硅熔体中3C-SiC的生长及6H-SiC晶型的抑制

论述了从硅熔体中生长3C-SiC晶体过程中6H-SiC晶型控制的一般原理.采用将硅置于高纯石墨坩埚中使其在高温条件下熔化,坩埚内壁石墨自然熔解于硅熔体中形成碳饱和的硅熔体,在石墨表面形成厚约0.2mm的SiC薄层.X射线衍射(XRD)、X射线光电子能谱(XPS)、Raman散射等分析表明所制备样品为3C-SiC多晶体.实验结果进一步证明从硅熔体中生长3C-SiC晶体过程中,通过适当调整工艺参数可以抑制6H-SiC晶型的形成.     

新型耐高温导线的研制

根据新型耐高温导线的主要性能技术要求，设计了镀镍铜线＋高硅氧玻璃纤维纱绕包＋耐高温涂覆液浸渍结构的耐高温导线。为使新型耐高温导线能在500℃的高温环境中长期使用，在绝缘绕制时涂覆耐高温材料，这改进了原有高硅氧玻璃纤维纱绕包的传统工艺。采用高硅氧玻璃纤维纱绕包和耐高温涂覆层生产的新型耐高温导线，在电性能和机械性能方面都取得令人满意的效果。     

硅熔体中3C—SiC的生长及6H—SiC晶型的抑制

论述了从硅熔体中生长3C－SiC晶体过程中6H－SiC晶型控制的一般原理,采用将硅置于高纯石墨坩埚中使其在高温条件下熔化。坩埚内壁石墨自然熔解于硅熔体中形成碳饱和的硅熔体,在石墨表面形成厚约0．2mm的SiC薄层。X射线衍射（XRD）、X射线光电子能谱（XPS）、Raman散射等分析表面所制备样品为3C－SiC多晶体,实验结果进一步证明从硅熔体中生长3C－SiC晶体过程中,通过适当调整工艺参数可以抑制6H－SiC晶型的形成。     

硅晶片化学机械抛光中的化学作用机理

通过分析硅晶片化学机械抛光过程中软质层的形成及其对材料去除过程的影响,研究了使用纳米CeO2磨料进行化学机械抛光中的化学作用机理.分析表明,软质层是抛光液与硅晶片反应形成的一层覆盖在硅基体表面的腐蚀层,其硬度比基材小,厚度大约在几个纳米.软质层的存在一方面增大单个磨料所去除材料的体积,增加材料去除速率;另一方面减小了磨料嵌入硅晶片基体的深度,这对于实现塑性磨削,降低抛光表面粗糙度,都起着重要的作用.     

衬底结构特征对硅基螺旋电感性能的影响

使用三维电磁场模拟的方法对不同硅衬底结构螺旋电感进行了模拟和分析.通过改变衬底的电导率、隔离层的厚度以及隔离层的材料、衬底引入硅锗合金层等模拟,分析了电感性能的变化.结果表明随着电导率的减小,电感的性能会增强,但改善的幅度会逐渐减小.厚的SiO2隔离层有利于减小衬底损耗,但是会给工艺增加难度.采用低k材料作为隔离层是改善电感性能的一种比较理想的方法.     

衬底结构特征对硅基螺旋电感性能的影响

使用三维电磁场模拟的方法对不同硅衬底结构螺旋电感进行了模拟和分析.通过改变衬底的电导率、隔离层的厚度以及隔离层的材料、衬底引入硅锗合金层等模拟,分析了电感性能的变化.结果表明随着电导率的减小,电感的性能会增强,但改善的幅度会逐渐减小.厚的SiO2隔离层有利于减小衬底损耗,但是会给工艺增加难度.采用低k材料作为隔离层是改善电感性能的一种比较理想的方法.     

硅熔体中3C-SiC的生长及6H-SiC晶型的抑制

论述了从硅熔体中生长 3C- Si C晶体过程中 6 H- Si C晶型控制的一般原理 .采用将硅置于高纯石墨坩埚中使其在高温条件下熔化 ,坩埚内壁石墨自然熔解于硅熔体中形成碳饱和的硅熔体 ,在石墨表面形成厚约 0 .2 m m的Si C薄层 .X射线衍射 (XRD)、X射线光电子能谱 (XPS)、Ram an散射等分析表明所制备样品为 3C- Si C多晶体 .实验结果进一步证明从硅熔体中生长 3C- Si C晶体过程中 ,通过适当调整工艺参数可以抑制 6 H- Si C晶型的形成 .     

