DOI: 10.1002/cssc.201000118 Thin-Film Composite Materials as a Dielectric Layer for Flexible Metal–Insulator–Metal Capacitors Jitendra N. Tiwari, Jagan Singh Meena, Chung-Shu Wu, Rajanish N. Tiwari, Min-Ching Chu, Feng-Chih Chang, and Fu-Hsiang Ko* [a] Introduction Currently, there has been increasing demands on reducing the feature size in microelectronic products and more interested in the development of electronic circuits on flexible substrates to meet the growing worldwide demand for low processing tem- perature, low-cost fabrication, large-area, and lightweight devi- ces. In addition, ultra-low dielectric constant (k) materials are crucial for minimizing resistive-capacitive (R-C) delay, power consumption, and cross-talk noise. [1] In addition, most of the organic–organic nanocomposites are known as low-k dielectric material. Therefore, organic–inorganic nanocomposite materi- als [2–4] have attracted a lot of attention for building large-area and mechanically flexible electronic devices. These materials are also widely pursued because they offer numerous advan- tages in terms of ease of processing, good compatibility with a variety of substrates, and great opportunity for structural modifications. Apart from the above mentioned, there is also a strong desire to develop new large-scale materials that can meet the growing demand for miniaturization, high-speed per- formance, and flexibility for microelectronic devices. And the next generation of intermetal dielectric (IMD) materials for mi- croelectronic devices must have an ultra-low k value of less than 2.0 to meet the National Technology Roadmap for Semi- conductors. [5] Over the last decade, the SiO 2 aerogel film has been devel- oped by many researchers for applying it to IMD in microelec- tronics. Its low k-value makes it applicable to the ultra-large scale integrated (ULSI) devices among various candidate mate- rials. However, for applying it to ULSI devices as an IMD, some drawbacks such as weak mechanical strength, relatively high moisture adsorption, and leakage current behavior should be improved. The functional groups of precursor materials play a major role in overcoming moisture adsorption and leakage current behavior. The functional groups originated from in- complete hydrolysis and condensation reactions. For example, ÀOH as a residual group induces the moisture adsorption through hydrogen bonding when exposed to moisture. [6] As a result, this moisture adsorption degrades the dielectric proper- ties due to its polar nature. Plasma and annealing treatments using various gases enhance the dielectric properties of SiO 2 aerogel films by the removal of residual organic and OH groups. [7–9] However, the above method was time consuming, very tedious, and required high-temperature processing. There- fore, material scientists need to put effort towards finding new and advanced materials for metal–insulator–metal (MIM) ca- pacitors. Herein, we report the room temperature new organic–or- ganic (1-bromoadamantane–Pluronic P123) nanoscale compo- site thin-film (NCTF) as an intermetal dielectric layer for a flexi- ble MIM capacitor fabricated on a polyimide (PI) substrate using sol-gel spin processing, and the insulating properties have been examined. The insulating properties of MIM capaci- tor prepared employing 1-bromoadamantane-P123 NCTF as a dielectric layer exhibited low leakage current density, good ca- pacitance density, and a low k-value. The MIM capacitor with [a] Dr. J. N. Tiwari, J. S. Meena, C.-S. Wu, R. N. Tiwari, M.-C. Chu, Prof. F.-C. Chang, Prof. F.-H. Ko Institute of Nanotechnology Department of Materials Science and Engineering National Chiao Tung University 1001 Ta Hsueh Road, Hsinchu, 30050, R.O.C. (Taiwan) Fax: (+ 886) 3-5744689 E-mail : fhko@mail.nctu.edu.tw A new organic–organic nanoscale composite thin-film (NCTF) dielectric has been synthesized by solution deposition of 1- bromoadamantane and triblock copolymer (Pluronic P123, BASF, EO 20 -PO 70 -EO 20 ), in which the precursor solution has been achieved with organic additives. We have used a sol-gel pro- cess to make a metal–insulator–metal capacitor (MIM) compris- ing a nanoscale (10 nm-thick) thin-film on a flexible polyimide (PI) substrate at room temperature. Scanning electron micro- scope and atomic force microscope revealed that the deposit- ed NCTFs were crack-free, uniform, highly resistant to moisture absorption, and well adhered on the Au–Cr/PI. The electrical properties of 1-bromoadamantane-P123 NCTF were character- ized by dielectric constant, capacitance, and leakage current measurements. The 1-bromoadamantane-P123 NCTF on the PI substrate showed a low leakage current density of 5.5  10 À11 Acm À2 and good capacitance of 2.4 fF at 1 MHz. In addi- tion, the calculated dielectric constant of 1-bromoadamantane- P123 NCTF was 1.9, making them suitable candidates for use in future flexible electronic devices as a stable intermetal die- lectric. The electrical insulating properties of 1-bromoadaman- tane-P123 NCTF have been improved due to the optimized dipole moments of the van der Waals interactions. ChemSusChem 0000, 00, 1 – 7  2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim &1& These are not the final page numbers! ÞÞ