中子辐照的单晶硅参数研究

在不同温度和红外光照下，测量了经中子辐照的单晶硅表面光电压，确定了其深能级的位置和少子扩散长度；由双能级复合理论，推导了中子辐照单晶硅的深能级复合中心和寿命的计算公式；计算了热中子辐照和高能中子辐照单晶硅后的深能级密度、费米能级和其他有关重要参数。     

离子注入和脉冲激光退火制备碲超饱和掺杂单晶硅pn结

Pn junctions based on single crystalline tellurium supersaturated silicon were formed by ion implantation followed by pulsed laser melting（PLM）.P type silicon wafers were implanted with 245 keV ¹²⁶Te⁺ to a dose of 2×10¹⁵ ions/cm²,after a PLM process（248 nm,laser fluence of 0.30 and 0.35 J/cm²,1-5 pulses,duration 30 ns）,an n⁺ type single crystalline tellurium supersaturated silicon layer with high carrier density(highest concentration 4.10×10¹⁹ cm^-3,three orders of magnitude larger than the solid solution limit) was formed,it shows high broadband optical absorption from 400 to 2500 nm.Current-voltage measurements were performed on these diodes under dark and one standard sun（AM 1.5）,and good rectification characteristics were observed.For present results,the samples with 4-5 pulses PLM are best.     

一种新型抗辐照SOI隔离结构

制备了一种新型抗辐照SOI隔离结构,它包含了薄SiO2/多晶硅/SiO2多层膜.利用这种结构制备的SOI器件在经受3×105rad(Si)的辐照后亚阈值特性未发生明显变化,漏电流也无增加,说明其抗辐照性能优于传统的LOCOS隔离结构.     

一种新型抗辐照SOI隔离结构

制备了一种新型抗辐照SOI隔离结构，它包含了薄SiO2/多晶硅/SiO2多层膜．利用这种结构制备的SOI器件在经受3×１０~5rad(Si)的辐照后亚阈值特性未发生明显变化，漏电流也无增加，说明其抗辐照性能优于传统的LOCOS隔离结构．     

中子嬗变掺杂单晶硅的电学性能研究

本工作用霍尔系数-电阻率测量,研究了不同原始单晶硅和掺杂温度对NTD Si在高温退火过程中电学性能回复的影响。本文给出了几种NTD Si的自由载流子浓度和迁移率的等时退火曲线和各种特征温度,并对实验结果作了简要讨论。     

SOI材料与器件的辐照效应

目前，ＳＯＩ（ＳｉｌｉｃｏｎＯｎＩｎｓｕｌａｔｏｒ）材料的一个主要用途是用来制作抗辐照电路，本文以ＳＩＭＯＸ（ＳｅｐｅｒａｔｉｏｎｂｙＩＭｐｌａｎｔａｔｉｏｎｏｆＯＸｙｇｅｎ）技术为主，详细论述了ＳＯＩ材料和器件（ＭＯＳＦＥＴ）的辐照特性及其机理，包括总剂量、瞬时和单粒子效应，并以总剂量效应为主。经过恰当的加固工艺和优化设计，可以制造出优良的抗辐照集成电路。     

抗中子辐照器件结构参数的确定

本文分析了高压二极管、低频功率晶体管等器件在中子辐照后电参数退化规律。为提高这些器件的耐中子辐照能力,给出了这些器件结构参数的设计要求,以及这种结构特点的器件设计中需注意的有关问题。     

单晶硅中氢与辐照缺陷的相互作用

对NTD氢区熔单晶硅进行了不同温度下等时退火,采用Hall电学方法测量了电阻率、迁移率随退火温度的变化规律.利用红外吸收技术测量了单晶硅氢区熔退火前后及NTD氢区熔单晶硅不同退火温度下与氢、辐照缺陷有关的红外振动吸收峰变化,对辐照缺陷的退火行为进行了探讨.实验证实NTD氢区熔单晶硅在150～650℃范围内等时退火具有显著特点:在500℃下退火,出现电阻率极小值,即出现浓度很高的过量浅施主;P型向N型转变温度为400℃,迁移率恢复温度为500℃,载流子恢复温度为600℃,均明显低于NTD氩区熔单晶硅转型温度及迁移率和载流子恢复温度,这与氢积极参与辐照缺陷相互作用直接相关.     

