Key Raw Materials in Semiconductor Manufacturing: Types of Wafer Substrates
Wafer substrates serve as the physical carriers of semiconductor devices, with their material properties directly influencing device performance, cost, and application scope. Below are the primary types of wafer substrates and their respective advantages and disadvantages:
1. Silicon (Si)
Market Share: Dominates over 95% of the global semiconductor market.
Advantages:
- Low Cost: Abundant raw materials (silicon dioxide) and mature manufacturing processes enable significant economies of scale.
- High Process Compatibility: Highly mature CMOS technology supports nanoscale fabrication (e.g., 3nm nodes).
- Excellent Crystal Quality: Capable of producing large-sized (12-inch primary, 18-inch under development) low-defect single crystals.
- Stable Mechanical Properties: Easy to cut, polish, and process.
Disadvantages:
- Narrow Bandgap (1.12 eV): High leakage current at elevated temperatures, limiting efficiency in power devices.
- Indirect Bandgap: Extremely low light emission efficiency, unsuitable for optoelectronic devices (e.g., LEDs, lasers).
- Limited Electron Mobility: Inferior high-frequency performance compared to compound semiconductors.
ZMSH's silicon wafers
2. Gallium Arsenide (GaAs)
Applications: High-frequency RF devices (5G/6G), optoelectronic devices (lasers, solar cells).
Advantages:
- High Electron Mobility (5–6× that of silicon): Ideal for high-speed, high-frequency applications (mmWave communications).
- Direct Bandgap (1.42 eV): Efficient photoelectric conversion, forming the foundation of infrared lasers and LEDs.
- Thermal/Radiation Resistance: Suitable for aerospace and high-temperature environments.
Disadvantages:
- High Cost: Scarce material with complex crystal growth (prone to dislocations); wafer sizes are small (6-inch primary).
- Mechanical Brittleness: Prone to fragmentation, resulting in low processing yields.
- Toxicity: Strict control required for arsenic handling.
ZMSH's GaAs wafers
3. Silicon Carbide (SiC)
Applications: High-temperature/high-voltage power devices (EV inverters, charging piles), aerospace.
Advantages:
- Wide Bandgap (3.26 eV): Withstands high voltages (breakdown field strength 10× that of silicon) and operates at >200°C.
- High Thermal Conductivity (3× that of silicon): Efficient heat dissipation enhances system power density.
- Low Switching Losses: Improves power conversion efficiency.
Disadvantages:
- Challenging Substrate Preparation: Slow crystal growth (>1 week) and difficult defect control (microtubes, dislocations); costs 5–10× that of silicon.
- Small Wafer Sizes: Mainstream 4–6 inches; 8-inch development ongoing.
- Difficult Processing: High hardness (Mohs 9.5) makes cutting and polishing time-consuming.
ZMSH's SiC wafers
4. Gallium Nitride (GaN)
Applications: High-frequency power devices (fast chargers, 5G base stations), blue LEDs/lasers.
Advantages:
- Ultra-High Electron Mobility + Wide Bandgap (3.4 eV): Combines high-frequency (>100 GHz) and high-voltage characteristics.
- Low On-Resistance: Reduces device power consumption.
- Heterogeneous Epitaxy Compatibility: Often grown on silicon, sapphire, or SiC substrates to lower costs.
Disadvantages:
- Difficulty in Bulk Crystal Growth: Mainstream relies on heterogeneous epitaxy, with lattice mismatch-induced defects.
- High Cost: Self-supporting GaN substrates are expensive (2-inch wafers can cost thousands of dollars).
- Reliability Challenges: Current collapse effect requires optimization.
ZMSH's GaN wafers
5. Phosphorus-Indium (InP)
Applications: High-speed optoelectronics (lasers, detectors), terahertz devices.
Advantages:
- Ultra-High Electron Mobility: Supports >100 GHz high-frequency operation (superior to GaAs).
- Direct Bandgap with Wavelength Matching: Critical for 1.3–1.55μm fiber-optic communications.
