化学汽相沉积掺砷多晶硅膜初探

分别用AsH_3、SiH_4和Ar作源气和携带气体,在常规的水平高频加热汽相沉积系统中沉积了掺砷多晶硅膜。研究了影响膜的沉积速率及电阻率的诸因素。并与国外报导的同类工作作了比较。发现:一、掺砷多晶硅膜的电阻率与气相中[As)/[Si]的关系中确实存在有一最小值。即随着气相中[As]/[Si]的不断增加,多晶硅膜的电阻率下降,但到某一值后,反而会随着气相中的[As]/[Si]增加而增加。二、除气相中的[As]/[Si]、晶粒大小等影响掺砷多晶硅膜的电阻率以外,气体中的含水量对沉积后掺砷多晶硅膜的电阻率影响颇大。三、俄歇能谱分析发现高掺砷多晶硅膜中的氧含量和砷含量相当。认为该现象的出现和沉积时气相中AsH_3的存在有关。并可能是目前不易制得低电阻率(≤10~(-3)Ωcm)掺砷多晶硅膜的原因。     

N~+型重掺杂硅快速氧化新方法──氟化氢增强氧化之二

本文对重掺杂单晶硅和多晶硅薄膜的加HF增强氧化的行为进行了研究。氧气中HF含量为480ppm,温度为750至900℃。发现重掺磷或砷的硅的氧化反应速率很快,速率常数比轻掺杂硅的干氧氧化提高了几十倍至几百倍。而重掺硼的硅单晶对氧化速率并无明显影响。文中对重掺杂元素和HF增强硅氧化的机理作了分析,并提出了一个物理模型,可以较好地解释实验现象。     

掺砷多晶硅的热氧化

在ＥＥＰＲＯＭ的研制中，为了研究掺砷多晶硅与单晶硅氧化的相对关系，进行了８００℃湿氧氧化和１０００℃干氧氧化实验，结果表明，经过工艺优化，选择适当的工艺方案，获得了较理想的多晶硅与单晶硅氧化速率比。     

重掺锑单晶硅及其掺杂和生长方法

叙述了生长重掺锑单晶硅的必要性,困难性和克服这些困难的方法;还叙述了生长重掺锑单晶硅时固-液界面对晶体生长的影响以及如何获得理想的界面形状,介绍了一些典型的晶体生长参数和掺杂方法;讲座了生长重掺锑单晶硅时的组分过冷以及避免的方法.还讨论了如何提高重掺锑单晶硅的晶体完整性,指出了生长重掺锑单晶硅的关键在于找到形成稳定固--液界面的条件,防止组分过冷的发生,为此,要使用较小的晶体生长速度,在较大的纵向温度梯度热场中生长晶体,此外,应在满足晶体电阻率要求的前提下,尽量使掺入锑量控制在最低限度.     

湿氧中掺磷多晶硅的热氧化

湿氧中温度范围为700—850℃,根据线性——抛物线的速率定律来研究重掺磷多晶硅及单晶硅衬底的特性·不掺杂或以1.1×10~（19）—2.2×10~（21）cm~（-3）的磷用扩散法或离子注入法均匀掺杂的多晶硅被用来与轻掺杂或重掺杂硅衬底的（100）、（110）和（111）面比较研究·磷浓度大于1×10~（20）cm~（-3）引起氧化速率的显著增加,然而超过1×10~（21）cm~（-3）氧化速率趋向于变成饱和·观察到氧化初始阶段的快速氧化。初始氧化并不适合线性——抛物线的速率定律·掺磷多晶硅的电阻率对磷浓度约6×10~（20）cm~(-3)有一个最小值为5×10~（-4）Ω-βm·多晶硅厚度被氧化减小以后,初始的电阻率几乎保持常数·另外,没有观察到沿着晶粒边界有增强氧化的迹象。     

四探针Mapping自动测试仪中电阻率温度系数的规范化拟合多项式的应用

本文回顾了单晶硅及扩散硅的电阻率温度系数(TCR)的实验结果,认为美国ASTM的TCR曲线是比较完整,确切的.利用我们开发的规范化多项式拟合方法,可将它表示成五阶多项式.将它存入具图像识别四探针定位功能自动测试系统的计算机中后,可以立即得到折合到23℃的硅单晶断面的电阻率分布.本文阐述了规范化拟合的原理,给出了单晶硅的TCR的拟合结果.     

