Enhanced hole mobility in non-(001) oriented sidewall corner of Si pMOSFETs formed on (001) substrate

By means of the TEM images, the channel width of (001) silicon pMOSFETs is separated into the flat and rounded corner parts. The underlying stress distribution is obtained via a process simulation. Then, a systematic analysis of the measured drain current leads to a remarkable result: The hole mobility in the non-(001) corner is about two times higher than the (001) flat one, valid for all channel widths involved. This is due to the multi-facets around (110) and (111) orientations. The confirmative evidence is also presented: (i) the increased value of the parameter η in effective field to maintain the mobility universality and (ii) the low frequency noise measurement to ensure the corner gate oxide integrity. Therefore, the non-(001) p-channel sidewall corner formed on (001) substrate can constitute a promising narrow device.