蓝宝石衬底片的精密加工

对SiO2磨料抛光蓝宝石衬底片进行了研究。结果表明,采用大粒径、高浓度的SiO2磨料抛光,可以获得良好的表面状态和较高的去除速率。抛光的适宜温度及pH值条件为:T=30℃;12.0>pH值≥9.0。并且,在抛光时应加入适量添加剂,方可获得较为理想的表面状态和较高的去除速率。实验同样证明,这种低成本、高质量的抛光除了可以应用于蓝宝石的抛光以外,还可以应用在其它一些硬质材料的抛光工艺中。     

蓝宝石衬底片化学机械抛光的研究

为了提高蓝宝石化学机械抛光（CMP）效果，对其抛光工艺进行了研究。采用SiO2磨料对蓝宝石衬底片进行抛光，分析了抛光时的温度、pH条件、磨料粒径及浓度，结果表明，采用80nm大粒径、高浓度的SiO2磨料，既可以保证抛光速率，又能得到良好的表面状；当pH值在10～12时，可加速蓝宝石在碱性条件下的化学反应速率，从而提高抛光速率；在30℃时，能较好地平衡化学作用与机械作用，获得平滑表面；加入适量添加剂，可增大反应产物的体积，易于提高机械作用的效果，以获得较高的去除速率。     

不同磨料对蓝宝石CMP的影响

在化学机械抛光(CMP)系统中,磨料是决定去除速率和表面状态的重要因素。在单一磨料下进行了单因素实验,在不同的压力、转速、流量和温度下对比了SiO2磨料和Al2O3磨料对蓝宝石去除速率及表面状态的影响;同时也探究了混合磨料对蓝宝石去除速率的影响。研究表明,在单一磨料的CMP实验中,当压力为4 psi(1 psi=6 894.76 Pa)、转速为80 r/min、流量为70 mL/min和温度为35℃时,SiO2磨料对蓝宝石的去除速率高,表面状态好;在混合磨料的CMP实验中,和单一的SiO2磨料相比,Al2O3/SiO2混合磨料对蓝宝石的去除速率要低很多,而SiO2/CeO2混合磨料的去除速率要比单一SiO2磨料的略高一些。     

磨料对蓝宝石衬底去除速率的影响

蓝宝石晶体已经成为现代工业,尤其是微电子及光电子产业极为重要的衬底材料,提高其化学机械抛光效率是业界无法回避的问题。在CMP系统中,磨料是决定去除速率及表面状态的重要因素。分析了化学机械抛光过程中抛光液中磨料的作用以及抛光机理,在确保表面状态的基础上,研究了抛光液中磨料体积分数、粒径和抛光液的黏度对速率的影响,指出纳米磨料是蓝宝石衬底抛光的最佳磨料。选用合适的磨料体积分数、粒径及抛光液黏度,不仅获得了良好的去除速率,而且有效地解决了表面状态方面的问题。     

蓝宝石衬底材料CMP去除速率的影响因素

阐述了蓝宝石衬底应用的发展前景及加工中存在的问题,分析了蓝宝石衬底化学机械抛光过程中pH值、压力、温度、流量、抛光布等参数对去除速率的影响。提出了采用小流量快启动的方法迅速提高CMP温度,在化学作用和机械作用相匹配时(即高pH值、大流量或低pH值,小流量)可得到较高去除速率,且前者速率高于后者。实验采用nm级SiO2溶胶为磨料的碱性抛光液,使用强碱KOH作为pH调节剂,并加入了适当的表面活性剂及螯合剂等。工艺参数为压力0.18MPa、温度45℃、转速60r/min,采用Rodel-suba 600抛光布,在保证表面质量的同时得到的最大去除速率为11.35μm/h。     

