Sub-micron-structure machining on silicon by femtosecond laser

Sub-micron-structure machining on silicon substrate was studied by direct writing system of femtosecond laser with the central wavelength of 800 nm, pulse duration of 120 fs and repetition rate of 1 kHz. Three kinds of experiments were conducted: 1) the effect of photoresist on silicon; 2) machinability of different orientations of silicon; and 3) the size of micro-structure and the cross-section shape. Photoresist SU8 was coated onto silicon substrates in thicknesses of 100 μm. SU8 remained on the silicon substrate while the silicon under the machined SU8 was removed after laser machining. Orientations of (100), (110), and (111) silicon substrates were machined with the laser power of 60 μW and the scanning speed of 3 mm/min. Spike morphologies were observed on all three orientations of silicon substrates without obvious directional difference of these spikes on different silicon substrates. In addition, the ablation threshold energies were also similar. In the consideration of ablation energy, one numerical model of the machining parameters has been proposed to simulate the cross-section of the micro-structure. The predicted shape by simulation can fit the profile of the cross-section shape well.

Effect of sintering on microstructures and properties of sub-micron Ti(C,N)-based cermets

The influence of different sintering processes, including vacuum sintering, vacuum sintering followed by HIP and sintering-HIP, on the microstructure and properties of sub-micron Ti(C,N) cermets with various binder contents was studied. Image analysis based on back-scattered electrons image observations was used to determine the morphologic and structural characteristics. Transverse rupture strength(TRS), hardness, fracture toughness were measured and TRS data were treated by Weibull statistics further. It is shown that a very significant improvement in TRS can be obtained by HIP or sintering-HIP treatment for the alloys with lower and middle binder content at the controlled cooling rate, but the effect is not obvious for the alloys with higher binder content. HIP is also helpful for improving the hardness of sub-micron Ti(C,N) cermets, however, but can lower the fracture toughness. The variation of these properties was interpreted in terms of the difference in morphologic and structural characteristics.

Microstructure and Strength of Laser Welds of Sub-micron Particulate-reinforced Aluminum Matrix Composite Al_2O_(3p)/6061Al

The microstructure of laser welds of sub-micron particulate-reinforced aluminum matrix composite Al_2O_(3p)/6061Al and the weldability of the material were studied. Experimental results indicated that because of the huge specific surface area of the reinforcement, the interfacial reaction between the matrix and the reinforcement was re- strained intenslvely at elevated temperature and pulsed laser beam. The main factor affecting the weldability of the com- posite was the reinforcement segregation in the weld resulting from the push of the liquid/solid interface during the soli- dification of the molten pool. The laser pulse frequency directly affected the reinforcement segregation and the reinfor- cement distribution in the weld, so that the weldability of the composite could be improved by increasing the laser pulse frequency. On the basis of this, a satisfactory welded joint of sub-micron paniculate-reinforced aluminum matrix com- posite Al_2O_(3p)/6061Al was obtained by using appopriate welding parameters.

Impact-disrupted gunshot residue：A sub-micron analysis using a novel collection protocol

The analysis of gunshot residue(GSR) has played an integral role within the legal system in relation to shooting cases. With a characteristic elemental composition of lead, antimony, barium, and a typically discriminative spheroidal morphology, the presence and distribution of GSR can aid in firearm investigations. In this experiment, three shots of low velocity rim-fire ammunition were fired over polished silicon collection substrates placed at six intervals over a 100 cm range. The samples were analysed using a Field Emission Gun Scanning Electron Microscope(FEG-SEM) in conjunction with an X-flash Energy Dispersive X-ray(EDX) detector, allowing for GSR particle analyses of composition and structure at the sub-micron level. The results of this experiment indicate that although classic spheroidal particles are present consistently throughout the entire range of samples their sizes vary significantly, and at certain distances from the firearm particles with an irregular morphology were discerned, forming "impactdisrupted" GSR particles, henceforth colloquially referred to as "splats". Upon further analysis, trends with regards to the formation of these splat particles were distinguished. An increase in splat frequency was observed starting at 10 cm from the firearm, with 147 mm^(-2) splat density, reaching a maximal flux at 40 cm(451 mm^(-2)), followed by a gradual decrease to the maximum range sampled. Moreover, the structural morphology of the splats changes throughout the sampling range. At the distances closest to the firearm, molten-looking particles were formed, demonstrating the metallic residues were in a liquid state when their flight path was disrupted. However, at increased distances-primarily where the discharge plume was at maximum dispersion and moving away from the firearm, the residues have had time to cool in-fight resulting in semi-congealed and solid particles that subsequently disrupted upon impact, forming more structured as well as disaggregated splats. The relative compositions of the characteristic elements that are present in GSR also change in the different splat morphologies sampled,which may contribute to the particles' physical structures. Two distinct populations of splats were also observed: circular and elongated, which suggest the residues hit the substrate at different angles. The difference in the splat impact angle can be ascribed to the position of the residues within the firearm discharge plume; particles get caught up in the vortex that is created by the discharge gases behind the projectile as it leaves the barrel, thereby affecting their directionality and flight time. This reasoning could also justify the existence of both spheroidal and splat particles at certain distances. The novel sampling and analytical techniques used in this experiment have provided previously unknown information in relation to GSR structure and formation which could have greater implications to its current analysis amongst laboratories and law enforcement agencies worldwide.

