基于胶体球掩模板法制备图形化蓝宝石衬底

制备并研究了纳米级图形化蓝宝石衬底.采用磁控溅射技术在蓝宝石衬底上沉积 SiO2薄膜,利用自组装方法在SiO2薄膜上制备单层聚苯乙烯(PS)胶体球阵列,利用感应耦合等离子体干法刻蚀将周期性PS胶体球的图形转移到SiO2薄膜上,通过湿法腐蚀制备了纳米级图形化蓝宝石衬底.利用扫描电子显微镜对胶体球掩膜、SiO2纳米柱掩膜和图形化蓝宝石衬底结构进行了观察,研究了湿法腐蚀蓝宝石衬底的中间产物对刻蚀的影响,分析了腐蚀温度和腐蚀时间对蓝宝石衬底的影响.结果表明,湿法腐蚀的中间产物会降低蓝宝石衬底的刻蚀速率.蓝宝石衬底的腐蚀速率随着腐蚀温度的升高而加快;在同一腐蚀温度下,随着腐蚀时间的增加,图形尺寸进一步减小.     

激光刻蚀硅磁敏三极管发射区引线槽的研究

提出了一种激光与微电子机械加工系统 (MEMS)相结合刻蚀硅磁敏三极管发射区引线槽的方法。实验结果表明 ,利用这种新方法刻蚀的硅磁敏三极管发射区引线槽具有刻蚀速率大、质量好的优点 ,并且可以实现对 ,〈111〉晶向硅片无掩膜加工。     

商品有机玻璃片微结构的深刻蚀研究

研究应用O2反应离子刻蚀(RIE)直接深刻蚀商用有机玻璃(PMMA)片，以实现微结构的三维微加工，工艺简单，加工成本较低，为微器件的高深宽比加工提出了新方法。试样采用Ni作掩膜，以普通的光刻胶曝光技术和湿法刻蚀法将Ni掩膜图形化。工作气压、刻蚀功率等工艺参数对刻蚀速率影响较大。在刻蚀过程中，掩膜上的金属粒子会被刻蚀气体离子轰击而溅射散落出来，形成微掩膜效应。利用这种RIE技术，在适当的溅射功率及气压下，刻蚀速率较快，且获得了较陡直的微结构图形，刻蚀深度达120μm。     

电极距离对激光电化学刻蚀速率及钻蚀的影响

利用溶液回路电流和红外热像监测,研究了电极距离对半导体激光电化学刻蚀速率和电化学横向钻蚀特性的影响.实验结果表明,电极距离由15 cm缩短为5 cm后,回路电流数值增大,其变化率增加约15.4%,等量化学热生成时间至少缩短2/3,说明缩短电极距离使半导体激光电化学刻蚀速率加快;当电极距离分别为20、15、10和5 cm时,垂直晶向刻蚀50 μm直线凹槽,所得凹槽实际宽度分别为100、85、70和60 μm,其晶向影响受到明显抑制,横向钻蚀大幅减小.研究结果说明,通过电极距离调节这一简单方式,有可能解决激光电化学刻蚀速度慢、横向钻蚀严重等难题.     

Ti掩膜图形层对外延生长GaN薄膜晶体质量的影响

采用氢化物气相外延(HVPE)方法在2英寸(1英寸=2.54 cm)c面蓝宝石衬底上外延生长了高质量GaN单晶薄膜.在GaN生长过程中引入点状和条状两种金属Ti掩膜图形层,研究了不同Ti掩膜图形层对外延生长GaN薄膜晶体质量的影响.使用微分干涉相差显微镜(DICM)、扫描电子显微镜(SEM)、阴极荧光光谱(CL)、喇曼光谱和X射线衍射(XRD)对制备的GaN样品结构和形貌进行了表征分析.实验结果表明,Ti掩膜图形层的引入可以在一定程度上改善GaN薄膜的表面形貌,缓解材料中的应力,降低GaN材料中的位错密度,提高材料的结晶质量.同时发现,相比于点状图形,条状Ti图形掩膜层可以更加有效地改善GaN材料的晶体质量,将位错密度降低到3.2×106 cm-2以下.     

