等离子体氧化制备超薄SiO2层的性质

利用等离子体氧化方法在单晶硅片上制备了厚度小于10nm的超薄SiO2层．通过傅里叶红外光谱(FTIR)、X射线光电子谱（XPS）、透射电子显微镜（TEM）、椭圆偏振法和电流电压（I-V）、电容电压（C-V）测量对生成的超薄氧化层性质进行研究．     

等离子体氧化制备超薄SiO_2层的性质

利用等离子体氧化方法在单晶硅片上制备了厚度小于 10 nm的超薄 Si O2 层 .通过傅里叶红外光谱 (FTIR)、X射线光电子谱 (XPS)、透射电子显微镜 (TEM)、椭圆偏振法和电流电压 (I- V)、电容电压 (C- V)测量对生成的超薄氧化层性质进行研究     

HfO2高K栅介质薄膜的电学特性研究

研究了高 K(高介电常数 )栅介质 Hf O2 薄膜的制备工艺 ,制备了有效氧化层厚度为 2 .9nm的超薄MOS电容。对电容的电学特性如 C-V特性 ,I-V特性 ,击穿特性进行了测试。实验结果显示 :Hf O2 栅介质电容具有良好的 C-V特性 ,较低的漏电流和较高的击穿电压。因此 ,Hf O2 栅介质可能成为 Si O2 栅介质的替代物。     

氨气预氮化制备超薄氮化硅薄膜及电学性能

为寻求制备性能良好的纳米厚度氮化硅(SiN_x)薄膜的方法,采用NH_3等离子体氮化、SiH_4/NH_3等离子增强化学淀积法及先氮化后淀积的方法制备了三种SiN_x薄膜,研究比较了三种薄膜的性质。用X射线光电子谱检测了NH_3等离子体氮化Si片得到的SiN_x薄膜的组分,利用椭圆偏振光谱仪测量薄膜厚度,估算了氮化速率。用NH_3和SiH_4作为反应气,分别在原始硅片和经过NH_3预氮化后的硅片上淀积厚度为5 nm、10 nm和50 nm的SiN_x薄膜。用电容-电压法研究了薄膜样品的电学性质,发现单纯用NH_3等离子体氮化的薄膜不适合做介质膜,而先用NH_3氮化再淀积SiN_x的样品比直接淀积SiN_x的样品界面性能明显改善,界面态密度降低到1～2×10~(11)eV~(-1) cm~(-2)。     

MOS结构电容高频C-V特性的应用

CMOS工艺的发展要求栅介质层厚度不断减薄,随着栅极漏电流的不断增大使用准静态的方法测量器件特性不稳定。根据这一情况,提出用高频电容电压(C-V)来评价深亚微米和超深亚微米器件工艺。通过高频C-V法结合MOS相关理论可以得到介质层的厚度、最大耗尽层宽度、阈值电压、平带电压等参数以及栅介质层中各种电荷密度的分布,用以评价栅介质层和衬底的界面特性。文章提出通过电导对测量结果进行修正,使其能够适用更小尺寸器件的要求,使高频C-V法能够在不同的工艺下得到广泛的应用。     

SiO_2-Si_3N_4栅介质膜陷阱特性的高频C-V分析

采用高频 C-V特性测试技术 ,研究由热氧化生成的超薄 Si O2 膜和低压化学汽相淀积法制备的非均匀结构 Si3N4膜 ,两者组成的栅介质膜的陷阱特性 (包括陷阱密度、能量和空间分布深度等参数 )。结果表明 :在栅复合膜陷阱电荷非稳态释放模型下建立的高频 C-V理论及其分析方法 ,可以很好地表征实验曲线 ,并获取所需的存储陷阱分布参数     

MFIS结构的C-V特性

研究了运用SOL-GEL方法制备的Au/PZT(铅锆钛)/ZrO2/Si结构电容即MFIS(Metal/Ferroelectr c/Irsulator/Semiconductor)电容的方法,并对其进行了SEM、C-V特性测试及ZrO2介质层介电常数分析.研究了C-V存储窗口(Memory WindoW)电压与铁电薄膜和介质层厚度比的关系,得出MFIS电容结构中最佳铁电薄膜和介质层厚度比为7 10左右,在外加电压5V-+5V时存储窗口可达2.52V左右.     

