Study on deflection of X-ray mask membrane in stepper motion

Deflection of the X-ray mask membrane caused by stepper motion, i.e., changing the mask-to-wafer gap and stepping the wafer parallel to the mask, was evaluated. The effects of film tension, mask configuration and velocity of wafer stage movement on the membrane behavior were examined. The deflection caused by parallel stepping in the proximity gap is very sensitive to the parallelism between the mask and the wafer. The membrane deflection of less than 2 μm and the relaxation time of less than 0.2 sec were observed under the condition of a 20 μm gap and within 0.2 μm/20 mm of mask inclination. It was confirmed that the relaxation time is inversely proportional to the tension of the film. It was also found that the mesa-type mask is capable of reducing the relaxation time to about 30 % less than that of a conventional mask, and that the membrane deflection of the mesa-type mask becomes almost half that of the conventional one. The mesa-type mask is thought to effectively reduce the membrane deflection and the relaxation time.     

Optical reflectance and transmittance of tissues: principles andapplications

A discussion is presented of diagnostic and dosimetric optical measurements in medicine and biology. Topics covered include: tissue optical properties, tissue boundary conditions, and invasive versus noninvasive measurements. Clinical applications of therapeutic dosimetry and diagnostic spectroscopy are discussed. The principles of diffuse reflectance and transmittance measurements are presented. Experimental studies illustrate reflectance spectroscopy and steady-state versus time-resolved measurements     

Optical properties of annealed,single GaAs quantum wells: Cap doping and mask width dependence

Band edge absorption measurements are used to characterize the degree of Al-Ga intermixing (blue-shifting) and the linear optical loss of waveguides formed in five annealed and encapsulated single GaAs quantum well laser heterostructure wafers which differed only by the amount of Zn doping in the GaAs cap layer. In addition to the transmission measurements, secondary ion mass spectroscopy data was used to verify the diffusion of Zn before and after annealing. High zinc doping in the cap is observed to cause quantum well disordering below the encapsulant (Si₃N₄) and is attributed to impurity induced layer disordering. Moderate doping in the cap results in selective area intermixing via controlled gallium vacancy production. A stripe width dependence is also observed, which suggests a role of lateral diffusion of species which affect the intermixing. For an undoped (n⁻) cap, the degree of intermixing is heavily dependent on the arsenic overpressure used during the anneal and is independent of the nitride stripe width suggestive of a volumetric Fermi level dependent production of vacancies within the cap.     

Temperature dependence of reflectance and transmittance of theartery exposed to air during laser irradiation

Reflectance, transmittance, and temperature of the arterial wall exposed to air are measured during laser irradiation for different heating dynamics. Temperature dependence of the reflectance and transmittance is then deduced. The results show a competing effect between temperature and dehydration, resulting in a distinct minimum of transmittance and maximum of reflectance. As a consequence, a direct correlation of reflectance and transmittance with temperature is only possible for a specific dynamics     

光学剪切电子散斑技术的改进与应用

介绍了一种新型光学测量技术——剪切电子散斑技术的改进与应用,它是一种有效的基于激光技术,测量三维物体表面变形和形貌的非接触测量方法。与传统方法相比,改进后的方法光路结构和采用的算法更加简单,可广泛应用于表面应变、张力、材料特性的测量,残余应力的估计,表面泄露的监测以及物体表面三维形貌测量等领域。     

Polished TFT's: surface roughness reduction and its correlation todevice performance improvement

Chemical-mechanical polishing (CMP) has been applied to the fabrication of n-channel polysilicon thin film transistors (poly-Si TFT's). Three different polishing conditions are compared: (1) polishing before; (2) polishing after; and (3) both polishing before and after the a-Si recrystallization. Devices with no polishing act as control samples. Experiments consistently reveal that devices with post-anneal polishing exhibit the best performance, Two-fold improvement of drain current is attributed to the smoother active polysilicon surface. The electrical characteristics of a post-anneal polished TFT in terms of field effect mobility μ_FE, threshold voltage V_T, and subthreshold swing S can be further improved if hydrogenation is employed. It is also found that a large decrease in the poly-Si surface roughness leads to higher dielectric breakdown strength and improved short-channel effects. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) results are presented and correlated with electrical results     

Satellite laser altimetry of terrestrial topography: verticalaccuracy as a function of surface slope, roughness, and cloud cover

