SiO2和Si3N4/SiO2薄膜表面驻极态的改善

描述了为改善其表面驻极态的抗湿能力，对Si基Si3N4和Si3N4/SiO2薄膜驻极体所进行的化学表面修正的基本原理。以六甲基二硅胺（HMDS）和二氯二甲基硅烷（DCDMS）两种化学修正试剂对这类薄膜驻极体的改性效果进行了对比性的研究。结果指出：从抗湿能力考虑，经DCDMS修正的氮、氧化硅驻极体的电荷稳定性优于HMDS处理的样品，是由于这类修正形成了更完善的表面单分子疏水层；但如果从驻极体的储电热稳定性方面考虑，以HMDS处理的样品优于DCDMS样品，是由于被HMDS修正的表面层内形成了较高浓度的深能级陷阱。     

Numerical simulation of intrinsic defects in SiO2 and Si3N4

The electronic structure of major intrinsic defects in SiO₂ and Si₃N₄ was calculated by the MINDO/3 and the density-functional methods. The defects that are of interest from the standpoint of their ability to capture electrons or holes were considered; these centers include the three-and two-coordinated silicon atoms, the one-coordinated oxygen atom, and the two-coordinated nitrogen atom. The gain in energy as a result of capturing an electron or a hole with allowance made for electronic and atomic relaxation was determined for these defects. The experimental X-ray spectra for both materials are compared with calculated spectra.     

碳氟等离子体中CF2对SiO2，Si3N4和Si刻蚀的作用

The CF2 density and etch rate of SiO2, Si3N4 and Si are investigated as a function of gas pressure and O2 flow rate in fluorocarbon plasma. As the pressure increases, the self-bias voltage decreases whereas the SiO2 etch rate increases. Previous study has shown that SiO2 etch rate is proportional to the self-bias voltage. This result indicates that other etching parameters contribute to the SiO2 etching. Generally, the CF2 radical is considered as a precursor for fluorocarbon layer formation. At a given power, defluorination of fluorocarbon under high-energy ion bombardment is a main source of fluorine for SiO2 etching. When more CF2 radical in plasma, SiO2 etch rate is increased because more fluorine can be provided. In this case, CF2 is considered as a reactant for SiO2 etching. The etch rate of Si3N4 and Si is mainly determined by the polymer thickness formed on its surface which is dominated by the CF2 density in plasma. Etching results obtained by varying O2 flow rate also support the proposition.     

Role of CF2 in the etching of SiO2, Si3N4 and Si in fluorocarbon plasma

The CF2 density and etch rate of SiO2, Si3N4 and Si are investigated as a function of gas pressure and 02 flow rate in fluorocarbon plasma. As the pressure increases, the self-bias voltage decreases whereas the SiO2 etch rate increases. Previous study has shown that SiO2 etch rate is proportional to the self-bias voltage. This result indicates that other etching parameters contribute to the SiO2 etching. Generally, the CF2 radical is considered as a precursor for fluorocarbon layer formation. At a given power, defluorination of fluorocarbon under high-energy ion bombardment is a main source of fluorine for SiO2 etching. When more CF2 radical in plasma, SiO2 etch rate is increased because more fluorine can be provided. In this case, CF2 is considered as a reactant for SiO2 etching. The etch rate of Si3N4 and Si is mainly determined by the polymer thickness formed on its surface which is dominated by the CF2 density in plasma. Etching results obtained by varying O2 flow rate also support the proposition.     

晶态Si3N4／非晶SiO2同轴纳米线的电子显微学研究

Si3N4是一种用途广泛的功能材料，Si3N4纳米线有望在电子、光学和机械领域展现其特殊性能：在没有催化剂情况下，我们在硅衬底上直接合成了Si3N4／SiO2同轴纳米线。生长条件：氮气氛．生长温度1250℃．1.5h，自然冷却。利用电子衍射、高分辨像和电子X射线能谱技术，我们用Tacnai F30场发射电子显微镜研究了Si3N4／SiO2同轴纳米线的微观组织结构，探讨了这种纳米线的生长机制。     

Fabrication of low defect density 3C-SiC on SiO2 structures using wafer bonding techniques

This paper reports on a process to fabricate single-crystal 3C-SiC on SiO₂ structures using a wafer bonding technique. The process uses the bonding of two polished polysilicon surfaces as a means to transfer a heteroepitaxial 3C-SiC film grown on a Si wafer to a thermally oxidized Si wafer. Transfer yields of up to 80% for 4 inch diameter 3C-SiC films have been achieved. Homoepitaxial 3C-SiC films grown on the 3C-SiC on SiO₂ structures have a much lower defect density than conventional 3C-SiC on Si films.     

