Suppression of cobalt silicide agglomeration using nitrogen(N2+) implantation

In this paper, the effects of nitrogen coimplantation with boron into p⁺-poly gate in PMOSFETs on the agglomeration effects of CoSi₂ are studied. The thermal stability of CoSi₂/poly-Si stacked layers can be significantly improved by using nitrogen implantation. Samples with 40-nm cobalt silicide (CoSi ₂) on 210-nm poly-Si implanted by 2×10¹⁵/cm ² N₂⁺ are thermally stable above 950°C for 30 s in N₂ ambient. If the dose of nitrogen is increased up to 6×10¹⁵/cm², the sheet resistance of CoSi₂ film is not increased at all, and TEM photographs show that the agglomeration of CoSi₂ film is completely suppressed     

A novel process to form cobalt silicided p+ poly-Sigates by BF2+ implantation into bilayeredCoSi/a-Si films and subsequent anneal

A novel process that implants BF₂⁺ ions into thin bilayered CoSi/a-Si films has been shown to form cobalt silicided p ⁺ poly-Si gates with excellent gate oxide integrity and very small flatband shift. The effects of not only using the CoSi layer as an implantation barrier but also keeping the a-Si underlayer during the initial silicide formation both significantly suppress the boron penetration through thin gate oxide     

H2+和D2+谐波强度与波长的关系

为了了解H₂+及其同位素分子谐波光谱效率与激光波长之间的关系,采用求解2维薛定谔方程的方法,理论研究了600nm~1600nm激光波长下H₂+和D₂+谐波光谱强度随波长的变化关系。结果表明,光谱强度随波长增大而减小;在短波长区间,H₂+光谱强度减小的倍率要大于D₂+,在长波长区间,H₂+光谱强度减小的倍率要小于D₂+;此外,在弱光强下,H₂+光谱强度总是大于D₂+, 在强光强下,H₂+光谱强度在短波长区间小于D₂+, 而其在长波长区间大于D₂+; 核间距延伸和电荷共振增强电离在H₂+和D₂+谐波光谱强度变化上起到主要作用。这一结果对分子谐波调控是有帮助的。     

Various effects of silicidation on shallow p+ junctionsformed by BF2+ implantation into thin poly-Sifilms on Si substrates

Various effects of silicidation on shallow p⁺ n junctions formed by the scheme that implants BF₂⁺ ions into thin poly-Si films on Si substrates are described. A post-Ni silicidation just slightly improves the preformed junctions of the annealed sample. However, as the sample is first deposited with thin Ni films after the implantation and then annealed, the resulting junctions are much better than the preformed ones. Moreover, as the sample is deposited with Ti films, the resultant junctions are just slightly better the preformed ones     

Impact of nitrogen (N14) implantation into polysilicongate on high-performance dual-gate CMOS transistors

The effect of nitrogen (N₁₄)implant into dual-doped polysilicon gates was investigated. The electrical characteristics of sub-0.25-μm dual-gate transistors (both p- and n-channel), MOS capacitor quasi-static C-V curve, SIMS profile, poly-Si gate R_s , and oxide Q_bd were compared at different nitrogen dose levels. A nitrogen dose of 5×10¹⁵ cm^-2 is the optimum choice at an implant energy of 40 KeV in terms of the overall performance of both p- and n-MOSFETs and the oxide Q_bd. The suppression of boron penetration is confirmed by the SIMS profiles to be attributed to the retardation effect in bulk polysilicon with the presence of nitrogen. High nitrogen dose (1×10¹⁶ cm^-2) results in poly depletion and increase of sheet resistance in both unsilicided and silicided p⁺ poly, degrading the transistor performance. Under optimum design, nitrogen implantation into poly-Si gate is effective in suppressing boron penetration without degrading performance of either p- or n-channel transistors     

NaCl(OH-):(F2+)H色心激光的研究

文中报道了低温红外连续NaCl(OH-):(F2+)H色心激光的研究结果。当泵浦功率为4.5W,辅助光功率为34.5mW时,输出功率大于250mW,峰值波长为1.57μm。为保证色心激光稳定运转,必须要有辅助光。     

Effect of electron cyclotron resonance H+,Ne+, Ar+, and Xe+ plasma precleaning ontitanium silicide formation

