NiSi金属栅电学特性的热稳定性研究

研究了NiSi金属栅的各种电学特性及其热稳定性，提出一个物理模型用于解释当形成温度大于500 ℃时NiSi功函数随退火温度升高而增大的现象.测量了不同退火温度形成的NiSi材料的方块电阻，当退火温度大于400 ℃时，方块电阻达到最小，并在400—600 ℃范围内稳定.比较各种温度下形成的NiSi材料X射线衍射谱的变化，说明温度在400—600 ℃范围内NiSi相为最主要的成分.制备了以NiSi为金属栅的金属氧化物半导体电容.通过等效氧化层电荷密度及击穿电场E_bd的分布研 关键词： 金属栅 NiSi 炉退火 快速热退火     

高温退火处理下SiNx薄膜组成及键合结构变化

采用等离子增强化学气相沉积法, 以氨气和硅烷为反应气体, p型单晶硅为衬底, 低温下(200 ℃)制备了非化学计量比氮化硅(SiN_x)薄膜. 在N₂氛围中, 于500–1100 ℃范围内对薄膜进行热退火处理. 室温下分别使用Fourier变换红外吸收(FTIR)光谱技术和X射线光电子能谱(XPS)技术测量未退火以及退火处理后SiN_x薄膜的Si–N, Si–H, N–H键键合结构和Si 2p, N 1s电子结合能以及薄膜内N和Si原子含量比值R的变化. 详细讨论了不同温度退火处理下SiN_x薄膜的FTIR和XPS光谱演化同薄膜内Si, N, H原子间键合方式变化之间的关系. 通过分析FTIR和XPS光谱发现退火温度低于800 ℃时, SiN_x薄膜内Si–H和N–H键断裂后主要形成Si–N键; 当退火温度高于800 ℃时薄膜内Si–H和N–H键断裂利于N元素逸出和Si纳米粒子的形成; 当退火温度达到1100 ℃时N₂与SiN_x薄膜产生化学反应导致薄膜内N和Si原子含量比值R增加. 这些结果有助于控制高温下SiN_x薄膜可能产生的化学反应和优化SiN_x薄膜内的Si纳米粒子制备参数. 关键词： x薄膜')" href="#">SiN_x薄膜 Fourier变换红外吸收光谱 X射线光电子能谱 键合结构     

退火温度对Er/Yb共掺Al2O3薄膜的光致荧光光谱的影响

通过对不同退火条件下Er/Yb共掺Al_２O_３薄膜光致荧光(PL)光谱的 系统分析，研究了高Er/Yb掺杂浓度所导致的晶体场变化对薄膜PL光谱的影响，并结合薄膜结构分析，探讨了Al_２O_３薄膜的结晶状态在Er^３＋激活、PL光谱宽化 中的作用及可能的物理机理.研 究结果表明：退火处理所导致的Er^３＋ PL光谱的变化与薄膜的微观状态之 间有着密 切的联系.在600—750℃范围内，薄膜呈非晶态结构，薄膜荧光强度的增加主要是薄膜内缺 陷减少所致；在800—900℃范围内，γ-Al_２O_３相的出现是导致荧 光强度明显增加的主 要原因；当退火温度为1000℃时，Er，Yb的大量析出致使荧光强度的急剧下降.此外，对PL 光谱线形分析表明，各子能级跃迁的相对强度变化是导致荧光光谱宽化的主要因素. 关键词： Er/Yb共掺 ２O_３薄膜')" href="#">Al_２O_３薄膜 光致荧光     