电离辐射对Si_3N_4/SiO_2/Si双界面系统的作用

采用氩离子刻蚀XPS(X光激发电子能谱)分析对S i3N4/S iO2/S i双界面系统进行了电离辐照剖面分析。实验结果表明:电离辐照能将S iO2和S i构成的界面区中心向S i3N4/S iO2界面方向推移,同时S iO2/S i界面区亦被电离辐照展宽。在同样偏置电场中辐照,随着辐照剂量的增加电离辐照相当程度地减少位于S iO2/S i界面区S i3N4态(结合能B.E.101.8 eV)S i的浓度。同时辐照中所施偏置电场对S iO2/S i界面区S i3N4态键断开有显著作用。文中就实验现象的机制进行了初步探讨。     

超薄Si3N4/SiO2(N/O) stack栅介质及器件

成功制备了EOT(equivalent oxide thickness)为2.1nm的Si3N4/SiO2(N/O) stack栅介质,并对其性质进行了研究.结果表明,同样EOT的Si3N4/SiO2 stack栅介质和纯SiO2栅介质比较,前者在栅隧穿漏电流、抗SILC性能、栅介质寿命等方面都远优于后者.在此基础上,采用Si3N4/SiO2 stack栅介质制备出性能优良的栅长为0.12μm的CMOS器件,器件很好地抑制了短沟道效应.在Vds=Vgs=±1.5V下,nMOSFET和pMOSFET对应的饱和电流Ion分别为584.3μA/μm和-281.3μA/μm,对应Ioff分别是8.3nA/μm和-1.3nA/μm.     

超薄Si3N4/SiO2（N/O）stack栅介质及器件

成功制备了EOT(equivalent oxide thickness)为2.1nm的Si3N4/SiO2(N/O) stack栅介质,并对其性质进行了研究．结果表明，同样EOT的Si3N4/SiO2 stack栅介质和纯SiO2栅介质比较，前者在栅隧穿漏电流、抗SILC性能、栅介质寿命等方面都远优于后者．在此基础上,采用Si3N4/SiO2 stack栅介质制备出性能优良的栅长为0.12μｍ的CMOS器件，器件很好地抑制了短沟道效应．在Vds=Vgs=±1.5V下，nMOSFET和pMOSFET对应的饱和电流Ion分别为584.3μA/μｍ和－281.3μA/μｍ，对应Ioff分别是8.3nA/μｍ和－1.3nA/μｍ．     

LiNbO3/SiO2/Si薄膜的蓝光发射

采用射频磁控溅射方法制备了LiNbO3/SiO2/Si薄膜.通过X射线衍射(XRD)、电感耦合等离子体质谱(ICP-MS)和傅立叶变换红外吸收光谱(FT-IR)对薄膜的物相、晶体取向和成分进行了表征.采用荧光分光光度计研究了LiNbO3/SiO2/Si薄膜的光致发光.研究结果表明:在280 nm激发光的激发下,LiNbO3/SiO2/Si薄膜在室温下发射470 nm的蓝光,来源于LiNbO3薄膜与SiO2层界面处自捕获激子的辐射复合,发现在SiO2/Si薄膜上生长LiNbO3薄膜调制SiO2/Si薄膜的发光机制.     

Si3N4栅MOS器件的隧穿电流模拟

随着MOS器件尺寸按比例缩小到亚100 nm时代,栅绝缘层直接隧穿(Direct Tunnel-ing,DT)电流逐渐增大.使用Si3N4材料作为栅介质,利用其介电常数高于SiO2的特性,可以在一定时期内有效地解决隧穿电流的问题.文章在二维器件模拟软件PISCES-II中首次添加了模拟高k材料MOS晶体管的器件模型,并对SiO2和Si3N4栅MOS晶体管的器件特性进行了模拟比较.     

