Power Semiconductor Devices
Development of New Methods of Radiation-Thermal Processing in Production of Power Semiconductor Devices for Energy Saving Applications
Tech Area / Field
- PHY-SSP/Solid State Physics/Physics
3 Approved without Funding
Scientific-Practical Materials Research Centre NAS of Belarus, Belarus, Minsk
- University of Strathclyde, UK, Glasgow\nCentre for Electronic Materials, Devices and Nanostructures, UK, Manchester\nUniversity of Oslo / Department of Physics, Norway, Oslo
Project summaryThe purpose of the project is to establish a scientific basis and the subsequent technological innovations for the next generation production of fast power semiconductor devices (PSDs), including the high voltage diodes and thyristors used in various roles in energy saving equipment.
Technological development context.
PSDs are widely used through many sectors of the modern economy. They are of practical importance in any power electronic application. PSDs are finding increasing use in industrial, military, commerce, domestic and aerospace applications. PSDs enhance the capacity and quality of the transport and process industries and of energy systems; ecologically clean sources of energy such as wind and solar power and fuel cells rely greatly on the quality of their PSDs. /Bimal K. Bose."Energy, Environment, and Advances in Power Electronics" IEEE Transactions on Power Electronics, July 2000,vol.15, No.4, 688/.
Modern power engineering concentrates on improving energy efficiency, and this emphasis will only increase in the future. The achievements of today’s energy saving technologies depend upon the development of PSDs with excellent performance. An electric drive with frequency-pulsed control may provide energy saving up to 20-30% in industry, agriculture, medical and consumer equipment. The use of PSDs for gas-filled lamp management (it is known that these are 2-3 times more efficient than incandescent lamps) will make an additional 20% reduction in power consumption possible for these light sources. If the PSD characteristics are improved further, in particular in the switching speed of the devices, even greater economies are possible. For example, commutation energy losses can be reduced four fold by doubling the speed of diode-thyristor converter used today in electronic lighting. This is one reason for the importance and timeliness of further improving the operational characteristics of PSD devices. /G.Charitat, V.Benda, N.Stojadinovic."Progress in power semiconductors" Microelectronics Journal, 32 (2001) 395/.
Market research carried out recently in semiconductor power electronics shows great demand for PSDs with fast switching times, low conduction losses and low off state losses within consumer goods used in the developed world.
The PSD characteristics necessary for tomorrow technology require semiconductor devices with low levels of structural defects (these are usually introduced by necessary high temperature processing) and the use of new approaches for the current transfer process management problem. To meet these challenges serious physical and technological process studies are required.
Influence of the proposed project on progress in the field of development.
New semiconductor processing technological methods will be developed for the production of high-speed PSDs with an optimum trade off between dynamic and static characteristics of the devices, making it possible to achieve the minimum practical energy loss in all modes of operation.
The proper application of these new high speed PSDs will make it possible to use electric power in the most efficient way, and achieve 15-20% economies in power consumption, according to the preliminary estimation.
The use of energy-saving PSDs will also make improvements possible in industrial equipment operation, providing the maximal volume of manufactured product for the minimal expense in material resources.
The saving in reduced power consumption will not be the only economic benefit, as it will also allow a great reduction in the amount of environmental pollution thanks to a reduction in the quantity of fossil fuels burned to generate electricity.
Participants of the project.
The participants in the project are all members of one organization: the Institute of Solid State and Semiconductor Physics of the National Academy of Sciences of Belarus. The participants have experience in the design of radio frequency electronics and semiconductor devices for use in weaponry. The project is underpinned by the participant’s knowledge and leading technological capability in the field of solid-state physics and in the technology of semiconductors and semiconductor devices. More than 30 papers in leading scientific journals have been published, the majority of which received priority, and a number of patens and copyrights have been granted.
The four interconnected tasks and their outcomes are:
1. A program will be developed to model the dependence of PSD parameters upon the structural perfection of the source semiconductor crystals (both silicon and silicon-germanium alloys).
2. New combined thermal and radiation methods will be developed to introduce recombination centers with an optimum energy position within the semiconductor band gap, and with a uniformity of incorporated concentrations improved by 20-50% compared to either gold or platinum diffusion.