Nd-Fe-B/FeCo多层纳米复合膜的结构和磁性

制备了Nd₂₈Fe₆₆B₆/Fe₅₀Co₅₀多层纳米复合磁性薄膜，对溅射态和650℃退火处理15 min试样的相成分分析和微结构的观察显示，溅射态薄膜呈非晶态，经650℃退火处理15 min后，薄膜主要相成分为硬磁性Nd₂Fe₁₄B相和软磁性相FeCo(110)相.Nd₂Fe₁₄B相呈柱状，其易磁化c轴垂直于膜面，尺寸约10 nm.在硬磁性相和软磁性相之间存在少量富Nd相和非晶态，富Nd相大小约7 nm.磁性测量和分析表明，1)该系列薄膜退火态具有垂直于膜面的磁晶各向异性.2)对于固定厚度(10 nm)层Nd-Fe-B和不同厚度(t_FeCo=1—100 nm)层FeCo多层纳米复合膜,剩磁随软磁相FeCo 厚度的增加快速增加，而矫顽力则减小.当t_FeCo=5 nm时，最大磁能积达到200 kJ/m³. 3)硬磁相Nd-Fe-B层和软磁相FeCo层之间交换耦合导致剩磁和磁能积增强. 关键词： Nd-Fe-B/FeCo多层纳米复合膜 交换耦合 磁各向异性     

Cu/SiO2/Si(111)体系中Cu和Si的扩散及界面反应

室温下利用磁控溅射在p型Si(111)衬底上沉积了Cu薄膜. 利用X射线衍射和卢瑟福背散射分别对未退火以及在不同温度点退火后样品的结构进行了表征. 在此基础上，研究了Cu/SiO₂/Si(111)体系的扩散和界面反应. 实验结果表明：当退火温度高于450℃时出现明显的扩散现象，并且随着温度的升高，体系扩散现象会更加显著. 当退火温度低于450℃时没有铜硅化合物生成，当温度达到500℃时才有铜硅化合物生成. 关键词： 薄膜 扩散 界面反应 硅化物     

Si-W/Si/SiO2/Si(100)的横截面电子显微镜研究

本文用横截面电子显微镜法分析了Si-W/Si/SiO₂/Si(100)在440—1000℃退火后的晶化过程,以及各个界面的变化情况.发现Si-W合金膜中,WSi₂并未优先在表面、界面处形成晶核.当退火温度不高于700℃时,反应在合金膜内发生,表面、界面起伏和缓.退火温度高达800—1000℃时,界面、表面出现原子扩散,造成剧烈的界面起伏;表面则出现小的热沟槽,Si/SiO₂界面也出现高分辨电子显微镜才能观察到的起伏.表面、界面的原子迁移的动力来源于晶界与表面、界面张力.由于SiO₂中Si—O键很稳定,不易发生Si和O在界面处的互扩散,所以Si/SiO₂界面起伏很小. 关键词：     

Si-Al2O3复合薄膜的室温铁磁性

在Si-Al₂O₃复合薄膜中观察到室温铁磁性.Si的体积百分比为15 %的Si-Al₂O₃复合薄膜的磁性最强.Si的含量影响样品的磁有序,在样品中观察到了明显的磁畴.在不同气氛下,对样品进行快速热退火.退火样品的磁性测试结果的差别表明氧空位不是样品铁磁性的主要来源.我们认为铁磁性来源于Si与Al₂O₃基质界面之间的缺陷的磁耦合.改变Si的含量可以改变缺陷密度,从而控制铁磁耦合强度. 关键词： 2O₃薄膜')" href="#">Al₂O₃薄膜 室温铁磁性 掺杂 交换相互作用     

掺铒Si/Al2O3多层结构中结晶形态对1.54 μm发光的影响

利用脉冲激光沉积的方法制备掺铒 Si/Al₂O₃多层结构薄膜,获得了由纳米结构的Si作为感光剂增强的Er³⁺在1.54 μm高效发光.利用拉曼散射、高分辨透射电镜和光致发光测量研究了在不同退火温度下（600—1000 ℃）纳米结构Si层的结晶形态变化,及对Er³⁺在1.54 μm的发光的影响特征.研究发现最佳发光是在退火温度600—700 ℃.在这个条件下纳米Si的尺寸和密度,Si和Er的作用距离以及Er^{3+ 关键词： 铒 纳米硅 能量转移 氧化铝}     