超薄Si3N4/SiO2叠层栅介质可靠性研究

实验成功地制备出等效氧化层厚度为亚2nm的Nitride/Oxynitride(N/O)叠层栅介质难熔金属栅电极PMOS电容并对其进行了可靠性研究.实验结果表明相对于纯氧栅介质而言,N/O叠层栅介质具有更好的抗击穿特性,应力诱生漏电特性以及TDDB特性.进一步研究发现具有更薄EOT的难熔金属栅电极PMOS电容在TDDB特性以及寿命等方面均优于多晶硅栅电极的相应结构.     

Silicon nanocrystal formation upon annealing of SiO2 layers implanted with Si ions

The formation of silicon nanocrystals in SiO₂ layers implanted with Si ions was investigated by Raman scattering, X-ray photoelectron spectroscopy, and photoluminescence. The excess Si concentration was varied between 3 and 14 at. %. It was found that Si clusters are formed immediately after implantation. As the temperature of the subsequent annealing was raised, the segregation of Si accompanied by the formation of Si-Si₄ bonds was enhanced but the scattering by clusters was reduced. This effect is attributed to the transformation of loosely packed clusters into compact, separate-phase nanoscale Si precipitates, with the Raman peak observed at 490 cm^?1 being related to surface scattering. The process of Si segregation was completed at 1000°C. Nevertheless, characteristic nanocrystal photoluminescence was observed only after annealing at 1100°C. Simultaneously, scattering in the range 495–520 cm^?1, typical of nanocrystals, appeared; however, the “surface-related” peak at 490 cm^?1 persisted. It is argued that nanocrystals are composed of an inside region and a surface layer, which is responsible for their increased formation temperature.     

Effect of fast annealing on the electrical properties of SiO2/Si structures with thin layers of anodic silicon oxide

Effects of fast annealing on the properties of SiO₂/Si structures with thin, ～10 nm, layers of anodic silicon oxide formed on single-crystal Si substrates are studied in relation to the semiconducting properties of the silicon support and to the duration, temperature, and environment of thermal treatment. The optimal duration of high-temperature annealing of structures in an inert atmosphere for their application in the technology of nanosize MOS integrated circuits is determined.     

Photoluminescence of Si3N4 films implanted with Ge+ and Ar+ ions

The room-temperature photoluminescence emission and excitation spectra of Si₃N₄ films implanted with Ge⁺ and Ar⁺ ions were investigated as a function of the ion dose and temperature of subsequent annealing. It was established that the implantation of bond-forming Ge atoms during annealing right up to temperature T _a=1000 °C stimulates the formation of centers emitting in the green and violet regions of the spectrum. Implantation of inert Ar⁺ ions introduces predominantly nonradiative defect centers. Comparative analysis of the photoluminescence spectra, Rutherford backscattering data, and Raman scattering spectra shows that the radiative recombination is due not to quantum-well effects in Ge nanocrystals but rather recombination at the defects ≡Si-Si≡, ≡Si-Ge≡, and ≡Ge-Ge≡. Fiz. Tekh. Poluprovodn. 33, 559–566 (May 1999)     

Surface-related phenomena in the direct bonding of silicon and fused-silica wafer pairs

Direct bonding is the result of a complex interaction between chemical, physical and mechanical properties of the surfaces to be bonded and is therefore strongly correlated with the surface state of the materials. Phenomena characteristic of the actual bonding process are (a) the formation of an initial bond area, (b) bond energy, and (c) bond-front velocity. The effects of variations in surface state on these process characteristics have been investigated for silicon, oxidized silicon and fused-silica wafer pairs. The surface bond energy of hydrophilic wafers is in the range of 0.05–0.2 J/m² and is largely determined by the hydrogen bonds formed. The bond energy of hydrophobic wafers is a factor of 10 smaller and is determined by Van der Waals attractive forces. The bond-front velocity is determined by the surface state and the stiffness of the wafer. Both bond energy and bond-front velocity show ageing effects.     

