A method includes depositing a second dielectric layer over a first dielectric layer, depositing a third dielectric layer over the second dielectric layer, patterning a plurality of first openings in the third dielectric layer, etching the second dielectric layer through the first openings to form second openings in the second dielectric layer, performing a plasma etching process directed at the second dielectric layer from a first direction, the plasma etching process extending the second openings in the first direction, and etching the first dielectric layer through the second openings to form third openings in the first dielectric layer.