A method of forming a memory array includes forming a dielectric over a semiconductor, forming a charge-storage structure over the dielectric, forming an isolation region through the dielectric and the charge-storage structure and extending into the semiconductor, recessing the isolation region to a level below a level of an upper surface of the dielectric and at or above a level of an upper surface of the semiconductor, forming an access line over the charge-storage structure and the recessed isolation region, and forming an air gap over the recessed isolation region so that the air gap passes through the charge-storage structure, so that the air gap extends to and terminates at a bottom surface of the access line, and so that the entire air gap is between the bottom surface of the access line and the upper surface of the semiconductor.