High dose-rate hydrogen passivation of polycrystalline silicon CMOSTFTs by plasma ion implantation

Plasma ion implantation (PII) hydrogenation is an efficient method for defect passivation in polycrystalline silicon (poly-Si) thin film transistors (TFTs). We have developed a process that can achieve saturation of device parameter improvement in 30 min, whereas conventional plasma hydrogenation takes approximately 4 h. Our model predicts that much shorter process times are possible. We have analyzed the gate oxide charging which occurs during the PII process and controlled it to the extent that processed devices are damage-free. The long-term reliability of PII hydrogenated devices is superior to that of conventional parallel-plate plasma hydrogenated devices     

Fabrication of low dielectric constant materials for ULSImultilevel interconnection by plasma ion implantation

High dose-rate plasma ion implantation (PII) has been utilized to produce low dielectric constant (k) SiO₂ films for high quality interlayer dielectrics. The SiO₂ films are fluorine-doped/carbon-doped by PII with CF₄ plasma in an inductively-coupled plasma (ICP) reactor. It is found that the use of CF ₄ doping results in exceptional dielectric properties which differ significantly from fluorinated SiO₂. The dielectric constant of the SiO₂ film is reduced from 4.1 to 3.5 after 5 minute PII, other electrical parameters such as bulk resistivity and dielectric breakdown strength are also improved     

Plasma ion implantation hydrogenation of poly-Si CMOS thin-filmtransistors at low energy and high dose rate using aninductively-coupled plasma source

Defect passivation in polycrystalline silicon (poly-Si) CMOS thin-film transistors (TFT's) has been performed by plasma ion implantation (PII) hydrogenation process. Implantation at low energy (2 keV) and high dose rate(~10¹⁶/cm² S) was achieved by an inductively-coupled plasma source. The device parameter improvements are saturated in 3-4 min, which is much shorter than other hydrogenation methods reported in the literature. The stress measurements indicate that the devices hydrogenated by this new technique have much better long-term reliability than that hydrogenated by other techniques     

全方位离子注入技术

等离子体离子注入(PII)是一种用于材料表面改性的新型离子注入技术。PII分为两类,用于金属表面改性时称为等离子体源离子注入技术(PSII),用于半导体材料表面改性时称为等离子体浸没离子注入(PIII)。本文介绍一种新的PII技术,称为全方位离子注入(All Orientation Ion Implantation),采用横磁瓶电子迴旋共振等离子体源,样品上的负高压可以是直流、交流或脉冲方式,本装置可以工作在离子注入和动态离子束混合两种模式。     

Combinatorial Study of Temperature‐Dependent Nanostructure and Electrical Conduction of Polymer Semiconductors: Even Bimodal Orientation Can Enhance 3D Charge Transport

Temperature‐dependent (80–350 K) charge transport in polymer semiconductor thin films is studied in parallel with in situ X‐ray structural characterization at equivalent temperatures. The study is conducted on a pair of isoindigo‐based polymers containing the same π‐conjugated backbone with different side chains: one with siloxane‐terminated side chains (PII2T‐Si) and the other with branched alkyl‐terminated side chains (PII2T‐Ref). The different chemical moiety in the side chain results in a completely different film morphology. PII2T‐Si films show domains of both edge‐on and face‐on orientations (bimodal orientation) while PII2T‐Ref films show domains of edge‐on orientation (unimodal orientation). Electrical transport properties of this pair of polymers are also distinctive, especially at high temperatures (>230 K). Smaller activation energy (E _A) and larger pre‐exponential factor (μ ₀) in the mobility‐temperature Arrhenius relation are obtained for PII2T‐Si films when compared to those for PII2T‐Ref films. The results indicate that the more effective transport pathway is formed for PII2T‐Si films than for the other, despite the bimodally oriented film structure. The closer π–π packing distance, the longer coherence length of the molecular ordering, and the smaller disorder of the transport energy states for PII2T‐Si films altogether support the conduction to occur more effectively through a system with both edge‐on and face on orientations of the conjugated molecules. Reminding the 3D nature of conduction in polymer semiconductor, our results suggest that the engineering rules for advanced polymer semiconductors should not simply focus on obtaining films with conjugated backbone in edge‐on orientation only. Instead, the engineering should also encounter the contribution of the inevitable off‐directional transport process to attain effective transport from polymer thin films.     

