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Department of applied nanotechnology of Kurchatov Institute is one of the most modern Russian centers, that perform researches in the field of microwave electronics, superconducting materials, microfluidic and other breakthrough areas of science.
Теги: microfluidics microwave electronics superconducting materials микрофлюидика сверхпроводящие материалы свч-электроника
The Applied Nanotechnology Laboratory is part of the NBICS Centre (Сentre of nano-, bio-, informational, cognitive and socio-humanitarian technologies) and is located in the same building as the dedicated source of synchrotron radiation, the only one in Russia and the CIS. The laboratory was created under the direct supervision of the Director of the Kurchatov Institute M.V.Kovalchuk in several stages; two clean rooms were eventually built, in which more than 50 pieces of equipment were inastalled. By the beginning of 2015 the laboratory engineering infrastructure is mostly finished and more than 70% of the equipment put into operation.
The Department of Applied Nanotechnologies employs about 20 people. According to its Chief, Ph.D. Maxim Zanaveskin, here it is preferred to raise experts from their student days, and the team is formed from graduates with different specialisations from MIPT (SU), Lomonosov MSU, MPEI, MIREA, MEPhI.
The equipment
for a wide range of tasks
With the Laboratory’s equipment it is possible to research into a wide range of problems from different areas of electronics, microfluidics, neuromorphic systems and other cutting-edge areas of science. "In fact, we have a laboratory-type microelectronic factory", M.Zanaveskin says. In particular, the Laboratory is equipped with facilities for the epitaxy of different types, the optical contact lithography system for wafers with a diameter of up to 150 mm, the resistless lithography system, which can be used for the manufacture of masks for both photolithography and direct wafer writing, plasma chemical etching units, up to complex systems that make it possible in a single cycle to perform selective etching of the substrate followed by deposition of the passivating layers. Installing bonding allows splice wafers of different materials, which is especially in demand in the production of nanoelectromechanical and microelectromechanical systems. The unit for the atomic layer deposition is used to obtain film coatings on various surfaces including those with a very complex topology, for example, to generate gate dielectric or passivate mushroom valves. In the diagnostic room with a scanning electron microscope with the electron and ion microscopy features, optical microscops and a lithography nanoimprint system that forms an image on the wafer with a contact method. The most recent major acquisition was the installation of the electron-beam lithographer Raith EBPG5200 for wafers with a diameter of 200 mm.
In designing laboratories it was envisaged that the load chambers of the modular equipment are placed in clean rooms, and the reactors themselves are in the ‘grey zone’ with a lower purity class thus saving some space for more expensive clean rooms. Placement in the same building as the source of synchrotron radiation provides a lot of advantages, both purely organisational and scientific ones. In particular, a synchrotron may be used for deep lithography including microfluidics.
Despite the fact that most of the equipment for the laboratory had to be procured abroad, domestic developments are also presented here. "Among the Russian manufacturers I would like to note the SemiTEq, which produces, a wide range of high-vacuum process equipment under its own brand in St. Petersburg", says M.Zanaveskin. "The key competence of the company is the development and production of molecular beam epitaxy (MBE) systems for semiconductor materials А3N, А3В5 and wideband materials А2В6. When choosing a supplier, we chose the system SemiTEq STE3N3. The technical advantage of the system is the ability to produce films at higher temperatures than most competitors’ models. In our experience, this is a very useful feature as sometimes the temperatures well above 1000°C will be required. In addition, the advantage of the domestic equipment is the quick technical support, which is very important for our work".
According to M. Zanaveskin, domestic tool engineering for electronics is an essential task and can be solved given the right approach; a much more difficult problem is the lack of pure chemical components, e.g. pure gases, sources of gallium and aluminum, organometallic etc., which are not produced in Russia or are produced of the inadequate quality. The road will rise to meet the one who walks it. So, one should carry on.
Development of the microwave electronics
A key area of research conducted by the laboratory is the development of microwave electronics devices based on nitride heterostructures. State-of-the-art analogue microwave devices used in communication systems including the space sector as well as radar engineering.