Analysis of the sensitivity of laser ranging errors to surface conditions indicates that predicted single-shot range errors are primarily dependent on surface slope. Range errors are less sensitive to variations in surface roughness or reflectivity. Values of total surface slope and roughness for nine terrestrial landforms, derived from digital elevation data at a 186 m length scale, vary from 2° to 40° and 0.8 to 15 m, respectively, at a 90% frequency of occurrence. This range of surface morphologies yields a variation in single shot laser ranging error from 0.4 to 8 m, assuming system parameters for the proposed Topographic Mapping Laser Altimeter (TMLA) and a nominal 30% surface reflectivity. The total elevation accuracy of data obtained via satellite laser altimetry, although dominated by the range error, is also a function of additional error sources, including orbit ephemeris, atmospheric, and calibration errors. Averaging of multiple laser measurements improves the vertical accuracy of the elevation data by statistical reduction of random errors. During a three-year mission, two to three laser measurements will be acquired, on average, for each 200-m footprint at low to moderate latitudes, accounting for the latitudinal variation of ground track spacing and cloud cover. For high-latitude regions, the narrow spacing of satellite ground tracks in a polar orbit will provide frequent repeat observations yielding, on average, 4 to 25 measurements of each footprint over the Antarctic and Greenland ice sheets. Averaging of these multiple repeat observations at high latitude will yield an improvement in vertical accuracy by a factor of two to five     

Estimation of soil moisture and surface roughness parameters frombackscattering coefficient

A statistical inversion technique was implemented to estimate soil moisture and surface roughness parameters from the remotely sensed multifrequency backscattering coefficients. Both two- and three-frequency approaches were examined and tested in detail for the inversion technique. Initially the technique was tested with a simulated data set generated from various scattering models. Later it was applied to an experimental data set that provided, for a wide range of surface roughness and soil moisture, backscattering coefficients at many incidence angles and frequencies. It was found that, in general, the three-frequency approach produces more accurate results. However, under a favorable combination of frequencies and incidence angles, both approaches give results with a comparable accuracy. There is a potential that soil moisture could be estimated to an accuracy of about 2%. In the mean time the surface roughness parameters could be estimated to an accuracy of better than 10%     

表面粗糙度的激光及相关在线测量方法

随着机械加工自动化程度的提高 ,对表面粗糙度在线测量提出了越来越高的要求。目前 ,为了提高生产效率和实现生产的自动化 ,生产过程中实时检测愈加受到重视。传统的触针测量法 ,由于测量速度和测量条件的原因 ,不适于在线检测。光学测量方法近年发展很快 ,它是一种非接触测量法。根据测量原理可以归纳为干涉测量法、聚焦测量法、散射测量法、散斑测量法四种。本文重点介绍了这些技术进行表面粗糙度在线测量的原理和目前的研究结果。并对这些方法发展前景进行了分析和预测     

软X射线多层膜的光学性质和优化设计

一、引言 X射线多层膜是X激光和X光学的重要元件。近几年,不论在理论上还是在技术上,都得到了较快发展。 从X光晶体衍射角度出发,X射线多层膜可看作超晶格一维人工晶体。从薄膜光学出发,X射线多层膜是一类光学薄膜。这种薄膜的膜层很薄,折射率都接近1,并存在一定的吸收。X     

Optical and paramagnetic properties of synthetic diamond crystals irradiated with electrons and annealed

The optical and paramagnetic properties of single crystals of synthetic diamond grown by the temperature-gradient method in high-pressure apparatuses with the systems of catalytic solvents (Co, Fe) and (Ni, Fe) are studied at room temperature. The optical absorption spectra (in the wavelength range λ = 400–800 nm) and the spectra of electron spin resonance are registered for the initial diamond crystals, the crystals irradiated with 6 MeV electrons (the fluence 1.5 × 10¹⁸ cm^?2), and the irradiated diamonds subjected to isochronous thermal annealing in vacuum (for 60 min). It is shown that, with such treatment, the diamond crystals synthesized with different metal catalysts (Co or Ni) exhibit similar optical properties, but different paramagnetic properties. The data obtained by infrared spectroscopy and electron spin resonance spectroscopy are coincident for radiation defects and different for nitrogen centers (the P1 centers and exchange-coupled pairs of nitrogen atoms). The spectra of the electron spin resonance of the samples annealed at temperatures below 1273 K (in the case of the Co-containing catalyst) and 1073 K (in the case of Ni-containing catalyst) exhibited broad lines produced by residual impurities of the catalyst metal and were accompanied by a distortion of the spectrum of paramagnetic nitrogen in the form of a tilt of the ESR spectra with respect to the zero line.     