A vacuum integrated cluster tool process incorporating electron cyclotron resonance plasma cleaning, Ti sputter deposition, and rapid thermal annealing in N₂ is used to form a TiN_x<1/TiSi_y bilayer on (100) Si where the film composition is controlled by the preclean chemistry. Chemical cleaning with nominal 10 eV H⁺ completely removes native Si oxide resulting in a hydrogen terminated surface that promotes silicidation compared to one cleaned with buffered-oxide-etching (BOE). If the native oxide is only partially reduced, viz., SiO_x<2 surface, for example by shortening the H⁺ exposure time, then silicidation is largely inhibited and a thicker nitride layer is formed. Sputter cleaning with 50 to 250 eV Ar⁺ results in a bilayer that is roughly equivalent to that formed with BOE, whereas 50 to 150 eV Xe⁺ bombardment favors nitridation. Precleaning with >150 eV Ne⁺ promotes silicidation, thereby minimizing nitride thickness. The effects of precleaning are significant as the activation energy for TiSi_y formation is reduced from 1.8 eV characteristic of a BOE cleaned surface to 1.2 eV on Si etched with 250 eV Ne⁺. Mechanistically, the silicide kinetics are shown to be inhibited by the presence of a thin amorphous layer that is formed only when cleaning Si with Ar⁺ and Xe⁺ with the effect that both knock-on oxygen atoms and implanted noble gas atoms trapped within the amorphous layer retard the requisite solid-phase epitaxial regrowth kinetics. Recrystallizing the amorphous Si surface prior to metallization appears to restore the near-normal silicide kinetics that is characteristic of Ne⁺ cleaning     

The reverse anneal of junction characteristics in forming shallow p+-n junction by BF2+ implantation intothin Co films on Si substrate

Silicided shallow p⁺-n junctions, formed by BF₂ ⁺ implantation into thin Co films on Si substrates and subsequently annealed, showed a reverse anneal of junction characteristics in the temperature range between 550 and 600°C. The reverse anneal means behavior showing degradation of the considered parameters with increasing annealing temperature. A higher implant dosage caused a more distinct reverse anneal. The reverse anneal of electrical characteristics was associated with the reverse anneal of substitutional boron. A shallow p⁺-n junction with a leakage current density lower than 3 nA/cm₂, a forward ideality factor of better than 1.01, and a junction depth of about 0.1 μm was achieved by just a 550°C anneal     

Rapid thermal annealing effects on Si p+-n junctionsfabricated by low-energy FIB Ga+ implantation

Effects of rapid thermal annealing (RTA) on sub-100 nm p⁺ -n Si junctions fabricated using 10 kV FIB Ga⁺ implantation at doses ranging from 10¹³ to 10¹⁵ cm ^-2 are reported. Annealing temperature and time were varied from 550 to 700°C and 30 to 120 s. It was observed that a maximum in the active carrier concentration is achieved at the critical annealing temperature of 600°C. Temperatures above and below the critical temperature were followed by a decrease in the active concentration, leading to a `reverse' annealing effect     

红外激光与远紫外激光场驱动H2+辐射谐波

为了了解H₂+谐波辐射的过程,采用数值求解非玻恩-奥本海默近似薛定谔方程的方法,理论研究了H₂+在10fs/800nm红外激光与6fs/30nm远紫外激光驱动下谐波辐射的特点。结果表明,谐波辐射的贡献主要来源于拉比振荡、多光子共振电离、电荷共振增强电离以及离解态电离;随着远紫外光的加入,谐波光谱呈现能量间隔为远紫外光子能量的多重谐波截止结构;当远紫外光与红外激光的延迟时间大于零或小于零时,谐波光谱呈现红移和蓝移的现象。该研究对理解分子谐波辐射过程是有帮助的。     

Device simulation of submicrometer gate p+-i-p+ diamond transistors

Two-dimensional device simulation of submicrometer gate diamond p ⁺-i-p⁺ transistors with a SiO₂ gate insulator was investigated using the MEDICI device simulation program. A large modulation of the source-to-drain current was obtained in the accumulation mode. The computed diamond device characteristics were equivalent or better than the simulation results of 6H-SiC MESFET's. It was concluded that the problems in diamond MESFET associated with the deep acceptor levels due to boron doping can be overcome in the p⁺ -i-p⁺ diamond FET's because of the hole injection and the space charge limited current     

Improvement of low-temperature gate dielectric formed in N2O plasma by an additional CF4 pretreatment process

This study describes a novel technique to form low temperature oxide (<350°C). Low-temperature oxides were formed by N₂ O plasma in the plasma-enhanced chemical vapor deposition (PECVD) system with a CF₄ pretreatment. These oxides demonstrate excellent current-voltage (I-V) characteristics comparable to thermally grown oxides. Experimental results indicate that CF₄ plasma treatment can significantly improve the reliability of low-temperature oxides. With excellent electrical properties, the technique is highly promising for low-temperature processes     

Impact of Ge implantation on the electrical characteristics of TiSi2 p+/n shallow junctions with an a-Si (or apoly-Si) buffer layer