For growth processes the laboratory uses MBE and chemical vapor deposition (CVD) units. "With the CVD and MBE technologies nitride heterostructures can be obtained, and they are also used in the following stages of production of microwave devices, says M.Zanaveskin. According to the common practice, one method or the another is usually applied, we have learned to combine in a single process high CVD performance and the ability to create precise heterostructures following the MBE technology in order to obtain good electro-physical characteristics of devices. Currently, we are practically the only ones in the country capable of producing high-quality heterostructures on wafers with a diameter of 3 inches to create devices with a frequency range of 100 GHz and above".
The Laboratory works closely with Institute of Ultra High Frequency Semiconductor Electronics of RAS (IUHFSE RAS). In a joint operation, apart from obtaining high-quality heterostructures, laboratory specialists have achieved good results in the creation of the "non-burnt-in" contacts. If using a conventional technology, contacts are formed by depositing multiple layers of metal and then fusing them through the high-ohmic resistance layer, the solution jointly developed with the IUHFSE RAS for contacts etched is a "window" in the nitride deeper than the two-dimensional gas channel, and then Si-doped gallium nitride is built up through the MBE method. With this technology, the contact borders are sharper thus making it possible to bring together the source and outflow, and have less resistance, about 0.1-0.2 Ohms against at best 0.5 ohms when using "burning in".
The Laboratory’s developments in the production of microwave devices ignited the interest among a number of industrial enterprises, in particular, the leading Russian developer of microwave devices, RPC "Istok", and the Laboratory’s outcomes are gradually being introduced into production.
New-generation of High-temperature superconductors
The pulsed laser deposition units equipped with an excimer laser used in the Laboratory for the development of technologies to produce high-temperature superconductors (HTS) of the second generation. HTS wires are used in the production of current limiters, when a wire is a physical fuse; if the current exceeds a certain value, the material comes out of the superconducting state, and it does it faster than other physical counterparts. The same principle makes it possible not to provide for any additional power in electric networks, that is quite interesting for the energy sector. HTS wires allow making smaller engines that can be in demand in various fields such as shipbuilding.
Replacement of metal wires in the power lines with the HTS wires can significantly improve the transmitted electrical power without restructuring of the energy infrastructure. Such solutions have already been brought to the stage of implementation; in particular, a pilot project is being implemented in St. Petersburg.
The first-generation HTSC systems are a silver tube containing the HTS powder; although such a design of a conductor provides only a casual crystal interface characterised by high anisotropy. To achieve film formation with crystals oriented in the second-generation systems in an optimal way, it was decided to use epitaxy. The pulsed laser deposition units operate based on the following principle, in the high-vacuum or controlled-atmosphere context, an excimer laser beam is directed to the target, and the material is transformed into a plasma that flies onto a heated substrate thus creating a coating. The technology is optimal to obtain coatings from the complex stoichiometric compounds because during simple heating of the target the material components will have different speeds, and the impact of the laser directs the material in portions without decomposition into components.
By selecting the parameters of the cell of the material and substrate, the growth modes, the laboratory obtains a film of the oriented crystals. M.Zanaveskin says "In itself, the cultivation of high-temperature superconducting film on a single crystal is a relatively simple problem, and it is much more difficult to develop a technology to create wires that are suitable for use in the industry. We are forming the epitaxial HTS coating on long metal strips, either textured or amorphous, by setting the texture by assisting with ion beams. Our Laboratory succeeded first in Russia to create high-temperature superconducting wires of the second generation using materials of the domestic production, in particular, the substrates developed at the Bochvar Research Institute of Inorganic Materials".
The next phase of the project is to create long wires. To do this, first purchased in the country was a unit equipped with a powerful laser that allows you to continuously apply the HTS-coated tape with a length of up to 200 m. The process is sophisticated. It concerns creating a wire, you should apply at least five functional layers, so the tape is rewound several times, heated to a temperature of about 1000°C, and the previously deposited layers should be retained at each following stage.
The second-generation HTS wire is characterised by a current-carrying capacity approximately 100 times greater than the first one for the same section of the wire.
