Development of ultra shallow doping of semiconductors by ultra low energy ion beams

在硅技术中，人们认为电激活的超浅掺杂层在未来将是必要的。预计在2014年，源漏电极下的掺杂延伸层厚度将达到10 nm。在硅器件工艺中，硼被广泛用作p型掺杂剂。离子注入是一种有效的控制杂质注入固体的方法，但也会引入缺陷。离子注入后的高温退火会恢复硅的晶化并激活注入的掺杂剂。然而，在退火过程中会发生掺杂扩散，由于硼是硅中的快速扩散者，因此很难保持超浅掺杂的轮廓。在本研究中，为了减少注入过程中的损伤，研究了接近固体位移能的100 eV以下的超低能离子注入。在温度从RT到1073K的范围内，在本征硅衬底(电阻率为&gt；10000欧姆厘米)中注入了能量在30-500eV之间的硼离子。随着衬底温度的升高，200 eV能量下注硼后的方块电阻从100k欧姆下降到4k欧姆。当离子能量为300 eV，衬底温度为1073K时，薄膜的方阻最小，为2.8k欧姆。二次离子质谱仪分析表明，掺硼层的结深小于8 nm。

In silicon technology it is thought that an electrically activated, ultra-shallow doping layer will be necessary in the future. The thickness of dopant extension layers under the source and drain electrode is predicted to reach 10nm in the year 2014. Boron is widely used as p-type dopant in silicon-device technology. Ion implantation is a useful method for the controlled introduction of impurities into a solid; however, defects are also introduced. High-temperature annealing after ion implantation recovers the crystallization of silicon and activates the implanted dopant. However, diffusion of the dopant occurs during the annealing, and it is difficult to keep the ultra-shallow dopant profile because boron is the fast diffuser in Si. In this study, ultra-low-energy ion implantation below 100eV, which was close to the displacement energy of the solid, was examined to reduce the damage during implantation process. Boron ion of energy ranging between 30 and 500 eV, was implanted into intrinsic Si substrate (resistivity is > 10000 ohm cm) at temperatures ranging from RT to 1073K. Sheet resistance after boron implantation at the energy of 200 eV decreases from 100 k ohm to 4 k ohm with increasing the substrate temperature. The lowest sheet resistance of 2.8 k ohm was achieved at the ion energy of 300 eV and the substrate temperatures of 1073K. Junction depth of boron-doped layers was below 8 nm by the analysis of secondary ion mass spectroscopy.