深硅槽开挖工艺

本文介绍了硅槽应用,即硅槽隔离和硅槽电容,对器件性能的改善。并介绍了硅槽隔离和硅槽电容的形成步骤及硅槽刻蚀剖面的形貌控制,CBrF_3刻蚀硅槽侧壁保护层的形成等等。     

聚酰亚胺表面钝化工艺及对半导体器件可靠性和稳定性的影响

聚酰亚胺是一种新型耐高温钝化材料,涂敷在硅表面上形成的薄膜带有负电荷,可以削弱硅表面电势,此外聚酰亚胺还具有物理和化学性能稳定,耐辐射、电绝缘性好、韧件强、工艺简单、成本低,适合于批量生产等特点.本文将对用于硅台面和平面技术中的聚酰亚胺表面钝化工艺效果进行分析和介绍,以确定聚酰亚胺钝化与器件的可靠性和稳定性的关系.     

采用氧化多孔硅埋层的SOI工艺

在n/n~+/n结构的高浓度掺杂层上形成了多孔硅。多孔硅完全氧化以后,在隔离的单晶硅岛上制作CMOS器件。经测量,迁移率与体硅差不多,而且,硅的漏电很小。     

The effect of thermal-neutron radiation on the decomposition of an oxygen solid solution in silicon

This paper presents the analysis of peculiarities of defect formation in the course of thermal treatment in silicon single crystals grown by the Czochralski method and exposed to thermal-neutron radiation, under the modes usually applied in transmutation doping of silicon ingots. The processes of defect formation were estimated using X-ray diffuse scattering and IR-spectroscopy. It is demonstrated that such doping results in the variation of the state in the material lattice of impurities such as oxygen and carbon. Moreover, subsequent high-temperature annealing leads to the recovery of concentration of interstitial oxygen and does not result in the recovery of the carbon concentration in the lattice nodes. The effect is studied of radiation on peculiar features of the formation of oxygen-containing microdefects in a silicon lattice at high-temperature annealing, used for the formation of an internal getter in silicon wafers.     

Investigation of bulk and solar cell properties of ingots cast from compensated solar grade silicon

In this work, the effect of the concurrent presence of B and P on bulk and solar cell properties of directionally solidified multicrystalline ingots from commercially compensated solar grade silicon (SoG‐Si) feedstock produced by Elkem Solar was investigated. The initial B and P content prior to the directional solidification experiment was 1260 and 762 ppba, respectively. Two reference ingots have been solidified in a silica crucible from 100% electronic grade silicon (EG‐Si) feedstock, with 332 ppba of boron added. All ingots have been cast under similar process parameters. The resistivity measurements by Four Point Probe (FPP) are in good agreement with the net dopant content, i.e., N_A − N_D for p‐type material, measured by Glow Discharge Mass Spectrometer (GDMS). Bulk lifetime measurements show a decrease in the values compared to the EG reference. Lifetime distributions show the highest values of 13 and 19 µs at approximately half ingot height, compared to 30 and 44 µs in the reference ingots. This decrease can be due to the concurrent effect of compensation and of other impurities present in the ingot. However, the content of several transition metals measured by GDMS at half ingot height was not significantly higher than that of the reference ingots. Oxygen content as measured by Fourier Transform Infra‐Red (FTIR) spectroscopy shows no significant difference compared to the references. Solar cells made from the compensated ingots and processed under standard process conditions show efficiency values up to 15.5% and fill factor values up to 78%, comparable to conventional multicrystalline silicon cells. Copyright © 2010 John Wiley & Sons, Ltd.     

Modeling of poly-crystalline silicon ingot crystallization during casting and theoretical suggestion for ingot quality improvement

Finite element (FE) and cellular automaton (CA) models are used in order to predict the microstructure of Poly-Crystalline Silicon (PC-Si) ingots during casting in a directional solidification furnace. During solidification, the 3D-FE model is used to simulate thermal field inside the furnace, while the nucleation and growth of PC-Si are simulated by the modified version of CA model. In this model both nucleation at silicon-crucible interface and nucleation of equiaxed grains on impurities are modeled. The origin of impurity is considered SiC particles when carbon segregates during the solidification and precipitates as SiC particles if carbon solubility limit is reached. The model is evaluated with experimental data for different parameters, such as: the temperature profile at the top and bottom of the PC-Si, grain size, and the height of solidified silicon during solidification. A one-dimensional form of grain growth is observed at the crucible-silicon interface, while a more two-dimensional form of growth is predicted at higher silicon height. The microstructure of PC-Si shows that the grain size increases as a function of PC-Si ingot height. The effects of the cooling rate and competitive growth on the final microstructure of PC-Si are also investigated. The results show that less nucleation sites are formed at the bottom of the crucible with a slower cooling rate, which leads to a larger grain size. Furthermore, the grains at the crucible side walls tend grow inward at a lower cooling rate, which can significantly change the microstructure of PC-Si. This study shows that the competitive growth phenomena plays an important role in the final microstructure of silicon ingots. A simulated model is proposed which shows that by changing the density and location of nucleation sites it is possible to achieve more effective control on final PC-Si micro structure. This simulation helps to explain the crystal behavior observed in ingots cast under different conditions.     