硬盘基板化学机械粗抛光的实验研究

针对硬盘NiP/Al基板粗抛光,采用SiO2作为抛光磨料的碱性抛光液,在不同压力、转速、pH值、磨料浓度和活性剂体积浓度下,对硬盘基板粗抛光的去除速率和表面粗糙度的变化规律进行研究,用原子力显微镜观察抛光表面的微观形貌。最后对5个关键参数进行了优化。结果表明:当压力为0.10 MPa,转速为80 rad/min,pH值为11.2,磨料与去离子水体积比为1∶0.5,表面活性剂体积浓度为9 mL/L时,硬盘基板的去除速率为27 mg/min,粗抛后表面粗糙度为0.281 nm,获得了高的去除速率和较好的表面粗糙度,这样会大大降低精抛的时间,有利于抛光效率的提高。     

磨料特性对InP晶片集群磁流变抛光效果的影响

对InP晶片进行了集群磁流变抛光实验,研究了抛光过程中磨料参数(类型、质量分数和粒径)对InP材料去除速率和表面粗糙度的影响。实验结果表明,InP晶片的去除速率随磨料硬度的增加而变大,表面粗糙度受磨料硬度和密度的综合影响;在选取的金刚石、SiC、Al2O3和SiO2等4种磨料中,使用金刚石磨料的InP去除速率最高,使用SiC磨料的InP抛光后的表面质量最好。随着SiC质量分数的增加,InP去除速率逐渐增加,但表面粗糙度先减小后增大。当使用质量分数4%、粒径3μm的SiC磨料对InP晶片进行抛光时,InP去除速率达到2.38μm/h,表面粗糙度从原始的33 nm降低到0.84 nm。     

SiO_2/CeO_2混合磨料对微晶玻璃CMP效果的影响

在微晶玻璃表面的超精密加工中,抛光磨料是抛光液重要的组成部分,它不仅影响着微晶玻璃的去除速率,而且对表面的粗糙度有着重要的影响。把超大规模集成电路的CMP技术引入到微晶玻璃的抛光中,在分析SiO2/CeO2混合磨料对微晶玻璃表面作用原理的基础上,进行了大量的实验研究,结果表明,通过调节SiO2/CeO2的配比和优化相关工艺参数可以得到应用所需的粗糙度及在此粗糙度下最大的去除速率。     

蓝宝石衬底表面粗糙度的研究

简述了纳米级超光滑蓝宝石衬底的用途及发展前景,以SiO2为磨料并且加入了表面活性剂和螯合剂的碱性抛光液做了抛光实验。分析了表面粗糙度与抛光液pH值的关系,比较了不同压力对粗糙度的影响,研究了粗糙度随流量的变化规律;以原子力显微镜为主要检测工具,找到了制备超光滑蓝宝石衬底最佳CMP工艺,在保证抛光速率的同时使表面质量达到超光滑表面的要求,有效地降低了成本。     

TiO2薄膜CMP 抛光液组分的研究

在本文中,采用化学机械抛光(CMP)对TiO2薄膜进行平坦化处理,以降低TiO2薄膜表面粗糙度和提升抛光去除速率。实验基于优化的TiO2薄膜CMP工艺参数,通过研究抛光液组分：硅溶胶浓度、螯合剂和活性剂浓度以及抛光液pH值对材料去除速率和表面粗糙度的影响,获得最佳的抛光液组分。实验结果表明：在磨料SiO2浓度为8 %、螯合剂为10 ml/L、活性剂为50 ml/L,pH = 9.0时,TiO2薄膜材料去除速率(MRR)为65.6 nm/min,表面粗糙度(Ra)为1.26 ?(测试范围: 10 μm×10 μm),既保证了较高去除速率又降低了表面粗糙度。     

Simulation of a modified rotary timber machining process to improve surface form

Rotary machining is extensively used for planing and moulding operations within the woodworking industry. Although the surface form produced by this machining method is acceptable, the rotary machining action produces cutter marks on the wood surface so that further finishing operations, such as sanding, are often required to generate a product of acceptable standard. It has been theorised that the surface finish of planed and moulded timber products may be improved by oscillation of the cutter block in either a vertical or horizontal plane. This paper describes the use of a graphical simulation based on Simulink^® software to predict surface finish, and the use of computer simulation to model cutter-block oscillation. The result is a complete tool for effective design and optimisation of a hydraulic oscillation system, in combination with a surface form generator in order to improve surface form.     