低温退火对重掺砷直拉硅片的氧沉淀形核的作用

通过对比研究重掺砷直拉硅片和轻掺n型直拉硅片经过低温(450—800℃)和高温(1000℃)两步退火的氧沉淀行为,阐明了低温退火对重掺掺砷直拉硅片的氧沉淀形核的作用.研究指出：重掺砷硅片在450℃和650℃退火时的氧沉淀形核比在800℃退火时更显著,这与轻掺硅片的情况截然相反;此外,与轻掺硅片相比,重掺砷硅片在450℃和650℃退火时氧沉淀的形核得到增强,而在800℃退火时氧沉淀的形核受到抑制.分析认为,重掺砷硅片在450℃和650℃退火时会形成砷-空位-氧(As-V-O)复合体,它们促进了 关键词： 重掺砷直拉硅片 氧沉淀形核 低温退火     

牺牲Ni退火对硅衬底GaN基发光二极管p型接触影响的研究

本文通过在硅衬底发光二极管(LED)薄膜p-GaN表面蒸发不同厚度的Ni覆盖层,将其在N₂ ∶O₂=4 ∶1的气氛中、400℃—750℃的温度范围内进行退火,在去掉薄膜表面Ni覆盖层之后制备Pt/p-GaN欧姆接触层.实验结果表明:退火温度和Ni覆盖层厚度均对硅衬底GaN基LED薄膜p型欧姆接触有重要影响,Ni覆盖退火能够显著降低p型层中Mg受主的激活温度.经牺牲Ni退火后,p型比接触电阻率随退火温度的升高呈先变小后变大的规律,随Ni覆盖层厚度的增加呈先变小后变 关键词： 氮化镓 发光二极管 牺牲Ni退火 p型接触     

Structural and electrical characterization of the nickel silicide films formed at 850 °C by rapid thermal annealing of the Ni/Si(1 0 0) films

Nickel di-silicide formation induced by RTA process at 850 °C for 60 s in the Ni/Si(1 0 0) systems are investigated as a function of the initial Ni film thickness of 7-89 nm using XRD, RBS, SEM, X-SEM and AFM. Based on the XRD and RBS data, in the silicide films of 400-105 nm, NiSi and NiSi₂ silicide phases co-exist, indicating that Ni overlayer is completely transformed to NiSi and NiSi₂ silicide phases. SEM reveals that these films consist of large grains for co-existence of NiSi₂ and NiSi phases, separated from one another by holes, reflecting that NiSi₂ grows as islands in NiSi matrix. These films have low sheet resistance, ranging from 1.89 to 5.44 Ω/□ and good thermal stability. For thicknesses ≤ 80 nm RBS yields more Si-rich silicide phases compared to thicker films, whereas SEM reveals that Si-enriched silicide islands with visible holes grow in Si matrix. As the film thickness decreases from 400 to 35 nm, AFM reveals a ridge-like structure showing a general trend of decreasing average diameter and mean roughness values, while sheet resistance measurements exhibit a dramatic increase ranging from 1.89 to 53.73 Ω/□. This dramatic sheet resistance increase is generated by substantial grain boundary grooving, followed by island formation, resulting in a significant phase transformation from NiSi₂-rich to Si-rich silicide phases.     

Study of Ni/Si(1 0 0) solid-state reaction with Al addition

The characteristics of Ni/Si(1 0 0) solid-state reaction with Al addition (Ni/Al/Si(1 0 0), Ni/Al/Ni/Si(1 0 0) and Al/Ni/Si(1 0 0)) is studied. Ni and Al films were deposited on Si(1 0 0) substrate by ion beam sputtering. The solid-state reaction between metal films and Si was performed by rapid thermal annealing. The sheet resistance of the formed silicide film was measured by four-point probe method. The X-ray diffraction (XRD) was employed to detect the phases in the silicide film. The Auger electron spectroscopy was applied to reveal the element profiles in depth. The influence of Al addition on the Schottky barrier heights of the formed silicide/Si diodes was investigated by current-voltage measurements. The experimental results show that NiSi forms even with the addition of Al, although the formation temperature correspondingly changes. It is revealed that Ni silicidation is accompanied with Al diffusion in Ni film toward the film top surface and Al is the dominant diffusion species in Ni/Al system. However, no Ni_xAl_y phase is detected in the films and no significant Schottky barrier height modulation by the addition of Al is observed.     

