Method of forming inter-metal dielectric

摘要

A method of forming inter-metal dielectric (IMD). A substrate having a patterned metal layer thereon has at least one opening to expose the substrate. The aspect ratio of the opening is 3.5~4.5. Next, the opening is filled with a first dielectric layer, and voids are formed in the upper portion of the first dielectric layer due to the high aspect ratio opening. Thereafter, the first dielectric layer is etched to leave the first dielectric layer with a predetermined height in the opening without voids. Finally, a second dielectric layer is formed on the first dielectric layer to completely fill the opening.