非光敏BCB工艺技术研究

非光敏BCB介质具有介电常数小、吸水率低、热稳定性好、力学性能优良、固化温度低,以及表面平坦化特性好等优点,作为重要的介质材料,已经应用于薄膜多芯片组件(MCM)基板布线中.文章研究了薄膜多层布线工艺中非光敏BCB介质的涂覆、固化工艺,以及等离子刻蚀工艺;提出了优化的涂覆和固化工艺参数,使用适当的刻蚀掩膜以及优化后的刻蚀工艺参数,进行图形刻蚀,获得了厚度为4 μm、表面粗糙度小于150 nm的表面平整的非光敏BCB介质膜,并在薄膜MCM多层布线基板中得到较好运用.     

YBCO／LCMO双层膜微结构的HREM研究

La0.7Ca0.3MnO3(LCMO)薄膜是一种典型的巨磁阻(CMR)材料,在信息存储领域具有广阔的应用前景[1,2](如磁记录读出磁头等),而LCMO与高温超导材料YBa2Cu3O7(YBCO)组成的双层薄膜更显示出许多奇特的物理性质[3]。由于薄膜的微结构对其物理性能有很大影响,因此研究薄膜的微结构有助于对此类材料的磁性与超导电性相关机制的理解。本文利用高分辨电子显微镜系统地研究了YBCO/LCMO双层薄膜的显微结构。本文使用的YBCO/LCMO双层薄膜样品是在(100)LaAlO3(LAO)单晶衬底上,用脉冲激光沉积法制备的。制备的程序是:首先在衬底上沉积LCM…     

PZT薄膜微图形的制作精度的研究

采用典型的半导体光刻工艺用ＢＨＦ／ＨＮＯ３溶液成功地刻蚀了ＰＺＴ（５２／４８）薄膜。研究了薄膜的微观结构对微图形的制作精度的影响。结果表明，在薄膜中晶粒团聚区域和周围区域的刻蚀速率存在着差异，晶粒小的薄膜有利于获得高保真的从掩膜到薄膜的图形转移，晶粒团聚区域的尺寸基本决定了图形转移的误差。     

用于各向同性湿法刻蚀中的氮化硅掩膜

在硅的各向同性湿法刻蚀过程中,一般选用HNA溶液(即氢氟酸、硝酸和乙酸的混合溶液)作为刻蚀液,而氮化硅以其很好的耐刻蚀性而优先被选为顶层掩膜材料.在硅片上刻蚀不同的结构,通常需要选择不同的刻蚀液配比.而不同配比对于氮化硅掩膜的刻蚀速率也不一样.分别用PECVD和LPCVD两种方法在<111>型硅片上沉积了厚度为560和210 nm的氮化硅薄膜,研究和对比了它们在8种典型配比刻蚀液下的刻蚀速率,为合理制作所需要厚度的氮化硅掩膜提供有益参考.     

Cl2/Ar/BCl3 ICP刻蚀AlGaN的研究

感应耦合等离子体(ICP)刻蚀在AlGaN基紫外探测器台面制作中起着重要作用.在对比了ICP与RIE,ECR等干法刻蚀技术优缺点的基础上,采用Ni作为掩膜,Cl2/Ar/BCl3作为刻蚀气体,对金属有机化学气相淀积生长的n-Al0.45Ga0.55N进行了ICP刻蚀研究.刻蚀速率随着ICP直流偏压的增加而增加,刻蚀速率随着ICP功率的增加先增加较快后增加缓慢.最后结合刻蚀表面的扫描电镜(SEM)分析和俄歇电子能谱(AES)深度分析对刻蚀结果进行了讨论.分析表明,在满足刻蚀表面形貌的同时,较低的直流偏压下刻蚀速率较慢,但损伤较小,这对于制备高性能的紫外探测器是有利的.     