砷化镓等离子体阳极氧化及其在MOS场效应晶体管中的应用

本文报导了高频辉光放电等离子体中阳极氧化砷化镓、制备砷化镓自身氧化膜的低温、干法工艺。对氧化条件、影响氧化速率的因素、自身氧化膜的性质进行了初步研究。得到了均匀、透明、无定形的氧化膜,平均折射率为1.7～1.9。膜的击穿场强可达10~6Vcm~(-1)数量级,并对其C-V特性进行了测试。用GaAs等离子体自身氧化膜作MOS晶体管的栅绝缘层,制成了N沟道耗尽型场效应晶体管。其输出特性为饱和电流19mA,饱和压降3V,跨导0.7～4mS。栅、漏击穿电压18V,夹断电压-10V。研究表明,GaAs等离子体自身氧化膜是一个有应用前途的介质膜。     

PECVD法低温形成纳米级薄介质膜击穿特性的实验研究

对等离子体增强化学汽相淀积(PECVD)法制成纳米级SiOxNy薄膜组成的MIS结构样品,通过美国HP系列设备测试I-V特性、准静态及高频C-V特性.分析了薄膜I-V特性、击穿机理与各项电学性能;探讨了膜的击穿电场等电学参数以及击穿电场随反应室气压、混合气体比例、衬底温度的变化关系;给出了击穿等电性优良的PECVD形成SiOxNy薄介质膜的优化工艺条件.     

PECVD沉积双层SiNx对太阳电池性能的影响

提出了一种简单有效的制备双层SiNx薄膜的方法,其薄膜具有良好的减反射钝化特性。采用等离子体增强化学气相沉积(PECVD)的方法,通过控制SiH4和NH3气体流量比,在p型多晶硅衬底上生长单层及双层SiNx膜。随后使用薄膜测试分析仪测量了薄膜的厚度、折射率及反射率,并用Semilab WT-2000测量少数载流子寿命,通过测量量子效率,对单、双层膜电池进行了比较。实验结果表明:相比单层减反射钝化膜,采用双层SiNx膜,少数载流子寿命可以得到更好的改善,开路电压可提高约2 mV,短路电流可提高约40 mA,电池效率能提高0.15%。     

等离子体氧化nc-Si/SiO_2多层膜的蓝光发射

报道了在等离子体增强化学气相沉积 (PECVD)系统中用交替淀积 a-Si对其进行原位等离子体氧化的方法制备了 a-Si∶H/ Si O2 多层膜。随着 a-Si∶H子层的厚度从 3 .8nm减小到 1 .5 nm,a-Si∶H/ Si O2 多层膜的光吸收边和光致发光 (PL )出现了蓝移。在晶化的 a-Si∶ H/ Si O2 多层膜中不仅观察到室温下的红光带 (80 0nm)的发光峰 ,而且还观察到蓝光发射 (4 2 5 nm) ,结合 Raman,TEM和 PL测试 ,对其原因作了简单的分析     

Two-step fabrication of thin film encapsulation using laser assisted chemical vapor deposition and laser assisted plasma enhanced chemical vapor deposition for long-lifetime organic light emitting diodes

