采用闭管扩散方式实现了Zn元素在晶格匹配InP/In0.53Ga0.47As及晶格失配InP/In0.82Ga0.18As两种异质结构材料中的P型掺杂,利用二次离子质谱(SIMS)以及扫描电容显微技术(SCM)对Zn在两种材料中的扩散机制进行了研究。SIMS测试表明:Zn元素在晶格失配材料中的扩散速度远大于在晶格匹配材料中的扩散速度,而SCM测试表明:两种材料中的实际PN结深度与SIMS测得的Zn扩散深度之间存在一定的差值,这是由于扩散进入材料中的Zn元素并没有被完全激活,而晶格失配材料中Zn的激活效率相对更低,使得晶格失配材料中Zn元素扩散深度与PN结深度的差值更大。SCM法是一种新颖快捷的半导体结深测试法,对于半导体器件工艺研究具有重要的指导意义。
Zn diffusion experiments were carried out for the lattice-matched InP/In0.83Ga0.47As and the lattice-mismatched InP/In0.82Ga0.18As hetero structures using the closed tube diffusion. Secondary ion mass spectroscopy (SIMS) and scanning capacitance microscopy (SCM) techniques were used to study the diffusion mechanism of ZN in the two samples. The SIMS measurement results show that Zn has a larger diffusion velocity in the lattice-mismatched samples than in the lattice-matched samples. However, there were differences between the Zn diffusion depth measured by SIMS and PN junction depth measured by SCM in both materials. The reason is that the diffused Zn in these structures isn't completely activated. And in the lattice-mismatched sample Zn has an even smaller activation ratio, thus the difference between Zn diffusion depth and PN junction depth is even greater. These results show that the SCM technique is a novel and quick measurement method of junction depth, it is guidance for the research of semiconductor device process.