Glasses for microelectronics
Development of Glasses and Compositions with Possible Low Content of High-Toxic Components for Microelectronics
Tech Area / Field
- ENV-EHS/Environmental Health and Safety/Environment
3 Approved without Funding
Institute of Electronic Materials, Armenia, Yerevan
- Technical University Hamburg-Hamburg / Institute of Polymer Composites, Germany, Hamburg\nUniversity of North Texas / Department of Materials Science, USA, TX, Denton\nIowa State University of Science and Technology / College of Engineering / Materials Science and Engineering Department, USA, IA, Ames\nCNRS / Université de Rennes 1, France, Rennes\nUniversita di Messina, Italy, Messina\nPennsylvania State University / Materials Research Institute, USA, PA, University Park
Project summaryNumerous - sometimes mutually incompatible - requirements are made to the glasses used in microelectronics. These glasses must be maximal fusible for the exclusion of thermal emission of electrons lowering the solidity of microscheme. At the same time they must have a rather high temperature of softening for the efficiency of microscheme in the temperatures up to 200 ºC. They mustn’t crystallize in the temperature of welding to provide high wettability of soldering materials; they must be thermally and chemically compatible with them, they must have high physical-chemical, mechanical, dielectric, definite technological and exploitation properties. Many of required properties are defined mainly by the composition and the technology of synthesis of glasses and glass bases corresponding to the composites. In large extent glass base predetermines the choice of crystal additives as well, intended for the improvement of one or another property of composites.
Glasses satisfying the requirements mentioned above are easier to synthesize on the base of lead-borate eutectic (85 mass % PbO, 15 B2O3) with small additives ZnO, Al2O3, SiO2, GeO2, SnO2, RO. However, multileaden glasses are dangerous for human health and surroundings. Earlier we and other researchers took attempts to develop glasses with analogous with lead-borate glass properties not containing PbO. It wasn’t a success to find a full substitution for the mentioned glasses. At present an investigation is lead on the synthesis of glasses not containing PbO and alkaline oxides to achieve glass-solder materials with minimal temperature of welding (TW) 440 ºC by the executors of our institute in the frames of the project of ISTC A-1591. However, this temperature is not save from the point of view of thermal emission of electrons, that’s why in this proposal synthesis of glasses and glass-composition materials with TW 350-420 ºC for the needs of microelectronics is offered.
Chalcogenide glasses are maximal fusible, the average transformational temperature (TM) of which is from minus 60 to plus 450 ºC depending on the composition. But TEC of these glasses is very high between 168-425·10-7K-1 their volatility is also high. At the same time they are highly toxic, so they won’t be included in the work program of the project. Rather fusible glasses are achieved also in the systems containing PbO, Bi2O3, P2O5, GeO2, ZnO, V2O5, Ce2O3, TeO2, Tl2O3, CdO, BaO, SrO, fluorides and so on. Unfortunately many of the mentioned compositions are not harmless. So, PbO, CdO, TeO2, Tl2O3 refer to the first class of danger, V2O5, ZnO, P2O5, BaO, SrO, Bi2O3 and fluorides refer to the second and GeO2, Ce2O3 and B2O3,to the third class of danger.
Accordingly, the main objective of this proposal is the development of glasses and glass-composition materials with minimal content of highly toxic components. (å PbO, CdO, TeO2, Tl2O3 £ 60 mass %) and totality of properties, satisfying the requirements of microelectronics on materials contacting directly with microschemes or intended for their hermetic sealing in ceramic or metallic bodies.
To get the main goal of the project the following work must be carried out.
- choice of most convenient fusible systems with minimal content of highly toxic components for melting of glasses satisfying the requirements of the project, melting and elaboration of glasses, definition of their temperature limit of transformation and crystallization by the method of DTA (TC, TM, Tf, TCrstart, TCrmax, TCrend, TK);
- dilatometric definition of TEC, TM and temperature of deformation (TD) of most convenient glasses choosed on DTA; the choice of optimal composition of glasses, definition of their flowability in different temperatures and TW on their base, degrees of crystallization and phasal composition of crystals at TW;
- according to totality of properties definition of most convenient compositions of glasses for various use in microelectronics (hermetic sealing of glass-ceramic and metallic bodies of IMS, electrical isolation of the last ones, interlayer isolation of multilayer IMS, formation of resistive, electrical conductive and dielectric elements of MS, protective coverings of hybrid IMS and so on); melting of experimental group of glasses, definition of their main properties;
- choice or synthesis of crystal additives, intended for correction of the definite properties of glasses, their disintegration and fractionating by the sizes of particles, hashing with glasses in different proportions; definition of properties of the developed composites; choice of optimal admission, concentration and sizes of particles of fillers to achieve glass crystalline composites of various use in microelectronics;
- synthesis of experimental groups of glass crystalline composites of optimal compositions and properties for different use, definition of their compatibility with known organic clusters, intended for preparation of pastes; development of new compositions of clusters in case of necessity; preparation of pastes or slurries with glasses or glass crystalline composites, their test on correspondence to the demands of standards for definite purpose;
- discharging of glasses with high physical-chemical, thermal-physical and dielectric properties, but with comparatively high TW to use in other fields of science and technics (electro- and vacuum technics, device or mechanical engineering and so on), definition of their main properties, choice of the best, preparation of experimental groups of glasses and composites, preparation of pastes, test on correspondence of the demands of standards for definite purpose.
As a result of the project will be achieved.
- glasses with possibly low content of highly toxic components, with TW 350-420 ºC and TEC 60-120·10-7K-1 for needs of microelectronics;
- new crystalline materials (according to need) with negative meaning of TEC and high mechanical and dielectric properties;
- consistency with the change of main properties of glass bases depending on the presence of different fillers in it, their concentration, sizes of particles, modes of synthesis and exploitations, composites of optimal structures and properties for microelectronics coming up to the functioning standards;
- laboratory technologies of synthesis corresponding to the glasses, crystal materials and glass composites of various assignments for determination of concrete practical tasks;
- glasses and glass cements with minimal content of highly toxic components with the TW 350-550 ºC and TEC (60-180)·10-7K-1, new composites and pastes on their basis for various use in electro- and vacuum technics, device- and mechanical engineering, etc.;
- experimental groups of developed glasses, glass composites and pastes of various assignments for test in interested enterprises.
We hope that the developed glasses and composites on their basis will be useful for the users of these materials. The consistency of the synthesis and the change of properties of glasses in fusible systems with minimal content of highly toxic components will interest the developers of materials like this as well. Besides glass composites possibly new crystalline materials with negative meaning of TEC, with high mechanichal and dielectric properties will be required for the synthesis of ceramic and thermal-shock resistant refractory composites as well.
Theoretical importance of the project is defined by the enrichment of the database of glasses, glass-ceramic, ceramic and composite materials, as well as crystalline materials with negative meaning TEC and pastes of various assignments.
The project completely corresponds to purposes and tasks of ISTC by its content and staff. The topic of the project is within scientific interests and facilities of Leading institute-executor. The manager, scientific leader and many potential executors of the project have an experience of many years of scientific work with glasses and composite materials intended, in particular, for hermetic sealing of microschemes and pressure seals, formation of refractory, protective and dielectric covers, resistive and electrical conductive pastes for use in microelectronics.
The tasks connected with the execution of the project, but out of the frames of specialization of its executors, in particular, development of new compositions of organic clusters for preparing paste, will be solved with the help of foreign collaborators. They will take part in the search of enterprises interested in the results of the project and new areas for the use of developed materials. The collaborators will also take part in the discussion of the results achieved in the frames of the project, in preparation of publication and their reports.
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.