SIMOX SOI埋氧注氮工艺对埋氧中固定正电荷密度的影响

在SIMOX SOI材料的埋氧中注氮是为了增强该类材料的抗辐射能力.通过C-V研究表明，对于埋氧层为150 nm的SIMOX SOI材料来说，当在其埋氧中注入4×10¹⁵cm^-2剂量的氮后，与未注氮埋氧相比，注氮埋氧中的固定正电荷密度显著增加了；而对于埋氧层为375nm的SIMOX SOI材料来说，当注氮剂量分别为2×10¹⁵cm^-2和3×10¹⁵cm^{-2关键词：SIMOX埋氧注氮固定正电荷密度}

Effect of implantation of nitrogen into SIMOX buried oxide on its fixed positive charge density

In order to obtain greater radiation hardness for SIMOX (separation by implanted oxygen) materials, nitrogen was implanted into SIMOX BOX (buried oxide). However, it has been found by the C-V technique employed in this work that there is an obvious increase of the fixed positive charge density in the nitrogen-implanted BOX with a 150 nm thickness and 4×10¹⁵cm^-2 nitrogen implantation dose, compared with that unimplanted with nitrogen. On the other hand, for the BOX layers with a 375　nm thickness and implanted with 2×10¹⁵ and 3×10¹⁵cm^-2 nitrogen doses respectively, the increase of the fixed positive charge density induced by implanted nitrogen has not been observed. The post-implantation annealing conditions are identical for all the nitrogen-implanted samples. The increase in fixed positive charge density in the nitrogen-implanted 150 nm BOX is ascribed to the accumulation of implanted nitrogen near the BOX/Si interface due to the post-implantation annealing process according to SIMS results. In addition, it has also been found that the fixed positive charge density in initial BOX is very small. This means SIMOX BOX has a much lower oxide charge density than thermal SiO₂ which contains a lot of oxide charges in most cases.