Practical microfluidics
Microelectronic technology can be used not only in electronics and power engineering, but also in biology. As is known, the problem of determining the structure of proteins is very important for creating modern medicines. This structure is determined at the experimental station of the Kurchatov Synchrotron Radiation Source. The peculiarity of protein crystallization is its sensitivity to many parameters, in particular, to the gravity. The most qualitative crystals are grown in space in microgravity conditions. Such studies have been initiated by M.V.Kovalchuk in the early 1990s at the Institute of Crystallography of RAS, and then at the Kurchatov Institute. There are various systems for the implementation of the growth of protein crystals on space satellites and stations. In particular, the very promising is the use of so-called microfluidic.
In collaboration with the Institute of Crystallography of RAS, the laboratory develops a microfluidic device based on the microchip. The idea is to use emulsion of oil and water, where microdroplets of the aqueous solution serve as containers for samples that are separated by oil. In the microchip of approximately 5 × 2 cm is located to 1 thousand samples which reproduce the different conditions for protein crystallization. A device with multiple syringe pumps and the microchip is compact that ensures minimization of costs for its transportation into space.
Developments based on memristors
The existence of the memristor, the fourth passive electronic element, was theoretically predicted in 1971 on the basis of the symmetry analysis of parameters of electronic networks. The main property of this element is the dependence of its resistance on the value of charge. Thus, the conductivity of the memristor is determined by not only the immediate value of the applied voltage, but also the entire "history" of his previous work.
Memristors can be used to create systems of multi-bit memory. Another area of application of memristors is the commutation. Laboratory studies the problem of creation on the basis of memristor of switching elements for programmable logic integrated circuits (PLIC). If the semiconductor switching elements are placed on a chip, memristors can be integrated in the passive layers of the chip over the MOS structure, that allows to optimize the design of the PLIC. Besides, memristors have a small thickness and are characterized by rather high radiation resistance.
Also in cooperation with other groups of the NBICS Centre the laboratory explores the prospects of using of memristors in neuromorphic systems. Now these systems are based on classical semiconductor MOS-elements, but it is predicted that the implementation of the memristors to emulate the connections between neurons will greatly simplify hardware implementation of neural network algorithms. The need for an integrated approach to the construction of neuromorphic information processing systems, which are capable of learning, object classification and decision making, was formulated a few years ago by M.V.Kovalchuk. The study of the properties of the memristor systems is an important part of this research area.
Although the implementation of memristors and some others studied in the laboratory problems, at first glance, have a rather vague prospects for industrial implementation, experience shows that many solutions yesterday seemed impossible, today are widely used, and tomorrow are replaced by more modern and efficient technologies. "The main thing for a scientist is to the research results were in demand", says M.Zanaveskin. "Although we are the representatives of the academic school, but try to move the fundamental knowledge as close to the application area".
The Department of Applied Nanotechnologies employs about 20 people. According to its Chief, Ph.D. Maxim Zanaveskin, here it is preferred to raise experts from their student days, and the team is formed from graduates with different specialisations from MIPT (SU), Lomonosov MSU, MPEI, MIREA, MEPhI.
The equipment
for a wide range of tasks
With the Laboratory’s equipment it is possible to research into a wide range of problems from different areas of electronics, microfluidics, neuromorphic systems and other cutting-edge areas of science. "In fact, we have a laboratory-type microelectronic factory", M.Zanaveskin says. In particular, the Laboratory is equipped with facilities for the epitaxy of different types, the optical contact lithography system for wafers with a diameter of up to 150 mm, the resistless lithography system, which can be used for the manufacture of masks for both photolithography and direct wafer writing, plasma chemical etching units, up to complex systems that make it possible in a single cycle to perform selective etching of the substrate followed by deposition of the passivating layers. Installing bonding allows splice wafers of different materials, which is especially in demand in the production of nanoelectromechanical and microelectromechanical systems. The unit for the atomic layer deposition is used to obtain film coatings on various surfaces including those with a very complex topology, for example, to generate gate dielectric or passivate mushroom valves. In the diagnostic room with a scanning electron microscope with the electron and ion microscopy features, optical microscops and a lithography nanoimprint system that forms an image on the wafer with a contact method. The most recent major acquisition was the installation of the electron-beam lithographer Raith EBPG5200 for wafers with a diameter of 200 mm.
