high-temperature or highly corrosive environments. At the same time, its strong radiation resistance makes it an indispensable material for extreme settings such as aerospace and high-energy physics applications.

B. The Technical Significance of Different Crystalline Forms
The polymorphic diversity of silicon carbide (such as 4H-SiC and 6H-SiC) profoundly influences its properties and application scenarios.

Main application scenarios and comparison of advantages and disadvantages between 4H-SiC and 6H-SiC

• 4H-SiC It is currently the preferred crystal type in the power device field, as its high electron mobility and isotropic properties enable devices such as MOSFETs and diodes to deliver superior performance.

• 6H-SiC Although it exhibits excellent thermal conductivity, its electron mobility is lower than that of 4H-SiC, which limits its application in high-performance power devices—instead, it finds greater use in the optical field.

The Correlation Between Defects and Properties in Silicon Carbide Crystals
The performance of silicon carbide crystals is closely tied to the defect density within them—defects such as screw dislocations and step defects, for instance, can degrade a device's breakdown voltage and reliability. Consequently, reducing crystal defect density has become a central technical challenge in the preparation of silicon carbide materials.

C. Comparison with Other Materials

1. Key Performance Differences from Traditional Silicon (Si)
Compared to silicon, SiC significantly outperforms it in terms of electric field breakdown strength, thermal conductivity, and saturated electron velocity. For instance, SiC devices of the same power rating can be as small as 1/10 the size of their silicon counterparts, dramatically reducing system size and weight.

2. The Complementary and Competitive Relationship with Gallium Nitride (GaN)
Silicon carbide and gallium nitride are the two mainstream materials of the third-generation semiconductors. Silicon carbide excels in high-voltage and high-power applications, while gallium nitride performs better in high-frequency and medium-to-low-power scenarios. The two materials exhibit a complementary relationship in fields such as power electronics and communications, yet they also compete in certain application areas.

II. Key Technologies for Silicon Carbide Chips

A. Material Preparation Technology
The growth and processing of silicon carbide single crystals directly determine the performance and yield of devices.

Silicon Carbide Single-Crystal Growth Technology

• Sublimation Method (PVT) : Silicon carbide powder is converted into a gaseous phase via high-temperature sublimation, and then single crystals are grown on seed crystals. This method is highly mature, but it tends to result in high dislocation densities.

• Chemical Vapor Deposition (CVD) : SiC thin films are generated via gas-phase reactions, making them suitable for epitaxial growth and offering superior surface quality.

Technical challenges in wafer size and quality
Silicon carbide wafers have gradually expanded in size from 4 inches to 6 inches and then to 8 inches, but the larger the wafer, the more challenging it becomes to control defects. Moreover, the high manufacturing costs of large-size wafers remain a significant bottleneck hindering industrialization.

B. Device Manufacturing Process

Power Device Design

• SiC MOSFET Compared to silicon MOSFETs, SiC MOSFETs exhibit lower switching losses at high voltages, but their gate oxide layer quality still requires further improvement.

• Schottky Diode (SBD) : SiC SBDs, with their lower forward voltage drop and shorter reverse recovery time, are critical components in photovoltaic inverters and electric vehicle chargers.

Surface Treatment and Packaging
Surface polishing, etching, and packaging processes are critical to the performance of silicon carbide devices. Enhancing the package's thermal management capabilities and the device's mechanical strength are key technologies for extending its service life.

C. Technological Bottlenecks and Innovation

1. Technical Challenges in Defect Density Control
Currently, the main technical challenge for silicon carbide materials is reducing the density of dislocation and step defects. Adopting new epitaxial growth techniques and optimizing crystal growth conditions are key approaches to addressing this issue.

2. The Brittleness Issue in Wafer Processing
The brittleness of SiC crystals makes them prone to cracking and damage during processing. However, new cutting and polishing technologies, combined with an optimized stress-control process, hold promise for minimizing these issues.

III. Core Application Areas of Silicon Carbide Chips

A. New Energy Vehicles
The core requirement for new-energy vehicles is a highly efficient, low-loss electric control system, and silicon carbide chips play a critical role in the following areas:

• Improve inverter efficiency to make the electric motor more efficient;

• Increase the power density of fast-charging stations to shorten charging times;

• Reduce energy loss and extend the driving range of electric vehicles.

B. Energy Industry

1. Photovoltaic Power Inverter
Silicon carbide power devices significantly enhance the conversion efficiency of photovoltaic inverters thanks to their high efficiency and low switching losses.

2. Wind Power Generation System
In wind power systems, silicon carbide chips excel in DC transmission and inverters due to their high-voltage capability and high power density.

C. High-Voltage Power Transmission

1. High-Voltage Direct Current Transmission (HVDC)
SiC devices can effectively reduce energy loss while withstanding higher voltages, making them a crucial support for the future of power transmission.

2. Rail Transit and Industrial Power Sources
Silicon carbide devices are widely used in traction converters for rail transportation and in high-power power converters for industrial applications.

D. Communications and Other High-Tech Fields

1. 5G Communication Base Station
Silicon carbide power devices in 5G base stations meet the stringent energy-efficiency demands of communication equipment, thanks to their high-frequency and low-loss characteristics.

2. Aerospace
In the aerospace field, SiC chips are widely used in satellites and radar systems due to their high-temperature resistance and radiation tolerance.