Method and apparatus for chemical/mechanical planarization (CMP) of a semiconductor substrate having shallow trench isolation

摘要

A method to planarize the surface of a semiconductor substrate having shallow trench isolation (STI) reduces erosion of a silicon nitride planarization stop layer, reduces dishing of large areas of the shallow trench isolation, and prevents under polishing of the surface of the semiconductor substrate that will leave portions of the silicon dioxide that fills the shallow trenches covering the silicon nitride planarization stop exposed, is described. The method to planarize the surface of a semiconductor substrate having shallow trenches begins by chemical/mechanical planarization polishing at a first product of platen pressure and platen speed to planarize the semiconductor substrate. Polishing at a first product of platen pressure and platen speed will cause a high rate of material removal with low selectivity to increase production throughput. The silicon nitride stop layer will be examined to determine an end point exposure of the silicon nitride stop layer. When the end point exposure of the silicon nitride stop layer is reached, chemical/mechanical planarization polishing at a low product of platen pressure and platen speed is started to planarize the semiconductor substrate of slow over polish to control thickness of a trench oxide of the shallow trench isolation to reduce dishing and minimize erosion. The method further has the step of buffing the surface of the semiconductor substrate to remove any residue from the chemical/mechanical planarization polishing and to remove any microscratches from the surface of the semiconductor substrate.