Method of making a semiconductor device with a low permittivity region

摘要

A method of making a semiconductor device (10) having a low permittivity region (24) includes forming a first layer (30/42) over a surface of a trench (20), and etching through an opening (70) in the first layer that is smaller than a width (W2) of the trench to remove a first material (38) from the trench. A second material (44) is deposited to plug the opening to seal an air pocket (40) in the trench. The low permittivity region features air pockets with a high volume because the small size of the opening allows the second material to plug the trench without accumulating significantly in the trench.