A thin film encapsulation layer was fabricated through two-sequential chemical vapor deposition processes for organic light emitting diodes (OLEDs). The fabrication process consists of laser assisted chemical vapor deposition (LACVD) for the first silicon nitride layer and laser assisted plasma enhanced chemical vapor deposition (LAPECVD) for the second silicon nitride layer. While SiN_x thin films fabricated by LAPECVD exhibits remarkable encapsulation characteristics, OLEDs underneath the encapsulation layer risk being damaged during the plasma generation process. In order to prevent damage from the plasma, LACVD was completed prior to the LAPECVD as a buffer layer so that the laser during LACVD did not damage the devices because there was no direct irradiation to the surface. This two-step thin film encapsulation was performed sequentially in one chamber, which reduced the process steps and increased fabrication time. The encapsulation was demonstrated on green phosphorescent OLEDs with I–V-L measurements and a lifetime test. The two-step encapsulation process alleviated the damage on the devices by 19.5% in external quantum efficiency compared to the single layer fabricated by plasma enhanced chemical vapor deposition. The lifetime was increased 3.59 times compared to the device without encapsulation. The composition of the SiNx thin films was analyzed through Fourier-transform infrared spectroscopy (FTIR). While the atomic bond in the layer fabricated by LACVD was too weak to be used in encapsulation, the layer fabricated by the two-step encapsulation did not reveal a Si–O bonding peak but did show a Si–N peak with strong atomic bonding.     

VHF-PFLWD法制备μc-SiGe薄膜的研究

分别以Si2 H6和GeH4及SiH4和GeH4两种组合气体为源气体,用甚高频等离子增强化学气相沉积(VHF-PECVD)制备μc-SiGe薄膜.用Raman散射光谱和原子力显微镜(AFM)对薄膜的结构进行研究.结果表明:与SiH4和GeH4制备的薄膜系列相比,Si2H6和GeH4制备的薄膜中Ge的融入速率相对较慢;用...     

纳米金刚石薄膜的制背

采用微波等离子体化学气相沉积系统,利用氢气、甲烷、氩气和氧气为前驱气体,在直径为5 cm的(111)取向镜面抛光硅衬底上沉积出高平整度纳米金刚石薄膜.利用扫描电镜、X射线衍射谱和共焦显微显微拉曼光谱我们分析了薄膜的表面形貌和结构特征.该薄膜平均粒径约为20 nm.X射线衍射谱分析表明该薄膜具有立方相对称 (111)择优取向金刚石结构.在该薄膜一阶微显微拉曼光谱中,1 332 cm-1附近微晶金刚石的一阶特征拉曼峰减弱消失,可明显观测到的三个拉曼散射峰分别位于1 147 cm-1、1 364 cm-1和1 538 cm-1,与己报导的纳米金刚石拉曼光谱类似.该方法可制备出粒径约为20 nm粒度分布均匀致密具有较高含量的sp3键的纳米金刚石薄膜.     

Contamination of silicon and oxidized silicon wafers during plasma etching

Neutron activation analysis has been used to study the type and level of contamination of silicon and oxidized silicon wafers exposed to various plasmas used in silicon device processing. Silicon wafers exposed to plasmas in a reactor previously used to remove SiN passivation layers from Au metallized wafers were found to be heavily contaminated with Au (up to ∼10¹⁴ atoms/cm²). Au contamination of oxidized silicon wafers similarly treated was two to three orders of magnitude smaller regardless of whether SiO₂ etched faster or slower than Si in the plasmas used. Wet chemical cleaning of contaminated Si subsequent to plasma exposure was relatively ineffective in removing residual Au. This is interpreted as indicating indiffusion of Au during plasma exposure of Si. Exposure to a polymer forming plasma reduced the level of Au contamination of Si by nearly two orders of magnitude due to effective “sealing” of reactor surfaces by polymer film. Further, the level of contamination of Si was observed to decrease by over two orders of magnitude with usage time of the reactor during a 300-day time period when no Au containing materials were introduced into the reactor.     

The aligned Si nanowires growth using MW plasma enhanced CVD

New and simple modification of vapor-liquid-solid process for Si nanowires growth based on microwave plasma enhanced chemical vapor deposition that uses solid-state Si target as a source of Si atoms was developed. The method was temperature and pressure controlled evaporation of solid phase of Si source in hydrogen microwave plasma. Aligned growth of Si nanowires was performed in local electric field by applying of constant negative bias to substrate holder. Deposited Si nanowires were studied by scanning electron microscopy (SEM), Raman and photoluminescence spectroscopy. Correlation between photoluminescence spectra and Si nanowires properties were studied.     

