The present invention provides apparatus, methods, and systems for fabricating memory structures methods of forming pillars for memory cells using sequential sidewall patterning. The invention includes forming first features from a first template layer disposed above a memory layer stack; forming first sidewall spacers adjacent the first features; forming second features that extend in a first direction in a mask layer by using the first sidewall spacers as a hardmask; depositing a second template layer on the mask layer; forming third features from the second template layer; forming second sidewall spacers adjacent the third features; and forming fourth features that extend in a second direction in the mask layer by using the second sidewall spacers as a hardmask. Numerous additional aspects are disclosed.