硒砷碲摄象管靶面中碲含量及分布对其光电特性的影响

引言硒砷碲摄象管(Saticon)是一种具有分辨率高,暗电流小,惰性小等优良特性的光导摄象管,它的各项技术指标都已达到氧化铝管的水平,已广泛用于彩色广播电视摄象系统。硒砷碲摄象管靶面是由无定型硒(Se)做主体材料而掺以一定比例的砷(As)、碲(Te)、而组成的。掺 As 的目的是增加无定型 Se 材料的热稳定性。由实验研究已证明,在无定型 Se 中均匀掺以7—15%原子比的 As 可得到即热稳定性好,又保持无定型 Se 良好光电特性的靶面、掺 Te 的目的是改善靶面的光谱响应。实验已表明纯 Se 或掺 As10—15%的 Se     

掺杂氧化物源向硅中的高浓度砷扩散

研究了掺砷 SiO_2和掺砷 Ge/SiO_2扩散源的性质随卧式开管淀积箱中 O_2浓度的变化。氧化物中掺入 Ge 的作用是增加腐蚀速率,以及减少 AsH_3氧化时所引入的 As_2O_3。元素 As 在氧化物中进行扩散要比As_2O_3快得多,这就增加了跨越硅—氧化物交界面处 As 的输运。可以看到氧化物的予扩散 H_2退火产生类似的作用。由改变淀积箱中的 O_2浓度 Co_2来控制源的掺杂,扩散结果表明,其薄层电阻 Rs 是随(Co_2)~(-1)而变化。借助于氧化物中 As 的克分子数 C_(AS)~(sio)_2,则 Rs α(C_(AS)~(SiO_2))~(-2)。可看到对于 t≥40分时,Rs 是随时间按 t~-1/2减小。对于较短时间,由于 As 电激活部分表面浓度的变化,As 扩散变得复杂起来。分别表示了Si 中 As 扩散的各种分布,并借助于与扩散系数有关的浓度对扩散方程的介进行了讨论。然而,可以看到,在 H_2中的预退火引起随后扩散的 As 是有反常的电学分布。     

掺镓单晶硅太阳电池和组件的光致衰减性能研究

分别使用掺镓和常规掺硼单晶硅片制备了太阳电池与组件,对电池进行了光照和空焊处理,再采用Halm电池电性能测试仪测试了两种单晶硅太阳电池和组件在光照和空焊实验前后的光电性能.实验结果表明,在相同光照条件下,采用掺镓单晶硅片所制太阳电池的光衰率比用掺硼单晶硅片的低0.91％.空焊后的掺镓单晶硅太阳电池各项光电性能参数的一致性没有出现明显变化,这有利于减少太阳电池之间的失配损失.还发现掺镓单晶硅太阳电池组件的CTM(cell to module)值高于掺硼单晶硅太阳电池组件的CTM值.总之,掺镓单晶硅太阳电池能更好地抑制光致衰减效应,并减小串焊工艺对太阳电池光电性能的影响,获得更高的太阳电池组件功率.     

200 mm Trench MOSFET管用硅外延电阻率管控

200 mm重掺As衬底的MOSFET外延片在后续芯片制程中,由于还需要经历高温环节(大于1100℃),因此衬底中As的自掺杂效应将再次出现,从而使外延片边缘区域的电阻率降低明显。在外延过程中,需要将外延片边缘区域的电阻率有意控制略高于中心区域。在控制过程中通过引入Offset(差值)的管理方法,确保外延层边缘3 mm区域与中心区域的偏差减小,从而实现片内管芯之间性能一致。     

CZ重掺锑硅单晶的锑和氧杂质

介绍了重掺锑硅单晶生长和应用中的主要特点,并对单晶生长过程中出现的关键问题,如锑的挥发、氧含量减少的原因进行了探讨并提出了一些解决办法     

p型硅外延层电阻率的控制

计算表明，ｐ型硅外延层的电阻率对其生长速度和生长温度的变化都是十分敏感的。为了保证ｐ型硅外延片的电阻率具有良好的可控性和重现性，除了充分抑制重掺硼衬底的自掺杂作用外，还需十分严格地控制硅外延片的生长温度和速度。     

Detection of characteristic signals from as-doped (<1 at.%) regions of silicon by transmission electron microscopy and convergent-beam electron diffraction

Characteristic signals were detected from As-doped (< 1 at.%) regions of silicon by dark-field transmission electron microscopy and convergent-beam electron diffraction. A slight intensity increase was observed in 220 dark-field images, which may be explained by an increase of scattering amplitude due to the As doping. The doped region showed a much higher intensity in 004 dark-field images. The characteristic high intensity was observed for specimens with As concentrations of about 0.09-0.8 at.%. Convergent-beam electron diffraction patterns obtained from the As-doped region showed a characteristic rocking curve for 004 reflection. These characteristics should originate from incoherent elastically scattered electrons due to a static lattice distortion around the doped As atoms. The observed characteristics in dark-field images and rocking curves of the 004 reflection should be a good probe not only for investigating the concentration of doped atoms in Si lattice, but also for the amount of impurity and/or point defects in other crystalline materials.     