Disadvantages:
- Brittleness and High Cost: Substrate prices are over 100× that of silicon; wafer sizes are small (4–6 inches).
ZMSH's InP wafers
6. Sapphire (Al₂O₃)
Applications: LED lighting (GaN epitaxial substrates), consumer electronics covers.
Advantages:
- Low Cost: Cheaper than SiC/GaN substrates.
- Chemical Stability: Corrosion-resistant and insulating.
- Transparency: Suitable for vertical-structure LEDs.
Disadvantages:
- Lattice Mismatch with GaN (>13%): Requires buffer layers to reduce epitaxial defects.
- Poor Thermal Conductivity (≈1/20 that of silicon): Limits performance in high-power LEDs.
ZMSH's sapphire wafers
7. Aluminum Oxide/Ceramic Substrates (e.g., AlN, BeO)
Applications: Heat dissipation substrates for high-power modules.
Advantages:
- Insulation + High Thermal Conductivity (AlN: 170–230 W/m·K): Ideal for high-density packaging.
Disadvantages:
- Non-Single-Crystal: Cannot directly grow devices; used solely as packaging substrates.
ZMSH's Alumina ceramic substrate
8. Specialized Substrates
- SOI (Silicon on Insulator):
- Structure: Silicon/silicon dioxide/silicon sandwich.
- Advantages: Reduces parasitic capacitance, radiation hardness, and leakage current (used in RF, MEMS).
- Disadvantages: 30–50% higher cost than bulk silicon.
- Quartz (SiO₂): Used in photomasks, MEMS; heat-resistant but brittle.
- Diamond: Highest thermal conductivity (>2000 W/m·K) under development for extreme heat dissipation.
ZMSH's SOI wafer,Quartz wafer,Diamond substrate
Summary Comparison Table
| Substrate |
Bandgap Energy (eV) |
Electron Mobility (cm²/Vs) |
Thermal Conductivity (W/mK) |
Mainstream Size |
Core Applications |
Cost |
| Si |
1.12 |
1,500 |
150 |
12-inch |
Logic/Storage Chips |
Lowest |
| GaAs |
1.42 |
8,500 |
55 |
4-6-inch |
RF/Opto-electronic Devices |
High |
| SiC |
3.26 |
900 |
490 |
6-inch (R&D 8-inch) |
Power Devices/Electric Vehicles |
Extremely High |
| GaN |
3.4 |
2,000 |
130-170 |
4-6-inch (Heteroepitaxy) |
Fast Charging/RF/LED |
High (Heteroepitaxy, etc.) |
| InP |
1.35 |
5,400 |
70 |
4-6-inch |
Optical Communications/Terahertz |
Extremely High |
| Sapphire |
9.9 (Insulator) |
- |
40 |
4-8-inch |
LED Substrate |
Low |
Key Factors for Selection
- Performance Requirements: High-frequency applications favor GaAs/InP; high-voltage/high-temperature applications require SiC; optoelectronics prefer GaAs/InP/GaN.
- Cost Constraints: Consumer electronics prioritize silicon; high-end fields accept premium pricing for SiC/GaN.
- Integration Complexity: Silicon CMOS compatibility remains unrivaled.
- Thermal Management: High-power devices prioritize SiC or diamond-based GaN.
- Supply Chain Maturity: Silicon > Sapphire > GaAs > SiC > GaN > InP.
Future Trends
Heterogeneous integration (e.g., GaN on silicon, SiC on GaN) will balance performance and cost, driving advancements in 5G, electric vehicles, and quantum computing.
ZMSH's Services
As an integrated manufacturing and trading semiconductor materials comprehensive service provider, we deliver full-chain product supply chain solutions—from wafer substrates (Si/GaAs/SiC/GaN, etc.) to photoresists and CMP polishing materials. Leveraging self-developed production bases and a globalized supply chain network, we combine rapid response capabilities with professional technical support to empower clients in achieving stable supply chain operations and technological innovation win-win outcomes.
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