Forming structures such as fins in a semiconductor layer according to a pattern formed by oxidizing a sidewall of a layer of oxidizable material. In one embodiment, source/drain pattern structures and a fin pattern structures are patterned in the oxidizable layer. The fin pattern structure is then masked from an oxidation process that grows oxide on the sidewalls of the channel pattern structure and the top surface of the source/drain pattern structures. The remaining oxidizable material of the channel pattern structure is subsequently removed leaving a hole between two portions of the oxide layer. These two portions are used in one embodiment as a mask for patterning the semiconductor layer to form two fins. This patterning also leaves the source/drain structures connected to the fins.