The patent's assignee is STMicroelectronics S.r.l.
News editors obtained the following quote from the background information supplied by the inventors: "The present disclosure relates to an electronic device for implementing digital functions and miniaturized logic gates, based on molecular functional elements, and to a method for digital computation implemented by such a device.
"An electronic processing system, employing one or more of the above-mentioned devices, and a method for manufacturing the same device are also within the disclosure.
"The evolution of microelectronics, particularly applied to processors and electronic computers based on integrated circuits, has developed over the last decades while keeping the extraordinary pace foreseen by the so-called 'Moore's Law'. This emerged particularly in the increasingly improved miniaturization of integrated electronic circuits, or in the increasing computational capacity that can be obtained while keeping dimensions constant, which in turn depends on the number of functional elements (for example, logic gates) that can be integrated in a given space, and on the operating speed of such functional elements.
"This evolution was made possible due to improvements mainly in technology, while the founding principles of the micro-electronic circuits, which for decades have been based on transistors as base elements, remained unaltered.
"Actually, the above-mentioned evolution involved the design, manufacturing and integration of more and more fast, miniaturized, and increasingly energy-efficient transistors. Regarding miniaturization, the key aspect was, and still is, the ability to use lithographic manufacturing processes on smaller and smaller spatial scales.
"However, such technological evolution seems to be reaching its limit. Costs and feasibility of lithographic processes on scales that are smaller than the current ones appear to be problematic.
"In order to overcome the barriers and limits set forth above, it is felt a need for a quality breakthrough related to concept itself of devices, processing systems, and electronic computers, according to what may be briefly defined as a transition from micro-to nano-electronics.
"A transition from micro- to nano-electronics involves particularly applying physical laws that are even more fundamental than those employed in transistors, for example, quantum phenomena on an atomic-molecular scale.
"Therefore, research in this field pursues the chance to devise so-called nano-electronic 'transistor-like' devices (such as 'molecular transistors' or 'tri-gate transistors') that, while being based on quantum phenomena, aim to reproduce the operation of conventional transistors. However, nano-electronic 'transistor-like' solutions have severe drawbacks, since to date they do not allow obtaining the same performance of the state-of-the-art micro-electronic transistors. Furthermore, a transistor-based system includes complex interconnections, which are obtained by lithographic processes, thus not allowing overcoming the above-mentioned limitations of such lithographic processes.
"A further line of research, mostly developed by academic institutions, relates to a type of so-called 'transistor-less' devices, i.e., devices not involving the use of transistors.
"This line of research comprises, e.g., QCAs--'Quantum-dot Cellular Automata'. QCAs are based on the principle that, since the properties of materials change radically at the nano-scale, at such a scale processing methods, exploiting quantum phenomena at an atomic-molecular scale, such as the electrostatic interaction combined with quantum tunneling effect and quantum charge confinement, can operate. Such processing methods can be much more efficient compared to those based on switches, such as transistors.
"QCAs provide for functional units composed of, e.g., 6-dot cells (i.e., six atoms or groups of atoms), capable to assume two different polarized states and a neutral state, corresponding to different charge configurations around the different atoms or groups of atoms, each equivalent to a respective 'confinement site'. Each cell can be obtained, for example, by means of two molecules, each of which comprising three confinement sites. The possibility to obtain, by means of QCAs, single functional units such as memory cells, binary lines, logic inverters, up to single Boolean logic gates, has been shown.
"However, to date, QCAs did not prove to be capable of implementing complex processors, since the implementation of prior art complex QCA cell processors use substantially conventional lithographic processes, to the extent of the spatial resolution of a single QCA cell, with all the above-mentioned limitations thereof.
"A further drawback of prior art QCA solutions, particularly at a molecular scale, is that they are implemented on the basis of molecules that are highly symmetrical in structure and electric configuration, while real molecules tend to be asymmetric, at least due to the deposition thereof on substrates, together with other possibly similar molecules.
"The use of not exactly symmetric molecules is a severe limitation on the performance that can be obtained by QCAs.
"From what has been stated above, it shall be apparent that the desire to provide nano-electronic integrated devices with digital processing performance comparable to those of current micro-electronic circuits and processors, and at a reasonable cost, is largely unmet."