A new technology for forming a titanium-silicide shallow junction by combining germanium implantation with an amorphous-silicon (or a poly-silicon) buffer layer has been proposed for MOSFETs. The use of a buffer layer between Ti and Si can avoid the consumption of bulk-silicon and the recession of TiSi₂ film into the source/drain junctions during the silicidation process. In this study, the important role of germanium-implantation on the formation of TiSi₂ contacted p⁺/n junctions was examined. After subsequent implantation of Ge⁺ and B⁺ into the TiSi₂ film, samples were annealed at different temperatures to form p ⁺/n junctions and C54-TiSi₂. Since the penetration of titanium atoms was suppressed due to the germanium-implantation, the periphery leakage and the generation leakage were improved and TiSi₂/Si interfaces were even smooth. Therefore, p⁺/n junctions with a very low leakage current (0.192 nA/cm ² at -5 V) and an excellent forward ideality factor (n≈1.002) can be obtained. From the secondary ion mass spectrometry (SIMS) analysis, the junction depth is 400     

Ultrashallow junctions for ULSI using As2+implantation and rapid thermal anneal

Using As₂⁺ ion implantation and rapid thermal anneal, 40-nm n⁺-p junctions are realized. The junction formed with p^- substrate shows very low leakage current (<0.5 nA/cm²) up to 2-V reverse bias. The introduction of a heavily doped (10¹⁸ cm^-3 level) p region generates a significantly higher leakage current due to the onset of band-to-band tunneling. Using varied geometry devices with a given area, the major tunneling current is shown to be confined in the perimeter of the device, and a method to suppress this leakage is suggested     

偏振光谱法观察Na_2A~1∑_u~+～b~3Ⅱ_u微扰能级的超精细结构

在分子光谱和量子化学领域中，Na_2分子的结构和光谱的重要性是众所周知的。对于Na_2单重态的激光光谱研究已经得到了大量的结果。相比之下，Na_2三重态的研究则困难得多，因为从其基态（？）到三重态的跃迁是偶极禁戒的。尽管如此，人们还是找到了直接研究三重态的途径，这就是通过（？）微扰能级观察三重态。     

Electrical properties of MOSFET's with N2O-nitridedLPCVD SiO2 gate dielectrics

Electrical properties of MOSFETs with gate dielectrics of low-pressure chemical-vapor-deposited (LPCVD) SiO₂ nitrided in N₂O ambient are compared to those with control thermal gate oxide. N₂O nitridation of CVD oxide, combines the advantages of interfacial oxynitride growth and the defectless nature of CVD oxide. As a result, devices with N₂O-nitrided CVD oxide show considerably enhanced performance (higher effective electron mobility), improved reliability (reduced charge trapping, interface state generation, and transconductance degradation), and better time-dependent dielectric breakdown (TDDB) properties (t_BD ) compared to devices with control thermal oxide     

氟化锂晶体F2心光致电离及F2和F2+心激光特性研究

室温下利用337nm脉冲激光照射着色LiF晶体,有效地将F2心转变成F2+心,其浓度高于1016cm-3。利用消象散三镜折叠腔,研究了LiF晶体F2和F2+心激光特性。实际工作表明,利用氮分子激光作为处理光束,可获得较长时间稳定的F2+心激光输出。     

A novel self-aligned TiN formation by N2+implantation during two-step annealing Ti-salicidation for submicrometerCMOS technology application

A new technology of self-aligned TiN/TiSi₂ formation using N₂⁺ implantation during two-step annealing Ti-salicidation process has been developed. The formation of TiN was confirmed by RBS analysis. The leakage currents of n⁺/p junction diodes fabricated using this technology were measured to investigate the phenomena of Al spiking into Si-substrate. The measured reverse-bias leakage current of diode per unit junction area with Al/TiN/TiSi₂ contact is 1.2 nA/cm² at -5 V, which is less than all of reported data. Also it can sustain the annealing process for 30 min at 500°C. Thus, TiN formed with this technology process is suggested as a very effective barrier layer between TiSi₂ and Al for submicron CMOS technology applications     

Double-drift-region (p+pnn+) avalanche diode oscillators

The advantages of a double-drift-region avalanche diode oscillator are discussed. Conventional structures (p⁺nn⁺or n⁺pp⁺) are essentially single-drift-region devices in that transit-time delay (for IMPATT mode) and zone transit (for TRAPATT mode) occur in a single region of one impurity type. The proposed structure (p⁺pnn⁺) has two drift regions and is essentially two complementary avalanche diode oscillators in series.     

The effect of Co incorporation on electrical characteristics of n+/p shallow junction formed by dopant implantation into CoSi2 and anneal

The impact of Co incorporation on the electrical characteristics has been investigated in n⁺/p junction formed by dopant implantation into CoSi₂ and drive-in anneal. The junctions were formed by As⁺ (30 or 40 keV, 1×10¹⁶ cm ^-2) implantation into 35 nm-thick CoSi₂ followed by drive-in annealing at 900°C for 30 s in an N₂ ambient. Deeper junction implanted by As⁺ at 40 keV was not influenced by the Co incorporation. However, for shallower junction implanted by As ⁺ at 30 keV, incorporation of Co atoms increased its leakage current, which were supposed to be dissociated from the CoSi₂ layer by silicide agglomeration during annealing. The mechanism of such a high leakage current was found to be Poole-Frenkel barrier lowering induced by high density of Co traps