US Patent 9831117 Self-aligned double spacer patterning process

Embodiments of the present disclosure are a method of forming a semiconductor device and methods of patterning a semiconductor device. An embodiment is a method of forming a semiconductor device, the method including forming a first hard mask layer over a semiconductor device layer, the first hard mask layer comprising a metal-containing material, forming a second hard mask layer over the first hard mask layer, and forming a first set of metal-containing spacers over the second hard mask layer. The method further includes patterning the second hard mask layer using the first set of metal-containing spacers as a mask, forming a second set of metal-containing spacers on sidewalls of the patterned second hard mask layer, and patterning the first hard mask layer using the second set of metal-containing spacers as a mask.