原子光刻用亚稳态氖原子束源的研究

研制了一台用于原子光刻的亚稳态氖原子束源 ,其束流强度可达 3 3× 10 14 atoms/s·Sr.。研究了束流强度的变化规律 ,并对其机理进行了探讨。     

磁约束铜蒸气放电中亚稳态铜原子密度的测量

利用自吸收方法测量了磁约束铜蒸气放电余辉初期的铜２Ｄ５／２亚稳态原子密度。对亚稳态原子的弛豫情况，同普通铜蒸气激光器进行了对比，分析了磁约束放电条件下亚稳态原子的弛豫机制。为建立重复频率运转的磁约束铜蒸气激光器提供了基础     

铜蒸气激光振荡自终止的再认识

铜蒸气激光器是典型的自终止激光器,其激光跃迁通道的下能级是与基态没有光学联系的亚稳态,积累的布居将自动地终止激光。与早先认为主要是激光跃迁本身造就了亚稳态的布居不同,对放电激励的铜蒸气激光器,电子与基态铜原子的碰撞形成对亚稳态的持续激励,电子与激光上能级铜原子的碰撞随着电子温度的降低构成强的消激励作     

硅表面直接生长十八烷基硅烷小分子自组装单层抗蚀剂的亚稳态氦原子光刻技术

选取不同尺寸和形状的物理掩模,以硅表面直接生长的十八烷基硅烷小分子自组装单分子层作为抗蚀剂,硅（100）为衬底,亚稳态氦原子作为曝光源,利用湿法化学刻蚀方法在衬底上制备具有纳米尺寸分辨率的硅结构图形。基于扫描电子显微镜、原子力显微镜的表征结果表明：原子光刻技术可以把具有纳米尺度分辨率的正负图形通过化学湿法刻蚀技术很好地传递到硅片衬底上,特征边缘分辨率达到20nm左右,具有较高的可信度和可重复性。正负图形相互转化的临界曝光原子剂量约为5×1014atomscm-2,曝光时间约为20min。     

钇原子亚稳态寿命的测量

原子的寿命是原子的重要参数之一。本文的寿命测量方法涉及原子束中原子的速度分布的测量。理论和实验已经证实,对于原子束中原子速度分布的测量,采用激光感应荧光的方法比传统的机械斩波法方法更为方便,且具有更高的分辨率,尤其是对超声速的束流。在此基础上,利用基态原子无穷长的寿命以及亚稳态原子在飞行过程中的衰减,比较测量到的原子基态和亚稳态的速度曲线,可以确定原子亚稳态的寿命。其原理与束箔法测量相似。 在本文实验中,用激光感应荧光法测量到的是原子数密度的速度分布,即信号是:     

利用激光泵浦测量传能反应Xe(~3P_(0,2)) N_2的绝对截面

在束-气池构型下用脉冲激光泵浦技术测量了亚稳态Xe(~3P_0)和Xe(~3P_2)与N_2传能生成N_2(B,v)的绝对截面.并讨论了该方法在研究亚稳态原子传能及反应中的适用性.     

原子光刻促使芯片面积更小

7年前,贝尔实验室的物理学家发明了原子光刻技术,即使用中性原子代替光在表面刻蚀图形,目前已在世界范围内进行研究。尽管在工业上得到应用还需一段时间,但使科学家们感兴趣的是该技术提供了一个可以将现有依赖于光的光刻方法制造的芯片面积缩小10倍的方法。     

增强腔在大失谐原子光刻中的应用

对增强腔在大失谐光场原子光刻中的实现进行了详细的讨论 ,通过增强腔对激光光束的压缩和功率的增强可达到近共振原子光刻的要求。数值结果显示相对于近共振原子刻印结果 ,在增强腔下光束中心处沉积的原子条纹宽度将更细 ,为原子刻印提供了一种实现条纹精细度较高的新型方案。     

空心阴极限制性放电的氦-氖激光器

空心阴极放电是一种新的激励技术,用低电压就可放电,激活区为空心阴极中的阴极位降区与负辉区.由于这两个区域中存在高能电子,使氦原子激发产生足够多的亚稳态,故也可以获得氦-氖激光.本文报导了通过外部触发能实现低气压下的空心阴极放电,激光输出功率有几倍的增加.本文采用笛子形空心阴极,它是内径为4毫米、长度为55厘米的无氧铜管, 每隔5厘米开一个孔,对准孔的位置上面安装上阳极,共有十个阳极,如图1所示.     