High-gain polarization-insensitive optical amplifier

A polarization-insensitive optical amplifier (PIOA) consisting of two serial semiconductor laser amplifiers (SLAs) is studied theoretically and experimentally. A polarization-insensitive isolator (PII) inserted between the two SLAs serves not only to eliminate the coupling cavity, but also to rotate any polarized forward light by 90°. Experimental results show a maximum fiber-to-fiber gain of 29 dB. PIOA gain deviation for the input polarization launch angle is just 0.6 dB compared to an original value of 5-6 dB in a single SLA. A theoretical analysis shows that it is necessary to achieve a PII rotation design error of less than 0.5° in order to suppress deviation below 0.1 dB. PIOA noise figure deviation, for the input signal polarization launch angle, was only 0.1 dB from both the experimental and theoretical results even though there was a rotation error of 2°     

Effect of Spacer Length of Siloxane‐Terminated Side Chains on Charge Transport in Isoindigo‐Based Polymer Semiconductor Thin Films

A series of isoindigo‐based conjugated polymers (PII2F‐C_mSi, m = 3–11) with alkyl siloxane‐terminated side chains are prepared, in which the branching point is systematically “moved away” from the conjugated backbone by one carbon atom. To investigate the structure–property relationship, the polymer thin film is subsequently tested in top‐contact field‐effect transistors, and further characterized by both grazing incidence X‐ray diffraction and atomic force microscopy. Hole mobilities over 1 cm² V^?1 s^?1 is exhibited for all soluble PII2F‐C_mSi (m = 5–11) polymers, which is 10 times higher than the reference polymer with same polymer backbone. PII2F‐C₉Si shows the highest mobility of 4.8 cm² V^?1 s^?1, even though PII2F‐C₁₁Si exhibits the smallest π–π stacking distance at 3.379 Å. In specific, when the branching point is at, or beyond, the third carbon atoms, the contribution to charge transport arising from π–π stacking distance shortening becomes less significant. Other factors, such as thin‐film microstructure, crystallinity, domain size, become more important in affecting the resulting device's charge transport.     

SFBC MIMO-OFDM peak-to-average power ratio reduction by polyphase interleaving and inversion

Many PAPR reduction schemes have been proposed for OFDM systems. Among these, the signal scrambling methods such as the partial transmit sequences (PTS) (S. H. Muller, et al., 1997) and selective mapping (SLM) (R. W. Bauml, et al., 1996) are attractive as they obtain better PAPR property by modifying OFDM signals without distortion. These schemes can also be applied to a SFBC MIMO-OFDM system, which is advantageous for dispersive channels, in a straightforward way by performing signal scrambling on data sequence before it is distributed to the transmit antennas according to employed encoding scheme. Note however that in the case of PTS PAPR reduction in the time domain is not possible, which leads to prohibitively large complexity of such scheme. In this letter, we introduce more effective approach, the polyphase interleaving and inversion (PII) PAPR scheme and its reduced complexity version (RC-PII), which is designed to suppress peaks in SFBC-OFDM, transmit diversity.     

基于PII控制器的XCP带宽补偿算法

 XCP在多瓶颈网络中存在缺陷,利用率和公平性显著下降.本文根据控制论中的反馈补偿原理,提出一个基于PII控制器的XCP带宽补偿算法.仿真实验表明该带宽补偿算法能够有效消除XCP在多瓶颈网络中的缺陷,各条链路都能够获得100％的利用率,各条瓶颈流都能够获得最大最小公平带宽.     

