Si1-xGex/Si多层异质外延结构的研究

对制作的Ｓｉ１－ｘＧｅｘ／Ｓｉ多层异质外延结构进行了研究。并对其做了反射高能电子衍射（ＲＨＥＥＤ）、Ｘ射线衍射（ＸＲＤ）和扩展电阻（ＳＲ）等测量，给出了利用这种结构研制出的异质结双极晶体管（ＨＢＴ）的输出特性曲线。     

Si／Si1—xGex异质结器件

本文综述了国外Si/Si_(1-x)Ge_xHBT的发展状况,把出Si_(1-x)Ge_xHBT的特点和优越性,分析了Si_(1-x)Ge_xHBT的制造技术和设备要求,指出了Si/Si_(1-x)Gex器件的应用前景。     

Si_(1-x-y)Ge_xC_y合金半导体技术及其应用

随着半导体材料及工艺水平的迅速发展,Si1-x-yGexCy合金材料在近年内受到了广泛重视。C组分的引入所带来的应变补偿作用,很好地解决了Si1-xGex合金中的晶格失配问题,使Si衬底上生长的外延层质量和厚度都得到相应提高,并且由于C组分所带来的能带补偿作用,使材料的光电特性也得到改进。文章综述了Si1-x-yGexCy合金的研究进展及其物理特性,并对其在FET、HBT、光电子器件等方面的应用进行了详细的阐述。     

SiGeC薄膜表征对于光刻对准性能的影响研究

Si1-x-yGexCy是继Si和GaAs之后又一重要的半导体材料。由于Si1-x-yGexCy具有优于纯Si材料的良好特性,器件和制程又可与Si工艺兼容,采用Si1-x-yGexC及其Si1-x-yGexCy/Si异质结所制作出来的器件如异质结双极晶体管(Heterojunction Bipolar Transistor,HBT),其电性能几乎可达到GaAs等化合物半导体制作的同类器件的水平,而且在成本上低于GaAs HBT。因此Si1-x-yGexCy可能是未来微电子发展进程中必不可少、并起着关键作用的一种材料。文章对Si1-x-yGexCy薄膜的表征进行了探索,在总结大量数据的基础上,验证了利用Si1-x-yGexCy薄膜的反射率进行光学表征的方法的可行性。同时,文章系统研究了Si1-x-yGexCy薄膜的工艺条件、薄膜成份、薄膜厚度等参数对光刻对准性能的影响。     

Si_(1-x)Ge_x/Si多层异质外延结构的研究

对制作的 Ｓｉ１－ｘＧｅｘ／Ｓｉ多层异质外延结构进行了研究。并对其做了反射高能电子衍射（ＲＨＥＥＤ）、Ｘ射线衍射（ＸＲＤ）和扩展电阻（ＳＲ）等测量,给出了利用这种结构研制出的异质结双极晶体管（ＨＢＴ）的输出特性曲线。     

Si／Si1—xGex应变层异质结双极晶体管（HBT）交直流特性的仿真研究

本报道了Ｓｉ／Ｓｉ１－ｘＧｅｘ应变异质结双极晶体管（ＨＢＴ）交直流特性的仿真结果，通过用叠代法求解漂移－扩散方程的数值解，确定器件的直流特性，再利用瞬态激励法，求解器件的交流特性参数，将基区Ｇｅ摩尔含量ｘ为０．２，０．３１的ＨＢＴ的模拟结果分别与有关献报道的实验结果进行了比较，两的结果符合良好。     

Si/SiGe/Si双异质结晶体管(HBT)的负阻特性

同质结硅双极晶体管在共射极状态下工作中,在高集电极--发射极电压、大电流下,由于热电正反馈,容易发生热击穿,这限制了晶体管的安全工作区域.本文报道了在大电流下,由于热电负反馈,重掺杂基区Si/SiGe/HBT出现了负阻特性,并对这一现象进行了新的解释,认为这是由于大电流下耗散功率增加,基区俄歇复合导致电流增益随温度增加而减小的结果.这一现象有利于改善大电流下双极晶体管的抗烧毁能力,证明Si/SiGe/HBT适于大功率应用.     

