Si—SiO2及其在电离辐照下的等离激元

用ＸＰＳ分析技术对抗辐射加固与非加固的Ｓｉ－ＳｉＯ２进行了电离辐照前后Ｓｉ的一级等离激元（定位于Ｂ．Ｅ．１１６．９５ｅＶ）及ＳｉＯ２一级等离激元（定位于Ｂ．Ｅ．１２２．０ｅＶ）的研究。实验结果表明：存在一个由这两种等离激元组成的界面，在电离辐射的作用下，此界面区向ＳｉＯ２表面方向展宽，界面中心向ＳｉＯ２表面方向移动；两种Ｓｉ－ＳｉＯ２界面区中的ＳｉＯ２一级等离激元的浓度在正电场中辐照均随辐照剂量的增加而增加，而非加固样品中一级等离激元浓度在正电场中随辐照剂量的变化所产生的变动快于加固样品；在同一辐照剂量下加正电样品中等离激元浓度的变化远明显于不加电样品。     

Si3N4／SiO2叠层栅MOS电容抗辐照总剂量研究

本论文主要分析了SiN4/SiO2叠层栅MOS电容总剂量效应,叠层栅MOS电容中SiO2为20nm,Si3N4厚度分别为40nm和110nm,通过辐照前后电容CV曲线的对比分析,发现CV曲线的正方向漂移主要是由于界面态电荷的作用,同时氧化物俘获电荷也起到一定的作用.同时也发现叠层栅中Si3N4越厚,将产生越多的界面态电荷和氧化物俘获电荷.     

抗辐射加固与非加固工艺制备Si/SiO_2电离辐照的XPS深度剖析

采用氩离子刻蚀XPS分析方法对抗辐射加固与非加固工艺制备的Si/SiO_2系统进行电离辐照深度剖析。实验结果表明:在辐照剂量及偏置电场相同条件下辐照,非加固样品的界面区比加固样品界面区宽;同一工艺生长的SiO_2,衬底杂质浓度低的样品其界面区窄于衬底杂质浓度高的样品;辐照样品的Si过渡态密度最高位滞后于未辐照样品的;同时,加固样品Si过渡态及剩余氧的密度最高位出现慢于非加固样品的;衬底杂质浓度高的样品其Si过渡态及剩余氧的密度最高位的出现快于衬底杂质浓度低的样品的;此外含剩余氧的过渡层要比含Si过渡态的过渡层薄。最后根据实验结果,对Si/SiO_2三层模型进行了修正。     

基于高级硅刻蚀和硅氧化工艺的软X射线干涉光刻分束光栅的优化设计

基于严格的矢量耦合波方法,对13.4nm(92.5eV)软X射线正入射于周期140nm的Si光栅和SiO2光栅的一级衍射效率进行了模拟计算,结果表明SiO2光栅的最大一级衍射效率远比Si光栅高,同时也比目前用于13.4nm软X射线干涉光刻的Cr/Si3N4复合光栅高.本文提出用高级硅刻蚀工艺和硅氧化工艺制作深高宽比纳米级SiO2光栅的新方法,可以解决直接刻蚀制作此光栅难度大的问题,适用于制作上海光源(SSRF)软X射线干涉光刻分束光栅.     

Si/SiO2系统的总剂量辐射损伤及辐射感生界面态的能级分布

对比了目前常用的三种用54HC电路制作工艺制作的MOS电容的总剂量辐射实验结果,并从微观氧化物电荷、界面态的感生变化及其界面态的能量分布变化等角度,研究了在不同制作工艺条件下,54HC电路Si/SiO2系统总剂量辐射损伤特性.     

钝化层结构对氚辐伏电池转换性能的影响

在辐射伏特效应同位素电池(辐伏电池)中,器件的辐伏转化性能不仅受限于换能器件所用的半导体材料、结构或加载放射源的种类,还受换能器件表面钝化层结构的影响。为在氚化钛源加载的平面单晶硅PN结辐伏电池(氚辐伏电池)中得到最佳的钝化效果,本文设计了3种不同的钝化层结构,考察其初始输出性能和抗辐射性能,并单独研究了氚化钛源出射的X射线对单晶硅换能器件的辐射损伤。结果显示:在辐伏电池初始输出性能方面,Si/SiO2/Si3N4结构Si/B-Si glass/Si3N4结构Si/Si3N4结构;在抗氚化钛源辐射损伤方面,Si/Si3N4结构Si/B-Si glass/Si3N4结构Si/SiO2/Si3N4结构,Si/B-Si glass/Si3N4结构具有最佳的抗X射线辐射衰减性能。氚化钛源出射的X射线对辐射损伤效应起主要作用,XPS结果显示,X射线长时间辐照造成了单晶硅表面平整性的破坏。     