In designing laboratories it was envisaged that the load chambers of the modular equipment are placed in clean rooms, and the reactors themselves are in the ‘grey zone’ with a lower purity class thus saving some space for more expensive clean rooms. Placement in the same building as the source of synchrotron radiation provides a lot of advantages, both purely organisational and scientific ones. In particular, a synchrotron may be used for deep lithography including microfluidics.
Despite the fact that most of the equipment for the laboratory had to be procured abroad, domestic developments are also presented here. "Among the Russian manufacturers I would like to note the SemiTEq, which produces, a wide range of high-vacuum process equipment under its own brand in St. Petersburg", says M.Zanaveskin. "The key competence of the company is the development and production of molecular beam epitaxy (MBE) systems for semiconductor materials А3N, А3В5 and wideband materials А2В6. When choosing a supplier, we chose the system SemiTEq STE3N3. The technical advantage of the system is the ability to produce films at higher temperatures than most competitors’ models. In our experience, this is a very useful feature as sometimes the temperatures well above 1000°C will be required. In addition, the advantage of the domestic equipment is the quick technical support, which is very important for our work".
According to M. Zanaveskin, domestic tool engineering for electronics is an essential task and can be solved given the right approach; a much more difficult problem is the lack of pure chemical components, e.g. pure gases, sources of gallium and aluminum, organometallic etc., which are not produced in Russia or are produced of the inadequate quality. The road will rise to meet the one who walks it. So, one should carry on.
Development of the microwave electronics
A key area of research conducted by the laboratory is the development of microwave electronics devices based on nitride heterostructures. State-of-the-art analogue microwave devices used in communication systems including the space sector as well as radar engineering.
For growth processes the laboratory uses MBE and chemical vapor deposition (CVD) units. "With the CVD and MBE technologies nitride heterostructures can be obtained, and they are also used in the following stages of production of microwave devices, says M.Zanaveskin. According to the common practice, one method or the another is usually applied, we have learned to combine in a single process high CVD performance and the ability to create precise heterostructures following the MBE technology in order to obtain good electro-physical characteristics of devices. Currently, we are practically the only ones in the country capable of producing high-quality heterostructures on wafers with a diameter of 3 inches to create devices with a frequency range of 100 GHz and above".
The Laboratory works closely with Institute of Ultra High Frequency Semiconductor Electronics of RAS (IUHFSE RAS). In a joint operation, apart from obtaining high-quality heterostructures, laboratory specialists have achieved good results in the creation of the "non-burnt-in" contacts. If using a conventional technology, contacts are formed by depositing multiple layers of metal and then fusing them through the high-ohmic resistance layer, the solution jointly developed with the IUHFSE RAS for contacts etched is a "window" in the nitride deeper than the two-dimensional gas channel, and then Si-doped gallium nitride is built up through the MBE method. With this technology, the contact borders are sharper thus making it possible to bring together the source and outflow, and have less resistance, about 0.1-0.2 Ohms against at best 0.5 ohms when using "burning in".
The Laboratory’s developments in the production of microwave devices ignited the interest among a number of industrial enterprises, in particular, the leading Russian developer of microwave devices, RPC "Istok", and the Laboratory’s outcomes are gradually being introduced into production.
New-generation of High-temperature superconductors
The pulsed laser deposition units equipped with an excimer laser used in the Laboratory for the development of technologies to produce high-temperature superconductors (HTS) of the second generation. HTS wires are used in the production of current limiters, when a wire is a physical fuse; if the current exceeds a certain value, the material comes out of the superconducting state, and it does it faster than other physical counterparts. The same principle makes it possible not to provide for any additional power in electric networks, that is quite interesting for the energy sector. HTS wires allow making smaller engines that can be in demand in various fields such as shipbuilding.
Replacement of metal wires in the power lines with the HTS wires can significantly improve the transmitted electrical power without restructuring of the energy infrastructure. Such solutions have already been brought to the stage of implementation; in particular, a pilot project is being implemented in St. Petersburg.
The first-generation HTSC systems are a silver tube containing the HTS powder; although such a design of a conductor provides only a casual crystal interface characterised by high anisotropy. To achieve film formation with crystals oriented in the second-generation systems in an optimal way, it was decided to use epitaxy. The pulsed laser deposition units operate based on the following principle, in the high-vacuum or controlled-atmosphere context, an excimer laser beam is directed to the target, and the material is transformed into a plasma that flies onto a heated substrate thus creating a coating. The technology is optimal to obtain coatings from the complex stoichiometric compounds because during simple heating of the target the material components will have different speeds, and the impact of the laser directs the material in portions without decomposition into components.
