A method for fabricating a semiconductor device with improved performance is disclosed. The method comprises providing a substrate including a first region and a second region; forming at least one isolation region having a first aspect ratio in the first region and at least one isolation region having a second aspect ratio in the second region; performing a high aspect ratio deposition process to form a first layer over the first and second regions of the substrate; removing the first layer from the second region; and performing a high density plasma deposition process to form a second layer over the first and second regions of the substrate.