【作者】 张红治；

【导师】 胡礼中；

【作者基本信息】 大连理工大学 ， 微电子学与固体电子学， 2008， 博士

【摘要】 扫描近场光学显微术(SNOM)是一种新型纳米尺度结构和信息研究的强有力的光电子学工具,它打破了传统光学衍射极限的限制,分辨率可达到纳米量级。其重要的应用之一是适应现代信息社会发展的需求,实现超高密度光存储。一般来说,用于超高密度光存储的扫描近场光学显微传感头由三个主要部分组成:半导体激光器、光电探测器和微探尖。这里的微探尖质量和性能将直接影响整个扫描近场光学显微系统。因此,如何制备高质量的微探尖已经成为近年来的研究热点。目前国内外制备微探尖的方法有很多种。对于光纤探尖,主要有热拉伸法和化学腐蚀法;对于介质和半导体材料探尖,主要有湿法刻蚀、干法刻蚀、混合法刻蚀、金属有机物化学气相沉积(MOCVD)和自组织液相外延法等等。根据我们实验室现有的条件,针对上面几种方法出现的问题,本论文提出了一种新型的GaAs材料微探尖制备方法——选择液相外延方法。这种方法的基本思想是在已经外延生长好的垂直腔面发射激光器(VCSEL)结构表面沉积一层掩膜,然后利用常规的光刻和湿法刻蚀手段在掩膜上面形成尺寸和周期与激光器出光窗口一致的窗口阵列,最后利用掩膜对液相外延生长的阻断作用在窗口中液相外延生长出金字塔状微探尖。这种方法不仅可以将微探尖直接生长在激光器的出光表面上,省略了探尖转移的步骤,还自动解决了微探尖与激光器出光窗口的对准问题,并为实现多探尖并行扫描提供了工艺基础。在研究过程中,我们使用GaAs(001)衬底模拟VCSEL外延片表面,采用选择液相外延方法制各GaAs微探尖阵列,并用扫描电子显微镜(SEM)对微探尖阵列进行表征。结果表明,在合适的条件下,微探尖呈金字塔状,并具有较好的分布周期性和一致性。本文详细介绍了该种方法的工艺流程,包括掩膜的制备、光刻、湿法刻蚀、液相外延等等。研究了不同掩膜对微探尖生长的影响以及不同形状和不同取向的窗口设计对微探尖生长的影响,得到了不同窗口中微探尖的生长过程,优化了微探尖制备的液相外延生长条件。除此之外,考虑到工艺兼容等问题和拓展选择液相外延方法制备的微探尖的应用范围,我们还开发了两套微探尖的剥离技术(浓盐酸选择腐蚀缓冲层法和氨水选择腐蚀衬底法)与一套转移技术,成功地将微探尖从衬底上面剥离并转移到VCSEL的出光窗口表面,实现了微探尖和激光器的集成。这样使得选择液相外延方法制备的微探尖也可以应用于其它种类的扫描探针显微镜。最后,本论文介绍了晶体生长形态学中的布拉维法则、BFDH理论和SHAPE晶体生长形态模拟软件,采用这两种理论和SHAPE软件对GaAs晶体生长形态进行了预测和模拟,得到的预测结果和模拟结果与实验结果吻合得比较好。本项研究工作连续得到了两项国家自然科学基金(《用于超高密度光存储的集成式SNOM微探尖的选择生长研究》No.60377005和《影响GaAs微探尖阵列选择外延生长质量的关键技术研究》No.60777009)、科技部重大基础研究前期研究专项(《超高密度光存储》No.2004CCA03700)和高等学校博士学科点专项科研基金(《用于SNOM传感器的GaAs微探尖阵列选择生长质量改进技术》NO.20060141026)的支持,并已成功获得国家发明专利一项,批准号为ZL 03 1 33404.0。更多还原

【Abstract】 Scanning near-field optical microscopy （SNOM） is a novel photoelectrical tool for the research down to the nanometer scale. It uses the evanescent field confined at the tiny aperture to provide images of rough surfaces with a resolution beyond the classical optical diffraction limit. One of the most important potential application of SNOM may be found in ultra-high density optical recording. Generally speaking, SNOM sensor is composed of three main parts, semiconductor laser, photoelectronic detector and the microtip. Since microtip is one essential part of SNOM, the fabrication of high quality microtips has become a key issue.Up to now, many microtip fabricating techniques have been explored. As for fiber microtips, the main fabrication techniques are thermal stretching and chemical etching. As for semiconductor microtips, the main fabrication techniques are wet etching, MOCVD, mixed etching, self-assembled liquid phase epitaxy and so on. According to the conditions of our lab, we present a new simple selective liquid phase epitaxial growth of GaAs pyramidal microtips. The main steps of the technology can be divided into three parts. First, a 20-30nm thick thin film is deposited on the treated GaAs substrate. Second, the periodic windows with regular sizes are created in the mask using standard photolithography and wet etching. Third, the GaAs substrate with the mask openings is loaded into a conventional LPE system to carry out the selective liquid phase epitaxial growth of microtips in an atmosphere of Pd-purified hydrogen. This method not only can grow GaAs microtips directly on the VCSEL wafer and avoid transferring microtips but also settle the problems of aligning the microtips with light-emiting windows of lasers. It also provides a technology basis for batch production and parallel scanning with several microtips.The （001） GaAs substrates are used instead of VCSEL wafers in our preliminary experiments, Scanning electron microscopy （SEM） is used to characterize the morphology of GaAs microtips. The results indicate that in appropriate conditions the microtips are pyramid-like and distribute uniformly on the wafers.This technology of fabricating microtips is introduced in great detail in this thesis, including mask preparation, photolithography, wet etching and liquid phase epitaxial growth. The effects of different masks and different mask openings on the liquid phase epitaxial growth of GaAs microtips are investigated. The morphological evolution of GaAs microtips in different mask openings are also illustrated and the LPE experimental conditions are optimized to improve the quality of tips. Besides, we also provide two methods to transferring GaAs microtips, selective wet etching Al_0.7Ga_0.3As buffer layer using concentrated HCl solution and selective wet etching GaAs substrate by diluent ammonia solution. Both of the two methods are compatible with selective liquid phase epitaxy. Furthermore, we realize the integration of microtips and VCSEL, which expands the application of the selective liquid phase epitaxial GaAs microtips for other scanning probe microscopy.In the end, Bravais law, BFDH theory and SHAPE software are employed to preview and simulate the morphology of GaAs microtips grown in free growth system. And the results agree with the experimental results well.This work is financially supported by two National Nature Science Foundations of China under project No.60377005 and No.60777009, Special Fund for Preliminary Research of Key Basic Research Project from Ministry of Science and Technology of China under project No.2004CCA03700 and Special Research Fund for Doctoral Program of Higher Education under project No.20060141026. One national patent has been authorized and the Patent Number is ZL 03 1 33404.0.更多还原