What is High Purity Material?
Any element or compound contains a certain amount of impurities. When the total content of impurities in the substance is very low, the purity of the substance can be divided into three grades: pure, high purity and ultra high purity. High purity materials usually refer to elemental or compound materials with impurity content<10ppm (1ppm is one part per million). Driven by engineering fields such as semiconductor devices and advanced manufacturing, improving the purity of materials has become an important direction for the development of modern materials. The preparation methods of high purity materials include chemical purification preparation methods such as electrolytic refining, ion exchange, and solvent extraction, and physical purification preparation methods such as segregation purification, zone smelting, and electron beam refining. Each method has certain limits for the purification of specific impurity elements. Therefore, in the preparation process of high purity materials, several methods are often used together to make the materials reach the target purity. Electron beam refining is a metallurgical technique that uses a high-energy-density electron beam as a heat source to heat, melt, and maintain materials at a higher temperature for refining. In the process of electron beam refining, the melt is fully degassed, which is conducive to the removal of impurities and inclusions, and is one of the most effective methods for preparing high-purity materials. The improvement of high purity materials in chemical, electrical, optical, magnetic properties and mechanical properties makes high purity materials show inherent properties and is widely used in the fields of semiconductor, optics and electronics.
Figure 1. Appearance pictures of high purity materials
What are the Application of High Purity Materials?
- High Purity Materials as Electronic Materials: The semiconductor industry is the foundation of the electronic information industry. High purity quartz material is a key basic material in the semiconductor industry, mainly used in electronic substrates. High purity quartz material is also the raw material of quartz glass crucible, which can be used to prepare monocrystalline silicon and polycrystalline silicon, and is an indispensable material in the electronics industry and solar cell industry. In the above application fields, high purity quartz materials have high requirements on the content of impurities such as alkali metals and transition metals, which need to be less than 1ppm.
- High Purity Materials as Precious Metal Targets: Physical vapor deposition (PVD) is one of the key technologies for preparing thin film materials, and sputtering targets are a very important key consumable in the PVD process. Common sputtering targets are precious metal targets, such as gold, silver, platinum, ruthenium and other metals. As an important supporting material in the semiconductor process, precious metal targets are in increasing demand. Target purity, micro-resistance control, and overall target assembly quality determine the quality of semiconductor targets. Therefore, the application of high purity precious metal elemental materials can improve the processing technology of high purification, refinement and high efficiency of semiconductor materials.
- High Purity Materials as Optical Materials: The purity of luminescent materials affects properties such as light purity, luminous efficiency, and light transmittance. High purity luminescent materials have excellent monochromatic luminescence purity, high luminous efficiency and high laser damage threshold. High purity light-emitting materials are generally high purity compound materials. Such materials can be used in the field of optical devices as protective films for metal mirrors, low-refractive-index materials in photonic crystals, nano-ceramic films, and infrared optical materials.
- C.H.L. Goodman. The need for high purity materials [J]. J.Cryst. Growth, 1986, 75(1), 1-14.