A method of forming a semiconductor device comprises forming a patterned masking material comprising parallel structures and parallel trenches extending at a first angle from about 30° to about 75° relative to a lateral direction. A mask is provided over the patterned masking material and comprises additional parallel structures and parallel apertures extending at a second, different angle from about 0° to about 90° relative to the lateral direction. The patterned masking material is further patterned using the mask to form a patterned masking structure comprising elongate structures separated by the parallel trenches and additional parallel trenches. Exposed portions of a hard mask material underlying the patterned masking structure are subjected to ARDE to form a patterned hard mask material. Exposed portions of a semiconductive material underlying the patterned hard mask material are removed to form semiconductive pillar structures. Semiconductor devices and electronic systems are also described.