单晶硅中氢与辐照缺陷的相互作用

对NTD氢区熔单晶硅进行了不同温度下等时退火,采用Hall电学方法测量了电阻率、迁移率随退火温度的变化规律.利用红外吸收技术测量了单晶硅氢区熔退火前后及NTD氢区熔单晶硅不同退火温度下与氢、辐照缺陷有关的红外振动吸收峰变化,对辐照缺陷的退火行为进行了探讨.实验证实NTD氢区熔单晶硅在150～650℃范围内等时退火具有显著特点:在500℃下退火,出现电阻率极小值,即出现浓度很高的过量浅施主;P型向N型转变温度为400℃,迁移率恢复温度为500℃,载流子恢复温度为600℃,均明显低于NTD氩区熔单晶硅转型温度及迁移率和载流子恢复温度,这与氢积极参与辐照缺陷相互作用直接相关.     

双极晶体管中子辐照实验研究

利用中子辐照拉长线静态测试方法对15种硅双极晶体管进行了中子辐照损伤的实验研究;给出了这些晶体管电流增益与中子注量的关系;估算了损伤常数,测试或推算出损伤阈φ0.5;讨论了拉长线静态测试的退火效应、测试电流大小及伴生γ射线对测试结果的影响;对不同种类的晶体管抗中子辐照性能进行了简单的比较。     

组合激光辐照单晶硅的热作用数值分析

利用有限元法对组合激光辐照单晶硅的温度及应力场进行了数值分析,在组合激光与连续激光平均功率密度相同的前提条件下比较了组合激光和连续激光分别作用于单晶硅的损伤效果。计算结果表明,组合激光与连续激光相比更有利于实现对单晶硅的热损伤;组合激光作用下单晶硅内部的Von Mises应力、轴向应力和环向应力比在连续激光作用下要大,组合激光对单晶硅的损伤比连续激光更强。     

LASOS—laser annealed silicon on sapphire

Laser annealing techniques were successfully incorporated into standard MOS/SOS processing to increase transistor channel mobility and processing yield. Silicon islands were photolithographically defined and chemically etched (by KOH) on standard SOS wafers. The islands were exposed to radiation from an excimer laser (λ = 2490 Å) having a pulse duration of 25 ns, a beam size in the range of 0.1-0.2 cm², and an energy density in the range of 0.5 - 1.0 J/cm². Using standard processing techniques MOS transistors were fabricated and characterized. It was found that exposure at an energy density of ∼0.80 J/cm²results in rounding the Si island edges, thus eliminating the "V"-shaped groove profile of the gate oxide and improving Al step coverage. The electrical characteristics of MOS transistors fabricated over laser annealed islands exhibited a 30-percent increase in channel mobility with a small negative shift (<0.2 V) in the transistor threshold voltage.     

组合激光对单晶硅热作用的数值分析

为了提高激光加工中单晶硅材料对激光能量的耦合效率,采用一个短脉冲激光和一个长脉冲激光形成组合激光辐照单晶硅,使用COMSOL软件对该过程进行模拟,得到了组合激光长短脉冲间的延迟时间和长脉冲激光能量密度的变化对作用效果的影响,并与总能量相等的毫秒激光单独作用的效果进行比较;实验测量得到的不同能量密度的激光作用单晶硅后损伤形貌,与数值计算结果的趋势吻合。结果表明,组合激光能提高材料对激光的耦合效率;不同的延迟时间会影响组合激光的作用效果,最佳延迟时间为0.1ms;组合激光中毫秒激光能量密度占比较低时,作用效能较明显,随着毫秒激光能量密度占比的提高,对作用效果的提升相对变缓。该研究结果可以为组合激光的应用提供理论和实验依据。     

An investigation of laser annealed and metal-induced crystallizedpolycrystalline silicon thin-film transistors

We report results on thin-film transistors (TFTs) made from a new hybrid process in which amorphous silicon (a-Si) is first converted to polycrystalline silicon (poly-Si) using Ni-metal-induced lateral crystallization (MILC), and then improved using excimer laser annealing (laser MILC or L-MILC). With only a very low shot laser process, we demonstrate that laser annealing of MILC material can improve the electron mobility from 80 to 170 cm²/Vs, and decrease the minimum leakage current by one to two orders of magnitude at a drain bias of 5 V. Similar trends occur for both p- and n-type material. A shift in threshold voltage upon laser annealing indicates the existence of a net positive charge in Ni-MILC material, which is neutralised upon laser exposure. The MILC material in particular exhibits a very high generation state density of ~10¹⁹ cm^-3 which is reduced by an order of magnitude in L-MILC material. The gate and drain field dependences of leakage current indicate that the leakage current in MILC transistors is related to this high defect level and the abruptness of the channel/drain junction. This can be improved with a lightly doped drain (LDD) implant, as in other poly-Si transistors     