3. Methods of semiconductor processing using high temperatures and radiation will be developed and implemented for diodes and thyristors. The stability of the electronic devices will also be studied under thermal, electric and heat stressing.
4. New semiconductor processing methods will be developed to control the switching speed of PSDs with current IF(IT) і10 A and voltage UR і1000 V, providing trr values for diodes within 50-500 nS and tg value for thyristors in the range 10-100 mS. PSD quality will also be improved by a 30-70 fold reduction in leakage current, and 20-40% reduction in forward voltage drop UF(UT); the production yield values will be improved by a reduction of 60-70% in device characteristic scatter. This will be achieved without changing the basic technological process.
The novelty of the project is in the use of the new methods of combined radiation-thermal processing in PSD production, based on spatially non-uniform introduction of recombination centers and precise techniques to dynamically manage the population of impurity-defect complexes within the semiconductor crystals during device manufacture. This proposed approach will lead to fast PSDs with more ideal switching behavior due to improved speed, lower voltage drops when turned on, and lower leakage current when turned off, such device performance would not be attainable using other PSD manufacturing processes.
The application of the project results will be in the electronic and electro-technical industrial fields. The expected deliverables of the project will have wide application for the many types of power electronic devices. The methods offered are likely to reduce the manufacturing cost of products, increase the working temperature range of devices available and to provide significant energy saving. The devices manufactured using the new technique will outperform those presently produced, and the developed technology will be tested and qualified for mass production. It is presupposed that intellectual property developed during the project will be protected.
Realization of goals and tasks of ISTC. Undertaking the project will:
– Give the scientists and specialists, previously working on "weapons", the possibility to re-orientate their abilities for peaceful activity, by involvement in the creation of new semiconductor production techniques for peaceful purposes within the framework of the project.
– Integrate the project participants in the international scientific community and will allow them to address themselves to applied studies in the fields of energy saving and environmental protection.
– Help to solve the national and international problems of reducing material resource consumption; the fast PSD devices when adopted will enable more efficient manufacturing production, providing the maximum number of manufactured products for the minimum raw material expense.
– Support the project participants’ transition to the market economy, since the expected PSD product of the project will be introduced into mass produced energy saving equipment.
Scope of work.
The project duration is 36 months. 19 researchers will be involved in the work. 9 of these are presently specialists in the field of weapon design. Total efforts will constitute-6264 man/days and during the course of the work the former weapons researchers will contribute 4264 man/days of time. When the project is completed the four primary objectives will have been met:
– The theoretical analysis of static and transient processes in traditional power devices.
– The choice of optimal recombination center distribution within the device structure for the best combination of operational device characteristics.
– A study of radiation and thermal defect formation in the silicon and silicon-germanium alloys used for power devices production.
– Development of new methods of radiation and thermal processing in PSD production, and practical implementation in the industrial PSD manufacturing processes.
The role of foreign collaborators.
Scientific collaborations and joint publications exist with Prof. A.Peaker of Manchester University (Great Britain), Dr. M.Yakushev from Strathclyde University (Glasgow, Great Britain) and Prof. B. Svensson from Oslo University (Norway). During the project there will be joint use of equipment, cross checking of results, and joint seminars. The Manchester University is ready to provide the equipment with estimated labor expenses, equipment cost, depreciation and energy costs of 20,000 Euro for testing the technological aspects of this project.
Technical approach and methodology.
The preliminary experiments of the project participants have proved that specific types of radiation-induced defects in silicon are quite thermally stable and that their properties are superior to the centers produced by gold and platinum diffusion used in present technology. Of especial importance is the uniformity of the distribution of centers, this is typically 20-50% better than for the diffused centers. The influence of heating and cooling regimes during device production on electronic and physical material characteristics has been investigated.
A combination of computer modeling and measurements of static and transient device operation characteristics for the radiation and high temperature processed components are key elements of the chosen problem solving approach. Alongside mass manufactured silicon diodes and thyristors, experimental bipolar structures made from silicon-germanium alloys will be studied. Measurements of the key device and material parameters will be conducted using established instrumentation and techniques.