真空高阻区熔Si单晶中的微缺陷及其少子寿命

通过在Ar气氛及真空环境中进行的高阻区熔Si单晶生长实验,分析了晶体直径、晶体生长环境及晶体生长速率对晶体中微缺陷及少子寿命的影响及产生这种影响的原因.单晶生长实验表明,与在Ar气氛下的单晶生长相比,在真空环境下采用较低的晶体生长速率即可生长出无漩涡缺陷的单晶,而当晶体生长速度较高时,尽管可以消除漩涡,但单晶的少子寿命却有明显的下降.     

高阻真空区熔硅单晶的生长

介绍了高阻真空区熔硅单晶的研制工艺,研制出了导电类型为p型,电阻率(3～5)×103 Ω·cm及(1～2)×104Ω·cm两种规格的真空区熔硅单晶,其中电阻率(3～5)×103Ω·cm规格单晶的研制除需要进行真空区熔提纯外,还要进行微量的p型区熔掺杂.单晶直径30～35 mm,晶向〈111〉.经检测无位错及漩涡缺陷,单晶的少数载流子寿命达到1500μs以上.     

直拉区熔联合法硅单晶生长技术研究

通过直拉工艺生长直径60 mm的N型100单晶,之后以该单晶作为原料,采用区熔工艺生长成50 mm(2英寸)N型111单晶,单晶的电阻率为2.71~5.35Ω·cm,少子寿命为500~750μs,氧碳含量均低于1×16 cm-3。实验表明,通过直拉工艺和区熔工艺联合方式研制的低阻硅单晶具有电阻率控制准确、氧碳含量低、工艺易于实施等特点。同时,对直拉区熔联合法生长单晶的技术特点进行了探讨。     

直径52～65mm探测器级Si单晶的真空制备

为了制备纯度11N以上、直 径Φ大于 45mm并且各项性能指标满足探测器级要求的大直径 超高纯单晶Si材料,本文在真空气氛下提纯并生长Φ52～65mm探测器级区熔(FZ,float zone)Si单晶, 并对真空气氛和直径增加所带来的晶体不稳定生长、高断面电阻率不均匀率和漩涡缺陷 等问题的产生原因和解决方式进行了深入研究。结果表明,丹麦加热线圈表面带有台阶 和十字开口,是提纯和生长Φ大于45mm 多晶Si和单晶Si的理想线圈;适当提高单晶转速和 生长速度有利于降低断面电阻率不均匀率,且提高转速的效果更加明显;真空气氛下, 提高热场对中性可抑制漩涡缺陷的产生,其对漩涡缺陷的影响比单晶Si生长速度更加显 著,这是与Ar气气氛FZ不同的;多晶Si提纯次数越多单晶Si寿命越低,降低多晶Si原 料中的P/B和重金属原始含量有利于提高单晶Si寿命;若要制备少子寿命大于800μs, 符合探测器级标准的Φ52～65mm Si单晶 ,多晶Si原料少子寿命应大于3000μs。     

中子嬗变掺杂(NTD)硅单晶在压阻传感器中的应用

半导体器件用的硅单晶,通常是在直拉或区熔时从外部引入杂质制备的,即在硅单晶体生长时掺入所需杂质.因此,在掺杂时,由于杂质在硅中的分凝效应,导致掺入杂质分布的不均匀,再加上拉晶工艺因素的影响,使硅单晶产生杂质条纹等缺陷,使单晶在轴向和径向都会有较大的掺杂分布起伏,导致单晶电阻率的非均匀性.对大直径、高电阻率的硅单晶电阻率的不均匀性更为突出.硅压阻传感器对硅单晶电阻率的均匀性同样有较高的要求,如果原始单晶电阻率均匀性     

生长系统对高阻区熔硅单晶径向电阻率变化的影响

分别采用L4375-ZE区熔炉和CFG/1400P区熔炉,生长了N型、(1.5～4.5)×103Ω.cm和P型、(1.0～5.0)×104Ω.cm两种规格的高阻区熔硅单晶,单晶的直径为52～54 mm,晶向为<111>。经对单晶的电阻率及其径向分布进行检测对比后发现,在加热线圈几何结构(包括上下表面角度、内径尺寸及台阶设计)基本相同、单晶生长速率相同且上、下晶轴旋转具有相同配置的情况下,不同的单晶生长系统所生长的单晶,其电阻率径向均匀性有明显差异,用L4575-ZE区熔炉生长的单晶的电阻率径向分布更均匀。     

φ200mm太阳能电池用直拉硅单晶生长中导流系统的研究

利用数值模拟,对CZ硅单晶生长系统中导流系统调整和改进,得到不同导流系统下的氩气流场和全局温场. 研究发现在导流系统中引入导流筒及冷却功能后,氩气流场得到明显的改善,晶体中纵向温度梯度均匀性改善,固液界面趋于平坦,有利于结晶潜热的散发和单晶径向电阻率的均匀性. 研究表明改进导流系统能提高结晶潜热散发速率,有利于提高晶体拉速.     

微波反射光电导衰退技术在InGaAs台面结器件工艺中的应用

微波反射光电导衰退法是一种非接触式的半导体材料少子寿命表征手段，本文用微波反射光电导衰减法测试了台面InGaAs光电器件制备中各单项工艺(刻蚀、腐蚀、硫化)中InCaAs样品的少子寿命分布，结果表明，离子刻蚀使得样品少子寿命降低，非均匀性增大，而湿法腐蚀能够在一定程度上修复离子刻蚀带来的损伤，损伤区域中心的少子寿命增大，寿命分布也更加均匀，硫化钝化能够进一步提高损伤区域少子的寿命，却使寿命分布均匀性变差。可见，微波反射光电导衰减法可以简单无损地得到样品少子寿命分布，对工艺改进具有重要的指导意义。     

φ200mm太阳能电池用直拉硅单晶生长中导流系统的研究

利用数值模拟,对CZ硅单晶生长系统中导流系统调整和改进.得到不同导流系统下的氩气流场和伞局温场.研究发现在导流系统中引入导流筒及冷却功能后,氩气流场得到明显的改善,晶体中纵向温度梯度均匀性改善,同液界面趋于平坦,有利于结晶潜热的散发和单晶径向电阻率的均匀性.研究表明改进导流系统能提高结品潜热散发速率,有利于提高晶体拉速.     

微波反射光电导衰退技术在InGaAs台面结器件工艺中的应用

微波反射光电导衰退法是一种非接触式的半导体材料少子寿命表征手段,本文用微波反射光电导衰减法测试了台面InGaAs光电器件制备中各单项工艺(刻蚀、腐蚀、硫化)中InCaAs样品的少子寿命分布,结果表明,离子刻蚀使得样品少子寿命降低,非均匀性增大,而湿法腐蚀能够在一定程度上修复离子刻蚀带来的损伤,损伤区域中心的少子寿命增大,寿命分布也更加均匀,硫化钝化能够进一步提高损伤区域少子的寿命,却使寿命分布均匀性变差.可见,微波反射光电导衰减法可以简单无损地得到样品少子寿命分布,对工艺改进具有重要的指导意义.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.