扫描隧道显微镜钨针尖的制备与表征

采用直流电化学刻蚀方法制备扫描隧道显微镜钨针尖,研究了电化学刻蚀过程中NaOH溶液浓度、钨丝浸入长度和刻蚀电压对针尖形貌的影响。通过扫描电子显微镜(SEM)测量针尖曲率半径和针尖纵横比值,以表征针尖的尺寸和形状;通过能谱仪(EDS)分析针尖表面成分,以表征表面清洁度;通过场发射显微镜(FEM)得到Fowler-Nordheim (F-N)曲线来检测针尖发射性能。实验结果表明,当溶液浓度为2 mol/L、钨丝浸入长度为4 mm、刻蚀电压为3 V时,可以得到曲率半径约为100 nm、纵横比值为13的针尖,且表面无钨的氧化层。FEM结果显示当对针尖施加500 V的负偏压时,针尖可以稳定发射50 nA量级的电流,且针尖性能具有良好的一致性。     

Electrolyte‐Gated n‐Type Transistors Produced from Aqueous Inks of WS2 Nanosheets

Solution‐processed, low cost thin films of layered semiconductors such as transition metal dichalcogenides (TMDs) are potential candidates for future printed electronics. Here, n‐type electrolyte‐gated transistors (EGTs) based on porous WS₂ nanosheet networks as the semiconductor are demonstrated. The WS₂ nanosheets are liquid phase exfoliated to form aqueous/surfactant stabilized inks, and deposited at low temperatures (T < 120 °C) in ambient atmosphere by airbrushing. No solvent exchange, further additives, or complicated processing steps are required. While the EGTs are primarily n‐type (electron accumulation), some hole transport is also observable. The EGTs show current modulations > 10⁴ with low hysteresis, channel width‐normalized on‐conductances of up to 0.27 µS µm^?1 and estimated electron mobilities around 0.01 cm² V^?1 s^?1. In addition, the WS₂ nanosheet networks exhibit relatively high volumetric capacitance values of 30 F cm^?3. Charge transport within the network depends significantly on the applied lateral electric field and is thermally activated, which supports the notion that hopping between nanosheets is a major limiting factor for these networks and their future application.     

纳米级三氧化二铝对碱性钨抛光液的影响

研究了纳米级三氧化二铝颗粒的加入对以二氧化硅为磨料的碱性钨抛光液的影响。首先用单一因素法分析了三氧化二铝与二氧化硅质量比对原有碱性钨抛光液的去除速率的影响,以及氧化剂体积分数和pH值对抛光液去除速率的影响,取最优值,然后对添加三氧化二铝抛光液抛光后晶圆表面粗糙度进行了测试分析。实验结果显示在三氧化二铝与二氧化硅质量比为1∶2,二氧化硅水溶胶与去离子水体积比为1∶1,氧化剂体积分数为2%,pH值为9时,去除速率达到175 nm/min,较原有碱性钨抛光液提高约1倍,表面粗糙度为2.24 nm,能满足实际生产要求。     

粉煤灰/Al-Mg合金基复合材料的实验研究

粉煤灰颗粒表面在收集、贮存过程中由于物理、化学吸附,使颗粒间相互聚集,分散性差。作为复合材料增强相时,颗粒的分散性直接影响复合材料的性能。先采用酸溶法对粉煤灰进行硫酸表面处理,再通过粉末冶金法制备改性粉煤灰/铝基复合材料。复合材料的密度随粉煤灰颗粒含量的增加逐渐减小,硬度随粉煤灰含量的增加先增加后降低,密度、硬度都随成型温度的升高而增大。SEM、XRD分析表明,经硫酸处理后的粉煤灰,其表面的极性降低,粉煤灰颗粒的分散性和活性提高,且硫酸只溶解在粉煤灰中的玻璃相,而晶体相不被溶解。650℃成型温度下粉煤灰在基体中分散均匀、硬度大、密度大,故650℃为较理想的成型温度。但复合材料中也存在缺陷,有少量气孔产生。     