脉冲钕玻璃激光对牙体硬组织结构影响的研究

用钕玻璃激光辐照牙釉质、牙本质及牙骨质表面超微结构．用扫描电镜进行观察。结果发现：牙釉质呈云或絮状熔融;牙本质及牙骨质呈重叠蜂窝状熔融;随激光剂量增加而熔融密度增加。     

Statistical characteristics of simulated radar imagery from baresoil surfaces: effects of surface roughness and soil moisturevariability

The potential of high-resolution radar imagery to estimate various hydrological parameters, such as soil moisture, has long been recognized. Image simulation is one approach to study the interrelationships between the radar response and the underlying ground parameters. In order to perform realistic simulations, the authors incorporated the effects of naturally occurring spatial variability and spatial correlations of those ground parameters that affect the radar response, primarily surface roughness and soil moisture. Surface roughness and soil moisture images were generated for a hypothetical 100×100 m bare soil surface area at 1 m resolution using valid probability distributions and correlation lengths. These values were then used to obtain copolarized radar scattering coefficients at 2 GHz (L band) and 10 GHz (X band) frequencies using appropriate backscatter models, which were then converted to a digital number within 0-255 gray scale in order to generate radar images. The effect of surface roughness variability causes variability in the radar image, which is more apparent under smooth soil conditions. On the other hand, the inherent spatial pattern in soil moisture tends to cause similar patterns in the radar image under rougher soil conditions. The maximum difference between contrast-enhanced mean values of the radar image digital number due to moisture variations occurs at surface roughness values in the 1.5-2.0 cm range     

Analysis of surface roughness and morphology of first-year sea ice melt ponds: implications for microwave scattering

Variations in wind forcing over summer first-year sea ice (FYI) melt ponds occur at hourly to weekly scales and are a significant contributor to microwave backscatter (/spl sigma//spl deg/) variability observed from spaceborne synthetic aperture radar (SAR) platforms (e.g., ENVISAT-ASAR and RADARSAT-1). This variability impairs our ability to use SAR to derive information on summer sea ice thermodynamic state and energy balance parameters such as albedo and melt pond fraction. The surface roughness contribution of FYI melt ponds in the Canadian Arctic Archipelago to like-polarized, C-band /spl sigma//spl deg/ estimates is analyzed through a spectral and statistical analysis of surface wave height profiles for varying wind speeds, upwind fetch lengths, and melt pond depths. A unique derivation of melt pond surface wave height spectra is presented based on digital video of melt pond surface wave trains. Significant scale surface roughness was observed even at wind speeds of 3 m/spl middot/s/sup -1/, resulting in small perturbation model estimates of /spl sigma//spl deg/ (HH) ranging from -5 dB at 20/spl deg/ incidence to -22 dB at 50/spl deg/ incidence. Results from a multivariate linear regression analysis show that 53.5% of observed variance in /spl sigma//spl deg/ (HH or VV) can be explained by wind speed, upwind fetch from melt pond edges, and melt pond depth, with no appreciable difference in the relative contribution of explanatory variables. Modeled omnidirectional /spl sigma//spl deg/ as a function of wind speed and incidence angle for 100-m transects collected throughout the melt pond season act to elaborate the role of fetch and depth, as well as the modulating effect of hummocks, on /spl sigma//spl deg/.     

Optical transmittance of thin GaAs wafers upon laser pumping in the region of exciton resonances and the continuum of states: Exciton-exciton interaction

The transmittance spectra of thin “pure” GaAs bulk wafers upon optical pumping corresponding to the band of the ground state of the exciton series are recorded at a temperature of T = 1.7 K. The wafers were grown by molecular-beam epitaxy and vapor-phase epitaxy. An increase in the line amplitude and width upon pumping is observed, with no noticeable changes in the spectral position of the line peak. The increase is similar to that observed upon pumping in the continuum of states, but occurs at a somewhat lower rate. Estimation of the concentration of excitons created by pumping provides a means for determining the exciton-exciton interaction constant and comparing the result with known data. The integrated absorption method makes it possible to refine the exciton polariton-free charge carrier and exciton polariton-impurity interaction constants. The differential photoabsorption of the samples at the pumping modulation frequency is measured. The resultant modulated absorption spectra demonstrate the connection between induced absorption and the formation of differential spectra.     

