基于MBE的fmax为157GHz的SiGeHBT器件

在模拟集成电路的应用中,不仅注重器件fT,而且注重晶体管最高振荡频率(fmax).文中以MBE生长的SiGe材料为基础,进行了提高SiGe HBT器件fmax的研究,研制出了fmax＝157GHz的SiGe HBT器件.     

射频Si/SiGe/Si HBT的研究

在Si／SiGe／SiHBT与Si工艺兼容的研究基础上，对射频Si／SiGe／SiHBT的射频特性和制备工艺进行了研究，分析了与器件结构有关的关键参数寄生电容和寄生电阻与Si／SiGe/Si HBT的特征频率fT和最高振荡频率fmax的关系，成功地制备了fT为2．5CHz、fmax为2．3GHz的射频Si／SiGe／SiHBT，为具有更好的射频性能的Si／SiGe／Si HBT的研究建立了基础。     

基于干/湿法腐蚀的自对准SiGe HBT器件

采用干/湿法腐蚀相结合技术，利用氢氧化钾（KOH）溶液和六氟化硫(SF6)对Si及SiGe材料进行腐蚀，研究自对准Si/SiGe HBT台面器件，获得了fT＝40GHz，fmax＝127.1GHz的结果．     

基于干/湿法腐蚀的自对准SiGe HBT器件

采用干/湿法腐蚀相结合技术,利用氢氧化钾(KOH)溶液和六氟化硫(SF6)对Si及SiGe材料进行腐蚀,研究自对准Si/SiGe HBT台面器件,获得了fT＝40GHz,fmax＝127.1GHz的结果.     

基于SOI结构的SiGe HBT频率特性研究

基于SOI技术原理,模拟仿真了SOI结构SiGe HBT的频率特性,并与相同条件下体SiGe HBT频率特性进行了比较分析。仿真结果显示,SOI结构中埋氧层BOX的引入,可使SOI结构SiGe HBT集电极-基极电容Ccb和衬底-基极电容Csb最大降幅分别达94.7%和94.6%,且最高振荡频率fmax增加2.7倍。研究结果表明,SOI结构大幅度改善了SiGe HBT的频率性能,适用于高速、高功率集成电路技术。     

微波功率SiGe HBT的温度特性

通过研究SiGe异质结双极型晶体管(HBT)的温度特性，发现SiGe HBT的发射结正向电压随温度的变化率小于同质结Si双极型晶体管(BJT). 在提高器件或电路热稳定性时，SiGe HBT可以使用比Si BJT更小的镇流电阻.同时SiGe HBT共发射级输出特性曲线在高电压大电流下具有负阻特性，而负阻效应的存在可以有效地抑制器件的热不稳定性效应，从而在温度特性方面证明了SiGe HBT更适合于微波功率器件.     

SiGe HBT的脉冲中子及γ辐射效应

测量了反应堆脉冲中子及γ辐照SiGe HBT典型电参数变化.在反应堆1×1013cm-2的脉冲中子注量和256.85Gy(Si)γ总剂量辐照后,SiGe HBT静态共射极直流增益减小了20%.辐照后基极电流、结漏电流增大,集电极电流、击穿电压减小.特征截止频率fT基本不变,fmax略有减小.初步分析了SiGe HBT反应堆脉冲中子及γ辐射的损伤机理.     

SiGe HBT 60Co γ辐照总剂量效应

测量了SiGe HBT直流增益在60Coγ辐照过程中随剂量及器件电流注入水平的变化。实验结果显示在累计辐照剂量超过5 000 Gy(Si)后,器件电流增益变化与辐照剂量存在线性反比关系,且增益损伤系数与器件电流注入水平有关;器件在受到总剂量为2.78×104Gy(Si)辐照后,器件静态基极电流Ib、集电极电流Ic、静态直流增益及最大振荡频率fmax出现不同程度退化;但器件其他电参数如截止频率fT、交流增益|H21|及结电容(CCBO)与辐照前相比未出现显著退化。利用MEDICI数值模拟分析了SiGe HBT参数退化机理。     

SiGe HBT的脉冲中子及γ辐射效应

测量了反应堆脉冲中子及γ辐照SiGe HBT典型电参数变化.在反应堆1×1013cm-2的脉冲中子注量和256.85Gy(Si)γ总剂量辐照后,SiGe HBT静态共射极直流增益减小了20%.辐照后基极电流、结漏电流增大,集电极电流、击穿电压减小.特征截止频率fT基本不变,fmax略有减小.初步分析了SiGe HBT反应堆脉冲中子及γ辐射的损伤机理.     

极端低温下SiGe HBT器件研究进展

系统地介绍了极端低温下SiGe HBT器件的研究进展。在器件级,分析了能带工程对SiGe HBT器件特性的影响,分析了极端低温下器件的直流、交流、噪声特性的变化,以及器件的特殊现象。在电路级,分析了基于SiGe HBT的运算放大器、低噪声放大器和电压基准源电路的低温工作特性。研究结果表明,SiGe HBT器件在低温微电子应用中具有巨大潜力。     

Si/SiGe n-MODFETs on thin SiGe virtual substrates prepared by means of He implantation

Si/SiGe n-type modulation-doped field-effect transistors grown on a very thin strain-relieved Si/sub 0.69/Ge/sub 0.31/ buffer on top of a Si(100) substrate were fabricated and characterized. This novel type of virtual substrate has been created by means of a high dose He ion implantation localized beneath a 95-nm-thick pseudomorphic SiGe layer on Si followed by a strain relaxing annealing step at 850/spl deg/C. The layers were grown by molecular beam epitaxy. Electron mobilities of 1415 cm/sup 2//Vs and 5270 cm/sup 2//Vs were measured at room temperature and 77 K, respectively, at a sheet carrier density of about 3/spl times/10/sup 12//cm/sup 2/. The fabricated transistors with Pt-Schottky gates showed good dc characteristics with a drain current of 330 mA/mm and a transconductance of 200 mS/mm. Cutoff frequencies of f/sub t/=49 GHz and f/sub max/=95 GHz at 100 nm gate length were obtained which are quite close to the figures of merit of a control sample grown on a conventional, thick Si/sub 0.7/Ge/sub 0.3/ buffer.     

