Electron holographic mapping of two-dimensional doping areas in cross-sectional device specimens prepared by the lift-out technique based on a focused ion beam

Recently, electron holography has been successfully applied to analyze two-dimensional (2D) dopant distribution in semiconductor devices with high resolution and high sensitivity. The preparation of proper specimens is a fundamental step for the practical application of electron holography in the semiconductor industry. Therefore, it is important to explore a reliable and quick specimen preparation method. In our current work, we have tried to use the lift-out technique based on a focused ion beam, to fabricate cross-sectional CMOS device specimens for electron holographic observation. Using the lift-out technique, specimens with a large area and uniform thickness can be prepared directly from integrated circuit wafers in a very short time. Specimens with a complex and unknown dopant distribution were examined using off-axis electron holography. In the reconstructed phase images, the different 2D doping areas in a CMOS device, such as source, drain, well and substrate, were revealed successfully. The advantages and disadvantages of the technique are discussed.     

Prediction of nanopattern topography using two-dimensional focused ion beam milling with beam irradiation intervals

Beam irradiation intervals are a critical parameter in the fabrication of nanopatterns via focused ion beam (FIB) milling. The beam irradiation intervals are defined in terms of the overlap. In this paper, the nanopattern height on a silicon surface is predicted using a mathematical FIB milling model that varies the overlap. The proposed model takes into account the angle dependence of the sputtering yield and redeposition effect, together with the superposition of a bi-Gaussian beam. The model was verified by comparing the results of a nanopattern machining experiment to those of a simulation based on the model. The simulation calculated the final two-dimensional geometry from ion milling parameters. The results of the simulation indicate that the proposed model is more precise than one that only considers the superposition of a Gaussian beam.     

Imaging one-dimensional and two-dimensional planar photodiode detectors fabricated by ion milling molecular beam epitaxy CdHgTe

Imaging one-dimensional (1-D) and two-dimensional (2-D) arrays of mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) planar photodiodes were fabricated by ion milling of vacancy-doped molecular beam epitaxy Cd_xHg_1−xTe layers. Sixty-four-element 1-D arrays of 26×26 μm² or 26×56 μm² diodes were processed. Zero-bias resistance-area values (R₀A) at 77 K of 4×10⁶ Θcm² at cutoff wavelength λ_CO=4.5 μm were measured, as well as high quantum efficiencies. To avoid creating a leakage current during ball bonding to the 1-D array diodes, a ZnS layer was deposited on top of the CdTe passivation layer, as well as extra electroplated Au on the bonding pads. The best measured noise equivalent temperature difference (NETD) on a LWIR array was 8 mK, with a median of 14 mK for the 42 operable diodes. The best measured NETD on a MWIR array was 18 mK. Two-D arrays showed reasonably good uniformity of R₀A and zero-bias current (I₀) values. The first 64×64 element 2-D array of 16×16 μm² MWIR diodes has been hybridized to read-out electronics and gave median NETD of 60 mK.     

数字全息法测量透明物体变形的修正

采用数字全息可以测量透明物体的厚度变形场,但我们此前的研究忽略了应力导致的折射率变化,给测量带来了误差,本文对这个问题进行了讨论,修正了物光的相位变化与物体厚度变形间的关系。相较于修正前的公式,新增加了一个修正项,通过测量带孔有机玻璃试件在均布拉伸载荷作用下的厚度变形,并将测量结果与理论计算结果进行比较,发现用修正前的关系式得到的变形量偏大,而修正后的结果与理论值吻合很好,证明此修正是正确和必要的。     

Two-dimensional dopant profiling in semiconductor devices by electron holography and chemical etching delineation techniques with the same specimen

The electron holography and chemical etching delineation techniques were successfully employed to assess two-dimensional (2D) dopant profiles in semiconductor devices. The results obtained from both techniques with the same specimen were precisely compared and discussed in order to evaluate the performance limits of these techniques. It was demonstrated that both techniques are very effective in obtaining reliable 2D dopant profiles in nanodevice.     

