论文部分内容阅读
为了降低GaAs功率FET的互调失真(IMD),掺杂分布的修正是一种有效的手段。对外延工艺来说,要可重复地、并且均匀性良好地制备所要求的杂质分布是一项困难的任务。这种缺陷已促使人们研究用离子注入的方法来制造高级的线性功率 FET。为了探索有源层掺杂分布与互调失真之间的关系,提出了一个解析的器件模型。这些计算揭示了失真电平变化的复杂性质,这种变化是由非线性跨导和输出电导相互之间的一部分关系产生的。用器件模型来鉴定注入的剂量和能量,以便实现最佳的有源层杂质分布。根据这些结果,在器件制造中先做一次深的硒注入而后用浅的铍注入来补偿表面层的掺杂浓度。晶体管的互调失真是用双音方法测量的。为了进行比较,还估测了具有平的掺杂分布的常规外延 FET。这一比较表明:通过采用修正的注入分布,在监测点三级互调积可以提高4dB。实验表明:对离子注入的晶体管来说,最大输出功率和最小互调失真的调谐条件实质上是相同的,从而与具有平的掺杂分布的常规器件的特性形成了明显的对照。这些性能上的优点以及掺杂参量的高度的均匀性和重复性都表明离子注入是制造高级线性功率 FET 的一种有效的技术。
In order to reduce the intermodulation distortion (IMD) of the GaAs power FET, doping profile modification is an effective method. For an epitaxial process, it is a difficult task to prepare the desired impurity profile repeatedly and uniformly. This flaw has prompted research into advanced linear power FETs using ion implantation. In order to explore the relationship between the active layer doping profile and intermodulation distortion, an analytical device model is proposed. These calculations reveal the complex nature of the distortion level changes that result from the mutual relationship between the nonlinear transconductance and the output conductances. The device model is used to identify the dose and energy injected to achieve the best active layer impurity profile. Based on these results, a deep selenium implant was made in the device and then a shallow beryllium implant was used to compensate for the doping concentration of the surface layer. Transistor intermodulation distortion is measured by the two-tone method. For comparison, a conventional epitaxial FET with a flat doping profile was also evaluated. This comparison shows that by using a modified injection profile, the level 3 intermodulation can be increased by 4 dB at the monitoring point. Experiments have shown that the tuning conditions for maximum output power and minimum intermodulation distortion are substantially the same for ion implanted transistors, in contrast to the conventional device with a flat doping profile. These performance advantages, as well as the high degree of uniformity and repeatability of the doping parameters, indicate that ion implantation is an effective technique for making advanced linear power FETs.