Ionizing radiation tolerance and low-frequency noise degradation inUHV/CVD SiGe HBT's

The effect of ionizing radiation on both the electrical and 1/f noise characteristics of advanced UHV/CVD SiGe HBT's is reported for the first time. Only minor degradation in the current-voltage characteristics of both SiGe HBT's and Si BJT's is observed after total radiation dose exposure of 2.0 Mrad(Si) of gamma-radiation. The observed immunity to ionizing radiation exposure suggests that these SiGe HBT's are well suited for many applications requiring radiation tolerance. We have also observed the appearance of ionizing-radiation-induced generation-recombination (G/R) noise in some of these SiGe HBT's     

深亚微米应变SiGe沟PMOSFET特性模拟

为研究深亚微米尺度下应变 Si Ge沟改进 PMOSFET器件性能的有效性 ,运用二维数值模拟程序MEDICI模拟和分析了 0 .1 8μm有效沟长 Si Ge PMOS及 Si PMOS器件特性。Si Ge PMOS垂直方向采用 Si/Si Ge/Si结构 ,横向结构同常规 PMOS,N+ -poly栅结合 P型δ掺杂层获得了合理阈值电压及空穴局域化。研究表明 ,经适当设计的 Si Ge PMOS比对应 Si PMOS的 IDmax、gm、f T均提高 1 0 0 %以上 ,表明深亚微米尺度 Si Ge沟PMOSFET具有很大的性能提高潜力     

High frequency performance of Si/sub 1-x/Ge/sub x//Si/sub 1-y/Ge/sub y//Si/sub 1-x/Ge/sub x/ HBTs

The results of a theoretical study of the performance of high speed SiGe HBTs is presented. The study includes a group of SiGe HBTs in which the Ge concentration in the base is 20% higher than that in the emitter and collector (i.e. y=x+0.2). It is shown that the composition dependences of f/sub T/ and the F/sub max/ are non-monotonic. As the Ge composition in the emitter and collector layers is increased, f/sub T/ and f/sub max/ first decrease, then remain constant and finally increase to attain their highest values.<>     

Low-frequency noise in UHV/CVD epitaxial Si and SiGe bipolartransistors

In this work a comprehensive investigation of low-frequency noise in ultrahigh vacuum/chemical vapor deposition (UHV/CVD) Si and SiGe bipolar transistors is presented. The magnitude of the noise of SiGe transistors is found to be comparable to the Si devices for the identical profile, geometry, and bias. A comparison with different technologies demonstrates that the SiGe devices have excellent noise properties compared to AlGaAs/GaAs heterojunction bipolar transistors (HBT's) and conventional Si bipolar junction transistors (BJT's). Results from different bias configurations show that the 1/f base noise source is dominant in these devices. The combination of a 1/Area dependence on geometry and near quadratic dependence on base current indicates that the 1/f noise sources are homogeneously distributed over the entire emitter area and are probably located at the polysilicon-Si interface. Generation/recombination (Gm) noise and random telegraph signal (RTS) noise was observed in selected Si and SiGe devices. The bias dependence and temperature measurements suggest that these G/R centers are located in the base-emitter space charge region. The activation energies of the G/R traps participating in these noise processes were found to be within 250 meV of the conduction and valence band edges     

Hole confinement and low-frequency noise in SiGe pFETs onsilicon-on-sapphire

We present the dc, ac, and low-frequency noise characteristics of SiGe channel pFETs on silicon-on-sapphire (SOS). The SiGe pFETs show higher mobility, transconductance, and cutoff frequency compared to the Si control devices. A significant reduction in low-frequency (1/f) noise is observed in the SiGe pFETs, and understood to be the result of a lower border trap density sampled at the Fermi-level due to the valence band offset. The linear g_m of the SiGe pFET's at 85 K shows a secondary peak which is attributed to the turn-on of the surface channel     

Si间隔层对利用低温Si缓冲层生长高弛豫SiGe层的影响

利用低温生长Si缓冲层与Si间隔层相结合的方法生长高弛豫SiGe层,研究了Si间隔层在其中的作用. 利用化学腐蚀和光学显微镜，观察了不同外延层厚度处位错的腐蚀图样. 研究了不同温度下生长的Si间隔层对SiGe外延层中位错形成、传播及其对应变弛豫的影响. 结果表明Si间隔层的引入，显著改变了外延层中位错的形成和传播，进而使得样品表面形貌也呈现出较大的差异.     

A 0.18-/spl mu/m RF SiGe BiCMOS technology with collector-epi-free double-poly self-aligned HBTs

This paper describes an RF SiGe BiCMOS technology based on a standard 0.18-/spl mu/m CMOS process. This technology has the following key points: 1) A double-poly self-aligned SiGe-HBT is produced by adding a four-mask process to the CMOS process flow-this HBT has an SiGe epitaxial base selectively grown on an epi-free collector; 2) two-step annealing of CMOS source/drain/gate activation is utilized to solve the thermal budget tradeoff between SiGe-HBTs and CMOS; and 3) a robust Ge profile design is studied to improve the thermal stability of the SiGe-base/Si-collector junction. This process yields 73-GHz f/sub T/, 61-GHz f/sub max/ SiGe HBTs without compromising 0.18-/spl mu/m p/sup +//n/sup +/ dual-gate CMOS characteristics.