原子束全息技术制作任意微细图形研究

从波粒二象性原理出发，研究了用氖原子束计算全息技术制作任意纳米结构的基本原理和方法，克服了用激光梯度场控制原子堆积，只能制作单一点、线等周期性纳米结构的不足。分析讨论了原子全息与光学全息的区别，指出只有经激光冷却的原子束才满足全息技术所要求的相干条件和衍射条件。最后采用罗曼Ⅲ型迂回位相编码方法设计了氖原子束计算全息片，介绍了操纵氖原子束制作纳米任意结构的实验系统。     

应用激光激发的原子荧光法在低分辨率检测系统中间接观测氖原子的高分辨率光谱

应用激光激发的原子荧光法,在低分辨率检测系统中间接观测到氖原子2p_3→4s_1~1和2p_7→4d_3跃迁的高分辨光谱.进一步证实以前认定的氖原子谱线5919.037为2p_7→4d_3跃迁的结论是正确的.     

砷化镓晶片表面的XPS研究

用X射线光电子能谱分析技术（XPS）研究了几种砷化镓抛光片及经不同表面处理方法处理的砷化镓晶片表面的化学计量比和表面化学组成。结果表明砷化镓抛光片的表面自然氧化层中含有Ga2O3、As2O5、As2O3及元素As；表面化学计量比明显富镓，而经过适当的化学处理后这些表面特性能得到较大改善。     

应用光电流光谱法测定氖原子的高分辨光谱

应用光电流光谱技术,测量了氖原子跃迁2P_4→4S_1和2P_3→4S_1的精细结构,首次认定了氖原子谱线5919.037埃为2P_7→4d_3跃迁。获得的光谱谱线轮廓具有典型的对称性线型,测得的谱线半宽度为3.2千兆赫。     

Crystallographic Orientation Identification in Multicrystalline Silicon Wafers Using NIR Transmission Intensity

Near-infrared (NIR) polariscopy is a technique used for the non-destructive evaluation of the in-plane stresses in photovoltaic silicon wafers. Accurate evaluation of these stresses requires correct identification of the stress-optic coefficient, a material property which relates photoelastic parameters to physical stresses. The material stress-optic coefficient of silicon varies with crystallographic orientation. This variation poses a unique problem when measuring stresses in multicrystalline silicon (mc-Si) wafers. This paper concludes that the crystallographic orientation of silicon can be estimated by measuring the transmission of NIR light through the material. The transmission of NIR light through monocrystalline wafers of known orientation were compared with the transmission of NIR light through various grains in mc-Si wafers. X-ray diffraction was then used to verify the relationship by obtaining the crystallographic orientations of these assorted mc-Si grains. Variation of transmission intensity for different crystallographic orientations is further explained by using planar atomic density. The relationship between transmission intensity and planar atomic density appears to be linear.     

Effect of interfacial and bulk organic contamination on the quality of thin silicon oxide

The effect of organic contamination of silicon (HF-last cleaned) and silicon dioxide (as-received) wafer surfaces on the quality of gate oxide was studied. Controlled contamination by model organics as well as cleanroom contamination conditions were investigated. Wafers were oxidized under oxidizing or inert ramp-up ambient to grow ultrathin thermal oxides (30 /spl Aring/). Surface and electrical characterization of the oxides was done by Auger sputter profiling, tunneling atomic force microscopy (TAFM) and gate oxide integrity (GOI) measurements. For oxides grown in an inert ambient during ramp-up, HF-last cleaned wafers had a large number of carbon-based defects as compared to as-received wafers. Oxygen in the ramp-up ambient oxidized and volatilized organics resulting in good quality thin gate oxides for HF-last cleaned wafers. However, for as-received wafers, the defect density was increased in an oxidizing ramp-up ambient. A probable mechanism for degradation of the gate oxide quality on HF-last wafers in an inert ramp-up ambient is investigated.     

