Early Bit Line Air Gap Formation

摘要

Dummy bit lines of are formed in a sacrificial layer at locations where bit lines are to be formed, with bit lines separated by trenches that extend through the sacrificial layer. Enclosed air gap structures are formed in the trenches between the dummy bit lines. Subsequently, the dummy bit lines are replaced with metal to form bit lines.

主权项

1. A method of forming air gap structures between conductive lines, the method comprising:
forming a first layer; forming a second layer on the first layer; patterning the second layer using a selective etch that provides an etch rate of the second layer that is substantially higher than an etch rate of the first layer thereby forming a first trench in the second layer at a location where an air gap between conductive lines is to be formed; depositing a third layer in the first trench the third layer encapsulating an air gap in the first trench; removing the patterned second layer to form a second trench while the air gap remains in place; depositing a bather layer and conductive line metal in the second trench; and performing Chemical Mechanical Polishing (CMP) to remove excess conductive line material while leaving conductive line material in the second trench to form a conductive line.