Self-aligned double patterning (SADP) is a form of double patterning. It is sometimes referred to as pitch division, spacer or sidewall-assisted double patterning. The SADP process uses one lithography step and additional deposition and etch steps to define a spacer-like feature. SADP, which has been used to extend NAND to the 1xnm node, is now moving into logic. In the SADP process, the first step is to form mandrels on a substrate. Then, the pattern is covered with a deposition layer. The deposition layer is then etched, which, in turn, forms spacers. Finally, the top portion undergoes a chemical mechanical polishing (CMP) step.