By selecting the parameters of the cell of the material and substrate, the growth modes, the laboratory obtains a film of the oriented crystals. M.Zanaveskin says "In itself, the cultivation of high-temperature superconducting film on a single crystal is a relatively simple problem, and it is much more difficult to develop a technology to create wires that are suitable for use in the industry. We are forming the epitaxial HTS coating on long metal strips, either textured or amorphous, by setting the texture by assisting with ion beams. Our Laboratory succeeded first in Russia to create high-temperature superconducting wires of the second generation using materials of the domestic production, in particular, the substrates developed at the Bochvar Research Institute of Inorganic Materials".
The next phase of the project is to create long wires. To do this, first purchased in the country was a unit equipped with a powerful laser that allows you to continuously apply the HTS-coated tape with a length of up to 200 m. The process is sophisticated. It concerns creating a wire, you should apply at least five functional layers, so the tape is rewound several times, heated to a temperature of about 1000°C, and the previously deposited layers should be retained at each following stage.
The second-generation HTS wire is characterised by a current-carrying capacity approximately 100 times greater than the first one for the same section of the wire.
Practical microfluidics
Microelectronic technology can be used not only in electronics and power engineering, but also in biology. As is known, the problem of determining the structure of proteins is very important for creating modern medicines. This structure is determined at the experimental station of the Kurchatov Synchrotron Radiation Source. The peculiarity of protein crystallization is its sensitivity to many parameters, in particular, to the gravity. The most qualitative crystals are grown in space in microgravity conditions. Such studies have been initiated by M.V.Kovalchuk in the early 1990s at the Institute of Crystallography of RAS, and then at the Kurchatov Institute. There are various systems for the implementation of the growth of protein crystals on space satellites and stations. In particular, the very promising is the use of so-called microfluidic.
In collaboration with the Institute of Crystallography of RAS, the laboratory develops a microfluidic device based on the microchip. The idea is to use emulsion of oil and water, where microdroplets of the aqueous solution serve as containers for samples that are separated by oil. In the microchip of approximately 5 × 2 cm is located to 1 thousand samples which reproduce the different conditions for protein crystallization. A device with multiple syringe pumps and the microchip is compact that ensures minimization of costs for its transportation into space.
Developments based on memristors
The existence of the memristor, the fourth passive electronic element, was theoretically predicted in 1971 on the basis of the symmetry analysis of parameters of electronic networks. The main property of this element is the dependence of its resistance on the value of charge. Thus, the conductivity of the memristor is determined by not only the immediate value of the applied voltage, but also the entire "history" of his previous work.
Memristors can be used to create systems of multi-bit memory. Another area of application of memristors is the commutation. Laboratory studies the problem of creation on the basis of memristor of switching elements for programmable logic integrated circuits (PLIC). If the semiconductor switching elements are placed on a chip, memristors can be integrated in the passive layers of the chip over the MOS structure, that allows to optimize the design of the PLIC. Besides, memristors have a small thickness and are characterized by rather high radiation resistance.
Also in cooperation with other groups of the NBICS Centre the laboratory explores the prospects of using of memristors in neuromorphic systems. Now these systems are based on classical semiconductor MOS-elements, but it is predicted that the implementation of the memristors to emulate the connections between neurons will greatly simplify hardware implementation of neural network algorithms. The need for an integrated approach to the construction of neuromorphic information processing systems, which are capable of learning, object classification and decision making, was formulated a few years ago by M.V.Kovalchuk. The study of the properties of the memristor systems is an important part of this research area.
Although the implementation of memristors and some others studied in the laboratory problems, at first glance, have a rather vague prospects for industrial implementation, experience shows that many solutions yesterday seemed impossible, today are widely used, and tomorrow are replaced by more modern and efficient technologies. "The main thing for a scientist is to the research results were in demand", says M.Zanaveskin. "Although we are the representatives of the academic school, but try to move the fundamental knowledge as close to the application area".
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