Excimer laser patterning of high-Tcsuperconducting thin films of YBCO

The patterning by excimer laser ablative etching of thin superconducting films of YBCO on MgO and fused silica substrates which were fabricated by laser sputtering is discussed. The etch rate as a function of laser fluence, wavelength, and number of pulses has been investigated. Although etched film surfaces were found to be considerably smoother than annealed films, the laser etching itself was found not to be a totally thermal process     

深紫外激光对GaN薄膜的激光抛光研究

为了研究157nm深紫外激光的激光抛光加工特性,采用小光斑对GaN半导体薄膜进行了微平面扫描刻蚀.通过探讨激光工艺参量与激光抛光质量的影响关系,得到了最佳的工艺参量范围.结果表明,随着激光抛光扫描速率的增加,材料加工表面粗糙度值Ra逐渐减小,其中扫描速率在0.014mm/s～0.015mm/s处,激光抛光质量最高;而激光抛光扫描间距的减小,或者脉冲频率的增加,都将导致被加工表面粗糙度增大;当脉冲频率取8Hz时,抛光效果较好,表面粗糙度值Ra≈20nm.     

10%TMAH硅湿法腐蚀技术的研究

研究了浓度为10%的四甲基氢氧化铵(TMAH)溶液,在不同量的Si粉掺杂下,对铝膜及硅衬底的腐蚀及其pH值的变化。测试了在满足铝膜极低的腐蚀速率(<1nm/min)时,不同温度下该腐蚀液对硅(100)、(111)和(110)晶面及SiO2介质膜的腐蚀速率。还介绍了添加剂—过硫酸铵(APODS)和吡嗪的加入对腐蚀表面形貌及腐蚀速率的影响。研究结果表明,存在着一个临界的硅粉添加量,超过此量后铝膜的腐蚀速率急剧降低。90℃时,在10%TMAH溶液中加入1 5mol/L硅粉、3 0g/LAPODS和2g/L吡嗪可以实现铝膜不被腐蚀,同时硅(100)面约有1μm/min的腐蚀速率,腐蚀表面平整。腐蚀后的铝膜表面同硅铝丝键合良好,实现了腐蚀工艺同CMOS工艺的完全兼容。     

Numerical Computation of AC Losses and Flux Profiles in High-Aspect-Ratio Superconducting Strips in Perpendicular AC Magnetic Field

We present the results of finite-element modeling of a YBCO thin-film superconductor deposited on a nonmagnetic substrate and on a weakly ferromagnetic substrate. The model was implemented using commercial software to calculate the ac loss in the presence of a sinusoidal external magnetic field applied perpendicular to the surface of the superconducting tape. A strategy is demonstrated to overcome the difficulties in the finite-element method due to the high aspect ratio of the YBCO film by using the computed values of ac loss for thicker samples to extrapolate the results to the actual physical thickness of the superconductor $( sim!! 1 muhbox{m})$. The effect of the width of the weekly ferromagnetic substrate upon the ac loss of the superconductor film has also been studied.      

GaAs vertical-cavity surface emitting lasers fabricated by reactive ion etching

GaAs quantum well vertical-cavity surface emitting lasers fabricated using low damage reactive ion etching are discussed. Lasers which are partially and completely etched through their structure are compared. The surface recombination velocity of exposed GaAs is not exacerbated in deep etched lasers; other loss mechanisms in shallow etched lasers have comparable impact on laser performance. Etched lasers exhibit low voltage and small differential series resistance at threshold, while devices fabricated by a combination of etching and ion implantation possess lower threshold current. It is found that reactive ion etching has little additional effect on laser operation, whereas the different device structures considered do influence laser performance.<>     

