Efficient preparation of microtip arrays for atom probe tomography using fs-laser processing

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Microtip arrays are standard specimen carriers in atom probe tomography (APT), typically fabricated from silicon and requiring focused ion beam (FIB) lift-out procedures.
• These commercial consumables can be costly, and the FIB lift-out process, along with platinum welding, introduces potential weaknesses and limitations.

Purpose of the Study:

• To present an alternative method for APT specimen preparation by directly fabricating microtip arrays on the sample material using fs-laser processing.
• To bypass the conventional lift-out procedure and eliminate the need for platinum welding, thereby reducing consumable use and potential artifacts.

Main Methods:

• Direct fabrication of microtip arrays on TiN coating on Si substrate using femtosecond (fs) laser processing.
• Final specimen preparation using annular FIB milling.
• APT analysis of TiN coating and Si substrate in laser-assisted mode using a commercial local electrode APT system.

Main Results:

• Successful APT measurements of TiN coating and Si substrate specimens prepared with the novel fs-laser method.
• Demonstrated versatility through voltage measurements of boron-doped silicon arrays and fs-laser processed arrays of other materials.
• Elimination of the lift-out step and platinum welding, addressing a common weak point in APT specimen preparation.

Conclusions:

• The fs-laser direct fabrication method offers a streamlined, cost-effective, and versatile approach to APT specimen preparation.
• This technique has the potential to significantly advance APT by enabling rapid, high-throughput analysis across a wide range of materials.
• The methodology reduces consumables consumption and simplifies the preparation process, making APT more accessible and efficient.