A process of forming a three-dimensional (3D) memory array includes forming a stack having a plurality of conductive layers of carbon-based material separated by dielectric layers. Etching trenches in the stack divides the conductive layers into conductive strips. The resulting structure includes a two-dimensional array of horizontal conductive strips. Memory cells may be distributed along the length of each strip to provide a 3D array. The conductive strips together with additional conductive structure that may have a vertical or horizontal orientation allow the memory cells to be addressed individually. Forming the conductive layers with carbon-based material facilitate etching the trenches to a high aspect ratio. Accordingly, forming the conductive layers of carbon-based material enables the memory array to have more layers or to have a higher area density.