单片式外延炉在硅外延生产中的应用

使用单片式外延炉生产的硅外延材料具有良好的厚度和电阻率均匀性。该外延炉具有良好的系统气密性、较大的生产能力、大直径外延(150～300mm)加工能力、较广阔的应用范围等优点,已经成为国际上硅外延片生产的发展主流。利用单片炉的各种优点,在150～200mm重掺砷和P型衬底上外延、150mmBiCMOS薄层外延、150mmSiGe和SOI外延等领域进行了生产应用。将所得性能参数和批式外延炉性能参数进行比较,获得的性能参数试验结果在原有基础上得到了很大的提高。实验研究结果应用于实际批量生产。     

Doping of trench capacitors by rapid thermal diffusion

A new rapid thermal diffusion process for shallow, heavily doped trench junctions in high density dynamic RAMs is described. Planar dopant sources are formed by spin-coating rigid substrates, such as silicon wafers or solid dopant sources, with liquid dopants. Diffusion takes place at high temperatures when the source, placed in proximity to the silicon wafer, releases dopant via evaporation followed by diffusion to the silicon surface. Well-controlled, heavily doped shallow junctions are readily obtained for B, P, and As. The doping process is shown to provide uniform doping of high-aspect-ratio trenches. Process control is achieved by controlling the wafer temperature and duration of the process. Junction depths near 0.1 μm have been demonstrated over the entire surface of trenches 0.7 μm in diameter and 6 μm in depth     

Precise arsenic doping of HgCdTe by MBE and effects on compositional interdiffusion

Characterization data are presented for arsenic-doped Hg_1−xCd_xTe epilayers, grown on CdZnTe substrates by molecular beam epitaxy. Arsenic incorporation is influenced both by the cracker-cell bulk temperature (As flux) and by the substrate surface temperature. An Arrhenius-type equation can be used to fit the As incorporation data, yielding characteristic energies of 1.54 and 6.61 eV for the As cell and HgCdTe surface temperatures, respectively, independent of alloy fraction. This relation allows significantly improved predictability and control in the As doping concentration. The effect of growth temperature on As incorporation is demonstrated using a multilayer test structure with composition stepped in a sequence, with x=0.6, 0.45, 0.3, 0.2, of n-type material, followed by the reverse sequence of As-doped material, with the As cell temperature held constant. Secondary ion mass spectroscopy profiles of this layer again indicate the strong As incorporation dependence on growth temperature. Composition profiles for as-grown and annealed pieces of the multilayer sample show greater interdiffusion for the As-doped region as compared to the undoped region, which is attributed to the Fermi-level enhancement effect.     

8英寸薄层硅外延片的均匀性控制方法

8英寸(1英寸=2.54 cm)薄层硅外延片的不均匀性是制约晶圆芯片良率水平的瓶颈之一.研究了硅外延工艺过程中影响薄外延层厚度和电阻率均匀性的关键因素,在保证不均匀性小于3％的前提下,外延层厚度和电阻率形成中间低、边缘略高的“碗状”分布可有效提高晶圆的良率水平.通过调整生长温度和氢气体积流量可实现外延层厚度的“碗状”分布,但调整温区幅度不得超过滑移线的温度门槛值.通过提高边缘温度来提高边缘10 mm和6 mm的电阻率,同时提高生长速率以提高边缘3 mm的电阻率,获得外延层电阻率的“碗状”分布,8英寸薄层硅外延片的的边缘离散现象得到明显改善,产品良率也有由原来的94％提升至98.5％,进一步提升了8英寸薄层硅外延片产业化良率水平.     

Generalized linear-parabolic law: a mathematical model for thermaloxidation of silicon

Silicon dioxide growth curves under a variety of oxidation conditions are analyzed. The results indicated that the growth curve is not the linear-parabolic equation as predicted by the Deal-Grove model. Instead, a generalized form of the linear-parabolic equation in which the coefficients are allowed to accommodate the change in the sign and thickness dependency is desirable to describe the silicon oxidation process. It is also shown that the thickness dependence of the rate constant with appropriate approximations can be expressed explicitly in a functional form     

Arsenic-doped polycrystalline silicon film for bipolar integrated circuits

The advantages of the use of As-doped polycrystalline silicon film over that of As-doped glass film in the fabrication of high speed bipolar integrated circuits have been shown. The films have been used for doping buried layer and emitter. Deposition conditions optimized for the As-doped polycrystalline silicon film allows low junction leakage to be attained with low pipe density. During the course of the work the mechanism for the formation of pipes have been suggested.     

Molybdenum germanide ohmic contact to n-GaAs

GeMo refractory ohmic contacts for n-type GaAs with a specific contact resistivity as low as 10-6?cm2 have been obtained on 1018cm-3 epitaxial layers. This low resistivity was obtained by contact annealing under As overpressure. Contacts using As-doped Ge layers and annealed without As overpressure have also been realised; in this case the obtained resistivity was 5 × 10-6?cm2. The ohmic contact formation resulted from the creation of an n + layer by Ge overdoping and the formation of a molybedenum germanide stable phase.