Electron beam induced current study of ion beam milling type conversion in molecular beam epitaxy vacancy-doped CdxHg1−xTe

Ion milling has been used to type convert molecular beam epitaxy vacancy-doped Cd_xHg_1−xTe, and electron beam induced current measurements have been performed to study the pn-junction depth dependence on milling time, milling current and vacancy concentration. The junction depth seems to initially increase linearly with time for depths up to ∼ 4 μm, then possibly as the square root of time at larger depth. For given x, the depth increases with decreasing vacancy concentration. For the same annealing temperature, high x samples have lower carrier concentration and greater junction depth than low x samples. Up to 4 μm, junction depth is proportional to milling current density as well as milling time.     

Markers prepared by focus ion beam technique for nanopositioning procedures

Positioning on the nanometer scale with replaceable nanotools requires well defined positioning marks to restore the coordinate system with nanoscale accuracy. In this work we propose such patterns (references, markers) consisting of self-organized surfaces and hierarchic patterns written by the focus ion beam (FIB) technique. These patterns are realized either by a deposition of platinum or by cuts with different width, length, height and/or depth. The hierarchic patterns allow the use of automatic search routines for the recovery of the coordinate system on a sample surface. These patterns contain relative large markers for optical detection and are refined down to the nanoscale level. Finally, mesoscopic, self-organized features within these FIB written patterns enables an accurate positioning of the probe on the sample with nanoscale accuracy.     

Experimental study of a swept reflectometer with a single antenna for plasma density profile measurement

The feasibility of a swept microwave reflectometer, with one antenna only, for plasma electron density measurement is studied. Experimental results obtained in the laboratory by simulating the plasma with a metallic mirror are presented.     

电镀包埋制备可减薄粉末样品的研究

为了获取更多的粉末颗粒样品内部结构细节信息 ,需要对其进行减薄 ,但常规的由块状样品制备薄膜的方法[1] ,不能解决粉末颗粒的减薄问题。而采用电镀方法[2 ] ,使粉末包埋在金属膜中 ,则是一种可行的方案。本文采用一种电镀包埋法制备ＴＥＭ薄膜样品 ,得到满意的效果。实验方法1 若粉末颗粒度较大 ,则先用玛瑙研钵研磨一下 ,使颗粒的平均粒度达到 30 μｍ左右即可。以乙醇作分散介质均匀分散已处理的微颗粒试样 ,然后滴到事先已清洗干净的金属Ｎｉ片上。待分散介质挥发至半干时 ,Ｎｉ片连同样品水平放置在电镀槽底作阴极。2 配制以下成分的…     

A novel harmless trimming for micro-device with defects and particles in arbitrary geometry by fine milling of focused ion beam

A novel method combining focused ion beam (FIB) milling and image processing for fine trimming of micro-device is introduced in detail in this paper. By using small beam spot size and beam current, selective milling can be realized according to requirement in terms of the difference of gray scale color intensity between defects and useful areas of the FIB images. A magnetoresistive head and ink jet spray head of color printer trimming were described as examples. Trimming result shows that the method is practical and suitable for the fine trimming of micro-device by the selective milling.     

High-contrast measurement of refractive-index profile in fused single-mode fibre couplers with high resolution by deconvolution

The optical contrast of the refracted near-field measurement method for fibre refractive-index profiles has been improved by a factor of about five by using numerical apertures adapted to the coupler to be measured. A spatial resolution of 0.3 mu m was achieved by deconvolving with the effective scanning near field.<>     

GaInAs junction FET with InP buffer layer prepared by selective ion implantation of Be and rapid thermal annealing

GaInAs JFETs were fabricated on VPE-grown GaInAs layers. The pn junctions have been realised with Be ion implantation and rapid thermal annealing. The devices show a high transconductance of 130 mS/mm and an electron saturation velocity of 1.8 × 107 cm/s. Channel mobilities measured at the complete device are as high as 6800 cm2/Vs. These excellent device properties are due to the use of an undoped InP buffer layer which avoids the diffusion of Fe from the substrate into the active layer. The data were supported by S-parameter measurements which gave a frequency limit of 20 GHz for gate dimensions of 1.6 by 200 ?m2.     

