Dummy copper deprocessing

A method of removing two or more layers of material from an area of a target, the method comprising:

• defining the target area to be removed;
• directing a focused ion beam a first time toward a first layer of material, thereby substantially removing the first layer of material from the target area;
• directing a oxygen containing gas toward the target area;
• directing a focused ion beam a second time toward the target area to remove any remaining material from said first layer of material, thereby producing a substantially uniform smooth floor in the milled target area;
• and
• directing a focused ion beam toward a second layer of material, thereby substantially removing the second layer of material from the target area.

A method of removing material from an area of a target, the method comprising:

• defining the target area of a first material to be removed;
• forming a layer of a second material over the target area, said layer capable of interacting with a focused ion beam to increase the uniformity of the removal of the first material by the focused ion beam;
• directing a focused ion beam toward target area in a first pattern, characterized by a first pixel spacing greater than a spot size characterizing the focused ion beam;
• directing the focused ion beam toward target area in a second pattern characterized by a second pixel spacing, the second pixel spacing being less than the first pixel spacing and less than or approximately equal to the ion beam spot size, thereby substantially removing the material from the target area;
• directing a oxygen containing gas toward the target area;
• and
• directing a focused ion beam toward the target area to remove any remaining material, thereby producing a substantially uniform smooth floor in the milled target area.

A focused ion beam system for removing multiple layers of material, the apparatus comprising:

• an ion source;
• an ion column including deflection electrodes for directing the ion beam, the deflection electrodes programmed for first directing the focused ion beam to etch the copper at multiple first locations spaced sufficiently separated to prevent formation or propagation of the etch-resistant regions in the material to be removed and then for directing the focused ion beam to etch at multiple overlapping locations spaced apart less than the first locations are spaced apart to produce a uniform, planar milled target area;
• and
• a gas injection system for directing a precursor gas toward the target to form under bombardment of the ion beam a sacrificial layer, the ion optical elements and the gas injection system being adjusted to deliver ions and precursor gas at rates such that during each dwell period, a layer of decomposition products is formed, interacts with ion beam in etching the material, and is itself substantially removed so that etching of the material is substantially uniform over the area on the target with and the decomposition products substantially removed.