Silicidation in Ni/Si thin film system investigated by X-ray diffraction and Auger electron spectroscopy

Silicide formation induced by thermal annealing in Ni/Si thin film system has been investigated using glancing incidence X-ray diffraction (GIXRD) and Auger electron spectroscopy (AES). Silicide formation takes place at 870 K with Ni₂Si, NiSi and NiSi₂ phases co-existing with Ni. Complete conversion of intermediate silicide phases to the final NiSi₂ phase takes place at 1170 K. Atomic force microscopy measurements have revealed the coalescence of pillar-like structures to ridge-like structures upon silicidation. A comparison of the experimental results in terms of the evolution of various silicide phases is presented.     

X-ray photoelectron spectroscopy study of NiSi formation on shallow junctions

The influence of boron (B)/arsenic (As) on X-ray photoelectron spectroscopy (XPS) study of NiSi formation on shallow junctions is investigated in this paper. The Ni-silicide film was formed after 30 s soak anneal at 450 °C on ultra shallow p+/n or n+/p junctions. The atomic ratio of Ni/Si profile in depth was probed by XPS and the results show that a uniform NiSi layer forms on B-doped p+/n junction while a non-uniform, Ni-rich silicide layer forms on As-doped n+/p junction. It does not agree with the results of other independent phase identification methods such as X-ray diffraction, Rutherford backscattering spectroscopy, and Raman scattering spectroscopy, which all demonstrate the formation of NiSi on both n+/p and p+/n junctions. Comparing the raw binding energy spectra of Ni and Si for each silicide film, the similar spectra for Ni signals are revealed. But the Si signals with an obviously smaller intensity is found to be responsible for the apparent Ni rich silicide formation on As-doped n+/p junction. It indicates that As atoms in the silicide film can affect the sputtering yield of Ni and Si, while no noticeable effect is observed for B atoms. More As atoms than B atoms segregation into the silicide layer is indeed verified by secondary ion mass spectroscopy. And micro-Raman scattering spectroscopy further confirms that the degree of crystallinity for NiSi on n+/p junction is inferior to that on p+/n junction.     

The modulation of Schottky barrier height of NiSi/n-Si Schottky diodes by silicide as diffusion source technique

This paper reports that the Schottky barrier height modulation of NiSi/n-Si is experimentally investigated by adopting a novel silicide-as-diffusion-source technique, which avoids the damage to the NiSi/Si interface induced from the conventional dopant segregation method. In addition, the impact of post-BF₂ implantation after silicidation on the surface morphology of Ni silicides is also illustrated. The thermal stability of Ni silicides can be improved by silicide-as-diffusion-source technique. Besides, the electron Schottky barrier height is successfully modulated by 0.11~eV at a boron dose of 10¹⁵~cm^-2 in comparison with the non-implanted samples. The change of barrier height is not attributed to the phase change of silicide films but due to the boron pile-up at the interface of NiSi and Si substrate which causes the upward bending of conducting band. The results demonstrate the feasibility of novel silicide-as-diffusion-source technique for the fabrication of Schottky source/drain Si MOS devices.     

Enhanced formation of periodic arrays of low-resistivity NiSi nanocontacts on (0 0 1)Si0.7Ge0.3 by nanosphere lithography with a thin interposing Si layer

In this study, we demonstrated significant enhancement of the formation of low-resistivity NiSi nanocontacts with controlled size on (0 0 1)Si_0.7Ge_0.3 substrates by combining the nanosphere lithography with the use of a new Ni/a-Si bilayer nanodot structure. Low-resistivity NiSi with an average size of 78 nm was observed to be the only silicide phase formed in samples annealed at 350-800 °C. The presence of the interposing Si layer with appropriate thickness was found to effectively prevent Ge segregation and maintain the interface stability in forming NiSi nanocontacts on (0 0 1)Si_0.7Ge_0.3. As the annealing temperature was increased to 900 °C, amorphous SiO_x nanowires were observed to grow from silicide nanocontact regions. The NSL technique in conjunction with a sacrificial Si interlayer process promises to be applicable in fabricating periodic arrays of other low-resistivity silicide nanocontacts on Si_1−xGe_x substrates without complex lithography.     

