METHOD FOR PREPARING SEMICONDUCTOR DEVICE STRUCTURE WITH AIR GAP STRUCTURE

The present disclosure provides a method for preparing a semiconductor device structure. The method includes forming a first metal plug, a second metal plug, a third metal plug, and a fourth metal plug over a semiconductor substrate; forming an energy removable liner covering the first metal plug, the second metal plug, the third metal plug, and the fourth metal plug; performing an etching process to remove a portion of the energy removable layer from the substrate, while remaining an energy removable block between the first metal plug and the second metal plug in the cell region; forming a dielectric layer covering the energy removable block and the first metal plug, the second metal plug, the third metal plug, and the fourth metal plug; performing a thermal treating process to transform the energy removable layer into a first air gap structure including a first air gap enclosed by liner layer;