8% Efficient thin‐film polycrystalline‐silicon solar cells based on aluminum‐ induced crystallization and thermal CVD

A considerable cost reduction could be achieved in photovoltaics if efficient solar cells could be made from polycrystalline‐silicon (pc‐Si) thin films on inexpensive substrates. We recently showed promising solar cell results using pc‐Si layers obtained by aluminum‐induced crystallization (AIC) of amorphous silicon in combination with thermal chemical vapor deposition (CVD). To obtain highly efficient pc‐Si solar cells, however, the material quality has to be optimized and cell processes different from those applied for standard bulk‐Si solar cells have to be developed. In this work, we present the different process steps that we recently developed to enhance the efficiency of pc‐Si solar cells on alumina substrates made by AIC in combination with thermal CVD. Our present pc‐Si solar cell process yields cells in substrate configuration with efficiencies so far of up to 8·0%. Spin‐on oxides are used to smoothen the alumina substrate surface to enhance the electronic quality of the absorber layers. The cells have heterojunction emitters consisting of thin a‐Si layers that yield much higher V_oc values than classical diffused emitters. Base and emitter contacts are on top of the cell in interdigitated finger patterns, leading to fill factors above 70%. The front surface of the cells is plasma textured to increase the current density. Our present pc‐Si solar cell efficiency of 8% together with the fast progression that we have made over the last few years indicate the large potential of pc‐Si solar cells based on the AIC seed layer approach. Copyright © 2007 John Wiley & Sons, Ltd.     

Hydrogen plasma passivation of bulk GaAs and Al0.3Ga0.7As/GaAs multiple-quantum-well structures on Si substrates

Hydrogen (H) plasma passivation effects on GaAs grown on Si substrates (GaAs on Si) are investigated in detail. H plasma exposure effectively passivates both the shallow and deep defects in GaAs on Si, which improves both the electrical and optical properties. It was found that the minority carrier lifetime is increased and the deep level concentration is decreased by the H plasma exposure. In addition, after H plasma exposure, room temperature photoluminescence (PL) for Al_0.3Ga_0.7As/GaAs multiple-quantum-well (MQW) on Si is enhanced with a decrease in the spectral width.     

Effect of elemental plasma on metal/Si films by partially ionized beam deposition

The observation of surface cleaning during self-ion-assisted vacuum deposition of epitaxial Ag films on Si(111) is discussed. The details of the self-cleaning effect are then compared among the three metal/Si systems Ag/Si, Cu/Si, and Al/Si. The films were all grown at room temperature using a partially ionized beam (PIB) deposition system under high vacuum. The impurities C, O, and H were detected by secondary ion mass spectrometry. Reduction of these species both at the interface and in the films was observed due to the addition of ∼1-2% of 1-3 keV ions to the depositing beam. It was seen that for the Al case the cleaning effect was restricted more closely to the interface. It is argued that a possible origin of the enhancement of the cleaning in the films is the presence of an elemental metal plasma above the crucible during the Ag and Cu (but not Al) depositions. This plasma differs from that induced in sputter techniques in several important ways, primarily in that no foreign gas is used. The removal of O by PIB in the Ag/Si case is credited with the ability to achieve thin film sheet resistivities close to the bulk value, a feat not found possible for Al.     

新型结构碳材料——碳纳米针

采用钟罩式微波等离子体化学气相沉积(MWPCVD)设备,以氢气和甲烷作为反应气源,制备了一种新型结构碳材料--碳纳米针.通过扫描电子显微镜和拉曼光谱仪对其形态结构和成份进行了分析研究,结果表明,该种新型结构碳材料具有与碳纳米棒、碳纳米丝相似的性质,而且由于这种碳纳米针独特的结构,更适用于作为扫描探针显微镜的电子探针,从而使得其在某些领域(如电子源探针、扫描探针显微技术、纳米电子器件等)具有潜在的应用前景.