Single‐Step Deposition of Au‐ and Pt‐Nanoparticle‐Functionalized Tungsten Oxide Nanoneedles Synthesized Via Aerosol‐Assisted CVD,and Used for Fabrication of Selective Gas Microsensor Arrays

Tungsten oxide nanostructures functionalized with gold or platinum NPs are synthesized and integrated, using a single‐step method via aerosol‐assisted chemical vapour deposition, onto micro‐electromechanical system (MEMS)‐based gas‐sensor platforms. This co‐deposition method is demonstrated to be an effective route to incorporate metal nanoparticles (NP) or combinations of metal NPs into nanostructured materials, resulting in an attractive way of tuning functionality in metal oxides (MOX). The results show variations in electronic and sensing properties of tungsten oxide according to the metal NPs introduced, which are used to discriminate effectively analytes (C₂H₅OH, H₂, and CO) that are present in proton‐exchange fuel cells. Improved sensing characteristics, in particular to H₂, are observed at 250 °C with Pt‐functionalized tungsten oxide films, whereas non‐functionalized tungsten oxide films show responses to low concentrations of CO at low temperatures. Differences in the sensing characteristics of these films are attributed to the different reactivities of metal NPs (Au and Pt), and to the degree of electronic interaction at the MOX/metal NP interface. The method presented in this work has advantages over other methods of integrating nanomaterials and devices, of having fewer processing steps, relatively low processing temperature, and no requirement for substrate pre‐treatment.     

ULSI多层互连中的化学机械抛光工艺

介绍了化学机械抛光(CMP)技术在大规模集成电路多层互连工艺[1]中的重要作用,对CMP过程和CMP的影响因素进行简单分析。总结出CMP技术在多层互联平坦化中的优势,介绍目前常用互连材料中SiO2介质及其金属材料钨和铜的化学机械抛光常用分析机理,并简单介绍了各种互联材料常用的抛光液及抛光液的组分,对抛光液作了简单的对比。针对传统CMP过程存在的问题,分析了皮带式和固定磨料的CMP技术。     

一种复合钨海绵体钡钨阴极

通过分析影响钡钨阴极蒸发的各种因素,结合实际生产中的工艺要求,介绍了一种复合钨海绵体钡钨阴极制造工艺,能够有效降低钡钨阴极蒸发。     

Tungsten‐Based Materials for Lithium‐Ion Batteries

Lithium‐ion batteries are widely used as reliable electrochemical energy storage devices due to their high energy density and excellent cycling performance. The search for anode materials with excellent electrochemical performances remains critical to the further development of lithium‐ion batteries. Tungsten‐based materials are receiving considerable attention as promising anode materials for lithium‐ion batteries owing to their high intrinsic density and rich framework diversity. This review describes the advances of exploratory research on tungsten‐based materials (tungsten oxide, tungsten sulfide, tungsten diselenide, and their composites) in lithium‐ion batteries, including synthesis methods, microstructures, and electrochemical performance. Some personal prospects for the further development of this field are also proposed.     

CNT对BST陶瓷微波介电性能的影响

采用XRD及SEM研究(Ca0.61Nd0.26)TiO3对微波介质陶瓷Ba4Sm9.33Ti18O54的结构和微波介电性能的影响。获得了一些性能较好的微波介质陶瓷(1–x)Ba4Sm9.33Ti18O54-x(Ca0.61Nd0.26)TiO3,其微波介电性能如下:εr=75,Q·f为8985GHz,τf为–8.2×10–6℃–1(x?=0);εr为75,Q·f为9552GHz,τf为–14.4×10–6℃–1(x?=0.2)。     

一种金属填充硅通孔工艺的研究

硅通孔(Through silicon via)的互连技术是3D IC集成中的一种重要工艺。报道了一种高深宽比的垂直互连穿透硅通孔工艺,其通孔的深宽比达到50以上;研究了利用钨填充硅通孔的一些关键工艺,包括阻挡层淀积工艺和钨填充工艺,分析了不同填充工艺所造成的应力的变化。最后获得了一种深宽比达到58∶1的深硅通孔无缝填充。