High-purity quartz sand is primarily composed of SiO2. It is a fundamental raw material in advanced industries such as photovoltaics, semiconductors, telecommunications, and aerospace. We will explore its various categories, purity levels, and crucial applications. With a special focus on its role in the production of quartz crucibles, its role will be introduced.
1. Categories and Purity Levels of Quartz Sand
| Category | Purity (SiO2 level) | Main Application |
| Common High-Purity Quartz Sand | ≥99.9~99.99% (3N~4N) | Everyday optical glass, optical devices, and electro-optical sources. |
| High-Purity Quartz Sand | ≥99.99 (4N) | Photovoltaic-grade tubes/rods/plates and high-end optical/laser devices |
| ≥99.998 (4N8) | Semiconductor-grade tubes/rods, photovoltaic crucibles, and optical fiber preforms | |
| ≥99.9992% (5N2) | Semiconductor-grade crucibles with inner coating | |
| Synthetic Ultra High Purity Quartz Sand | ≥99.9999% (6N) | Semiconductor-grade crucibles and inner coatings |
2. Important Application —Quartz crucible for the direct pulling of monocrystalline silicon
Quartz crucibles play a pivotal role in the Czochralski (CZ) and Float Zone (FZ) methods of growing silicon single crystals. The crucial aspects of a quartz crucible include:
Bubble Layer: Contains numerous bubbles. So heating evenly to ensure thermal insulation effect.
Transparent Layer: Uniformly dense, smooth surface, and extremely low bubble density. So we need to enhance crucible strength and lower inner surface temperature.
3. Market Demand
Photovoltaic Single Crystal Silicon Industry Requirements for Quartz Crucibles
| Development Direction of Monocrystalline Silicon | Macroscopic Performance Requirements for Crucibles | Specific Performance Requirements for Crucibles |
1. Significantly increase the amount of feedstock and pull multiple single crystal silicon rods RCZ recycling/CCZ continuous feeding | Large size, | Meeting the requirements for crystal pulling, especially in terms of various performance aspects (particularly the transparent layer) |
| Long lifetime (＞400h) | Low bubble content in the transparent layer | |
| Bubble resistance in the transparent and intermediate layers | ||
| High strength | High viscosity of the crucible at the crystal growth temperature | |
| 2. Improved full-length yield and crystallization rate | High stability in the inner layer structure | Low bubble content in the transparent layer |
| 3. High-Quality Crystal Rods (High Carrier Lifetime, Low Oxygen Concentration) | High purity | Low impurity content in the transparent layer |
| 4. Low Non-Silicon Cost | Low cost | Low-cost quartz sand, low processing costs |
The following table shows the expected demand for quartz crucibles in the next few years. As can be seen from the table, silicon wafers are developing towards larger sizes.
Elevated purity requirements drive the need for advanced processing of high-purity quartz sand.
Demand increases for larger, higher-quality silicon single crystals. The importance of high-purity quartz sand becomes even more prominent. The quality of quartz crucibles determines whether they meet the stringent requirements of the photovoltaic and semiconductor industries. This makes high-purity quartz sand a cornerstone material for the unremitting pursuit of technological progress.
We also have an article introducing the high-quality quartz sand production process and industry barriers, can check it out here.
This dynamic interplay between material properties and industrial needs. It highlights its key role in the evolving field of advanced technology.