六方氮化硼薄膜制备及其压电响应的研究

采用射频(RF)磁控溅射的方法,通过改变工艺参数在n型Si(100)片上制备六方氮化硼(h-BN)薄膜。通过傅立叶红外(FTIR)光谱仪,X射线衍射(XRD)仪进行结构表征,原子力显微镜(AFM)进行表面形貌和压电性能表征。测试结果表明,在射频功率为300 W、衬底温度为500℃、工作压强在0.8Pa、N2与Ar流量比为4∶20和衬底偏压在-200V时制备的六方BN薄膜具有高纯度、高c-轴择优取向,颗粒均匀致密,粗糙度为2.26nm,具有压电性并且压电响应均匀,符合高频声表面波器件基片高声速、优压电性要求。薄膜压电性测试研究表明,AFM的PFM测试方法适用于纳米结构半导体薄膜的压电性及其压电响应分布特性的表征。     

A continuously pulsed copper halide laser with a cable-capacitor Blumlein discharge circuit

Experimental characteristics of a continuously pulsed copper halide laser with a cable-capacitor Blumlein discharge circuit are reported. Quartz laser tubes 1 m in length and 1.5 and 2.5 cm in diameter were employed to study the effects of the electrical circuit, lasant, and buffer gas on laser performance. Measured properties of the Blumlein circuit are compared with an analytic solution for an idealized circuit. Both CuCl and CuBr with neon and helium buffer gas were studied. A maximum average power of 12.5 W was obtained with a 1.5 nF capacitor charged to 8 kV and discharged at 31 kHz with CuCl and neon buffer gas at 0.7 kPa in a 2.5-cm-diam tube. A maximum efficiency of 0.72 percent was obtained at 9 W average power. Measurements of the radial distribution of the power in the laser beam and the variation of laser power at 510.6 and 578.2 nm with halide vapor density are also reported. Double and continuously pulsed laser characteristics are compared, and the role of copper metastable level atoms in limiting the laser pulse energy density is discussed.     

Dishing and nitride erosion of STI-CMP for different integration schemes

In this paper, we investigate the effects of integration schemes on the STI-CMP performance of two polishers, as well as the influence of consumables and process parameters. The experiment was based on both the blanket-oxide wafers and the patterned wafers processed using 0.18 μm technology. The polishing capability was evaluated, based on the results collected using metrology tools such as Opti-probe, Tencor profiler; atomic force microscope (AFM), and x-ray-scanning electron microscopy (X-SEM) analysis.     

Interdependence of buffer gas pressure and optimum interpulse delay in a burst-mode copper halide laser

The variation of the laser output energy of a 100 pulse burst with interpulse delay has been studied for each of the copper halides CuCl, CuBr, and CuI as a function of the tube temperature and of the buffer gas pressure for helium and neon. The tube bore was 12 mm and the specific discharge energy was 3.8 mJ ċ cm^-3. For CuI, the optimum interpulse delay decreases with increase in tube temperature and with decrease in the buffer gas pressure. At each temperature and pressure the optimum interpulse delay is shorter for helium than for neon. Although the formation of the laser pulse is intimately connected with the mechanism of breakdown in the discharge tube, the effect of this mechanism on the optimum interpulse delay is small and the latter is determined mainly by the dissociation-recombination cycle of the copper halide. The increase in optimum interpulse delay with buffer gas pressure suggests that either collisions with halogen atoms or molecules or superelastic electron collisions are responsible for the decay of the population of the metastable copper atoms.