基于高介电常数薄膜的MEMS静电式超级电容器制备及电学特性研究
发布时间：2019-06-09 12:26
【摘要】：MEMS超级电容器是能源存储中的先进领域,对于MEMS传感器、医疗、交通等方面的发展发挥着越来越重要的作用。根据工作原理不同,MEMS超级电容器可以分为电化学超级电容器和静电式超级电容器,电化学超级电容器近年来发展较快,其具有能量密度大、循环寿命长等优点。相比于电化学超级电容器,静电式电容器的能量密度较低,但是具有非常高的功率密度和可靠性。为了解决静电式超级电容器能量密度低的问题,可以从两个方面进行研究:(一)增大电极的比表面积;(二)选用介电常数高的电介质。本文分别从以上两个方面进行研究,并对MEMS静电式超级电容器的制备工艺进行了设计。具体研究内容主要包括以下三个部分:1、为了增大MEMS静电式超级电容器电极的比表面积,本文分别采用湿法刻蚀和干法刻蚀的方法在硅基底上制备三维凹槽阵列。对于湿法刻蚀,研究了掩膜版尺寸、刻蚀液配比等因素对刻蚀形貌的影响,并使用扫描电子显微镜(SEM)对凹槽阵列的形貌进行了表征,最终得到的凹槽阵列比表面积增大约为76.9%。对于干法刻蚀,刻蚀得到高深宽比凹槽阵列的形貌以及可靠性通过SEM进行表征,分析了在不同掩膜版尺寸下刻蚀凹槽的侧壁垂直度及粗糙度,最终得到的凹槽阵列比表面积增大约为14倍。2、本文提出将CaCu_3Ti_4O_(12)(CCTO)薄膜应用于MEMS静电式超级电容器中,提高电容器的介电常数。首先,通过溶胶-凝胶法在硅基底上制备烧结温度分别为700℃、800℃、900℃条件下的CCTO薄膜,分别采用扫描电镜(SEM)、X射线衍射仪(XRD)和能谱仪(EDS)分析薄膜的表面形貌、结晶状况以及物相组成,结果得到800℃烧结温度下的CCTO薄膜质量最佳。然后,使用半导体特性分析仪测试其电流-电压(I-V)和电容-电压(C-V)特性,得到薄膜的最大阈值电压为47V,能量密度达到3.2J/cm~3。同时,本文首次研究了高介电常数CCTO薄膜中存在的介质充电现象,并分析了介质充电对静电式超级电容器性能的影响。3、对MEMS静电式超级电容器的制备工艺进行了设计。分别就电极制备、电介质制备以及可靠性等方面进行了讨论。提出阳极氧化法制备电介质薄膜的方法,并进行了初步实验和电学特性分析。下一步将继续开展实验进行优化和验证。
[Abstract]:MEMS supercapacitor is an advanced field of energy storage, which plays a more and more important role in the development of MEMS sensor, medical treatment, transportation and so on. According to the working principle, MEMS supercapacitors can be divided into electrochemical supercapacitors and electrostatic supercapacitors. Electrochemical supercapacitors have developed rapidly in recent years and have the advantages of high energy density and long cycle life. Compared with electrochemical supercapacitors, electrostatic capacitors have lower energy density, but have very high power density and reliability. In order to solve the problem of low energy density of electrostatic supercapacitors, two aspects can be studied: (1) increasing the specific surface area of the electrode; (2) selecting the dielectric with high dielectric constant. In this paper, the above two aspects are studied, and the preparation process of MEMS electrostatic supercapacitor is designed. The main research contents are as follows: 1. In order to increase the specific surface area of MEMS electrostatic supercapacitor electrode, three-dimensional groove array was fabricated on silicon substrate by wet etch and dry etch, respectively. For wet etch, the effects of mask size and etched liquid ratio on the etched morphology were studied, and the morphology of the groove array was characterized by scanning electron microscope (SEM). Finally, the specific surface area of the groove array increases by about 76.9%. For dry etch, the morphology and reliability of groove array with high aspect ratio are characterized by SEM. The sidewall verticality and roughness of etched groove under different mask sizes are analyzed. Finally, the specific surface area of the groove array is increased by about 14 times. 2. In this paper, CaCu_3Ti_4O_ (12) (CCTO) thin film is applied to MEMS electrostatic supercapacitors to improve the dielectric constant of the capacitors. Firstly, CCTO thin films were prepared on silicon substrate by sol-gel method at sintering temperatures of 700 鈩，
本文编号：2495554
[Abstract]:MEMS supercapacitor is an advanced field of energy storage, which plays a more and more important role in the development of MEMS sensor, medical treatment, transportation and so on. According to the working principle, MEMS supercapacitors can be divided into electrochemical supercapacitors and electrostatic supercapacitors. Electrochemical supercapacitors have developed rapidly in recent years and have the advantages of high energy density and long cycle life. Compared with electrochemical supercapacitors, electrostatic capacitors have lower energy density, but have very high power density and reliability. In order to solve the problem of low energy density of electrostatic supercapacitors, two aspects can be studied: (1) increasing the specific surface area of the electrode; (2) selecting the dielectric with high dielectric constant. In this paper, the above two aspects are studied, and the preparation process of MEMS electrostatic supercapacitor is designed. The main research contents are as follows: 1. In order to increase the specific surface area of MEMS electrostatic supercapacitor electrode, three-dimensional groove array was fabricated on silicon substrate by wet etch and dry etch, respectively. For wet etch, the effects of mask size and etched liquid ratio on the etched morphology were studied, and the morphology of the groove array was characterized by scanning electron microscope (SEM). Finally, the specific surface area of the groove array increases by about 76.9%. For dry etch, the morphology and reliability of groove array with high aspect ratio are characterized by SEM. The sidewall verticality and roughness of etched groove under different mask sizes are analyzed. Finally, the specific surface area of the groove array is increased by about 14 times. 2. In this paper, CaCu_3Ti_4O_ (12) (CCTO) thin film is applied to MEMS electrostatic supercapacitors to improve the dielectric constant of the capacitors. Firstly, CCTO thin films were prepared on silicon substrate by sol-gel method at sintering temperatures of 700 鈩，
本文编号：2495554
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