一种激光刻蚀制作圆柱形介质天线的方法

圆柱形介质加载四臂螺旋天线因宽波束、圆极化、体积小等优点被认为是微小卫星天线的理想方案。为了解决介质加载四臂螺旋天线制作的难点,提出了一种全新的磁控溅射金属化加激光刻蚀的新工艺,采用计算机数控结合激光刻蚀的柔性加工技术,制作出3维立体的四臂螺旋结构,制备了应用于微小卫星系统的介质加载四臂螺旋天线,相对于传统工艺, 大大提高了加工精度,并缩短了加工周期。结果表明,天线的电气性能达到了设计要求,且具有良好的机械性能。该研究为以后此类曲面共形天线的制作提供了参考。     

Bulk growth of single crystal silicon carbide

Silicon carbide (SiC) is a promising wide bandgap semiconductor material particularly suitable for future high power devices operable at high temperatures (>200 °C), at high frequencies, and in harsh environments (chemical and radiation) due to its unique physical and crystallographic properties. The absence of SiC liquid phase, under easily achievable growth conditions of pressure and temperature has created unique challenges for crystal growers.This paper reviews the basics of bulk growth processes, including source sublimation, mass transport of the Si and C species to the growing seed and crystallization. The growth process is shown to be a self-congruent phenomenon where the mass transport of the vapor species and the heat dissipation at the surface of phase transformation are interrelated. This process results in reduction of the growth velocity as a function of crystal thickness. Major mechanisms of defect generation in the grown crystal are discussed.     

皮秒激光加工制备钛酸锶单晶超亲水表面

报道了一种通过皮秒激光加工快速制备钛酸锶(SrTiO3)单晶超亲水表面的方法。室温下,采用皮秒激光加工系统,在SrTiO3单晶表面刻蚀出整齐的周期性线排列沟槽结构,使SrTiO3单晶表面浸润性向亲水方向转变。研究了不同划线间隔对表面接触角大小的影响。结果表明:接触角的大小随划线间隔的变化而变化,间隔越大,接触角越大;当沟槽间隔小于150μm时,得到超亲水表面。其机理是:根据Wenzel模型,增大表面粗糙度可以使表面浸润性向亲水方向转变;并且沟槽结构产生了虹吸现象,也增强了亲水性。     

Manufacturability of single and double-gate ultrathin silicon filmfully depleted SOI technologies

Of several possible devices that can be used for sub-70 nm node technologies, two are built on ultra thin SOI layers. Scaling of such thin silicon layer SOI devices is constrained by the severe short channel control problem. To alleviate this, double-gate structures have been proposed by Wong et al. (1999), Chang et al. (2000), and Ieong et al. (2000). In this paper, we assess the manufacturability of single-gate (SG) and symmetric double-gate (DG) devices for gate lengths between 15 and 70 nm. Our results show that SG devices are not only manufacturable but also have tighter distributions than DG devices; inverter ring oscillator (RO) stage delays and power consumption are also better for SG devices. Besides gate length we find two additional major sources of variation: silicon thickness and encapsulation width. We show that for an optimized double-gate device with minimized parasitic resistance, CD variations become a dominant factor at 20-nm gate lengths despite superior electrostatic integrity. Also, the work function of metal gates must be controlled to better than ±0.1 eV (3σ) to avoid severe manufacturability problems     

应用于中红外波段的阵列化多孔硅一维光子晶体的制备

首先通过光刻工艺制作了阵列化岛状硅衬底,然后利用交替变换阳极腐蚀电流,通过合理地控制制备参数,适当的热氧化条件,成功地制备了禁带中心位于5μm、6μm、7μm、10μm的阵列化多孔氧化硅一维光子晶体.随后在其表面淀积一层低应力的Si3N4,通过原子力显微镜(AFM)和傅里叶红外反射谱(FTIR)测试证明,沉积Si3N4后该结构仍然具有良好的平整度和较高的反射特性.该阵列结构不但具有较好的隔热和高反射特性,而且岛状的阵列结构可使其与其他器件互联变得简单易行,必将为制备多功能、一体化器件提供有利条件.