Method and structure for enhancing channel performance in a vertical gate all-around device, which provides a device comprising: a source region; a drain region aligned substantially vertically to the source region; a channel structure bridging between the source region and the drain region and defining a substantially vertical channel direction; and a gate structure arranged vertically between the source region and the drain region and surrounding the channel structure. The channel structure comprises a plurality of channels extending substantially vertically abreast each other, each bridging the source region and the drain region, and at least one stressor interposed between each pair of adjacent channels and extending substantially along the vertical channel direction; the stressor affects lateral strain on the adjacent channels, thereby straining the channels in the vertical channel direction.