A novel solution-based self-assembly approach to preparing ultralong titanyl phthalocyanine sub-micron wires

Ultralong titanyl phthalocyanine （TiOPc） sub-micron wires have been synthesized by a novel solution-based self- assembly method. By using different solvents, changing the mass concentration and the solvent vapor pressure, the length and the shape of the wires can be adjusted. The mixed-phase properties of the TiOPc sub-micron wires were investigated by the ultraviolet-visible （UV-vis） absorption spectrum and X-ray diffraction. Organic transistors based on these wires were studied, which show the typical p-channel characteristics.

Effect of flow field distribution on the synthesis of sub-micron ZSM-5 molecular sieve in a quasi-solid system

Scale-up synthesis of sub-micron ZSM-5 molecular sieve in a quasi-solid system was investigated. Compared with traditional hydrothermal synthesis, the synthesis in a quasi-solid system has the advantages of high yield, short crystallization time, low energy consumption as well as low emissions. However, the high solid content in the quasi-solid system can cause the mass and heat transfer problems and make scalable production difficult. In order to solve the problem, we have developed a method for the optimization of the mass and heat transfer. By this method one can vary the flow field in the reactor by changing the stirrer speed. Scale-up synthesis of the sub-micron ZSM-5 molecular sieve in a quasi-solid system was carried out in a 5 L reactor with double propeller-type agitators. The process was investigated with product characterization using X-ray diffraction （XRD） and scanning electron microscopy （SEM） and the flow field information was collected using laser Doppler velocimetry （LDV）. The results showed that the flow field patterns can be tuned by using different stirrer speeds, the morphology and size of assynthesized of ZSM-5 can be effectively controlled.

Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

Pattem imprinting in deep sub-micron static random access memories （SRAMs） during total dose irradiation is inves- tigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell＇s static noise margin （SNM） and the background data, and study the influence of irradiation on the probability density function of ASNM, which is the difference between two data sides＇ SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation （STI） oxide rather than from the gate oxide of the micron-device.

Effects of Mg content on aging behavior of sub-micron Al_2O_(3p)/Al-Cu-Mg composites

30%Al2O3p/Al-Cu-2.0Mg composite and Al2O3p/Al-Cu-2.5Mg composite with 0.3μm-Al2O3 particles were fabricated. Age-hardening behaviors of two composites and the related matrix alloys were studied by means of Brinell-hardness measurement, DSC and TEM. The results show that the hardness of the composite is improved obviously because of the addition of sub-micron Al2O3 particles. But the hardness increment of Al2O3p/Al composite after aging is lower than that of the related matrix alloy. Moreover, the formation of GP region is suppressed by the addition of sub-micron Al2O3 particles, which broadens the exothermic peak of S' phase. The increment of Mg content has a different influence on accelerating the aging processes of aluminum alloys and the composites, and the hardness also increases.