Effect of NaOH solution on surface textured ZnO: Al films prepared by pulsed direct current magnetron sputtering

Transparent conducting Al-doped ZnO (ZnO:Al, AZO) thin films were prepared at substrate temperature of 270 °C by pulsed direct current magnetron sputtering. NaOH solution (5 wt%) was employed to etch the AZO films at room temperature, and the surface textured AZO films were obtained successfully. The relationship between the surface textured structures and the etching process controlled by etching time was discussed. The textured morphology of the etched AZO films became clear as increasing the etching time, and the AZO film etched for 30 min exhibited uniformly and distinctly crater-like surface textured structure. Correspondingly, the haze and the resistivity increased with the increasing etching time. And the resistivity of the AZO film etched for 30 min was 3.2×10⁻³ Ω cm.     

Reduction of Dislocation Density in HVPE-Grown GaN Epilayers by Using In Situ-Etched Porous Templates

In this paper, a method was demonstrated to reduce the dislocation density of GaN film grown by hydride vapor phase epitaxy (HVPE) on an in situ selective hydrogen-etched GaN/sapphire template. The dislocations regions were etched by hydrogen to form cavities. The porous structure was formed on the GaN template grown by metal organic chemical vapor deposition after in situ hydrogen etching. The etching condition was optimized by modulating the etching temperature, pressure, and etching time. Two-step buffer layer growth and high temperature GaN film deposition were carried on the porous template. The growth parameters were optimized to keep the porous structure unfilled. The dislocations originally located in etched cavities could not propagate to the next layer grown by HVPE. Therefore, the dislocation density could be significantly reduced. High crystal quality of GaN is obtained with a low dislocation density. The full width at half-maximum FWHM of (002) is 35 arcs, and the FWHM of (102) is 48 arcs.     

On the reflection pattern made by a laser beam on the etched surface of germanium

A laser beam is shot on the surface of single-crystal germanium, after etching. From the reflection pattern, the characteristics of etched pits and hillocks are examined and it is found that etched pits not only are simple holes but also are convex. In addition, a new reflection pattern in the orientation of [110] is reported. These new data will be applied to decide the orientation of single-crystal growth and the effect of dislocation in crystal.     

GaInP/AlGaInP index waveguide-type visible laser diodes with dry-etched mesa stripes

GaInP/AlGaInP index waveguide-type visible-light laser diodes with dry-etched mesa stripes have been fabricated by Cl/sub 2/ reactive ion beam etching for the first time. The AlGaInP cladding layer, which is normally very difficult to dry etch due to problems with Al oxidation and the low volatility of In and its reaction products, was etched smoothly with high depth accuracy. The etched mesa stripes were buried by metal organic vapour-phase epitaxy without crystal discontinuity at the regrown surface. The threshold current under room-temperature pulsed operation is 35 mA (L=300 mu m), which is almost the same value as that for wet-etched lasers.<>     

GaAs的CH_4／H_2反应离子腐蚀研究

在前研究ＩｎＰ的ＣＨ４／Ｈ２反应离子腐蚀的基础上，进行了ＧａＡｓ的ＣＨ４／Ｈ２反应离子腐蚀研究。ＧａＡｓ的腐蚀速率比ＩｎＰ慢，随ＣＨ４／Ｈ２组份之比值、工作压强、总流量率等而改变，从２ｎｍ／ｍｉｎ到８ｎｍ／ｍｉｎ。当总流量率为３０～１２３ｓｃｃｍ之间、ＣＨ４／Ｈ２＝０．１８，腐蚀后的表面总是光亮平滑的，损伤层的厚度≥３０ｎｍ。当用ＣＨ４／Ｈ２ＲＩＥ在ＣａＡｓ上制作深度＞０．６μｍ的结构时，必须要考虑高能离子的轰击给晶体造成的损伤和给光刻胶掩模造成的浸蚀，此时光刻胶作掩模已经不能满足要求，应改用介质薄膜。