Ⅰ. What is Quartz?
Quartz is a crystalline form of silicon dioxide (SiO₂), a naturally occurring mineral. It is known for its:
- High purity
- High melting point (~1,650°C)
- Low thermal expansion
- Excellent chemical resistance
- Electrical insulation
These characteristics make quartz an ideal material for manufacturing semiconductor-grade components, especially in high-temperature and high-purity environments.
Ⅱ. Quartz in the Semiconductor Industry
Although quartz is not used as the active material in chips (like doped silicon is), it is essential in various critical applications throughout the semiconductor manufacturing process:
1. Quartz Wafer Carriers & Boats
- Used during oxidation, diffusion, and annealing processes.
- Must withstand temperatures above 1,000°C and remain chemically stable.
- Designed to prevent contamination and ensure uniform heating of silicon wafers.
2. Quartz Tubes & Reaction Chambers
- Utilized in furnace systems where silicon wafers are processed in a controlled atmosphere.
- High-purity fused quartz avoids any outgassing or contamination that could affect wafer yield.
3. Quartz Crucibles
- In Czochralski (CZ) crystal pulling, quartz crucibles hold molten silicon as single-crystal silicon ingots are formed.
- These crucibles must have minimal impurity content (99.995% purity or higher) to avoid affecting semiconductor-grade silicon.
4. Quartz Etching and Cleaning Tanks
- Used in wet chemical processes (such as HF, HCl, or H₂SO₄ cleaning) due to quartz’s excellent acid resistance.
- Ensures stability and cleanliness in batch cleaning operations.
Ⅲ. Properties that Make Quartz Ideal for Semiconductor Use
|
Property |
Value/Advantage |
|
Chemical Formula |
SiO₂ |
|
Purity (for semiconductor) |
≥ 99.995% (often ≥ 5N grade) |
|
Melting Point |
~1,650°C |
|
Thermal Expansion |
Very low (~0.55 × 10⁻⁶ /°C) |
|
Dielectric Constant |
~3.8 (at 1 MHz) |
|
Electrical Conductivity |
Extremely low，excellent electrical insulator |
|
UV Transparency |
High, especially in synthetic quartz |
Ⅳ. Is Quartz a Semiconductor?
No, quartz is not a semiconductor in the conventional sense. It is an electrical insulator. However, in the semiconductor manufacturing industry, it is often referred to as a “semiconductor-grade quartz” because of its use in fabricating semiconductor devices. This can sometimes lead to confusion.
Ⅴ. Quartz vs. Silicon in Semiconductors
|
Aspect |
Quartz (SiO₂) |
Silicon (Si) |
|
Function |
Support and process material |
Active semiconductor material |
|
Electrical Role |
Insulator |
Semiconductor (can conduct when doped) |
|
Use Cases |
Furnaces, crucibles, cleaning systems |
Microchips, transistors, integrated circuits |
|
Crystal Structure |
Trigonal (hexagonal) |
Diamond cubic |
Ⅵ. Common Applications of Quartz in Semiconductor Fabrication
- Oxidation furnace tubes
- Diffusion and LPCVD wafer boats
- Single-crystal growth crucibles
- Cleaning equipment tanks
- Plasma etching windows
- Photomask substrates in photolithography
Ⅶ. Frequently Asked Questions (FAQs)
1) Is quartz used in making microchips?
A: Not directly. Quartz is used to support the process, not as the active material in chips.
2) What’s the purity level of quartz used in semiconductors?
A: Typically 99.995% (5N) or higher.
3) Why is quartz used in high-temperature semiconductor processing?
A: Because it can withstand temperatures above 1,000°C and has low thermal expansion, ensuring dimensional stability and chemical resistance.
Post time: Apr-17-2025