Material der Siliziumkarbid -Epitaxie

Silicon carbide, with the chemical formula SiC, is a compound semiconductor material formed by strong covalent bonds between silicon (Si) and carbon (C) elements. With its excellent physical and chemical properties, it plays an increasingly important role in many industrial fields, especially in the demanding semiconductor manufacturing process.

Ⅰ. Core physical properties of silicon carbide (SiC)

Understanding the physical properties of SiC is the basis for understanding its application value:

1) High hardness:

The Mohs hardness of SiC is about 9-9.5, second only to diamond. This means that it has excellent wear and scratch resistance.

Application value: In semiconductor processing, this means that parts made of SiC (such as robotic arms, chucks, grinding discs) have a longer life, reduce particle generation caused by wear, and thus improve the cleanliness and stability of the process.

2) Excellent Thermal Properties:

● High Thermal Conductivity: 

The thermal conductivity of SiC is much higher than that of traditional silicon materials and many metals (up to 300−490W/(m⋅K) at room temperature, depending on its crystal form and purity).

Application Value: It can dissipate heat quickly and efficiently. This is critical for the heat dissipation of high-power semiconductor devices, which can prevent the device from overheating and failure, and improve the reliability and performance of the device. In process equipment, such as heaters or cooling plates, high thermal conductivity ensures temperature uniformity and fast response.

● Low Thermal Expansion Coefficient: SiC has little dimensional change over a wide temperature range.

Application Value: In semiconductor processes that experience drastic temperature changes (such as rapid thermal annealing), SiC parts can maintain their shape and dimensional accuracy, reduce stress and deformation caused by thermal mismatch, and ensure processing accuracy and device yield.

● Excellent Thermal Stability: SiC can maintain its structure and performance stability at high temperatures, and can withstand temperatures up to 1600 ∘C or even higher in an inert atmosphere.

Application Value: Suitable for high-temperature process environments such as epitaxial growth, oxidation, diffusion, etc., and is not easy to decompose or react with other substances.

● Good Thermal Shock Resistance: Able to withstand rapid temperature changes without cracking or damage.

Application Value: SiC components are more durable in process steps that require rapid temperature rise and fall.

3）Superior Electrical Properties (especially for semiconductor devices):

● Wide Bandgap: The bandgap of SiC is about three times that of silicon (Si) (for example, 4H-SiC is about 3.26eV and Si is about 1.12eV).

Application value:

High operating temperature: The wide bandgap makes the intrinsic carrier concentration of SiC devices still very low at high temperatures, so it can operate at temperatures much higher than silicon devices (up to 300∘C or more).

High Breakdown Electric Field: The breakdown electric field strength of SiC is nearly 10 times that of silicon. This means that at the same voltage resistance level, SiC devices can be made thinner and the drift region resistance is smaller, thereby reducing conduction losses.

Strong radiation resistance: The wide bandgap also makes it have better radiation resistance and is suitable for special environments such as aerospace.

● High Saturation Electron Drift Velocity: The saturation electron drift velocity of SiC is twice that of silicon.

Application value: This enables SiC devices to operate at higher switching frequencies, which is beneficial to reducing the volume and weight of passive components such as inductors and capacitors in the system and improving the system power density.

4）Excellent Chemical Stability:

SiC has strong corrosion resistance and does not react with most acids, bases or molten salts at room temperature. It reacts with certain strong oxidants or molten bases only at high temperatures.

Application Value: In processes involving corrosive chemicals such as semiconductor wet etching and cleaning, SiC components (such as boats, pipes, and nozzles) have longer service life and lower risk of contamination. In dry processes such as plasma etching, its tolerance to plasma is also better than many traditional materials.

5）High Purity (High Purity achievable):

High-purity SiC materials can be prepared by methods such as chemical vapor deposition (CVD).

User Value: In semiconductor manufacturing, material purity is critical, and any impurities may affect device performance and yield. High-purity SiC components minimize contamination of silicon wafers or process environments.

Ⅱ. Application of Silicon Carbide (SiC) as Epitaxial Substrate

SiC single crystal wafers are key substrate materials for manufacturing high-performance SiC power devices (such as MOSFETs, JFETs, SBDs) and gallium nitride (GaN) RF/power devices.

Specific application scenarios and uses:

1) SiC-on-SiC epitaxy:

Use: On a high-purity SiC single crystal substrate, a SiC epitaxial layer with specific doping and thickness is grown by chemical vapor epitaxy (CVD) to construct the active area of SiC power devices.

