Investigation of the subustituional behavior and the electrical activation of implanted P and N impurities in SiC

1.注入N杂质在6H-SiC中的激活过程在N浓度低于2×10~(-1)/cm~(-3)的范围内，电激活是通过1200℃的退火来实现的。在1200℃的退火过程中，N杂质也促进了SiC亚晶格上N杂质的取代。但在N浓度大于2×10^&lt；20&gt；/cm^3范围内，N杂质激活的自由电子数随N浓度的增加而减少。在这种情况下，过量注入的N杂质优先占据了碳化硅中的间隙位置，而不是替代位置。6H-SiC中注入P杂质的激活过程取决于注入层是否被注入过程非晶化。在注入有非晶化的情况下，注入的P杂质可以占据硅亚晶位，而非晶化的注入层即使在1000℃下也会再结晶，这导致注入的P杂质立即被电激活。然而，在较高温度下的退火会导致注入的P杂质在碳化硅中的外扩散和重新分布。另一方面，在采用“热”注入技术进行注入而没有注入层非晶化的情况下，随着热处理温度的升高，P杂质在Si亚晶格位置上的浓度增加，从而导致SiC中自由电子浓度的增加。然而，“热”注入的碳化硅的自由电子浓度低于非晶化注入层的自由电子浓度。结果表明，注入的部分磷杂质占据了碳化硅中的间隙位置。

1. Activation Process of the implated N impurities in 6H-SiCIn the N concentration range below 2×10^<20>/cm^3, the electrical activation is achieved by annealing at 1200℃. The substitution of the N impurities on Si sublattice sites in SiC is also promoted during the annealing at 1200℃. However, in the N concentration range above 2×10^<20>/cm^3, the number of free electrons activated from N impurities is decreased with the increase of the N concentration. In this regime, it is suggested that the excess implanted N impurities preferably occupy the interstitial sites in SiC rather than the substitutional sites.2. Activation process of the implanted P impurities in 6H-SiCThe activation process of the implanted P impurities in 6H-SiC depends on whether the implanted layer is amorphized by implantation process. In the case of the implantation with the amorphization, the implanted P impurities can occupy the Si sublatties sites while the amorphized implant layer is re-crystallized by annealing even at 1000℃, which leads immediately the electrical activation of the implanted P impurities. However, in the annealing at higher temperature induces the out-diffusion and the redistribution of the implanted P impurities in SiC. On the other hand, in the case of the implantation without the amorphization of the implanted layer using "Hot" implantation technique, the concentration of the P impurities on the Si sublattice sites is increase by increasing the annealing temperature, which results in the increase of the free electron concentration in SiC. However, the obtained free electron concentration of the "Hot" implanted SiC is lower than the case of the amorphized implant layer. It is suggested that a part of the implanted P impurities occupy the interstitial sites in SiC.