Poxvirus virions: their surface ultrastructure and interaction with the surface membrane of host cells

Virions of vaccinia and orf viruses were examined by ultrahigh-resolution scanning electron microscopy using a non-coating method. Intracellular mature particles of vaccinia virus appeared to be covered with a net and ultrastructurally their surface consists of many fine ridges and globules, while the surfaces of orf virus mature particles recovered from infected cells consist of spirally running protrusions. The ridge-like structures of vaccinia virus were presumed to correspond to surface tubules shown by negative staining of this virus, while the spiral protrusions of orf virus were presumed to correspond to spiral threads having a criss-cross appearance by the same staining. Using scanning electron microscopy in which the samples were prepared by the conventional method, we observed: (i) many virions, i.e. one or two hundreds, or occasionally more reaching about one thousand particles, of the IHD strain of vaccinia virus, (ii) many or a moderate number of virions, i.e. about one hundred or fewer particles, of the 58 strain of cowpox virus and (iii) rather few virions, i.e. several tens or fewer particles, of the Iwate strain of orf virus on the free surface of each cell infected with these viruses. It must be noted that the number of virions detected considerably differed in respective cells examined. Virus budding was frequently observed at the cell surface of monolayer cells infected with vaccinia virus but it was never detected with cowpox or orf virus, indicating a difference in the mechanism of virus release between vaccinia and the other two viruses. When whole cells infected with vaccinia virus were examined by a combination of high-voltage and scanning electron microscopies, virions on the cell surface and those inside the cells were clearly differentiated. All virions on the cell surface had an envelope, and some of the envelopes had a slack and/or one or more bulges.     

表面粗糙度测量显微系统的技术分析和不确定度评定

基于扫描共焦原理的激光显微系统因其容易定位、精确测量微型轮廓、高分辨率等优点,顺应了现代社会对机械精密加工领域提出了更高要求的发展趋势。本文全面分析了基于扫描共焦原理的激光显微系统测量表面粗糙度的工作原理,并进行了关键技术的技术分析。研究了测量重复性、仪器示值误差、标准量块校准不确定度、温度等因素对精密测量实验的影响,提出了选用特殊材料、仪器等措施改善实验测量条件的方法,对激光显微系统测量结果进行了不确定度评定。最终结果表明这一研究可以普遍用于机械精密加工行业精密测量,对表面粗糙度测量具有指导意义。     

Intensity-dependent absorption in Cu and Ag metal mirrors--The role of temperature and surface roughness

The intensity-dependent absorption in diamond-turned Cu and Ag metal mirrors and mechanically polished Cu mirrors was investigated at 1.06 and 0.532 μm. The absorption increased with increasing intensity. The change is explained in terms of thermal mechanisms. The absorption is independent of the surface alterations introduced by irradiation. The observed reduction in damage resistance of the altered material may be caused by the interaction of light with the sharp edges produced by mechanical deformation.     

用图像处理技术计算薄膜厚度和表面粗糙度

应用数字图像技术处理薄膜的断面扫描电子显微照片,定量分析薄膜材料的厚度和表面粗糙度.根据薄膜的断面扫描电子显微照片的特征,用垂直投影法计算阈值,根据阈值对薄膜显微照片进行二值化处理,获取薄膜材料表面图像;再将二值化后的图像做垂直投影,确定薄膜表面区域,并根据该区域区间去除噪音.对已提取的薄膜表面细化,提取薄膜表面轮廓线;确定薄膜的平均表面并计算出表面的粗糙度.应用局部垂直投影法,确定薄膜与衬底之间的界面位置.根据薄膜的平均表面的位置和界面的位置,计算出薄膜的厚度.     

FTTH光接收机前置放大器的设计与改进

本文通过分析国内外FTTH光接收机应用前景和普通光接收机的前置放大器基础上，用MOS管替代通用放大模块。设计并经过优化改进找到了一款适合FTTH的CATV光接收机前置放大器。通过测试，性能指标完全符合要求．具有很好的实用价值。