Methods of forming a semiconductor device may include providing a feature layer having a first region and a second region. The methods may also include forming a dual mask layer on the feature layer. The methods may further include forming a variable mask layer on the dual mask layer. The methods may additionally include forming a first structure on the feature layer in the first region and a second structure on the feature layer in the second region by patterning the variable mask layer and the dual mask layer. The methods may also include forming a first spacer on a sidewall of the first structure and a second spacer on a sidewall of the second structure. The methods may further include removing the first structure while maintaining at least a portion of the second structure.