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NEC, National Institute for Materials Science, and Japan Science and Technology Agency Develop New 'Three Terminal Nanobridge' Switch Utilizing Deposition and Dissolution of Metallic Ions

Tokyo, Japan | Posted on December 06, 2005

(JCN Newswire) - NEC Corporation (NEC), the National Institute for Materials Science (NIMS) and the Japan Science and Technology Agency (JST) today announced the development of a new three-terminal switch, three-terminal NanoBridge(TM) (1*), which utilizes electrochemical reactions (deposition and dissolution) of metallic ions in a solid electrolyte (2*). Meeting the requirements for programmable-logic (3*) applications with its improved controllability, low resistance and reliability, the three-terminal NanoBridge(TM) switch solves the issues of its predecessor, the jointly developed two-terminal NanoBridge(TM) switch, bringing it closer to commercial application in this field. Results of this joint research project will be announced on December 6th at the International Electron Devices Meeting (IEDM) being held in Washington DC, U.S.A.

The two-terminal NanoBridge(TM) is composed of a solid electrolyte sandwiched between two terminals. A third terminal (a gate) has been added to this switch to create the new and advanced three-terminal NanoBridge(TM). This newly developed structure enables the following:

Greater control:
Control of the deposition and dissolution of metallic ions between the source and drain by applying voltage to the gate is realized, allowing the connection between the source and drain to be electrically connected and disconnected.

Lower power consumption:
A reduction in the electrical current flow during switching is enabled as the gate is insulated from all of the other electrodes.

Improved reliability:
Control of the thickness of the precipitated metal bridge is achieved, allowing a thicker bridge to achieve strong electromigration endurance (4*).

The increasing importance of time to market in the development of electronic appliances in recent years has significantly increased the market share for field programmable logic. Continuous reduction in LSI design features (Moore's Law) enables programmable logic to enhance chip performance and reduce its price. However, it is anticipated that further miniaturization will eventually become limited and lead to a higher demand for enhanced performance.

NEC, NIMS, and JST are jointly developing NanoBridge(TM) technology as a programmable logic circuit reconfiguration switch, a development which represents a significant breakthrough in this field. NanoBridge(TM) technology utilizes the atom switching effect of a nanometer scale metal bridge, in which an electrically conductive channel is created or annihilated by stretching a metallic bridge controlled by an electrochemical reaction inside a solid electrolyte. This compact switch reduces chip area to a fraction of that of conventional ones, resulting in lower costs and higher performance. However, under the assumption of the same chip size, NanoBridge(TM) technology allows multiple functions to be packed into a single chip with programmable logic, thereby enabling large-scale applications. This is also achieved without reducing the feature size of LSI (5*).

With the two-terminal NanoBridge(TM), switching between the on and off states was achieved by applying a voltage across the electrical path between the two terminals, resulting in the flow of a large electric current during switching. Therefore, a vast amount of power was consumed during switching, with greater chance of device breakdown due to an increase in joule heating. However, application to programmable logic necessitates a lower flow of current during switching.

The two key points of the newly developed three-terminal NanoBridge(TM) are as follows:
(1) The electrode area of the drain has been decreased to restrict the area in which metal can precipitate, allowing the source and drain to be connected by the metallic ions in the restricted area.
(2) The distance between the source and drain has been made shorter than the distance between the gate and the other electrodes in order to prevent any connection between the gate and the other electrodes by metal deposition before the connection is made between the source and drain.

By applying these two structural points, experimental operation of the three-terminal NanoBridge(TM) was successfully carried out, and a reduction in current by more than two digits as compared with the two-terminal NanoBridge(TM) during switching was confirmed. This technological advancement will enable a reduction in price and an improvement in performance of programmable devices, as well as improved development efficiency and higher performance of many electronic products such as mobile devices and digital TVs. Furthermore, owing to the reconfigurability of circuitry realized by NanoBridge(TM), every conceivable function will be enabled, even on small portable devices with limited LSI packaging space such as mobile phones.