Si_(1-x-y)Ge_xC_y三元系材料的应变补偿特性

研究了 Si1 - x- y Gex Cy 三元系材料的应变补偿特性 ,分析了固相外延方法制备的样品中注入离子的分布对应变补偿效果的影响 ,指出由于 Ge和 C的投影射程及标准偏差不同 ,二者在各处的组分比并不恒定 ,存在着纵向分布 ,因此各处的应变补偿情况也不尽相同 .利用高斯公式对不同位置的应变补偿效果进行了分析 ,得出了外延层中存在应变完全补偿区域时 Ge、C的峰值浓度比 NGe/ NC应满足一定的取值范围 .通过制备不同 C组分的样品对上述结论进行了验证 ,得出的结果与理论预言基本相符     

Si/Si1-x-yGexCy/Si heterojunctionbipolar transistors

We report the first Si/Si_1-x-yGe_xC_y /Si n-p-n heterojunction bipolar transistors and the first electrical bandgap measurements of strained Si_1-x-yGe_x C_y on Si (100) substrates. The carbon compositions were measured by the shift between the Si_1-x-yGe_xC_y and Si_1-xGe_x X-ray diffraction peaks. The temperature dependence of the HBT collector current demonstrates that carbon causes a shift in bandgap of +26 meV/%C for germanium fractions of x=0.2 and x=0.25. These results show that carbon reduces the strain in Si_1-x Ge_x at a faster rate than it increases the bandgap (compared to reducing x in Si_1-xGe_x), so that a Si _1-x-yGe_xC_y film will have less strain than a Si_1-xGe_x film with the same bandgap     

Si1-x-yGexCy-channel p-MOSFET'swith improved thermal stability

We report the fabrication of heterostructure Si_1-x-yGe _xC_y channel p-MOSFETs with low-carbon Si_1-x-y Ge_xC_y channels. The use of low carbon mole fraction (y=0.002) has only a small effect (≪kT) on the valence band offset. A carbon mole fraction of this value improves the thermal stability of the channel region and makes it possible to use conventional thermal oxidation and ion implant annealing without causing layer relaxation. A peak room-temperature hole mobility of 200 cm² /Vs was measured in a device with a 30-nm channel and a germanium mole fraction ramped from 10% to 40%     

Suppression of boron penetration in p-channel MOSFETs usingpolycrystalline Si1-x-yGexCy gatelayers

Boron penetration through thin gate oxides in p-channel MOSFETs with heavily boron-doped gates causes undesirable positive threshold voltage shifts. P-channel MOSFETs with polycrystalline Si_1-x-yGe_xC_y gate layers at the gate-oxide interface show substantially reduced boron penetration and increased threshold voltage stability compared to devices with all poly Si gates or with poly Si_1-xGe gate layers. Boron accumulates in the poly Si_1-x-yGe_xC_y layers in the gate, with less boron entering the gate oxide and substrate. The boron in the poly Si_1-x-yGe_xC_y appears to be electrically active, providing similar device performance compared to the poly Si or poly Si_1-xGe_x gated devices     

Nickel silicidation techniques for strained Si1?xGex, Si1?x?yGexCy, and Si1?yCy alloys material-device applications

A nickel silicide process for Si_1-xGe_x, Si_1-x-yGe_xC_y, and Si_1-yC_y alloy materials compatible with Si technology has been developed. Low-resistivity-phase (12–20 μΘ cm) nickel silicides have been obtained for these alloys with different low sheet-resistance temperature windows. The study shows that thin (15–18 nm) silicide layers with high crystalline quality, smooth silicide surface, and smooth interface between silicide and the underlying material are achievable. The technique could be used to combine the benefits of Ni silicide and Si_1-xGe_x, Si_1-x-yGe_xC_y, and Si_1-yC_y alloys. The technique is promising for Si or Si_1-xGe_x, Si_1-x-yGe_xC_y, and Si_1-yC_y alloy-based metal-oxide semiconductor, field-effect transistors (MOSFETs) or other device applications.     