Application value: The excellent thermal conductivity of the SiC substrate helps the device to dissipate heat, and the wide bandgap characteristics enable the device to withstand high voltage, high temperature and high frequency operation. This makes SiC power devices perform well in new energy vehicles (electric control, charging piles), photovoltaic inverters, industrial motor drives, smart grids and other fields, significantly improving system efficiency and reducing equipment size and weight.

2) GaN-on-SiC epitaxy:

Use: SiC substrates are ideal for growing high-quality GaN epitaxial layers (especially for high-frequency, high-power RF devices such as HEMTs) due to their good lattice matching with GaN (compared to sapphire and silicon) and extremely high thermal conductivity.

Application value: SiC substrates can effectively conduct a large amount of heat generated by GaN devices during operation to ensure the reliability and performance of the devices. This makes GaN-on-SiC devices have irreplaceable advantages in 5G communication base stations, radar systems, electronic countermeasures and other fields.

Ⅲ. Application of silicon carbide (SiC) as coating

SiC coatings are usually deposited on the surface of substrates such as graphite, ceramics or metals by CVD method to give the substrate SiC excellent properties.

Specific application scenarios and uses:

1) Plasma Etching Equipment Components:

Examples of components: Showerheads, Chamber Liners, ESC surfaces, Focus Rings, Etch Windows.

Uses: In a plasma environment, these components are bombarded by high-energy ions and corrosive gases. SiC coatings protect these critical components from damage with their high hardness, high chemical stability, and resistance to plasma erosion.

Application value: Extend component life, reduce particles generated by component erosion, improve process stability and repeatability, reduce maintenance costs and downtime, and ensure the cleanliness of wafer processing.

2) Epitaxial Growth Equipment Components:

Examples of components: Susceptors/Wafer Carriers, heater elements.

Uses: In high-temperature, high-purity epitaxial growth environments, SiC coatings (usually high-purity SiC) can provide excellent high-temperature stability and chemical inertness to prevent reaction with process gases or release of impurities.

Application value: Ensure the quality and purity of the epitaxial layer, improve temperature uniformity and control accuracy.

3) Other process equipment components:

Component examples: Graphite disks of MOCVD equipment, SiC coated boats (Boats for diffusion/oxidation).

Uses: Provide corrosion-resistant, high-temperature-resistant, high-purity surfaces.

Application value: Improve process reliability and component life.

Ⅳ. Application of silicon carbide (SiC) as other specific product components (Other Specific Product Components)

In addition to being a substrate and coating, SiC itself is also directly processed into various precision components due to its excellent comprehensive performance.

Specific application scenarios and uses:

1) Wafer Handling and Transfer Components:

Examples of components: Robot End Effectors, Vacuum Chucks, Edge Grips, Lift Pins.

Use: These components require high rigidity, high wear resistance, low thermal expansion and high purity to ensure that no particles are generated, no wafer scratches, and no deformation due to temperature changes when transporting wafers at high speed and high precision.

Application value: Improve the reliability and cleanliness of wafer transmission, reduce wafer damage, and ensure the stable operation of automated production lines.

2) High-Temperature Process Equipment Structural Parts:

Examples of components: Furnace Tubes for diffusion/oxidation, Boats/Cantilevers, Thermocouple Protection Tubes, Nozzles.

Application: Utilize SiC's high temperature strength, thermal shock resistance, chemical inertness and low pollution characteristics.

Application value: Provide a stable process environment in high temperature oxidation, diffusion, annealing and other processes, extend equipment life and reduce maintenance.

3) Precision Ceramic Components:

Component examples: Bearings, seals, guides, lapping plates.

Application: Utilize SiC's high hardness, wear resistance, corrosion resistance and dimensional stability.

Application value: Excellent performance in some mechanical components that require high precision, long life and resistance to harsh environments, such as some components used in CMP (chemical mechanical polishing) equipment.

4) Optical Components:

Component examples: Mirrors for UV/X-ray optics, optical windows.

Uses: SiC's high rigidity, low thermal expansion, high thermal conductivity and polishability make it an ideal material for manufacturing large-scale, high-stability mirrors (especially in space telescopes or synchrotron radiation sources).

Application value: Provides excellent optical performance and dimensional stability under extreme conditions.