Patterning for elongated VSS contact flash memory

摘要

A method of forming a contact in a flash memory device is disclosed. The method increases the depth of focus margin and the overlay margin between the contact and the stacked gate layers. A plurality of stacked gate layers are formed on a semiconductor substrate, wherein each stacked gate layer extends in a predefined direction and is substantially parallel to other stacked gate layers. An interlayer insulating layer is deposited over the plurality of stacked gate layers, and a contact hole is patterned between a first stacked gate layer of the plurality of stacked gate layers and a second stacked gate layer of the plurality of stacked gate layers. The contact hole is formed in an elongated shape, wherein a major axis of the contact hole is substantially parallel to the stacked gate layers. A conductive layer is deposited in the contact hole and excess conductive material is removed.