Experimental study on surface quality of silicon ingots prepared by electromagnetic continuous casting

The effects of technical parameters on the forming of surface defects of the silicon ingots prepared by electromagnetic continuous casting were investigated by the orthogonal experiment, and the corresponding defect formation mechanisms were discussed and established. The results indicate that the forming of the ripple and lap are mainly caused by the shrinkage of shell and controlled by the electromagnetic pressure, and the unmelted granules are those moving from the center to the edge on the liquid surface, which was directly cooled by the cold crucible wall and kept as unmelted state. The surface quality was shown to be significantly improved by increasing the input power, pulling velocity and the heat preservation time, and among them, the input power is the most important one.     

Comparison of the characteristics of solar cells fabricated from multicrystalline silicon with those fabricated from silicon obtained by the monolike technology

In order to raise the efficiency of solar cells and reduce the cost of their production, a new process for obtaining silicon ingots based on the so-called moonlike technology is developed. New technologies, which use “solar-grade” silicon, make it possible to fabricate solar cells at a lower cost with a higher efficiency of solar-energy conversion. It is exactly for this reason that the “monolike” process was tested and optimized by us for Kazakhstan solar-grade silicon. The aim of this study is a comparison of the characteristics of solar cells fabricated from “monolike” silicon with those of solar cells obtained on the basis of multicrystalline silicon grown by oriented crystallization. For our study, ingots of multicrystalline silicon are grown on an industrial scale and through the use of Kazakhstan-sourced silicon; solar cells are fabricated and the characteristics of the obtained silicon ingots and solar cells are studied.     

直拉单晶硅中埚跟比的精确计算研究

在直拉单晶硅生长过程中,埚跟比（即坩埚上升速度与晶体提拉速度的比值）的设置非常重要,它直接决定了液面位置的稳定性。其不但影响单晶硅成品的质量,而且不合理的埚跟比设置可能会在直拉单晶硅生长过程中出现变晶断苞,导致单晶生长失败。目前国内大多数光伏单晶硅生产商仅仅依靠人工经验来设置埚跟比,其准确性很难保证。采用体积元积分的方...     

Ion implantation of neon in silicon for planar amorphous isolation

A new planar isolation technique for silicon integrated circuits is presented. The process uses neon implantation to create high-resistivity regions of amorphous silicon between active devices on a common substrate. Excellent surface planarity is obtained, and no high-temperature processing ii required. Results on test devices and an amorphous isolated m.n.o.s. capacitor memory are described.     

Quantitative optical in-situ measurement of the dissolution rate of the silica crucible in the silicon Czochralski process

The dissolution of the silica crucible by the silicon melt acts as a source of oxygen doping in the growth of silicon single crystals by the Czochralski-method. Literature data on the dissolution rate of silica in silicon melts are available up to now only from ex-situ measurements. In the present work, the silica dissolution rate is measured for the first time by an in-situ technique. The decrease of the thickness of the wall of a silica crucible of a laboratory-scale Czochralski-crucible containing silicon melt is measured quantitatively by optical laser interferometry. It is demonstrated that the influence of relevant growth parameters of the silicon Czochralski process like temperature of the silica crucible wall and pressure of the Argon gas can be detected and quantitatively related to the dissolution rate.     

Traveling heater method preparation and composition analysis of CdTe ingots

Large polycrystalline CdTe charges for the subsequent growth of CdTe and CdZnTe crystals were prepared by the traveling heater method (THM). The composition of the produced material was evaluated by vapor pressure scanning (VPS) analysis. Results from these analyses were instrumental in improving the THM CdTe compounding process. The optimization of THM process parameters, such as the compounding rate and the loading configuration of the synthesis crucible, led to the preparation of polycrystalline CdTe ingots with small deviation from stoichiometry. For five out of six analyzed samples, tellurium content between 50.0012 and 50.0043 at. pct was achieved, which is well below the tellurium saturation limit of the single-phase solid in equilibrium with the molten zone at the chosen THM process temperature.     

Capacitance transient spectra of processing- and radiation-induced defects in silicon solar cells

Capacitance transient spectroscopy is used to study defects in chips of fully fabricated silicon solar cells. Characteristic differences are observed as a function of the crystal growth type (crucible grown or float zoned) and dopant (boron or aluminum) of the starting material, processing variables (diffused or implanted junctions, electron beam or furnace annealing) and radiation environment (1 MeV electron irradiation).