Calcium and Barium Fluoride Crystals for Microelectronics
Vapor Phase Growth of CaF2 and BaF2 Single Crystals
Tech Area / Field
- MAT-SYN/Materials Synthesis and Processing/Materials
8 Project completed
Senior Project Manager
Vavilov State Optical Institute (GOI) / Research and Technological Institute of Optical Materials, Russia, St Petersburg
- VNIIKhT (Chemical Technology), Russia, Moscow
- JENOPTIK, Germany, Jena\nCrystagon, Inc., USA, OH, Beachwood\nInstitut de Chimie de la Matière Condensée de Bordeaux, France, Pessac\nVITCON Projectconsult GmbH, Germany, Jena\nMaicom Quarz GmbH, Germany, Jena
Project summaryAt the present moment method of crystallization from melt is used to get single crystals of CaF2 and BaF2. Manufacture process of single crystals consists of two stages:
– Purification of the needed raw material from oxygencontaining impurities.
– Crystallization of melt of CaF2 or BaF2.
In the process a highly purified raw material is used – impurity content of alkaline and earth elements is not supposed to exceed 0.5 ppm.
The process of purification of the starting raw material from oxides takes substantial expenses as complicated equipment and expensive and highly toxic chemical reagents are used.
1. Considering variety of Ca and Ba raw materials, it is planned to analyze and technologically test them in order to select the optimum initial materials. The most difficult and expensive process of the present manufacture methods of high-pure fluorides of alkaline-earth metals is redistribution of provisional selective pision and removal of oxides from end-products. It is planned to research and develop more efficient pision methods of alkaline-earth metals during the hydrometallurgic manufacture stage of pure salts and oxygen removal during fluorination.
2. There are methods of deposition of single crystal fluoride films from vapor phase that are used for AR-coating of optical elements. There is a way to get MgF2 single crystals from vapor phase. In this work it is supposed to develop production methods of CaF2 and BaF2 single crystals using process of evaporation and subsequent condensation of vapors of metallic fluorides on substrate. This method allows performing purification from the most impurities in the process of single crystal growth.
The following aspects are planned to be researched in the project:
– analysis of the homegrown raw material and selection of the optimal one.
– development of the technical scheme of production of Ca and Ba salts of the needed purification.
– decrease of oxygen content in fluorides.
– manufacture method of highly pure CaF2 and BaF2 -raw material.
– kinetics of CaF2 and BaF2 deposition.
– process of afterpurification of CaF2 and BaF2 from oxigencontaining impurities during vapor phase growth.
– influence of technical parameters on properties of single crystals grown from vapor phase.
– optical and mechanical properties of single crystals of CaF2 and BaF2.
On the basis of the received data high-performance economical low-waste technology of highly pure CaF2 and BaF2 production would be developed which would allow to produce fluorides with the content of metals and oxygen of 1ppm.
The main basis of technology of single crystals of CaF2 and BaF2 growth would be developed.
It is expected that this method would allow producing single crystals of CaF2 and BaF2 highly purified from the most impurities in the process of growth.
At the end of the project equipment allowing to get the mentioned materials would be developed and demonstrated.
The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.
ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.