IEEE ELECTRON DEVICE LETTERS, VOL. 36, NO. 3, MARCH 2015 271 The Manipulation of Temperature Coefﬁcient Resistance of TaN Thin-Film Resistor by Supercritical CO 2 Fluid Huey-Ru Chen, Ying-Chung Chen, Ting-Chang Chang, Kuan-Chang Chang, Tsung-Ming Tsai, Tian-Jian Chu, Chih-Cheng Shih, Yi-Ting Tseng, Chih-Yang Lin, and Hua-Ching Lin Abstract— The manipulation of temperature coefﬁcient of resistance (TCR) in TaN thin-ﬁlm resistor (TFR) was demon- strated by electrical measurement and analysis through supercritical carbon dioxide (SCCO 2 ) ﬂuid treatment for the ﬁrst time. The negative TCR value of TaN TFR changes to positive TCR value through annealing process due to the growth and merge of TaN x grain. After SCCO 2 treatment, the positive TCR value was changed back to negative TCR value in TaN TFR. The TaN grain boundary isolated by dehydroxyl effect of SCCO 2 ﬂuid treatment causes the current conduction mechanism changed to hopping conduction from ohmic conduction. Index Terms—TaN, thin ﬁlm resistor, temperature coefﬁcient resistance, SCCO 2 . I. I NTRODUCTION W ITH the demand of portable electronic devices increasing greatly in the world, the integration of memory [1]–[8], display [9]–[11], logic device and passive devices (e.g. thin ﬁlm resistor (TFR)) [12]–[18] have become important in the recent years. Especially, a high accuracy TFR needs to make a light, thin, short and small product with a decrease of tolerance for electronic and optical devices applications. Tantalum nitride is a mechanically hard, chem- ically inner and corrosion-resistance material, and has good shock/heat resistant properties. These properties make the material attractive for many industrial applications for use as TFR material in portable electronic product. A low or near-zero temperature coefﬁcient of resistance (TCR) is also required for the purpose of high reliability in TFR. But how Manuscript received December 3, 2014; revised December 21, 2014 and January 5, 2015; accepted January 13, 2015. Date of publication January 23, 2015; date of current version February 20, 2015. This work was performed at the National Science Council Core Facilities Laboratory for Nano-Science and Nano-Technology in the Kaohsiung-Pingtung area and was supported by the National Science Council of the Republic of China under Contract NSC- 103-2112-M-110-011-MY3. The review of this letter was arranged by Editor C. P. Yue. (Corresponding authors: Y.-C. Chen and T.-C. Chang.) H.-R. Chen and Y.-C. Chen are with the Department of Electrical Engi- neering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan. (e-mail: ycc@mail.ee.nsysu.edu.tw). T.-C. Chang, Y.-T. Tseng, and C.-Y. Lin are with the Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (e-mail: tcchang3708@gmail.com). K.-C. Chang, T.-M. Tsai, T.-J. Chu, and C.-C. Shih are with the Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan. H.-C. Lin is with Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan. Color versions of one or more of the ﬁgures in this letter are available online at http://ieeexplore.ieee.org. Digital Object Identiﬁer 10.1109/LED.2015.2396196 Fig. 1. The schematic diagram of supercritical CO 2 ﬂuids systems and TaN TFR device structure for treatment. to make the TFR conform the requirement of a stricter spec for car-used electronic applications, the TCR control should be investigated according to physical mechanism through different treatment methods. Supercritical phase is peculiar with its characteristics of high penetration of gas and solubility of liquid. The supercritical water ﬂuid has tremendous oxida- tion property [19]. However, high critical temperature and high critical pressure are essential condition to achieve supercritical water ﬂuid, which is difﬁcult to realize through modern facilities. By adding a little water into supercritical CO 2 ﬂuids, the liquid water can attain to the supercritical ﬂuid phase due to the phase close to idea solution. In this study, TaN thin ﬁlm resistor devices were fabricated to do the current-voltage measurement and analysis. The thermal annealing and SCCO 2 ﬂuid treatment methods were applied so as to analyze the physical mechanism of carrier conduction in TFR devices. Conduction current ﬁtting together with vary-temperature current-voltage measurement data were thoroughly investigated, from which current conduction mechanisms was determined. Finally, a molecular reaction model was proposed to explain the inﬂuence of the SCCO 2 process on the current conduction mechanisms in TaN thin ﬁlm resistor. II. EXPERIMENTAL SETUP The experimental thin ﬁlm resistor devices (the left bottom scheme of Fig. 1) were prepared as follows: Firstly, the 0741-3106 © 2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.