【作者】 张东；

【导师】 边继明； 秦福文； 鞠振河；

【作者基本信息】 大连理工大学 ， 微电子学与固体电子学， 2013， 博士

【摘要】 自支撑金刚石膜基片既具有天然金刚石最高的弹性刚度系数又具有最高声速的优异性能,使之成为声表面波滤波器(SAW)最佳的衬底选择材料,避免了其它基片散热差的问题。压电薄膜／自支撑金刚石膜结构的SAW器件既利用了压电薄膜良好的压电特性和金刚石最高声速的优异性能,又充分利用了二者高导热性和优良耐热性的优点。所以这种结构是制作高频、大功率SAW滤波器的理想选择。本研究使用电子回旋共振等离子体增强有机物化学气相沉积(ECR-PEMOCVD)系统在自支撑金刚石厚膜上沉积制备了GaN和A1N压电薄膜,主要通过怎样在白支撑金刚石基片上得到性能优异的压电薄膜这一主题”开展了系统的研究工作。结论如下：1、ECR-PEMOCVD系统在自支撑金刚石厚膜基片上沉积制备GaN压电薄膜(1)基片温度对薄膜质量有很大的影响,基片温度为400℃时薄膜具有较好的结晶质量,呈高C轴择优取向。此时薄膜表面形貌光滑平整且具有较好的光学和电学特性。(2)改变TMGa源流量对薄膜进行了制备及其性能分析,TMGa流量是0.5sccm时薄膜具有较好的质量,而且此时的薄膜具有较高的择优取向和平整光滑的表面形貌。(3)改变N2流量,对薄膜进行了沉积制备,N2流量为100sccm时,薄膜具有较好的择优取向以及光滑的表面形貌,此时薄膜的电学性能比较优越。(4)缓冲层的改变对薄膜的制备影响较为明显,改变缓冲层的温度对薄膜进行了制备与分析,在温度适中的情形下,薄膜具有择优的生长取向和平整光滑的表面形貌。2、ECR-PEMOCVD系统在自支撑金刚石厚膜基片上沉积制备A1N压电薄膜(1)改变基片温度对样品薄膜质量影响较为明显。基片温度为600℃时,薄膜具有较高的择优取向和较平整光滑的表面形貌,该条件下的样品满足器件的制备要求。(2)N2流量对薄膜的影响较大,N2流量的大小直接影响到反应活性N粒子的多少,N2流量适中的情形下薄膜具有较高的择优取向以及平整的表面形貌。并对其薄膜样品的成分进行了分析,薄膜中N的含量很高,这与N空位有很大的关系。对薄膜进行了电学性能测试,结果表明薄膜样品为高阻抗性。实验检测发现改变基片温度、反应源流量以及缓冲层条件对样品的影响很明显。这说明自支撑金刚石厚膜上沉积压电薄膜的工艺要求很严格。实验中已经制备出满足SAW器件的高质量压电薄膜,这对提高SAW器件的频率有很大的作用。更多还原

【Abstract】 The freestanding thick diamond films combine the highest elastic stiffness coefficient and the excellent performance of maximum speed of sound; it is a reasonable substrate material with the SAW filter, which can avoid the problem of the poor heat than that of other substrates. The structure of piezoelectric film/freestanding thick diamond films can only use the piezoelectric film with excellent piezoelectric properties and freestanding thick diamond films with excellent properties of maximum speed of sound, but also make full use of both high thermal conductivity and excellent heat resistance advantage. Therefore, this structure can be the ideal material for preparing the high-frequency and high-power SAW filter. In this study, the piezoelectric films of high quality with good performance and application requirements were prepared on freestanding diamond thick films by the method of this process, which lays a good foundation for further device fabrication and application.In this study, the GaN and A1N films were prepared on the freestanding diamond thick films using by ECR-PEMOCVD system, which mainly through the theme "how to achieve the high quality piezoelectric films with good performance" to carry out the research work.The conclusion as following:1, The GaN piezoelectric film was prepared on freestanding diamond thick films by ECR-PEMOCVD.(1), The deposited temperature plays a important role for the quality of as-grown films, when the deposited temperature is400℃, the as-grown is of the good crystalline quality with the high C-axis oriented growth. The surface morphology of the sample is very smooth, which meets the requirements of the SAW device. Optical and electrical properties of the samples were tested, the results show that the as-grown films have excellent optical and electrical properties.(2), The GaN films were prepared with various TMGa flux and the properties of the as-grown films were investigated. When the TMGa flux is0.5sccm, the as-grown film is of the high quality with the high oriented growth and smooth surface morphology.(3), The GaN films were prepared with various N2flux and the properties of the as-grown films were investigated. When the N2flux is100sccm, the as-grown film is of the high quality with the high oriented growth and smooth surface morphology. The electrical properties of as-grown films were very excellent.(4), The buffer layer plays an important role for the quality of as-grown films, the GaN films were prepared with various buffer layer process and the properties of the as-grown films were investigated. The results show that when the deposition temperature of the buffer layer is proper, the as-grown film is of the high quality with the high oriented growth and smooth surface morphology.2, The A1N piezoelectric film was prepared on freestanding diamond thick films by ECR-PEMOCVD.(1), The deposited temperature plays a important role for the quality of as-grown A1N films, when the deposition temperature is too high or too low, it is not conductive to deposit the as-grown films. When the deposited temperature is400℃, the as-grown is of the good crystalline quality with the high C-axis oriented growth. The surface morphology of the sample is very smooth, which meets the requirements of the SAW device.(2), The N2flux plays a important role for the quality of as-grown A1N films, and the N2flux directly affect the quantity of the reactivity N-particle. When the N2flux is proper, the as-grown films is of the high-quality and high-preferred orientation as well as the smooth surface morphology. And we investigate the composition of the samples, the results show that the N content is high, which is due to the the N vacancies and the Al/N atomic percentage has a large effect on the quality of the as-grown films. We investigate the electrical properties of as-grown films, and the results show that the as-grown films have the high impedance.The experimental results show that deposition temperature, reaction source flux as well as buffer layer process are very important for depositing the as-grown films and the process of the as-grown piezoelectric films deposit on freestanding thick diamond films is very strict, which is affect on the quality of as-grown films with a slight change. The high-quality as-grown films have been prepared on the freestanding thick diamond substrate, and the piezoelectric film of high quality has a significant role to improve the frequency of the SAW devices.更多还原