February 11th, 2020
Fused quartz crucibles set the benchmark for performance in high-temperature applications where demanding process chemistries are a staple of the everyday working environment. The underlying materials and configurations of crucibles have varied significantly over time, which is perhaps a given considering they have been a central component of materials testing for millennia.
Early crucibles were derived from pottery and clay, lacking the key refractory properties that would become crucial as industrial processes became simultaneously more sophisticated and challenging. Silicon dioxide (SiO2) containers preceded fused quartz crucibles, establishing the benefits of silica-based materials in extremely harsh processing conditions – particularly with respect to extreme temperatures exceeding 1000°C (1832°F) and harsh chemical environments.
In this blog post, Saint-Gobain Quartz will briefly outline the development of fused quartz crucibles before exploring their primary applications in more depth.
Although materials, as varied as alumina (Al2O3), porcelain, mullite and zirconia (ZrO2), have been used to develop thermally-resistant and chemically-inert crucibles for high-temperature material processing applications, they are often unable to meet key processing requirements. This is particularly true when part of the processing objective is to avoid the diffusion of any contaminant in the high purity material placed within the crucible for melting or sintering.
The rich variety of available high-performance materials for crucibles enables the demands of process engineers in a range of application areas to be suitably satisfied. Quartz, for example, is the material of choice for industrial crystallization of silicon (Si) ingots via the Czochralski method – one of the chief applications for fused quartz crucibles.
Precious metals refining and special alloys manufacturing are among the oldest applications of quartz crucibles. These challenging markets require high-performance containers that can withstand without compromising the quality of the finished material. In some industries, bringing by diffusion impurities as low as 1 parts per million (ppm) could lead to the catastrophic rejection of products. Saint-Gobain Quartz has an unmatched understanding of these challenging chemistries, routinely designing tailormade components for optimum usage in terms of melting cycles and lifetimes in precious metals and special alloy markets. Crystal growth is potentially the most well-known application of fused quartz crucibles; an area that is constantly growing due to the increasing demand for high-purity electronic substrates extracted from synthetically-grown silicon billets.
Semiconductor grade silicon has an approximate melting point of 1425°C (2597°F), and this must be maintained throughout the Czochralski process as a seed crystal mounted on a rod is dipped into the molten mix and drawn up out of the crucible. Fused quartz crucibles are one of the only suitable components for the Czochralski method of growing single crystal silicon ingots, owing to their negligible expansion properties and superb resistance to thermal shock. Quartz crucibles also benefit from the additional characteristic of being non-conductive, with a nominal resistivity of 1 x 108 Ω.m at 1000°C.
At Saint-Gobain Quartz, we provide high purity fused quartz crucibles with a barium coating to meet the highest demands of the semiconductor industry. This proprietary coating is highly resistant to scratches which prevent potential issues during the loading step. It has an unlimited shelf-life and – unlike other barium coatings – does not hide any cosmetic defect in the inner surface of the crucible.
We provide quartz crucibles in standard and high purity formats and a variety of configurations to suit a range of application areas beyond crystal growing processes. These include:
Thanks to its long experience and flexible process, Saint-Gobain Quartz is able to design tailor-made solutions. A large variety of shapes are available that can be adapted to meet each customer’s needs. When most companies are focusing solely on mass products, Saint-Gobain’s Quartz Technical team is used to work on small or medium series, making sure they ultimately offer to their customer an optimum Cost of Ownership in their manufacturing processes.
Saint-Gobain Quartz develops and supplies high-performance containers for challenging areas of application. Our arc fused quartz crucibles are completely non-porous and are available in opaque and transparent grades, to suit the requirements of our customers.
See the full specification sheet for our industrial grade quartz crucibles here.