Infineon Presents First Results on Usage of Organic Materials for Next Generation Electronic Devices
With regards to integration density and clock frequency, electronic devices using organic materials may not be a direct alternative to silicon-based integration, but offer the potential of extremely low-cost manufacturing and a high degree of flexibility. While the production of integrated circuits using silicon or other crystalline semiconductors requires weeks and a large number of sequential processes with expensive equipment, organic electronics can be manufactured at substantially lower cost. The potential uses of organic electronics are correspondingly low performance and cost-sensitive applications.
Infineon demonstrated several organic components performing at levels previously unattainable. Thin-Film Transistors (TFTs) build by the researchers use organic semiconducting molecules as the active layer and provide charge carrier mobilities in excess of 1 cm 2/ Vs. Like silicon-based components, these organic transistors consist of several layers: substrate, gate electrode, gate insulator, source and drain contacts, organic semiconductors (e.g. pentacene or substituted oligothiophenes), and a protective passivation layer. Infineon reported at IEDM about developments of both hybrid organic/inorganic structures as well as pure organic chips. The latest research results at Infineon show that organic-based ICs have potential applications in high volume and cost-critical applications where silicon-based chips may be unsuitable, said Dr. Christoph Kutter, Senior Vice President of the Corporate Research Department at Infineon. The advances on performance and reliability demonstrated at the 2003 IEDM encourage us to continue our investigations of organic material for usage in new electronic devices.
New Organic Materials: Potential for High-Density Non-Volatile Memories
Numerous organic and inorganic materials have already been analyzed for non-volatile memory applications. Organic memories offer the potential of simple integration and simple cell concepts with very small cell sizes. In comparison to inorganic materials, the properties of the organic memory layers can be tailored by a selective change of the molecular structure. Furthermore, organic materials are often suitable for vacuum deposition as well as for low-cost spin coating processes.
Infineon researchers described the cell concepts and requirements for non-volatile memories based on novel organic memory materials. Memory cells built with this technology have already shown promising reliability data. For the first time, retention data of more than a year are shown for an organic memory material exhibiting conductance switching. Further investigations show the potential for scaling the material down to feature sizes of less than 20nm. This organic storage material is an attractive candidate for non-volatile memories.
New Polymer Material Enables Innovative DRAM Integration Concepts
Traditional silicon integration concepts are based on a few materials like silicon, silicon oxide and silicon nitride. Using only these materials limits the integration options. Resists - also used in conventional semiconductor processes - could be a fourth alternative, but are limited since processing at higher temperatures is not possible. Infineon co-developed a new thermally stable organic polymer combining the advantages of both worlds and demonstrated the feasibility of this organic material for a DRAM trench integration scheme. In this approach, a modified version of an organic spin-on-polymer is used with ideal gap fill properties, good planarization and temperature stability beyond 450°C. Test samples of 256M DDR DRAM chips fabricated on 140 nm ground rules show high yields. This concept demonstrates the feasibility of FEOL (Front-End Of Line) integration schemes utilizing the newly developed material. Furthermore the demonstrated integration scheme is capable of extending DRAM trenches to generations below 70nm.
New Molecular Thin Film Transistors Operate with Reduced Voltages
Organic electronics targets low performance and cost-sensitive applications. One of the most critical problems of the traditional organic Thin-film Transistors (TFTs) is the high operating voltage, which often exceeds 20V. In order to reduce the operating voltage and thereby the power consumption in organic TFT ICs, new ultra-thin gate dielectrics are necessary.
Infineon developed a new molecular TFT based on a high-mobility organic semiconductor (pentacene) and an ultra-thin (2.5nm), molecular self-assembling-monolayer (SAM) gate dielectric. With this breakthrough in the area of gate dielectrics for organic transistors, transistors operating down to 1V were realized exhibiting a subthreshold swing as low as 100 mV/decade. For a transistor with a channel length of 5µm a transconductance of 0.01µS/µm was measured - the highest transconductance reported for an organic semiconductor device up to today.
Infineon Technologies AG, Munich, Germany, offers semiconductor and system solutions for the automotive and industrial sectors, for applications in the wired communications markets, secure mobile solutions as well as memory products. With a global presence, Infineon operates in the US from San Jose, CA, in the Asia-Pacific region from Singapore and in Japan from Tokyo. In the fiscal year 2003 (ending September), the company achieved sales of Euro 6.15 billion with about 32,300 employees worldwide. Infineon is listed on the DAX index of the Frankfurt Stock Exchange and on the New York Stock Exchange (ticker symbol: IFX). Further information is available at www.infineon.com.
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