Fabrication of high-quality micro-cavity for filter cell of rubidium atomic clock

在芯片级铷原子钟中,需要微腔体来承载rb—87滤光泡,为此,提出了一种用于制作高品质微腔体的新技术。为了获得光滑的腔体侧面和避免腐蚀过程中凸角处产生削角现象,研究中采用了超声腐蚀技术和凸角补偿技术。首先,分别在纯kOH溶液,并结合搅拌和超声等方法,对(100)硅片进行湿法腐蚀,并运用激光共聚焦扫描显微镜对腐蚀后的{111}表面进行粗糙度测量,表明运用超声腐蚀技术可以获得光滑的{111}腔体侧面。在此基础上,引入条形掩模凸角补偿方法进行微腔体腐蚀。实验结果表明:在80℃、质量分数为30%kOH、超声频率和功率分别为59 kHz和160 W的溶液中腐蚀,其{111}腐蚀表面粗糙度为0.117μM,同时条形的长度取1200μM时,可以获得平滑规整的微腔体。In chip-scale rubidium atomic clock,the Rb—87 filter is required to be loaded in micro-cavity,so present a new technology for fabrication of the high-quality micro-cavity.In order to gain smooth side surfaces,i.e.Si( 111) plane,of micro-cavity and to avoid undercutting at the concave corner,ultrasonic etching and concave corner compensation techniques are used.First,silicon( 100) wafer is wet etched in the pure KOH etching solution with ultrasonic and stirring,and the roughness of Si { 111 } wet-etched surface is measured by laser scanning confocal microscope( LSCM).On this basis,a strip mask compensation method for concave corner is adopted for micro-cavity etching.The results show that the etched Si{ 111} surface roughness can achieve 0.117 μm( RMS) in mass fraction 30 % KOH etching solution at 80 ℃ with ultrasonic frequency of 59 kHz and power of 160 W,and when the strip length is 1 200 μm,smooth micro-cavity can be obtained.福建省重大科技项目前期研究计划资助项目(2005HZ1021

The CVD Synthesis, Transfer Technology of Graphene and its Thermal Management Application

石墨烯是一层由碳原子以sp2杂化结构连成的单原子层，石墨烯由于其超高的热导率，在散热领域有广阔的应用前景。目前石墨烯复合散热材料的研究相对较多，但对于二维石墨烯散热应用的研究相对较少。二维的石墨烯散热导流层在传统散热器的基础上更兼具体积小、易于集成、与微电子工艺兼容、散热性能更好等优势。但高质量、大面积石墨烯的制备与转移目前还存在诸多难点，对石墨烯的微纳米加工技术还存在很多问题。基于此，本文重点研究石墨烯的生长和转移技术的优化，利用有限元方法探究石墨烯散热导流层性能及其影响因素，旨在优化石墨烯的散热性能。 为了生长出大面积、高质量、连续性好的石墨烯，本文选择化学气相沉积法来制备石墨烯，通过控...Graphene is a monolayer material composed of carbon atoms with sp2 hybridization. With ultra-high thermal conductivity, graphene has a broad application in heat dissipation. Currently, most researches are related about graphene composite materials for heat dissipation rather than graphene heat spreader. Compared with traditional heat sink, graphene heat spreader has a lot of metrits such as flexib...学位：工学硕士院系专业：物理科学与技术学院_微电子学与固体电子学学号：1982013115297

Preparation of Single Layer Graphenes via an Optimized CVD Method

作为碳原子家族的最新成员,二维结构的石墨烯具备优异的物理化学性质和广阔的应用前景,成为新材料研究领域的热点研究对象。对化学气相沉积（CVD）法进行了优化,成功制备得到了高质量的单层石墨烯。优化后的实验工艺为：首先对铜箔进行化学抛光和退火预处理;然后将预处理后的铜箔加工成荷包状;氢气（H2）氛围下,以甲烷（CH4）为碳源,对石墨烯进行化学气相沉积;当甲烷和氢气体积流量分别为10 cm3/min和20 cm3/min时,在1 030℃条件下生长20 min制备得到最终样品。扫描电子显微镜（SEM）和激光喇曼光谱表征的结果显示：该方法制备的样品为大面积连续的单层石墨烯。As the latest member of the carbon family,the graphene with two-dimensional structure becomes a hot research subject in the new material research field due to its outstanding physical and chemical properties and wide application prospect.The single layer graphene with high quality was prepared successfully by the optimized chemical vapor deposition（CVD）method.In the optimized experiment process,the chemical polishing and annealing pre-treatment of the Cu foil were carried out firstly,then the pre-treated Cu foil was fabricated into a cavity shape;the CVD growth of the graphene was conducted with the methane（CH_4）as the carbon source under the hydrogen（H_2）atmosphere.The final samples were prepared at 1 030 ℃for 20 min with the CH_4 and H_2volume flow rates of 10 cm^3/min and 20 cm^3/min,respectively.The results characterized by the scanning electron microscope（SEM）and Raman spectroscopy show that the single layer graphene with high quality and large area can be obtained via this optimized CVD procedure.厦门市科技项目（3502Z20143003

Optimization of the Wet Transfer Technique of Graphene

石墨烯的转移过程决定着石墨烯的品质,进而对石墨烯基器件的性能有重要的影响。针对化学气相沉积（CVD）法生长的石墨烯在湿法转移过程中存在的问题,在常规湿法转移的基础上进行了优化研究。实验结果表明：基体背面石墨烯的刻蚀工艺可以有效解决铜箔残留问题;采用二次涂胶工艺可以大幅降低石墨烯的裂痕破洞密度;超声波处理有效提升了石墨烯表面残胶的去除效率。优化后的转移工艺可以明显降低石墨烯产品中的杂质数量和缺陷密度,提升石墨烯的表面洁净度,显著地提高石墨烯质量。The transfer process of graphene plays an important role in determining the quality of graphene,which further exerts an important influence on the performances of graphene-based devices.For resolving the problem in the wet transfer process of graphene grown by the chemical vapor deposition（CVD）method,the optimized procedure was researched based on the conventional wet transfer of graphene.The experimental results show that the residue of copper is effectively eliminated by an extra etching of the graphene deposited on the back of copper.The densities of surface cracks and holes are largely reduced with the two-step coating process.The removal efficiency of the residual polymer on the surface of graphene is significantly enhanced by the ultrasonic treatment.The optimized transfer procedure can obviously reduce the amount of impurities and defect density of graphene and significantly improve the surface cleanliness and quality of graphene.厦门市科技项目（3502Z20143003