精密数控抛光碳化硅表面去除特性研究

计算机数控精密机械抛光技术是制造高精度、高质量光学元件表面的主要技术之一。然而,对于碳化硅材料表面去除特性方面的研究却相对较少。在航天航空领域中,陶瓷类材料碳化硅的应用较为广泛。针对计算机数控精密机械抛光技术,根据一系列的抛光实验,研究并总结出碳化硅材料表面的去除机理。基于选择不同等级的四种变量参数:抛光磨头转速、抛光压力、磨头补偿量和抛光头角度,分析碳化硅材料表面的去除趋势。采用Taguchi方法可以有效优化实验设计参数、减少实验整体次数。结果表明:文中总结出对应的抛光参数组合和材料表面的去除特性,确保加工出高质量表面的碳化硅材料。     

Ultra-precision machining of reflector array for laser diode beam shaping

Ultra-precision machining is an effective approach to achieve high dimension accuracy and surface finish required in optical and laser components. An extensive study using a two-axis diamond turning machine is conducted to machine the reflector arrays used for laser diode beam shaping. To position the workpiece precisely, theoretical analysis is made so that the dimensional accuracy can be achieved. Investigations into machining burr reduction are carried out. With the process developed, reflectors with optical surface finish of 8 nm in Ra and minimized burr size of less than 0.5 μm have been achieved.     

虚共心腔变能量打孔的研究

目前,对于多脉冲激光打孔,往往都是采用平行平面腔而脉冲能量采用平均分配法.我们认为这对打孔的精度,表面质量及其重复性来讲是不太有利的.通过对谐振腔型的输出特性以及对脉冲能量的合理分配所进行的分析与实验表明,采用虚共心腔变能量打孔,孔的精度、表面质量及其重复性是可以得到改善的,特别是在降低打孔的锥度方面有一定突破.     

蓝宝石衬底分步清洗及其对后续氮化的影响

通过反射高能电子衍射仪(RHEED)分析蓝宝石衬底在经过双热电偶校温的ECR-PEMOCVD装置中清洗氮化实验表面晶质的RHEED图像,研究了常规清洗和ECR等离子体所产生的活性氢氮等离子体源对蓝宝石衬底清洗、氮化的实验.结果表明,经常规清洗后的蓝宝石衬底表面晶质差异较大,有些衬底再经通常的30min等离子体清洗是达不到要求的,而要根据情况施行分步清洗才能清洗充分,清洗充分的衬底经20min就可氮化出来,不充分的再长的时间也很难氮化.     

Structural properties of alloyed Ti/Al/Ti/Au and Ti/Al/Mo/Au ohmic contacts to AlGaN/GaN

Two alloyed ohmic contact structures for AlGaN/GaN–Ti/Al/Ti/Au and Ti/Al/Mo/Au were studied. Both structures were optimized for minimum ohmic contact resistance. Structures grown on sapphire and SiC substrates were used to investigate structural properties of ohmic contacts to AlGaN/GaN. Ohmic contacts to AlGaN/GaN on SiC showed higher contact resistance values compared to contacts to AlGaN/GaN on sapphire. Ohmic contact metals were etched on samples after annealing. The alloyed interface was studied with backside illumination under an optical microscope. Alloyed inclusions associated with threading dislocations were observed on the surface. For the AlGaN/GaN on SiC sample the inclusion density was an order of magnitude lower than for the sample on sapphire. Conductive atomic force microscopy with carbon nanotube tip was used to investigate topography and conductivity profile of the surface after ohmic contact metal removal by etching.     

