A novel laser direct write technique for fabrication of thin filmMICs

A technique for fabrication of thin-film circuits for microwave integrated circuit (MIC) application is presented. This low-cost fabrication technique utilizes laser direct write of copper patterns on alumina substrates. The method obviates the need for photomasks and photolithography. The film deposition mechanism, deposit film analysis, and MIC fabrication sequence are presented. Performance evaluation of MICs fabricated using this technique is also included     

Optical proximity correction for a versatile LCD based direct write maskless photoplotter

The digital simulation of a photoplotter’s direct write process, where the reconfigurable mask is a liquid crystal microdisplay, leads to the development of two proximity correction techniques. The first works by modifying dimensions and in adding serifs or assistant features to the original structure design. The second, more innovative and only exploitable with a grey level capable direct writing device, precompensates structures with a multilevel spatial modulation of the luminous energy. We also present the computer simulation used to develop these OPC techniques and confirm its performance by comparing modelled and experimental results.     

Technologies for electron beam direct writing

Development time of semiconductor devices which have a large volume of pattern data and fine feature size can be remarkably reduced by a high speed on-line system and an erase electron beam direct writing technology.Pattern data which is performed by a CAD system is converted by a VAX/780 and transmitted to an electron beam exposure system (EBES) through a communication controller at the speed of 1 Mbit/sec.Overlay accuracy less than 0.2 μm is obtained by scanning the alignment marks located at the periphery of a silicon wafer. The marks are fabricated by etching the silicon substrate to 2 μm depth.Radiation effects induced by electron beam irradiation is examined by Monte Carlo simulation.In production of ECL (emitter coupled logic) gate arrays using electron beam direct writing technology, the surface of the silicon nitride (SiN) interlevel insulation layer is coated with a thin conductive layer of TiW in order to avoid the charging phenomenon and the radiation damage caused by electron beam irradiation.     

High resolution acoustic probe

A novel ultrasonic probe for the measurement of field distributions in water is described. In an arrangement using a metal cone tip as the antenna and an acoustic lens with conventional large diameter transducer as the detector, a spatial resolution of ?/4 was achieved. Experimental results for a 4 MHz design are presented.     

A 500-MHz multi-banked compilable DRAM macro with direct write and programmable pipelining

This work describes a 500-MHz compiled eDRAM macro offered in a 90-nm logic-based process. The macro architecture is optimized for high bandwidth while enabling compilation in bank and data-word dimensions. A direct write scheme simultaneously improves random bank cycle time and row access time without signal loss. The benefits of ground sensing, reference cells, and bitline twisting was reviewed. A variable stage pipeline extends the macro bandwidth while offering flexibility in clock frequencies. The redundancy system is modified to support direct write and piping. Finally, BIST was enhanced to utilize electrically blown fuses, enabling one-touch test and repair. Hardware results was presented.     

High resolution spherical microwave holography

A practical technique is developed to determine the electric and/or magnetic field on objects and sources inside a spherical measurement surface. The technique, known as spherical microwave holography (SMH), provides a nondestructive, nonintrusive method of point-by-point evaluation of antennas and radomes over their spatial extent. The resolution capability of SMH is developed and demonstrated by measurements. Resolution in SMH is only limited by the measurement system's capabilities. Dielectric and metallic obstacles on the surface of a radome are located and identified. Resolution as small as 0.33λ₀ is demonstrated     

Very high resolution CARS spectroscopy in a molecular beam

Signal-to-noise calculations are presented for coherent anti-Stokes Raman spectroscopy (CARS) in a molecular beam. Using high peak power pulsed lasers and a high density molecular beam,S/Nfor the H2Q(1) line is expected to besim 10^{4}, with a Doppler width reduction from 1100 to 20 MHz.     

High voltage electron beam lithography

The advantage of high voltage electron beam lithography in submicron VLSI fabrication is outlined. Continuously-moving-stage EB systems with small deflection width are suited to high voltage electron beam machines. At 50 kV, the following experimental results were obtained:

• 1.(1) 0.75 μm lines of PMMA are formed on a 0.8 μm step.
• 2.(2) Dimension deviation from designed size due to proximity effect is below ±0.1 μm for line or space, ranging from 0.25 μm to 30 μm, adjacent to a large area.
• 3.(3) Dosages, required to obtain a resist pattern with vertical walls, are 50μC/cm² at 50 kV and 100 μC/cm² at 20 kV.
• 4.(4) Accurate position detection for a mark covered with thick overlayers can be achieved at 50 kV, but not at 20 kV.

     

POLYMETHYLMETHACRYLATE LANGMUIR-BLODGETT FILMS FOR HIGH RESOLUTION ELECTRON BEAM RESIST

Ultra-thin (20-100nm) polymethylmethacrylate(PMMA) films prepared by Langmuir-Blodgett techniques have been explored as high resolution electron beam resists. A Hitachi S-450 Scanning Electron Microscope (SEM) has been refitted for a high resolution electron beam exposure system. The lithographic properties and exposure conditions of LB PMMA films were investigated. 0.15μm lines-and-spaces patterns were achieved by using the SEM as the exposure tool. The results demonstrate that the etch resistance of such films is sufficiently good to allow patterning of a 20 nm aluminum film suitable for mask fabrication.     

The influence of ion beam parameters on pattern resolution

In nanofabrication the generation of phonons and secondary electrons by an incoming ion in a specimen gets important in limiting the resolution of the fabricated structures. A model is presented for calculating the effect of ion beam parameters (mass and energy) on the resolution and the production yield. In this model the phonon and secondary electron effect are calculated based on results for the scattering of the ions obtained with the Monte Carlo simulation program TRIM. The fabrication resolution is simulated for implantation, sputtering and beam induced etching and beam induced deposition.