Construction of Membrane Sieves Using Stoichiometric and Stress‐Reduced Si3N4/SiO2/Si3N4 Multilayer Films and Their Applications in Blood Plasma Separation

The novelty of this study resides in the fabrication of stoichiometric and stress‐reduced Si₃N₄/SiO₂/Si₃N₄ triple‐layer membrane sieves. The membrane sieves were designed to be very flat and thin, mechanically stress‐reduced, and stable in their electrical and chemical properties. All insulating materials are deposited stoichiometrically by a low‐pressure chemical vapor deposition system. The membranes with a thickness of 0.4 µm have pores with a diameter of about 1 µm. The device is fabricated on a 6” silicon wafer with the semiconductor processes. We utilized the membrane sieves for plasma separations from human whole blood. To enhance the separation ability of blood plasma, an agarose gel matrix was attached to the membrane sieves. We could separate about 1 µL of blood plasma from 5 µL of human whole blood. Our device can be used in the cell‐based biosensors or analysis systems in analytical chemistry.     

Use of incoherent light for annealing implanted Si wafers and growing single-crystal Si on SiO2

By using halogen lamps, we have annealed implanted Si wafers and recrystallised deposited poly-Si. A transient anneal was accomplished with a good uniformity on 4 in Si wafers with no redistribution of the dopant profile. By using a shaped spot, we obtained ?100? single-crystal Si, over an area 2 mm by several centimetres, on a SiO2 layer grown on a Si substrate, without seeding.     

Direct wafer bonding of III-V compound semiconductors forfree-material and free-orientation integration

This paper describes the use of direct wafer bonding technique to implement the novel concept of “free-material and free-orientation integration” which we propose. The technique is applied for various wafer combinations of an InGaAsP material system, and the properties of the bonded structures are studied in terms of the crystalline and electrical characterization through transmission electron microscope, X-ray diffraction, and so on. This technique's advantage for use in the fabrication of lattice-mismatched structures is confirmed by the crystalline characterization, together with its second advantage of enabling bonded structures with an orientation mismatch, is investigated. The high crystalline quality of the bonded structures with both lattice and orientation mismatches is proved, and the electrical property of the bonded interface is examined for some of them. We show a practicability in a laser fabricated on a lattice- and orientation-mismatched structure by direct bonding. The results demonstrate the remarkable feasibility of using the direct wafer bonding technique to obtain integrated structures of material- and orientation-mismatched wafers with satisfactory quality     

Effect of ion dose and annealing mode on photoluminescence from SiO2 implanted with Si ions

This paper discusses the photoluminescence spectra of 500-nm-thick layers of SiO₂ implanted with Si ions at doses of 1.6×10¹⁶, 4×10¹⁶, and 1.6×10¹⁷ cm⁻² and then annealed in the steady-state region (30 min) and pulsed regime (1 s and 20 ms). Structural changes were monitored by high-resolution electron microscopy and Raman scattering. It was found that when the ion dose was decreased from 4×10¹⁶ cm⁻² to 1.6×10¹⁶ cm⁻², generation of centers that luminesce weakly in the visible ceased. Moreover, subsequent anneals no longer led to the formation of silicon nanocrystallites or centers that luminesce strongly in the infrared. Annealing after heavy ion doses affected the photoluminescence spectrum in the following ways, depending on the anneal temperature: growth (up to ∼700 °C), quenching (at 800–900 °C), and the appearance of a very intense photoluminescence band near 820 nm (at >900 °C). The last stage corresponds to the appearance of Si nanocrystallites. The dose dependence is explained by a loss of stability brought on by segregation of Si from SiO₂ and interactions between the excess Si atoms, which form percolation clusters. At low heating levels, the distinctive features of the anneals originate predominantly with the percolation Si clusters; above ∼700 °C these clusters are converted into amorphous Si-phase nanoprecipitates, which emit no photoluminescence. At temperatures above 900 °C the Si nanocrystallites that form emit in a strong luminescence band because of the quantum-well effect. The difference between the rates of percolation and conversion of the clusters into nanoprecipitates allows the precipitation of Si to be controlled by combinations of these annealings. Fiz. Tekh. Poluprovodn. 32, 1371–1377 (November 1998)