单晶硅表面钝化层在低能电子辐照前后的SIMS和XPS分析

为了研究低能电子辐照对单晶硅器件表面钝化材料中产生的化学微结构的变化,在轻掺杂P型单晶硅基底上制作了三种表面钝化膜,分别是单一SiO₂钝化膜、SiO₂/Si₃N₄复合钝化膜、硼硅玻璃/Si₃N₄复合钝化膜,开展了表面钝化单晶硅在最大能量70 keV的加速器电子束下的辐照实验。样品在空气气氛下辐照6 h,用二次离子质谱(SIMS)测试了辐照前后三种表面钝化膜中Si、N、B的纵深变化,同时用Ar离子刻蚀X射线表面光电子能谱(XPS)对Si元素的化学结合状态进行测试分析。结果表明:对单一SiO₂钝化的轻掺杂P型材料,辐照在SiO₂/Si界面产生明显的材料结构变化,界面附近的SiO₂不再是完整化学计量比,而是SiO_x(x<2);对SiO₂/Si₃N₄复合钝化的轻掺杂P型材料,辐照对SiO₂     

离子束辅助沉积制备TiN/Si3N4纳米超硬膜的工艺研究

采用离子束辅助沉积法(Ion beam assisted deposition,IBAD)在单晶硅片上进行沉积制备了TiN/Si3N4纳米复合超硬薄膜;研究了辅助束流、轰击能量和Ti:Si靶面积比等工艺参数对TiN/Si3N4超硬纳米复合薄膜性能的影响.此外采用纳米硬度计、光电子能谱(X-ray photoelectron spectrum,XPS)和x射线衍射分析(X-raydiffraction,XRD)方法研究了纳米复合薄膜的性能、成分与组织结构;采用原子力显微镜(Atomic forcemicroscopy,AFM)分析了薄膜的表面形貌,并初步探讨了TiN/Si3N4纳米复合超硬薄膜的生长机理.     

原位光电子能谱研究La_2O_3/LaAlO_3/Si电子结构

在超高真空条件下,通过脉冲激光技术沉积La_2O_3/LaAlO_3/Si多层膜结构,原位条件下利用同步辐射光电子能谱研究了LaAlO_3作为势垒层的La_2O_3与Si的界面电子结构。实验结果显示,LaAlO_3中Al的2p峰在沉积和退火前后没有变化;衬底硅的芯能级峰在沉积LaAlO_3时没有变化,但在沉积La_2O_3薄膜和退火过程中,硅峰变弱;O的1S芯能级的峰由多种不用的氧化物薄膜层和反应物中的氧杂化而成。结果表明:LaAlO_3从沉积到退火当中,不参与任何反应,Si与LaAlO_3界面相当稳定;在体系中,阻挡层LaAlO_3起到阻挡硅扩散的作用,进一步表明La_2O_3与硅的界面不太稳定。     

Wilzbach气曝法氚标记三尖杉酯碱的定位效应研究

本文首次采用CNDO/2法研究了Wilzbach(气曝)法氚化三尖杉酯碱的定位效应,计算了三尖杉酯碱的各个部位的亲电超离位度S_r~(E),亲核超离位度Sr~(N)和自由基超离位度S_r~(R)。理论计算能很好地与实验结果符合。还证实了Wilzbach自辐照-诱导标记是一种亲电反应,参加反应的质点(粒子)是HeT+,T_2~+,T+,T_3~+,而不是氚原子和氚分子.Wilzbach高频气曝氚化法是从外部输入能量并活化。解离氚分子成原子,自由基等,参加反应的质点(粒子)是电子,氚原子。二者的反应机理不同,导致~3H标记位置的不同。该法可作为预测氚标记中草药定位效应的一种参考办法。     

Radiation-induced plasmons in Si-SiO2

The first level plasmons of Si in the pure Si state (corresponding to bonding energy (BE) of 116.95 eV) and in the SiO2 state (corresponding to BE of 122.0 eV) of Si-SiO2 prepared by irradiation hard and soft processing were studied with XPS before and after 60Co radiation.The experimental results indicate thatthere was an interface consisting of the two plasmons,this interface was extended by 60Co radiation, the fractions of the plasmon for Si in the Si-SiO2 werechanged with the variation of radiation dosage,the difference of the change in fraction of plasmonsfor the two kinds of samples was that the soft variedfaster than hard, the change of concentrations inplasmons for both hard and soft Si-SiO2 irradiatedin positive bias field were greater than that in bias-free field.The experimental results are explained from the view point of energy absorbed in form of quantization.     