Some preliminary results are given which show that the best resolution can be obtained for ions with high mass at low energy for all discussed fabrication techniques, while even the production yield is relatively high at these parameters.     

高灵敏度的多波长多光束干涉仪

作者用多纵模He-Ne激光照明多光束Fabry-Perot或Fizeau干涉仪,在一个自由光谱范围内,形成与不同波长对应的子条纹,相邻条纹间的间隔代表的波长数依赖于He-Ne激光腔的光学长度npL与F-P腔长nd之比r=nd/npL.当r是整数时,不同波长对应的相邻干涉级次相互重叠,条纹间隔为λ/2且强度最大;当r是分数时,r=N/M,N,M为互质的整数,相邻条纹之间间隔为λ/2M.不难做到M=10,条纹间隔为K/20.由于多光束干涉条纹细而锐,有利于读数精度提高,可以测量λ/500的程差变化,不需内插就可以给出空间分布的足够信息.这对光学元件的高精度面形检验及低密度流场显示有实际的应用前景.给出了应用的若干例子.     

High resolution AC temperature field imaging

Using a CCD camera and a multichannel lock-in scheme, the authors have enhanced the capabilities of photoreflectance microscopy to obtain a 2D image without scanning the sampler thus dramatically reducing the acquisition time. The photoreflectance images presented show Joule and Peltier heating of a polycrystalline Si 1 kΩ resistor across which a 30 mA peak to peak sinusoidal current is forced     

高分辨力单轴法线跟踪测量方法

为实现对大曲率表面轮廓进行高效、准确的非接 触测量,提出一种基于差动共焦原理的单轴法线跟踪式测量 方法,具有高分辨力和高信噪比的优点。分析了影响系统分辨力的因素,研究了在入射光为 高斯光束时倾斜对于差动 共焦探测的影响,通过理论模型及实验验证了光束倾斜时针孔偏移及针孔大小的最佳尺寸。 建立了相应的传感系统,实验表明,所建系统可以很好地跟踪被测表面,其轴向分辨 力优于5nm,组合高精度激光干涉测长系统后可用于大曲率表面轮廓的精密测量。     

High resolution fabrication of Josephson microbridges

Recent advances in fabrication techniques and performance of 100-nm-scale superconducting Josephson microbridges are reviewed. Fabrication requirements imposed by the desired electrical performance are discussed; these lead to very small device dimensions and a three-dimensional structure to ensure good cooling of the active region. Fabrication approaches based on electron-beam lithography and on edge-defined patterning with substrate steps both achieve the desired dimensions and geometries. The self-aligning step-edge approach is simpler and more versatile for dimensions <100 nm, however, and is also ideally suited for production of microbridges employing high-Tcrefractory superconductors. Device performance for recent ultrasmall microbridge devices is summarized and assessed in terms of future limits.     

高角度分辨率的信源分离算法

传统的波束形成算法在期望信号和干扰信号来向相近的情况下性能下降,不能很好地完成信源分离,针对此问题提出了一种高角度分辨率的信源分离算法。首先选取一种适合任意阵型的AR模型预测方法进行阵列扩展,然后利用基于独立分量分析的鲁棒性分离算法完成信号分离,通过结合阵列扩展和盲源分离的优点,本文提出的分离算法在不增加实际阵元数目的前提下具备比原阵列更高的角度分辨率。实际数据测试表明提出的算法能够在9元均匀圆阵上分离方位角来向间隔为0.5度的信号。     

High spectral resolution time-frequency distribution kernels

A new class of time-frequency distribution (TFD) kernels is introduced. Members in this class satisfy the desirable TFD properties and simultaneously provide local autocorrelation functions (LAF) that are amenable to high-frequency resolution modeling techniques. It is shown that members of the proposed class are product kernels, fast implementation multiplication-free kernels, recursive kernels, and optimum kernels with respect to autoterm localization     

High resolution two-dimensional ARMA spectral estimation

The authors present a practical algorithm for estimating the power spectrum of a 2-D homogeneous random field based on 2-D autoregressive moving average (ARMA) modeling. This algorithm is a two-step approach: first, the AR parameters are estimated by solving a version of the 2-D modified Yule-Walker equation, for which some existing efficient algorithms are available; then the MA spectrum parameters are obtained by simple computations. The potential capability and the high-resolution performance of the algorithm are demonstrated by using some numerical examples     

High resolution image formation from low resolution frames using Delaunay triangulation

An algorithm based on spatial tessellation and approximation of each triangle patch in the Delaunay (1934) triangulation (with smoothness constraints) by a bivariate polynomial is advanced to construct a high resolution (HR) high quality image from a set of low resolution (LR) frames. The high resolution algorithm is accompanied by a site-insertion algorithm for update of the initial HR image with the availability of more LR frames till the desired image quality is attained. This algorithm, followed by post filtering, is suitable for real-time image sequence processing because of the fast expected (average) time construction of Delaunay triangulation and the local update feature.     

RF-based electron beam timing measurement with sub-10fs resolution

Time of flight measurements of a relativistic electron beam have been performed and have demonstrated a resolution below 10fs. The electronics consisted of a heterodyne receiver incorporating an array of analogue phase detectors in order to reduce noise. The performance of the system makes it suitable for the challenging requirements of intra-pulse train timing measurements in a future linear collider.