沟槽型发射极SiGe异质结双极化晶体管新结构研究

提出了一种沟槽型发射极SiGe异质结双极化晶体管新结构. 详细分析了新结构中沟槽型发射极的引入对器件性能的影响，并对其机理进行研究. 新型发射极结构通过改变发射极电流路径使电阻分区并联，在不增大结电容的前提下，有效减小发射极电阻，提高器件的频率特性. 结果表明，新结构器件的截止频率和最大振荡频率分别增加至100.2 GHz和134.4 GHz，更重要的是沟槽型发射极结构的引入，在提高器件频率特性的同时，不会降低器件的电流增益，也不会增加结电容，很好实现了频率特性、电流增益和结电容之间的折中. 对沟槽型发射极进行优化设计，改变侧墙高度和侧墙宽度. 沟槽型发射极电阻不受侧墙高度改变的影响，频率性能不变；侧墙宽度增加，频率性能降低. 关键词： SiGe 异质结双极化晶体管 沟槽型发射极 发射极电阻

Research on SiGe heterojunction bipolar transistor with a trench-type emitter

A novel SiGe heterojunction bipolar transistor (HBT) with a trench-type emitter is presented. Effects of the trench-type emitter on device performance are analyzed in detail, and current transport mechanism of the novel device is studied. The emitter resistances are parallel partitions by changing current path. Under the precondition without increasing the junction capacitance, the resistances of the new emitter are reduced effectively, and the frequency characteristics of the device are improved. Results show that the cutoff frequency and the maximum oscillation frequency of the new device are increased to 100.2 GHz and 134.4 GHz, respectively. More important is that the frequency characteristics are improved by the introduction of the trench-type emitter, while the current gain is not reduced and the junction capacitance is also not increased. A good trade-off is achieved among frequency, current gain, and junction capacitance. The trench-type emitter is designed to be optimal. With the change in sidewall height, no effects are found on the emitter resistances, and the frequency characteristics do not change, while the frequency characteristics are reduced when the sidewall width is increased.
Keywords： SiGe HBT trench-type emitter emitter resistance