Radiation-induced plasmons in St-SiO_2

1IntroductionOneofthemostweaknessesOfelectricdevicesbasedonSt-SiOZisthatthedevicesmaylacetheirfunctionsbecauseinterfaCe,t.t..[i]andpositivecharge[']arecreatedbyionizationradiationintheSt-SiO2.Overthepasty6ars,anumberOfmodelshavebeensuggestedtoexplaintheoriginsofillterfaCestateandpositivecharge.Rowever,theoXygenvarancymodel,whichwasproposedbyelectronspinresonance(ESR)formeasurementofpointdefects[3]1isinconsistentwiththebondstraingradientmodel,whichwassuggestedthroughXPS[4],intheexplansti…     

Characterization of Annealing of Co60 Gamma-Ray Damage at the Si/Si02 Interface

The annealing of Co60 gamma-ray damage at the Si/SiO2 interface is a well behaved phenomenon. Based on the characterization of annealing over a temperature range of 25° to 300°C, a physical model is developed. This model suggests that the annealing of the radiation damage occurs in two phases: first, the Qf-like trapped positive charges are converted to acceptor-like fast-states, and second, the fast-states are gradually annihilated. Both of these phases occur at an accelerated rate at a given temperature in presence of hydrogen. The densities of trapped positive charges and fast-states reach saturation levels which depend on the level of radiation (dose rate), and the temperature. The tolerance level of an IC to radiation exposure depends on these saturation levels. The experimental results also indicate that the positive charges are trapped at the Si/SiO2 interface even if a negative gate-bias is applied during irradiation. Furthermore, it is unambiguously observed that once the holes are trapped at the interface, they do not move along the interface even under applied biases, but they move only toward Si where they become acceptor-like fast-states.     

Radiation-Induced Paramagnetic Defects in MOS Structures

We have subjected thermally grown films of SiO2 on Si substrates to Co60 gamma irradiation. Using electron spin resonance we observe three radiation-induced paramagnetic defect centers in the structures at room temperature. One resonance appears to be unambiguously associated with trivalent silicon bonded to three other silicons at the Si/SiO2 interface. Two other resonances are very much like resonances observed earlier in irradiated high purity bulk SiO2; those bulk SiO2 resonances have been associated with trivalent silicons bonded to three oxygens and unpaired electrons in nonbonding oxygen 2p orbitals.     

Xenon-ion-induced and thermal mixing of Co/Si bilayers and their interplay

Studies on ion-irradiated transition-metal/silicon bilayers demonstrate that interface mixing and silicide phase formation depend sensitively on the ion and film parameters, including the structure of the metal/Si interface. Thin Co layers e-gun evaporated to a thickness of 50 nm on Si(1 0 0) wafers were bombarded at room temperature with 400-keV Xe⁺ ions at fluences of up to 3 × 10¹⁶ cm⁻². We used either crystalline or pre-amorphized Si wafers the latter ones prepared by 1.0-keV Ar-ion implantation. The as-deposited or Xe-ion-irradiated samples were then isochronally annealed at temperatures up to 700 °C. Changes of the bilayer structures induced by ion irradiation and/or annealing were investigated with RBS, XRD and HRTEM. The mixing rate for the Co/c-Si couples, Δσ²/Φ = 3.0(4) nm⁴, is higher than the value expected for ballistic mixing and about half the value typical for spike mixing. Mixing of pre-amorphized Si is much weaker relative to crystalline Si wafers, contrary to previous results obtained for Fe/Si bilayers. Annealing of irradiated samples produces very similar interdiffusion and phase formation patterns above 400 °C as in the non-irradiated Co/Si bilayers: the phase evolution follows the sequence Co₂Si → CoSi → CoSi₂.     

Experimental Observations of the Chemistry of the SiO2/Si Interface

Changes in silicon surface preparation prior to thermal oxidation are shown to leave a signature by altering the final SiO2/Si interface structure. Surface analytical techniques, including XPS, static SIMS, ion milling, and newly developed wet-chemical profiling procedures are used to obtain detailed information on the chemical structure of the interface. The oxides are shown to be essentially SiO2 down to a narrow transitional interface layer (3-7 ?). A number of discrete chemical species are observed in this interface layer, including different silicon bonds (e.g., C-, OH-, H-) and a range of oxidation states of silicon (0 ? +4). The effect of surface preparation and the observed chemical species are correlated with oxide growth rate, surface-state density, and flatband shifts after irradiation.