Δ<i>I_DDQ</i>Testing of a CMOS Digital-to-Analog Converter Considering Process Variation Effects

In this paper, we present the implementation of a built-in current sensor (BICS) which takes into account the increased background current of defect-free circuits and the effects of process variation on ΔIDDQ testing of CMOS data converters. A 12-bit digital-to-analog converter (DAC) is designed as the circuit under test (CUT). The BICS uses frequency as the output for fault detection in CUT. A fault is detected if it causes the output frequency to deviate more than ±10% from the reference frequency. The output frequencies of the BICS for various (MOSIS) model parameters are simulated to check for the effect of process variation on the frequency deviation. A set of eight faults simulating manufacturing defects in CMOS data converters are injected using fault-injection transistors and tested successfully.

亚微米级ε型CL-20的制备、表征与性能

采用超临界气体抗溶剂(gasanti-solvent,GAS)技术制备了平均粒径为721.9nm的亚微米级ε型六硝基六氮杂异伍兹烷(CL-20),应用傅立叶变换红外光谱(Fourier translation infrared spectrum,FT-IR),对亚微米级CL-20的晶型进行了鉴别,并进行了小隔板试验、撞击感度和爆发点测试。研究结果表明,细化后的亚微米级ε型CL-20冲击波感度的隔板厚度降低了58.6%,撞击感度的特性落高提高了84.1%,而爆发点保持不变。

超临界GAS的工艺条件对CL-20粒度和晶型的影响

采用超临界气体抗溶剂(GAS)技术的半连续-静态工艺制备出平均粒径721.9nm的亚微米级ε型六硝基六氮杂异戊兹烷(CL-20),探讨了工艺条件对CL-20粒径和晶型的影响,测试了CL-20细化前后的冲击波感度和撞击感度。得到制备亚微米级ε型CL-20的最佳工艺条件为:压力平均升高速率4.0MPa/min,溶液初始浓度8g/100mL,系统压力10.5MPa,系统温度50℃。亚微米级ε型CL-20冲击波感度的隔板值降低58.6%,撞击感度的特性落高值提高84.1%。

配位键合剂-603对亚微米CL-20撞击感度的影响

用亚微米单质炸药CL-20和亚微米CL-20/配位键合剂-603(LBA-603)混合炸药的撞击感度试验研究了LBA-603对亚微米CL-20/LBA-603体系撞击感度的影响,并对LBA-603在混合炸药中的作用机理进行了探讨。结果表明,由于LBA-603与CL-20分子的-NO2基团形成诱导效应,LBA-603在亚微米CL-20表面形成一层黏附层,对亚微米CL-20起到包覆作用,包覆层具有能量缓冲、吸热、表面修饰的作用;亚微米CL-20/LBA-603混合炸药的撞击感度随LBA-603添加量的增加而降低,与单质炸药亚微米CL-20相比,添加质量分数10%的LBA-603后,混合炸药的特性落高(H50)提高了10.96 cm。

基于0.25μm CMOS工艺的1.8V Rail-to-Rail运算放大器

采用 TSMC 0.25μm CMOS 工艺,设计实现了一种低功耗、高增益带有恒跨导输入级的 Rail-to-Rail 运算放大器。基于 BSIM3V3 Spice 模型,采用 Hspice 对整个电路进行仿真,在 1.8V 的单电源电压工作条件下,直流开环增益达到 108.6dB,相位裕度为 57.2 度,单位增益带宽为 5MHz,功耗为 0.23mW。

弱磁场下低温中和法制备亚微米非晶态δ-FeOOH的研究

利用XRD和SEM分别对在弱磁场下通过低温中和法制备的羟基铁氧化物进行相成分和颗粒形貌分析.试验结果表明:无磁场下,产物是由部分球形和部分针状的α-FeOOH组成.0.1T磁场下,产物是纺锤形的γ-FeOOH,但是,其粒度分布很不均匀.0.3T磁场下,产物是球形的Fe1.833(OH)0.5O0.25.0.5T磁场下,产物是100nm左右的球形的非晶态δ-FeOOH.Fe1.833(OH)0.5O0.25是无磁场下制备的α-FeOOH向弱磁场下制备的δ-FeOOH转变的中间产物.并且,亚微米球形Fe1.833(OH)0.5O0.25和亚微米非晶态球形δ-FeOOH的粒度分布都很均匀.此外,弱磁场影响羟基铁氧化物的结晶度.