As a supplement to the background information on this patent application, NewsRx correspondents also obtained the inventor's summary information for this patent application: "One embodiment of the present disclosure is an electronic device based on molecular functional elements, for implementing digital functions and miniaturized logic gates, as well as a method for manufacturing the same device. Some embodiments are an electronic processing system, employing one or more of such devices, and a related method for electronic computation, which are improved so as to at least partially obviate the drawbacks described herein above with reference to the prior art.
"Particularly, an electronic device is proposed, that is based on physical quantum phenomena, while allowing the integration of several functional elements, such as to compose a processor or a complex logic network, and which can be manufactured at reasonable costs and provide high performance.
"One embodiment is an electronic device for implementing digital functions that includes an interposing region that includes a dielectric region; and a first electrode region and a second electrode region separated from each other by the interposing region, wherein said first and second electrode regions include a first electrode and a second electrode, respectively, that are configured to generate an electrode electric field in the interposing region depending on an electric potential difference to be applied to the first and second electrodes. The interposing region includes a molecular layer including a plurality of molecules, each configured to assume one or more electric states, in a controllable manner, according to a sensed electric field. The dielectric region has a spatially variable dielectric profile and is configured to determine a respective field profile of said electrode electric field and to spatially modulate said sensed electric field at the molecular layer.
"One embodiment of the disclosure is an electronic processing system that includes such a device.
"A method for electronic digital computation according to one embodiment of the disclosure includes:
"applying a potential difference between a first electrode and a second electrode of an electronic device that includes an interposing region between the electrodes, the interposing region including a dielectric region having a spatially variable dielectric profile, the interposing region including a molecular layer that includes a plurality of molecules, each configured to assume one or more electric states in a controllable manner according to a sensed electric field, the applying including generating an electrode electric field in the interposing region; and
"affecting the states of the molecules of the molecular layer by spatially modulating the sensed electric field at the molecular layer, said spatially modulating depending on a spatially variable field profile determined by the spatially variable dielectric profile of the dielectric region.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
"Further characteristics and advantages of the device, the system, the computational method and the manufacturing method according to the disclosure will be apparent from the description set forth below of preferred implementation examples, given by way of indicative, non-limiting example, with reference to the appended Figures, in which:
"FIG. 1 illustrates a sectional view of a device according to an embodiment of the present disclosure;
"FIG. 2 illustrates a sectional view of a dielectric region comprised in the device, and a spatially variable electric field profile within such a dielectric region;
"FIGS. 3A and 3B illustrate respectively a perspective view and a top view of a part of a molecular layer comprised in the device;
"FIG. 4 illustrates a side view of a molecule of the molecular layer;
"FIGS. 5A and 5B illustrate in a simplified manner a molecule of the molecular layer;
"FIG. 6 illustrates a neutral molecule with a high polarizability, i.e., an embodiment of a molecule of the molecular layer;
"FIGS. 7A-7C illustrate energy diagrams of the states that can be taken by such molecules, according to different implementation examples;
"FIG. 8 illustrates an example of polarization assumed by three adjacent molecules;
"FIGS. 9 to 13 illustrate sectional views of respective implementation examples of parts of the device according to the disclosure;
"FIGS. 14A and 14B show sectional views of further implementation examples of the device;
"FIG. 15 represents diagrams resulting from simulations of the electric field profile depending on a dielectric profile of the device;
"FIG. 16 illustrates a sectional view of a device according to a further embodiment of the present disclosure;
"FIG. 17 represents a top view of the molecular layer, in which a functional unit of the device is highlighted;
"FIG. 18 shows an output signal element of the device, seen from above;
"FIG. 19 represents a spatial and time diagram of the evolution of an electrode electric field, and the respective effect on the molecules of the molecular layer;
"FIGS. 20A and 20B illustrate respective implementation examples of a dielectric layer belonging to the dielectric region of the device;
"FIG. 21 represents a top view of a molecular layer portion configured to implement a binary line;
"FIGS. 22A to 22D represent top views of four operative conditions of a molecular layer portion operating as a universal logic gate NAND/NOR, according to an embodiment of the disclosure;
"FIG. 23 represents a scheme of an implementation example of an electronic processing system, according to the present disclosure."
For additional information on this patent application, see: Bramanti,
Keywords for this news article include: STMicroelectronics S.r.l.
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