钛－镍－硅固相反应形成的镍硅化物/n-硅(100)接触的I-V-T研究

在不同退火温度下，有一薄层钛覆盖层的镍－硅经过固相反应生成了镍硅化物/n-硅(100)接触，研究了其在80K到室温的电流－电压（I-V）特性。低温I-V曲线在低偏压区的电流显著地比传统的热电子发射（TE）模型预计的要大。用基于Tung的夹断模型简化得到的双肖特基势垒模型分析了实测的I-V曲线，从中可以得到肖特基势垒不均匀性的量度。较高温度退火导致较大的势垒不均匀性，意味着硅化物薄膜均匀性的变坏。钛覆盖薄层可以稍微提高硅化镍的相转变温度，以及形成的一硅化镍的热稳定性。     

Pt interlayer effects on Ni germanosilicide formation and contact properties

Ni and Ni(Pt) germanosilicide formation and their contact properties on n-type epitaxial Si_0.84Ge_0.16 have been studied in this work. It is revealed that compared to NiSi, NiSiGe has enhanced phase stability but worse morphology stability. It is also found that Pt incorporation in germanosilicidation improves the morphology of the germanosilicide film. The Schottky contact characteristics of NiSiGe and Ni(Pt)SiGe on n-SiGe were evaluated by current–voltage (I–V) technique at room temperature. NiSiGe/n-SiGe contact shows a Schottky barrier height (SBH) of 0.65 eV with little difference from that of NiSi/n-Si contact. However, the contact shows a reduced SBH with a markedly increased ideality factor and leakage current when annealing temperature increases to 650 °C, indicating thermal degradation of the contact quality. Pt incorporation increases the SBH to 0.73 eV. In addition, its diode parameters such as SBH, ideality factor, and reverse leakage show better conformity during the whole annealing temperature range (from 450 to 650 °C). Therefore, it is concluded that Pt interlayer between Ni and SiGe can modulate the barrier height of Ni germanosilicide and improve its contact properties.     

Synthesis and charge storage properties of double-layered NiSi nanocrystals

Based on bidirectional diffusion of Ni atoms, double-layered nickel silicide (NiSi) nanocrystals (NCs) for multilevel charge storage were fabricated, and their charge storage properties were examined. The double layer was produced by long-term thermal annealing (for 4 h at 900 °C) of a sandwich structure comprised of a thin Ni film of 0.3 nm sandwiched between two silicon-rich oxide (SiO_1.36) layers. Transmission electron microscopic image clearly exhibits a distinct NiSi nanocrystal double layer with a gap of about 7 nm between the mean positions of particle distribution in each NC layer. Capacitance–voltage measurements on the metal/oxide/semiconductor (MOS) capacitors with the double-layered NiSi nanocrystals are shown to have the apparent two plateaus of charge storage, the large memory window of about 9 V and the improved charge retention stability.     

Pd-Si薄膜固相反应的透射电子显微镜研究

本工作利用透射电子显微术研究了Pd-Si薄膜固相反应的初始生成相及生成相Pd₂Si与(111)取向Si衬底的取向关系随Pd膜厚度、退火温度等因素的变化规律。实验结果表明:在衬底保持室温的条件下,Pd沉积到Si(111)上时也能够生成一层外延的Pd₂Si,其厚度足以在常规的选区电子衍射中产生明显的信号。在170℃退火时,Pd-Si反应即可持续到生成200nm厚的外延的Pd₂Si。在Pd膜厚度为400nm的条件下,Pd₂Si与Si(111)衬底的取向关系为[0001]_(Pd2Si)轴织构。 关键词：