Patent ID: 6780731
Filing Date: 2004-08-24
Classification: H01L

Abstract:
A method for void-free filling a trench of high aspect ratio and stepped profile in a layered substrate comprising:providing a substrate comprising a first layer, over which is formed a second layer, over which is formed a third layer; forming in said substrate a high aspect ratio trench with an initial opening diameter in said third layer and said trench having side walls extending through said third and second layers and into said first layer; forming a step in the profile of the trench by removing an annular portion of the third layer surrounding said initial opening, thereby enlarging said initial opening diameter; depositing over the exposed sideways of said trench an initial layer of filling material, using a first high density plasma (HDP) deposition and sputtering process to achieve a first thickness which constricts said enlarged initial opening producing an overhang above said step, said deposition and sputtering process using oxygen and silan as reactant gases during a deposition portion of said process and oxygen or argon as a sputtering gas during a sputtering portion of said process, and said deposition and sputtering process having a ratio of deposition rate to sputtering rate (D/S) which is between 6 and 20 and a low bias power between 500 and 2000 W; sputtering said initial layer, in the presence of only the sputtering gas to eliminate said overhang and produce, thereby, a trench which is widest at an upper portion; depositing additional layers of filling material on the side walls of said trench, in a subsequent sequence of HDP deposition and sputtering processes using said reactant gases, sputtering gases of oxygen or argon or a mixture of oxygen and argon, and a ratio of deposition rate to sputtering rate (D/S) between 2 and 6; terminating said HDP deposition and sputtering process sequence when the trench has been filled to a height above the surface of the substrate.