Low-energy plasma CVD for epitaxy and in-situ doping of group-IV semiconductors in nanoelectronics

In a trend for highly-scaled semiconductor devices and quantumtunneling devices in Si large-scale integrated circuits (LSI), lowertemperature processing for epitaxy and in-situ doping is necessary and has been pursued because suppression of diffusion length is indispensable. We have been developing a low-energy electroncyclotron- resonance (ECR) plasma chemical vapor deposition (CVD) processing and we have enabled epitaxy of Si, Ge, Si-Ge alloy and Si-C alloy on Si (100) without substrate heating. Moreover, we have enabled in-situ doping of the Si epitaxial film without substrate heating and confirmed rectifying characteristics in p-n junction diodes by using the Si-Ge alloy and B-doped Si films. Moreover, p-type B atomic-layer (AL) doping in Si epitaxy without substrate heating was experimentally demonstrated. This AL doping technique is expected to be applicable not only to low-resistive semiconductor film formation but also to two-dimensional impurity-band formation which is far from thermal equilibrium. By using low-energy ECR nitrogen plasma, low-stress Si nitride film formation was also demonstrated by SiH4 reaction and modification of film properties by subsequent plasma nitridation. Therein, monitoring temperature and waiting for heating-up and cooling-down are not necessary. This means that semiconductor device fabrication becomes "smart" in a viewpoint of consuming time, materials, energy and human. Additionally, new concept of crystal structure transformation in Si from the diamond structure into non-diamond structure was suggested to explore novel property creation. Thus, the low-energy ECR plasma CVD processing is expected to contribute to various fields of material science, engineering and physics of nanoelectronic devices.