以纳米SiC为填料的激光重熔等离子喷涂陶瓷涂层组织及耐腐蚀性能的研究

在45#钢表面,以等离子喷涂技术制备了WC/Co-NiCrAl涂层(TC-1)。采用激光直接重熔等离子喷涂陶瓷涂 层技术制备了激光重熔WC/Co-NiCrAl/laser-remelting陶瓷涂层(FC-2);以纳米SiC粉末为填料,对等离子喷涂层进行 了填料下的激光重熔,制备了纳米SiC改性的WC/Co-NiCrAl/nano-SiC复合陶瓷涂层(FC-3)。采用X射线衍射、扫描电 镜对三种涂层微观组织进行了分析,同时对陶瓷涂层的耐腐蚀性能进行了研究。结果表明,TC-1涂层由WC,W2C, W6C2.54,W,Co,CoO组成;TC-2重熔层由WC,W2C,CoO及W组成;纳米改性后的重熔层TC-3由SiC,Si2W,WC,W及 CoO组成。在激光作用下,原等离子喷涂层WC/Co的片层状组织得以消除。与TC-1涂层相比,TC-2及TC-3陶瓷涂层 致密化程度明显提高,涂层耐腐蚀性能也得到了明显的改善。     

Time-resolved plasma diagnostic by laser-diode spectroscopy

A tunable diode laser has been used as a light source for line-of-sight absorption and Doppler-shift measurements. We have applied the method to perform plasma diagnostics in a magneto plasma dynamic (MPD) pulsed propulsor device and of an Ar⁺ laser tube plasma. Spectrally resolved argon absorption lineshapes of transitions of neutral and single ionized argon were recorded. A high temporal resolution (a few microseconds) is achieved by fast tuning the laser frequency at a repetition rate greater than 100 kHz. From the recorded spectra, we deduce the dynamics of the neutral components of the plasma in the thruster. We also demonstrate the possibility of direct ion diagnostics by the observation of ionic transitions, using red diode lasers in an Ar⁺-laser commercial tube     

α—Si TFT矩阵等离子体刻蚀技术的研究

本文介绍了α-Si TFT有源矩阵的CF_4等离子体刻蚀技术。分析了CF_4等离子体刻蚀α-Si:H和α-SiN_x的机理,对α-Si TFT的有源层与绝缘层之间刻蚀选择性和均匀性进行了研究,讨论了等离子体刻蚀速率与射频功率、反应室压力及衬底温度的依赖关系。根据实验结果总结了CF_4等离子体刻蚀速率随射频功率、反应室压力和衬底温度的增加而增大的规律,通过控制合适的工艺条件,成功地实现了选择性刻蚀并改善了刻蚀的均匀性。     

Polarization dependence of linewidth enhancement factor inInGaAs/InGaAsP MQW material

Measurements and calculations on the differential gain, the differential refractive index, and the linewidth enhancement factor have been performed for unstrained quantum-well (QW) material. The differential refractive index is considerably lower for the transverse magnetic (TM) polarization than for the transverse electric (TE) polarization, which is ascribed to absence of the plasma effect for the TM polarization. This has implications for the linewidth enhancement factor and thus linewidth and chirp in QW lasers     

激光干涉诊断电热化学发射装置产生的等离子体射流

叙述了用光楔错位干涉与高速摄影技术相结合诊断电热化学发射装置中等离子体发生器产生的等离子体射流的方法,得到了等离子体射流的电子密度和温度等参数的分布。该方法有助于改进电热化学发射装置中等离子体发生器的设计及其效能的提高。     

衬底位置对大面积CVD金刚石薄膜质量的影响

采用石英钟罩式微波等离子体化学气相沉积(MWPCVD)设备制备了大面积金刚石薄膜,结合X射线衍射谱(XRD)、扫描电子显微镜(SEM)和激光喇曼(Raman)谱等实验手段,较系统地研究了衬底位置对金刚石薄膜质量的影响规律.结果表明,在等离子体球内部的空间范围内,距等离子体球中心垂直距离越远衬底上所沉积的金刚石薄膜质量越好;通过调整衬底位置,可明显改善其上不同区域所沉积的金刚石薄膜质量,最后在等离子体球边缘附近可沉积出晶粒均匀一致几乎不舍非晶碳的大面积高质量金刚石薄膜.此研究为进一步改善大面积金刚石薄膜均匀性和薄膜质量提供了一种实用的途径.     

