Patent ID: 6921725

Claim:
A method of forming an aperture in a silicon oxide layer, the method comprising: generating a plasma containing fluorine and at least one element selected from the group consisting of bromine and iodine; accelerating ions from the plasma toward a surface of the silicon oxide layer; etching an exposed portion of the silicon oxide layer, thereby advancing an etch front into the silicon oxide layer and forming the aperture having sidewalls; absorbing components containing the at least one element on the sidewalls of the aperture; and continuing to advance the etch front and absorb components containing the at least one element on the sidewalls of the aperture until a desired aspect ratio is attained; wherein the desired aspect ratio is greater than about 5:1; and wherein a content of the at least one element is sufficient to produce a taper angle of the sidewalls of greater than about 87° at the desired aspect ratio.