溶胶-水热法制备亚微米4A分子筛

以湿硅胶和铝矾土为原料,采用溶胶-水热法合成了亚微米4A分子筛。采用X射线衍射(XRD)、扫描电镜(SEM)和红外光谱(FT-IR)等分析手段对溶胶-水热法制备的亚微米4A分子筛进行表征,并与常规水热法进行对比。结果表明:采用溶胶-水热法制备的产品结晶度为96%;产品形状规则,大小均匀、单一,呈正态分布且分布范围较窄;产品粒度较小,粒径≤1μm粒子体积分数可达到100%;4A分子筛(干基)钙离子(以碳酸钙计)交换容量为335 mg/g,白度为97%,完全满足洗涤助剂的要求。

溶胶-水热法制备亚微米4A分子筛

以硅胶湿样和铝矾土为原料,利用溶胶-水热法合成了亚微米4A分子筛,并采用XRD、SEM和FT-IR等分析手段与常规水热法合成的4A分子筛进行了对比。结果表明,采用溶胶-水热法制备的产品,结晶度为96%,形状规则、大小均匀、呈正态分布且分布范围较窄;粒度小于等于1μm的可达到100%;钙离子交换容量为335mgCa-CO3/g(干基)4A分子筛,白度为97%,完全满足洗涤助剂的要求。

亚微米CMOS电路中V_(DD)-V_(SS)ESD保护结构的设计

文章根据一个实际电路中ESD保护结构的设计,引出了一种亚微米CMOS IC中基于RC延迟而设计的VDD-VSS之间直接电压钳位结构,并结合例子中此结构前后的修改优化对该结构进行了详细的仿真分析。进一步比较了两种VDD-VSS电压钳位结构的优劣。最后阐述了亚微米CMOS电路的设计中,全芯片ESD结构的有效设计。

煅烧温度对SiC-Al_2O_3-Y_2O_3复合粉体分散性与烧结性的影响

为获得具有良好使用性能的碳化硅基陶瓷复合材料,以亚微米级Si C粉体和分析纯的Al(NO_3)_3与Y(NO_3)_3为主要实验原料、氨水为沉淀剂,用共沉淀包覆方法制备Si C-Al_2O_3-Y_2_O3纳米复合粉体,对复合粉体前驱体的DTA进行分析,并研究其在煅烧过程中的物相变化,以及煅烧温度对复合粉体的分散性和烧结性的影响。结果表明:Al_2O_3和Y_2O_3反应生成新相YAG,当YAG质量分数为10%、煅烧温度为600℃,复合粉体的烧结性能最好。

煤系高岭土插层-水热法制备亚微米级13X分子筛

以煤系高岭土为原料,制备了高岭土/二甲基亚砜插层复合物,并对产物进行表征,结果表明,在60℃超声水浴插层处理3 h,700℃热处理的插层剥离效果较好,制得的偏高岭土的粒径为100~900 nm。以制得的偏高岭土为原料,采用水热法成功制备了亚微米级13X沸石分子筛。利用XRD、SEM和静态饱和吸水量测定等手段对不同预晶化过程、晶化时间下制备的产物进行分析,并对亚微米级13X分子筛的生长过程进行了研究。预晶化时间4 h,晶化时间24 h条件下,制备的13X沸石分子筛晶体呈八面体晶型,形状规则,大小均一,粒径为100 nm,其相对结晶度为90.72%,静态饱和吸水率达33.17%。比表面积为909 m^2/g,总微孔容为0.15 cm^3/g,孔径大小为33×10^(-9)μm。

合成吡咯-苯胺共聚物亚微米颗粒及增强的超电容性

采用简单的化学氧化聚合直接合成吡咯-苯胺（Py-An）共聚物亚微米颗粒.所得共聚物的产率和电导率受聚合条件如共单体配比、聚合温度和氧单比的影响.当n（Py）/n（An）=7/3,氧单比为1,共聚温度为20℃时,共聚物具有相对较高的产率（57.5%）和电导率（2.61S/cm）.红外光谱（FT-IR）的分析结果表明,共聚物分子链由吡咯和苯胺链段构成,并随着共单体配比的不同而变化.扫描电镜（SEM）显示Py-An （7/3）共聚物呈现亚微米尺度的无规则颗粒状形貌,粒径约300-500nm.相对均聚物来说,Py-An（7/3）共聚物显示出更好的溶解性和赝电容特性.循环伏安（CV）的研究表明Py-An（7/3）共聚物的质量比电容为256F/g,且1000次循环后仍能保持初始比电容的97.6%.