Direct carbon patterning on a conducting substrate in an organic liquid
Direct carbon patterning on a conducting substrate in an organic liquid
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DOI：
10.1016/j.carbon.2005.11.003
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发表时间：
2006-04
期刊：
影响因子：
10.9
通讯作者：
Tomoaki Watanabe;Hao Wang;Yasuaki Yamakawa;M. Yoshimura
中科院分区：
文献类型：
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作者：
Tomoaki Watanabe;Hao Wang;Yasuaki Yamakawa;M. Yoshimura
经济、环保的图形化技术是提高非晶碳薄膜应用的关键。我们已经开发出一种直接图案化技术，允许同时沉积和图案化的无定形碳膜在有机液体中的基板上。近年来，类金刚石薄膜和硬质非晶碳薄膜由于具有高硬度、大光学带隙、高热导率和高电阻率等优点而受到人们的广泛关注。由于所有的应用都需要某些复杂的形状，直接构图成为使其能够在广泛的器件中使用的关键技术之一。目前，通过物理气相沉积（PVD）和/或化学气相沉积（CVD）与光刻[1]、用细颗粒烧蚀衬底[2]、催化剂图案化方法[3]等的组合，在衬底上沉积和图案化非晶碳膜。PVD和CVD昂贵且不环保，因为它们的前体和设备复杂，材料使用效率低，以及由于稀释的高能蒸汽物质而导致的高能耗。此外，光刻涉及几个复杂的过程，如蚀刻和掩模，这会导致额外的材料和热量浪费。作为我们尝试实现陶瓷材料的“软溶液处理”的一部分，其具有许多经济和环境优势[4，5]，我们首先开发了一种在液体中在导电基底上存款碳膜的新方法[6]。在该方法中，通过在基板和充当阳极的另一个电极之间施加DC电流，在室温下在乙醇中在基板的大面积上沉积碳膜。在本研究中，通过使用薄电极和控制其移动与射频电源，我们成功地在一个单一的步骤中沉积无定形碳膜的图案在基板上，没有特殊的预处理或后处理的基板或图案化的膜。以钨丝为电极，在Si（111）晶片上以一定的图形电沉积碳膜。对导丝进行电化学抛光，使头端直径小于1 μm。在室温下，将笔电极放置在乙醇中的基板附近几百微米内，并在两个电极之间施加射频功率（约21 MHz/5 W）。笔被安装在机电平台上，其运动由计算机控制，以创建给定的图案（图1）。由于笔和基板之间的小间隔，产生高度集中的电场;这使得能够创建精细图案。然而，需要比我们的设置中使用的笔控制器更精确的笔控制器。相比之下，笔和基板之间的大间隔需要高得多的电压并且导致宽图案。通过激光显微镜（VK-8500，Keyence Co.，Japan）和显微拉曼光谱（T64000，Atago-Jobin Yvon，France-Japan; Ex.波长514.5 nm）。图2示出了通过所提出的方法在Si晶片上写入的典型无定形碳图案的激光显微照片。该图案的线宽约为20-30 μm，无需任何后处理就能紧密地粘附在基底上。有人提出，当使用细线电极进行溶剂的电解时，在溶剂中发生局部焦耳加热。根据suitable 0008 -6223/$-见前页© 2005爱思唯尔.
Economical and environment-friendly patterning techniques are essential for increasing the applications of amorphous carbon films. We have developed a direct patterning technique that permits the simultaneous deposition and patterning of amorphous carbon films on substrates in organic liquids. In recent years, diamond-like carbon and hard amorphous carbon films have attracted considerable attention because of their high hardness, large optical band gap, high thermal conductivity, and high electrical resistivity. Since all the applications require certain complicated shapes, direct patterning becomes one of the key techniques to enable their usage in a wide range of devices. Currently, amorphous carbon films are deposited and patterned on substrates by the combination of physical vapor deposition (PVD) and/or chemical vapor deposition (CVD) with photolithography [1], ablation of substrates with fine particles [2], catalyst patterning method [3], etc. PVD and CVD are expensive and not environment-friendly because of their sophisticated precursors and equipment, inefficient use of materials, and high-energy consumption due to diluted high-energy vapor species. Moreover, photolithography involves several complicated processes such as etching and masking, which cause additional wastage of materials and heat. As a part of our attempt to achieve the ‘‘soft solution processing’’of ceramic materials, which has many economical and environmental advantages [4, 5], we first developed a novel method to deposit carbon films on a conductive substrate in a liquid [6]. In this method, carbon films are deposited on a large area of a substrate in ethanol at room temperature by applying a DC current between the substrate and another electrode that acts as the anode. In the present study, by using a thin electrode and controlling its movement with radio frequency power supply, we succeeded in depositing a pattern of amorphous carbon films on the substrate in a single step with no special pre-or post-treatment of either the substrate or the patterned films. A thin electrode consisting of a tungsten wire was used as a ‘‘pen’’to electrodeposit carbon films in a given pattern on a Si (111) wafer. The wire was electrochemically polished such that the tip was less than 1 μm in diameter. The pen electrode was placed near the substrate within several hundred micrometers in ethanol at room temperature, and radio frequency power (about 21 MHz/5 W) was applied between the two electrodes. The pen was mounted on an electromechanical stage whose movement was controlled by a computer in order to create the given pattern (Fig. 1). Due to the small separation between the pen and substrate, a highly concentrated electric field is generated; this enables the creation of a fine pattern. However, a more precise pen controller than that used in our setup is required. In contrast, a large separation between the pen and substrate requires a much higher voltage and leads to a broad pattern. The morphology, composition, and microstructure of the patterned carbon deposits were characterized by laser microscopy (VK-8500, Keyence Co., Japan) and micro-Raman spectroscopy (T64000, Atago-Jobin Yvon, France–Japan; Ex. wavelength of 514.5 nm). Fig. 2 shows the laser micrograph of a typical amorphous carbon pattern written on the Si wafer by the proposed method. The pattern, whose line width was about 20–30 μm, had tightly adhered to the substrate without any post-treatment. It is proposed that, when the electrolysis of a solvent is carried out using a thin wire electrode, local Joule heating occurs in the solvent. Under suitable0008-6223/$-see front matter© 2005 Elsevier …