Atom probe tomography specimen preparation

A method, comprising:

• receiving a wafer having a semiconductor structure;
• identifying a first region in the semiconductor structure;
• identifying a first structural element in the first region;
• replacing the first structural element with a second structural element;
• and
• preparing an atom probe specimen from the first region after the replacing,
• wherein the first region includes a test object of an atom probe tomography analysis, and the first structural element includes a material that is unidentifiable with respect to a material of the test object.

A method, comprising:

• receiving a wafer, the wafer including:
• a substrate,
• a first structure and a second structure over the substrate, and
• a dielectric layer between the first structure and second structure, the first structure including a first semiconductor body and a first upper structure over the first semiconductor body, the second structure including a second semiconductor body and a second upper structure over the second semiconductor body, the first semiconductor body and the second semiconductor body in a same layer and substantially identical to one another, the first upper structure and the second upper structure substantially identical to one another, and the dielectric layer surrounding the first upper structure and the second upper structure;
• forming an aperture in the dielectric layer by removing the second upper structure by etching;
• forming a third upper structure in the aperture, the third upper structure having a different material from the first upper structure;
• and
• forming an atom probe tomography test sample that includes at least a portion of the third upper structure, the forming the atom probe tomography test sample including:
• extracting a lamella that includes at least the portion of the third upper structure, the lamella including a plurality of shanks;
• and
• annularly milling a shank of the plurality of shanks using focused ion beam milling.