几种骨标本微波快速脱钙的电镜实验研究

大鼠胫骨、股骨颈、骨松质及人骨髓活检标本 ,经戊二醛固定后 ,用戊二醛 EDTA脱钙液 ,选择不同微波功率及时间进行脱钙。结果为微波功率 4 2 0W作用 1min加 70W 8～ 10min共 3～ 4次 ,既能达到脱钙目的 ,又能保存好细胞超微结构 ,分别适于几种硬度骨标本的电镜快速制样     

Planar optical waveguides prepared in GIL49 and BK7 glass substrates by K+-Na+ ion exchange with the electric field assistance

This report focuses on research into waveguides prepared by K⁺-Na⁺ ion exchange with the help of an electric field, and the subsequent comparison with waveguides prepared by pure thermal ion exchange. The goals of this work were to determine the characteristics of and to address the technological problems associated with waveguides prepared in two types of highly pure optical glass: special soda-lime silica GIL49 glass produced from pure raw materials and commercially prepared borosilicate BK7 glass. An appropriate chemical mixture, KNO₃:Ca(NO₃)₂ in the molar ratio of 41:59, was used as the source of potassium ions. Experiments were conducted at temperatures between 250 and 410°C, and electric field values between 0 and 150 V/mm. The number of modes, depth, profile, and the change in refractive index (Δn) were measured for samples from each type of glass under various technological conditions. All of these parameters can be controlled accurately and repeatedly by the electric field. These experiments have also shown that a particular advantage of these types of pure glass is the low waveguide optical losses (0.1 to 0.2 dB/cm) attainable.     

Comparative study of ZnO thin films prepared by plasma deposition and electron beam evaporation for use in photovoltaic devices

Undoped zinc oxide thin films were grown at room temperature using two techniques: plasma deposition (PD) and electron beam evaporation in an argon atmosphere. PD offers some advantages, such as low ion damage and low deposition temperature. The optical transmittance of the films deposited by both methods was higher than 80% in the near UV–VIS range; the energy band gap and index of refraction agree with values reported in the literature. The resistivity of films grown by PD was 3.1 × 10⁻² Ω cm, lower than the value of 1.2 × 10⁻¹ Ω cm found for plasma assisted e‐beam evaporated films. Copyright © 2010 John Wiley & Sons, Ltd.     

In vivo and real-time measurement of magnetic nanoparticles distribution in animals by scanning SQUID biosusceptometry for biomedicine study

Magnetic nanoparticles have been widely applied to biomagnetism, such as drug deliver, magnetic labeling, and contrast agent for in vivo image, etc. To localize the distribution of these magnetic particles in living organism is the first important issue to confirm the effects of magnetic nanoparticles and also evaluate the possible untoward effects. In this study, a scanning high T(c) rf-SQUID superconducting quantum interference devices (SQUIDs) biosusceptometry, composed of static SQUID unit and scanning coil sets, is developed for biomedicine study with the advantages of easy operation and unshielded environment. The characteristics tests showed that the system had the low noise of 8 pT/Hz at 400 Hz and the high sensitivity with the minimum detectable magnetization around 4.5 × 10(-3) EMU at distance of 13 mm. A magnetic nanoparticle detection test, performed by ex vivo scanning of the magnetic fluids filled capillary under swine skin for simulation of blood vessels in living bodies, confirmed that the system is feasible for dynamic tracking of magnetic nanoparticles. Based on this result, we performed further studies in rats to clarify the dynamic distribution of magnetic nanoparticle in living organism for the pharmacokinetics analysis like drug delivers, and propose the possible physiological metabolism of intravenous magnetic nanoparticles.     