Radiation-induced depassivation of latent plasma damage

Plasma treatments are widely used in microelectronic industry but they may leave some residual passivated damage in the gate oxides at the end of the processing. The plasma-induced damage can be amplified by metal interconnects (antenna) attached to the gate during the plasma treatments. Ionising radiation reactivates this latent damage, which produces enhanced oxide charge and Si/SiO₂ interface state density. Two CMOS technologies have been investigated, with 5 and 7 nm gate oxides. Threshold voltage shifts, transconductance decrease, and interface traps build-up are always larger for plasma damaged devices than for reference devices.     

Radiation from Linear Resonant Antenna in Weakly Ionized Plasma†

A theoretical study of radiation of electromagnetic and electroacoustic waves in lossy compressible weakly ionized plasma has been made and its dependence on the ratio of source to plasma frequencies has been investigated. A linearized theory is used such that the isotropic electron plasma is regarded as a single fluid continuum. A thin linear resonant antenna is used as the source of radiation and the propagation constant on it is assumed to be the same as in free space. The propagation constant is taken to be complex in plasma for both electromagnetic and electroacoustic waves. Also the effect of electron neutral particle collision is taken into account wherever it is effective. It is shown that propagation is almost unaffected by plasma when source frequencies much higher than the plasma frequency are used. But the effect of plasma on radiation is found to be profound at frequencies smaller than the plasma frequency. General expressions of radiation resistance for both the electromagnetic and eloctroacoustic waves have been obtained and under these conditions the half-wave dipole is treated as a special case. The results deduced for these are found to be in agreement with those wherever obtained earlier.     

FDTD Simulation of Electromagnetic Reflection of Conductive Plane Covered with Imhomogeneous Time-Varying Plasma

A finite-difference time-domain (FDTD) algorithm is applied to study the electromagnetic reflection of conduction plane covered with inhomogeneous, collision, warm, time-varying plasma. The collision frequency of plasma is a function of electron density and plasma temperature. Under the one-dimensional case, transient electromagnetic propagation through various plasmas have been obtained, and the reflection coefficient of EM wave through inhomogeneous time-varying plasma (ITVP), homogeneous time-varying plasma (HTVP) and inhomogeneous plasma (IP) are calculated under different conditions. The results illustrate that a plasma cloaking system can successfully absorb the incident EM wave.     

Theoretical and Experimental Studies of Terahertz Wave Propagation in Unmagnetized Plasma

The spacecraft will experience the well-known “blackout” problem when it re-entry into the Earth’s atmosphere, which results in communication failures between the spacecraft and the ground control center. It is important to study the properties of terahertz (THz) wave propagation in plasma for communications using THz wave is an alternative method for solving the blackout problem. The properties of THz wave propagation in plasma have been studied with the ZT-FDTD (Z-Transform Finite Difference Time Domain) method and experimental method in this paper. The dependence of plasma density, plasma collision frequency, thickness of plasma and THz wave frequency on the THz wave propagation are presented. The properties of 0.22THz electromagnetic wave propagation in plasma have been studied experimentally with shock tube, and the experimental results are in good agreement with the FDTD ones. Both the FDTD and experimental results indicate that communications using THz wave is an alternative and effective way to solve the blackout problem.     

Single damascene integration of porous Zirkon™ version 1 low-k dielectric films

Zirkon™ LK2000 version 1 dielectric film (Zirkon™ is a trademark of Shipley Company L.L.C), a porous methylsilsesquioxane (MSQ)-based spin-on dielectric with a k value targeted at 2.0, has been integrated in single damascene structures. For patterning, a dual SiC/SiO₂ CVD hard-mask was used. Surface treatments (DUV ozone (DUV-O₃), plasma treatments) were tested to solve the adhesion issues encountered at the CVD hard-mask and the low-k interface. Adhesion is only improved when plasma treatments are used. Analyses (FTIR, TDS, nano-indentation) show that the plasma treatments only modify the low-k surface. For integration, a plasma treatment (He, NH₃, N₂/O₂) prior to deposition of the CVD hard-mask was included. After patterning, copper metallization and CMP of the wafers, electrical evaluation shows that, compared to the reference wafer (no plasma treatment), plasma-treated wafers have a higher yield and a lower sheet resistance. The RC delay is slightly higher for the plasma-treated wafers than for the reference wafer.