A nanowire device having a plurality of internal spacers and a method for forming said internal spacers are disclosed. In an embodiment, a semiconductor device comprises a nanowire stack disposed above a substrate, the nanowire stack having a plurality of vertically-stacked nanowires, a gate structure wrapped around each of the plurality of nanowires, defining a channel region of the device, the gate structure having gate sidewalls, a pair of source/drain regions on opposite sides of the channel region; and an internal spacer on a portion of the gate sidewall between two adjacent nanowires, internal to the nanowire stack. In an embodiment, the internal spacers are formed by depositing photo-definable spacer material in dimples etched adjacent to the channel region. Photo-definable material remains in the dimples by altering the etch characteristics of material outside of the dimples and selectively removing altered photo-definable material outside of the dimples.