Silicide/strained Si1-xGex Schottky-barrierinfrared detectors

By employing a thin silicon sacrificial cap layer for silicide formation, the authors successfully demonstrated Pd₂Si/strained Si_1-xGe_x Schottky-barrier infrared detectors with extended cutoff wavelengths. The sacrificial silicon eliminates the segregation effects and Fermi level pinning which occur if the metal reacts directly with Si_1-x Ge_x alloy. The Schottky barrier height of the silicide/strained Si_1-xGe_x detector decreases with increasing Ge fraction, allowing for tuning of the detector's cutoff wavelength. The cutoff wavelength was extended beyond 8 μm in PtSi/Si _0.85Ge_0.15 detectors. It is shown that high quantum efficiency and near-ideal dark current can be obtained from these detectors     

Low-resistance bandgap-engineeredW/Si1-xGex/Si contacts

Bandgap-engineered W/Si_1-xGe_x/Si junctions (p⁺ and n⁺) with ultra-low contact resistivity and low leakage have been fabricated and characterized. The junctions are formed via outdiffusion from a selectively deposited Si_0.7Ge _0.3 layer which is implanted and annealed using RTA. The Si _1-xGe_x layer can then be selectively thinned using NH₄OH/H₂O₂/H₂O at 75°C with little change in characteristics or left as-deposited. Leakage currents were better than 1.6×10^-9 A/cm² (areal), 7.45×10^-12 A/cm (peripheral) for p⁺/n and 3.5×10^-10 A/cm² (peripheral) for n⁺/p. W contacts were formed using selective LPCVD on Si_1-xGe_x. A specific contact resistivity of better than 3.2×10^-8 Ω cm² for p ⁺/n and 2.2×10^-8 Ω cm² for n⁺/p is demonstrated-an order of magnitude n⁺ better than current TiSi₂ technology. W/Si_1-xGe _x/Si junctions show great potential for ULSI applications     

Enhanced mobility PMOSFETs using tensile-strained Si1-yCy layers

We demonstrate for the first time that carbon incorporation in Si epitaxial layers may be an alternative method to deposit enhanced mobility tensile-strained Si MOSFET channel layers directly on a silicon substrate, thereby eliminating the need to deposit a thick relaxed SiGe buffer layer, from which dislocations and other defects can propagate to the channel region. The fabrication and electrical properties of PMOSFETs with Si_1-yC_y alloy channel layers are reported in this paper for the first time. It is found that small amounts of C in Si films can produce high quality epitaxial material. PMOSFETs fabricated on these layers demonstrate enhanced hole mobility over that of control Si     

High performance Si/Si1-xGex resonanttunneling diodes

Resonant tunneling diodes (RTDs) with strained i-Si_0.4Ge_0.6 potential barriers and a strained i-Si quantum well, all on a relaxed Si_0.8Ge_0.2 virtual substrate were successfully grown by ultra high vacuum compatible chemical vapor deposition and fabricated using standard Si processing methods. A large peak to valley current ratio of 2.9 and a peak current density of 4.3 kA/cm² at room temperature were recorded from pulsed and continuous dc current-voltage measurements, the highest reported values to date for Si/Si_1-xGe_x RTDs. These dc figures of merit and material system render such structures suitable and highly compatible with present high speed and low power Si/Si_1-xGe_x heterojunction field effect transistor based integrated circuits     

Model Predictive Control of Si1−xGex Thin Film Chemical–Vapor Deposition

This paper integrates in situ robust and efficient fundamental models and noninvasive optical sensors with state-of-the-art estimation and model predictive control techniques in order to grow unusual and aggressive Si_1-xGe_x alloy films. A model predictive controller is presented that utilizes a dynamic process model and feedback from a spectral ellipsometer to reconstruct the current state of a Si_1-xGe_x growing film in real time. Si _1-xGe_x films grown utilizing feedback from a spectral ellipsometer are compared to films grown using open-loop recipes, which is the current industrial practice. These films are compared quantitatively utilizing the offline characterization techniques, auger spectrometry, and secondary-ion-mass-spectrometry analysis. The model predictive controller presented in this paper detects and rejects unmeasured disturbances allowing for precise control over film qualities. In this paper, films grown utilizing feedback from an optical sensor are shown to be up to 51% truer to desired profiles, when compared with similar films grown using open-loop recipes. The experimental results presented in this paper provide the first demonstration of feedback control using online optical film measurements to grow aggressive alloy composition profiles in which flow rates of several component gases and reactor temperatures must be varied simultaneously in order to achieve the profile of interest