Optical fiber sensor by cascading long period fiber grating with FBG for double parameters measurement

An optical fiber sensor for strain and temperature measurement based on long period fiber grating (LPFG) cascaded with fiber Bragg grating (FBG) structure has been proposed and realized both theoretically and experimentally. Theoretical analysis shows that two microstructures with similar sensitivities cannot be used for double parameters measurement. The LPFG is micromachined by the CO2 laser, and the FBG is micromachined by the excimer laser. For the validation and comparison, two FBGs and one LPFG are cascaded with three transmission valleys, namely FBG1 valley at 1 536.3 nm, LPFG valley at 1 551.2 nm, and FBG2 valley at 1 577.3 nm. The temperature and strain characteristics of the proposed sensor are measured at 45—70 °C and 250—500 με, respectively. The sensitivity matrix is determined by analyzing wavelength shifts and parameter response characterization of three different dips. The proposed optical fiber sensor based on LPFG cascaded with FBG structure can be efficiently used for double parameters measurement with promising application prospect and great research reference value.     

Cr2WO6 nanoparticles prepared by hydrothermal assisted method with selective adsorption properties for methylene blue in water

Cr₂WO₆ nanocrystallites were prepared using a facile hydrothermal assisted process. The microstructures and preferential adsorption performance for methylene blue (MB) of the prepared nanoparticles were investigated using a solid state reaction resulted in Cr₂WO₆ crystallites as a baseline. Their structural information were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometer, transmission electron microscopy, N₂–sorption BET surface area, thermogravimetric and differential scanning calorimeters. Results show that the Cr₂WO₆ nanocrystallines with ~50 nm in size are achieved by calcination at 650 °C for only 2 h using a hydrothermal product as precursor, while the micrometer sized Cr₂WO₆ crystallites synthesized by the solid state reaction at higher temperature (950 °C) for at least 20 h. For the as-prepared Cr₂WO₆ nanocrystallines, the adsorption performance were tested using methyl orange (MO), Rhodamine B (RhB) and methylene blue (MB). The adsorption ability was found to be in the order of MB>>RhB>MO owing to electrostatic interactions between the adsorbent and the dye. Results of this study provide a kind of promising alternative adsorbent for color removal from industrial wastewaters.     

Theoretical and experimental investigations of vibration waveforms excited by an electro-hydraulic type exciter for fatigue with a two-dimensional rotary valve

Conventional electro-hydraulic excitation is usually controlled by a servo valve employing a sliding spool type construction. However, the comparatively slow response of the servo valve will greatly limit the system's high-frequency performance. Therefore, a rotary valve with the rotary motion of the spool as a new excitation mechanism is proposed to obtain the desired excitation, especially a high-frequency excitation wave for fatigue. An electro-hydraulic exciter using a combination of a three-way two-dimensional rotary valve (2D rotary valve) and an unequal area piston is taken as an example. Analysis of the vibration output to a typical wave input yields an analytic solution of the vibration waveform excited by this electro-hydraulic system. The mathematical formulation of the harmonics is also derived. Additionally, an electro-hydraulic excitation test-bed is built to acquire an experimental excitation wave. Consequently, the analysis of the excitation waveform in an approximate analytical and experimental method is used to verify access to high-frequency excitation, even resonance excitation.     

Stripe-geometry laser with in-situ ohmic contact and self-aligned native surface oxide mask for current isolation prepared by molecular beam epitaxy

A simple stripe-geometry laser is prepared by molecular beam epitaxy with an in-situ ohmic contact stripe and self-aligned native surface oxide mask for current isolation. The thresholds are about 70 mA for 5 ?m-wide and 380 ?m-long stripes. The light/current characteristics are linear up to ?8?10 mW/mirror with a spontaneous emission level at threshold of ?0.3 mW/mirror. The temperature coefficient T0 measured for one wafer is as high as 255 K.