硅中的点缺陷的控制和利用

介绍依靠拉晶速度和固液界面处的轴向温度梯度之比，影响空位和自间隙原子在直拉硅单晶中的分布。合理设计热场分布，减少直拉硅单晶中的缺陷。低剂量氧离子注入能降低SIMOX硅片项层硅中的间隙原子浓度，从而降低穿透位错的密度。最近开发了一种称为MDZ的内吸除新技术，通过快速热退火控制硅片中空位浓度的分布，从而得到理想的氧沉淀行为，实现了可靠、可重复的内吸除。     

直拉硅单晶时旋转磁场的获得

一、引言大规模和超大规模集成电路的发展,对硅单晶质量提出了越来越高的要求。直拉硅单晶中的杂质氧,使晶体在生长或器件制造的热处理过程中,产生堆垛层错、位错环和硅氧沉淀等缺陷。另一方面,氧化物沉淀引入的位错对表面沾污有本征吸杂的作用。因此硅中氧浓度是单晶质量的重要标志。一般直拉硅单晶中的氧浓度都超过1×10~(18)原子/厘米~3,而且单晶头部含量高于尾部。纵向     

日本研究提高硅单晶少子寿命的最新进展

众所周知,硅单晶中的少子寿命是评价硅单晶质量的重要参数之一,因而找出影响少子寿命的主要因素,从而提高少子寿命是一个具有重要意义、又很热门的课题。最近日本电报和电话大众公司发表了一篇科研报告,介绍少子寿命是与硅单晶中的氧沉淀密切有关,并深入地定量讨论了它们之间的关系。在直拉硅单晶中,由于氧浓度较高,所以硅单晶在生长后的冷却过程中或以后的热     

直拉硅单晶热处理过程中氧及碳的行为

本文研究了CZ硅单晶在热处理过程中碳对产生氧施主和加快氧沉淀的作用。实验证实了碳在450℃时能抑制热施主的产生,在750℃时碳能促使生成新施主。在1050℃时由于碳的存在加快了氧的沉淀。实验结果认为CZ硅单晶氧含量小于8×10~(17)cm~(-3)时电阻率的热稳定性较好。     

水平磁场对熔体热对流抑制作用的理论分析

在直拉硅单晶生长过程中,熔体热对流对单晶质量有很大影响。一方面,热对流引起的温度波动可引起生长速率的变化,因晶体回熔而引入微缺陷,降低单晶的均匀性;另一方面,热对流将直接影响单晶中的间隙氧含量,并进一步影响到随后的氧沉淀形成。因此,在单晶生长过程中如何控制或抑制熔体的热对流越来越受到重视。     

硅中氧的热沉淀（上）

本文综述近年来国内外在硅单晶中氧杂质的热沉淀行为方面的研究工作。着重介绍了在不同的热处理条件下,氧在硅单晶中产生的各种热沉淀现象和性质,以及解释这些热行为的氧沉淀理论。最后讨论了硅中氧的各种热沉淀对硅材料及器件性能的影响,并展望了今后在这一领域尚需解决的问题。     

Ti-V复合低碳钢在回火过程中MC型碳化物的析出与强化行为

利用维氏硬度计、OM(光学显微镜)、EBSD(电子背散射衍射)和TEM(透射电子显微镜)对在600℃回火不同时间后的Ti-V复合微合金化马氏体钢的维氏硬度、微观组织及析出相随回火时间的演变进行了研究。结果表明:随回火时间的增长,实验钢的硬度变化为先下降后上升再下降。前期由于位错密度降低,引起实验钢硬度下降。回火开始后,由于析出相的沉淀强化作用,硬度逐渐上升,并在回火1 h时达到峰值。回火1 h后,析出相开始粗化并引起位错密度降低,实验钢的硬度又开始下降,并在100 h时达到最低值。在回火过程中析出相的形状和尺寸都发生了明显变化。在回火1 h时实验钢的主要强化机制为沉淀强化,沉淀强化增量占总强度的34.9%,而在回火100 h时沉淀强化仍是钢中的主要强化方式。     

直拉硅单晶生长中氧的分布与控制

硅中的间隙氧对于器件有着有害和有益的作用。因此,控制硅中氧的掺入和改进氧浓度轴向和径向分布是十分重要的。本文评述了硅中氧的掺人机理,描述了硅中氧的轴向和径向分布及氧条纹,给出了几种改进硅单晶生长中氧浓度分布的方法。     

CUSP磁场对直拉硅单晶氧浓度分布影响的数值模拟

利用有限元分析软件对φ300mm直拉硅单晶生长过程进行模拟,分析了保持CUSP磁场对称面与熔体坩埚界面交点处的径向分量不变的情况下,硅单晶中氧浓度分别随CUSP磁场通电线圈距离、通电线圈半径的变化规律.随着通电线圈距离和半径的增大,晶体熔体固液界面氧浓度均逐渐降低.随着通电线圈距离和半径的增大,硅熔体径向磁场强度逐渐增大,对坩埚底部熔体向晶体熔体固液界面处对流的抑制作用加强,固液界面下方熔体轴向流速减小,使得从坩埚底部运输上来的富氧熔体减少,继而固液界面处的氧浓度降低.随着线圈距离和半径的增大,为保持所需磁场强度,施加电流也逐渐增大,从而能耗增大,与增大通电线圈距离相比,增大通电线圈半径所需的电流较大.通过实验,将CUSP磁场对单晶中氧浓度分布影响的数值模拟结果与实际晶体生长进行了对比,实验结果验证了数值模拟的结果.     

热处理对掺镓直拉单晶硅中缺陷及少子寿命的影响

抑制p型单晶硅太阳能电池的光致衰减现象是光伏科技领域的热点和难点。掺镓直拉硅单晶工艺的突破以及在晶硅电池上的应用破解了这一难题,成功地抑制光致衰减。因为镓原子与硼原子共价半径的差异以及在太阳能电池制备过程中单晶硅片仍会经历不同条件的热处理,所以探究不同热处理条件对掺镓单晶硅中缺陷以及少子寿命的影响是非常有必要的。本文使用专利工艺技术制备掺镓硅单晶,并对掺硼和掺镓两种不同单晶硅片进行不同温度和时间的退火实验,对比分析不同样品的氧含量和少子寿命。结果发现:退火温度的升高、时间的延长以及预热处理都会降低两种硅片中的间隙氧含量以及少子寿命,同时促进了两组硅片中氧沉淀的形成。通过两组不同硅片对比表明,在相同条件下的退火处理,原子半径差异导致掺镓硅单晶硅的间隙氧含量下降速度更快,易形成更多的氧沉淀。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.