【作者】 黄文韬；

【导师】 钱佩信； 陈培毅；

【作者基本信息】 清华大学 ， 电子科学与技术， 2004， 博士

【摘要】 SiGe HBT器件具有优异的性能,在许多领域特别是高速和微波领域具有广泛应用,市场迅速发展。SiGe HBT微波单片放大电路作为一种通用器件,具有结构简单、互换性强以及可以单片集成等优点而发展迅速。本论文在国内首先进行了SiGe HBT微波单片放大电路的研究,开展了从外延设备、材料特性、工艺改进到电路设计和制作的一系列研究工作。在对SiGe外延设备进行大量研究的基础上,对UHV/CVD设备的结构和石墨加热器进行了改进,改善了SiGe/Si薄膜的组分和厚度的均匀性:Ge组分均匀性达到了±5%,SiGe薄膜的厚度均匀性达到了±8%。研究了SiGe薄膜的外延方法,得到了高质量的SiGe薄膜。对SiGe/Si薄膜的应变弛豫进行了研究,结果表明:与退火时间相比,炉温退火的温度对组分渐变和均匀组分的SiGe薄膜的应变弛豫起主要作用,温度越高,越容易弛豫;在910oC以下的快速热退火处理对SiGe薄膜的应变弛豫影响不大。在此基础上改进了SiGe HBT制作工艺,并开发了新的电路制作工艺。在国内首先研制成SiGe HBT微波单片放大电路。电路的S参数分析表明:电路的功率增益在850 MHz处为11.6 dB,在1950 MHz处为8.0 dB,在3000 MHz处为4.7 dB;在3000 MHz处输入端的驻波比为3.01:1,输出端的驻波比为2.66:1。在器件制作工艺中引入钛硅化合物,改善了SiGe HBT器件的欧姆接触;通过研究Ge组分梯度的SiGe HBT器件,表明在SiGe基区中引入Ge组分梯度可以提高SiGe HBT的特征频率fT。对UHV/CVD低温Si外延时的As外扩进行了深入研究,结果表明:在700oC下生长的Si外延层的As外扩0.16 μm,而在500oC下As外扩仅有0.06 μm,只需要较少的厚度就可以达到较高的击穿电压。在国内首先研究了SiGe HBT器件的电子辐照特性,并与Si BJT的电子辐照特性做了对比,结果表明SiGe HBT器件具有优异的抗辐照性能。更多还原

【Abstract】 Silicon-Germanium (SiGe) heterojunction bipolar transistors (HBTs) have shown marvelous performance in many areas for high-speed and microwave applications. SiGe HBTs can also be integrated with other devices on a monolithic silicon wafer. As an all-purpose circuit, Darlington-structure SiGe HBT microwave monolithic integrated circuits (SiGe HBT MMICs) has a good many advantages. They have simple structures and they not only can be replaced easily but also can be monolithically integrated in a Si wafer with other active devices and passive components. In this study, SiGe HBT MMIC research was done for the first time in China. A series of efforts was made on SiGe HBT MMIC including UHV/CVD SiGe epitaxial machine, SiGe film characteristics, process improvements, circuit design and fabrication.The structure of the self-made UHV/CVD and the design of the rapid-thermal graphite heater were improved based on the investigation of many SiGe epitaxial machines. The Ge mol fraction and thickness uniformity of SiGe film were obviously improved: the Ge fraction uniformity achieved ±5%, and the thickness uniformity achieved ±8%.High quality SiGe epitaxial layers with uniform or graded Ge profiles were successfully achieved based on the study of the SiGe epitaxial process on the SGE500-type UHV/CVD. The strain relaxation of SiGe films under different thermal processes was thoroughly studied. Compared with annealing time, furnace annealing temperature is much more important to the relaxation of SiGe film with uniform or graded Ge profile. The higher the temperature was, the easier was the strain of the SiGe film to relax. Rapid thermal annealing showed less effect on the strain relaxation of the SiGe film when the temperature was less than 910oC. <WP=5>Innovative study in China was done on the design and fabrication of SiGe HBT MMIC. A new fabrication process for this circuit was developed based on the study of SiGe uniformity, growth process, strain-relaxation and the SiGe HBT fabrication process. The analysis of scattering parameters showed that the SiGe HBT MMIC had good electrical performance: The power gain was 11.6 dB@850 MHz, 8.0 dB@1950 MHz and 4.7 dB@3000 MHz; the input voltage static wave ratio (VSWR) was 3.01:1@3000 MHz and the output VSWR was 2.66:1.Three methods were developed to improve the frequency performance of the SiGe HBT. TiSi2 was introduced to the fabrication process of SiGe HBT. SiGe HBTs with different Ge graded profile were thoroughly studied, and the transition frequency fT of the SiGe HBT was improved by this means. Selective growth of SiGe film on patterned Si wafers was also studied. The anti-radiation performance of SiGe HBT devices was studied for the first time in China. Analysis showed that the anti-radiation performance of SiGe HBTs is remarkably better compared with that of Si BJTs.The transition region thickness was 0.16 μm for the Si epitaxial layer grown at 700oC on the highly arsenic-doped Si substrates, and was only 0.06 μm under 500oC, which was much less than high-temperature Si epitaxy by APCVD. Thus the low-temperature epitaxial Si layer needs less film thickness to achieve the same breakdown voltage.更多还原