Formation of CoSi2 on strained Si0.8Ge0.2 using a sacrificial Si layer

Formation of CoSi2 using a sacrificial Si layer on strained Si0.8Ge0.2 has been investigated. It has been observed that this capping layer plays an important role in the silicide quality and in keeping the strain of the SiGe layer. When the Si layer is totally consumed and the silicide touches the SiGe layer, the SiGe layer relaxes and the resulting film has a high sheet resistance. On the other hand, if the sacrificial Si layer is thick enough to avoid this reaction a good quality cobalt disilicide can be formed and the SiGe layer remains strained.