Part of this research is being carried out under the management of the "Nano quantum conductor array" project (project leader: Dr. M. Aono in NIMS) being carried out by ICORP (International Cooperative Research Project) of JST, in collaboration with joint research by NEC and NIMS.

(*1) NanoBridge(TM) is a trademark of NEC Corporation.
(*2) A solid body in which ions can move freely.
(*3) LSIs whose circuitry can be reconfigured by customers, allowing device development time to be shortened and initial development costs to be dramatically cut. Reflecting the intense competition over device development, the programmable-logic market is expanding greatly.
(*4) When current is flowed through metallic wiring, metal atoms are driven by the electron flow and resistance becomes high. At worst, wires can even break. This breakdown becomes more evident when the metallic wiring is finer.
(*5) With conventional programmable logic, logic cells with a large number of transistors are used to reduce the number of switches. This is because the area of the semiconductor switch used for reconfiguration is large. As a result, in addition to degrading the usage efficiency ratio of the created circuits, this set up reduces the degree of freedom of pairing logic cells and the processing performance of parallel-arithmetic operations. On the contrary, since the size of the two-terminal NanoBridgeTM is one thirtieth the size of the conventional semiconductor switch, it is possible to use logic cells with fewer transistors. As a result, usage efficiency of the circuitry is improved by one digit, and the chip size for the same function performed by the two-terminal NanoBridgeTM is one tenth that for conventional programmable logic. Moreover, performance (namely, power consumption and operation speed) are improved.

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About The Japan Science and Technology Agency (JST):
The Japan Science and Technology Corporation was founded on October 1, 1996, through the integration of two organizations, the Japan Information Center of Science and Technology (JICST) and the Research Development Corporation of Japan (JRDC). JST is a key organization for implementing policies of the Science and Technology Agency (STA), at present, the Ministry of Education, Culture, Sports, Science and Technology (MEXT). JICST was mainly engaged in dissemination of the information related to science and technology, while JRDC was primarily involved in the promotion of basic research, technology development and transfer, and promotion of research exchange. In addition to continuing and further developing the activities of these two organizations, JST has new objectives to provide an adequate foundation for enhancing Japan's science and technology and to promote the development of cutting-edge and innovative research in line with the Basic Law of Science and Technology enacted and promulgated on November 15, 1995, and the Science and Technology Basic Plan decided by the Cabinet in May 1996. On October 1, 2003, the Japan Science and Technology Corporation was reorganized into an independent administrative institution called the "Japan Science and Technology Agency" under the leadership of governmental plans to reorganize and integrate special public corporations. The acronym has not changed.

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About The National Institute for Materials Science (NIMS):
The National Institute for Materials Science (NIMS) is an Independent Administrative Institution of Japan which was established in April 2001 by merging two existing research institutions, the National Research Institute for Metals (NRIM) and the National Institute for Research in Inorganic Materials (NIRIM). NIMS has pursued the research in four priority fields under the Mid-term Plan established in line with the Second Science and Technology Basic Plan of Japan; nanomaterials, environment and energy materials, safe materials and improvement of research and intellectual infrastructure.

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About NEC Corporation:
NEC Corporation (TSE: 6701)(NASDAQ: NIPNY)(UK: NEC.IL) is one of the world's leading providers of Internet, broadband network, and enterprise business solutions dedicated to meeting the specialized needs of its diverse and global base of customers. Ranked as one of the world's top patent-producing companies, NEC delivers tailored solutions in the key fields of computers, networking, and electron devices by integrating its technical strengths in IT and networks and by providing advanced semiconductor solutions through NEC Electronics Corporation. The NEC Group employs more than 140,000 people worldwide and had net sales of 4,855 billion yen (approx. $45.4 billion) in the fiscal year that ended in March 2005.

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Contact:
Diane Foley
NEC Corporation
d-foley@ax.jp.nec.com
+81-3-3798-6511

Copyright � NEC Corporation

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