蓝宝石光纤高温光学特性研究

实验研究了蓝宝石光纤在高温环境下(大于1000℃)的光学稳定性,以及光纤的自辐射、塑性弯曲对出射光信号的影响,结果表明蓝宝石光纤在高温下的光学传输损耗随时间增加,温度测量精度由信号的稳定性和光纤自辐射决定,而蓝宝石光纤的塑性弯曲引起的信号额外损耗比较小,在900nm处小于0.1 dB.光纤表面在高温下的永久损伤是产生这些性能劣变的主要原因,损伤的主要机制为外部杂质在高温下与光纤表面的相互作用.

Abstract：

The performance stability,self-radiation and plastically bend of sapphire fiber under high temperature are studied.Experimental results show the optical transmitter loss increases with time when sapphire fiber under high temperature environment.Temperature measurement precision depends on the stability of signal and the self-radiation of fiber.The additional loss caused by a single plastically bend is less than 0.1 dB at 900 nm,less than the loss.before bend.The permanent injury of the sapphire fiber surface is the main reason for deterioration.It is found that the surface injury is mainly attributed to the pollution of the fiber surface and the mutual reaction between the sapphire fiber and the polluted substance in the ambient environment.     

标准温度和衬底分步清洗对GaN初始生长影响RHEED研究

在经过校温的ECR-PEMOCVD装置上，通过分析RHEED(反射高能电子衍射)图像研究了常规清洗和ECR等离子体所产生的活性氢氮等离子体源对蓝宝石衬底进行清洗、氮化实验，结果表明：经常规清洗的蓝宝石衬底的表面晶质差异很大；按照经验清洗30min是不能清洗充分的，那么根据情况进行多步清洗就显得很重要了；结果表明清洗得很充分的衬底经20min的氮化出来，而未清洗充分的衬底20min或更长的时间是不能氮化出来的。     

Effects of Si-doping on structural and electrical characteristics of polar,semi-polar,and non-polar AlGaN epi-layers

The effects of Si-doping on the structural and electrical properties of the wurtzite AlGaN epi-layers grown on polar, semi-polar, and non-polar sapphire substrates by metal organic chemical vapor deposition (MOCVD) were studied with X-ray diffraction, scanning electron microscopy, and hall effect measurement. The characterization results showed that both the surface morphology and the crystal quality of the polar AlGaN samples grown on a-plane sapphire substrates was improved with increasing Si concentration due to the Si-induced increase in dislocation movement. It was also found that the folds on the surfaces of the semi-polar and non-polar AlGaN samples grown on m- and r-plane sapphire substrates, respectively were significantly reduced in consequence of the growth suppression along c direction by Si-doping. Moreover, owing to the enhanced crystal quality, an increase in both the mobility and the carrier density for the polar AlGaN samples grown on a-plane sapphire substrates was achieved as the Si-doping level was increased. In addition, a relatively high electron concentration was obtained from the undoped semi-polar AlGaN samples grown on m-plane sapphire substrate, which is helpful to fabricate high quality semi-polar AlGaN-based ultra-violet light emitting diodes (UV-LEDs).     

Picosecond gain dynamics of an actively mode-locked external-cavitylaser diode

We report a new experimental approach to study the temporal gain dynamics of an actively mode-locked external-cavity laser diode. The experiment can be viewed as an electrical pump-optical probe technique. Picosecond time resolution is achieved by synchronizing the actively mode-locked semiconductor laser to a mode-locked Ti:sapphire laser. The transmission of the Ti:sapphire pulses through the active region of the laser diode is then measured as a function of photon energy and delay time. Our experiment allows to investigate the dynamics of the entire gain spectrum with picosecond time resolution since the Ti:sapphire laser is wavelength tunable. On the basis of these data we are able to determine directly the wavelength dependence of the differential gain. The results compare well with microscopic calculations. The implication for the mode-locking behavior of the diode laser is discussed