Adding 3D to FIB or SEM Surface Imaging Information

Nanopatterning techniques and related parameters are generally well understood for traditional nanofabrication applications employing focused ion beam (FIB) milling or resist-based electron beam lithography (EBL) processes.

This article demonstrates how the new Raith NanoSense is used for in situ surface sensing and nanoprofilometry for focused ion and electron beam-induced process verification.

Complex and challenging deposition processes using FEBIP. Image credit: Raith

However, ground-breaking and sophisticated nanofabrication applications involving complex FIB patterning tasks or 3D-focused electron or ion beam induced deposition/etching processes (FEBIP/FIBIP) on novel materials may need detailed and complex process optimization and verification, often in time-consuming iterative cycles. This is because there is an almost “infinite” number of variable parameters for these complex processes involving gas chemistries or new ion species. SEM imaging offers only 2D information and therefore cross-sectioning or AFM techniques are usually involved to recover the required 3D information.

Nanosense scanning principle. Image credit: Raith

Example of deposition rate determination using height profiles of deposited lines applying electron beam induced deposition. Image credit: Raith

Efficient 3D Milling Profile Visualization

The new Raith NanoSense, available for eLINE Plus and ionLINE Plus, offers a much more simple and efficient solution to help qualify FIBIP/FEBIP and milling processes in situ within a matter of minutes. Nanoprofilometric scans, meant for additive (deposition) and subtractive (milling/etching) surface treatment, yield 3D information for determining milling or deposition rate in a highly efficient way, without the use of FIB-SEM technologies or need for monotonous sample uploading and ex situ AFM analysis.

In both eLINE Plus and ionLINE Plus, NanoSense can be implemented to achieve the consistent, expected, and reproducible results for 3D nanostructures and as well as to validate and optimize complex nanofabrication tasks. A standard nanomanipulator is available for both systems that can be upgraded with a surface-sensitive sensor to create height resolutions in the order of 5 nm.

Milling a rectangle with identical milling dose, yet applying different patterning strategies. (single pass, multipass, concentric outwards single pass). Image credit: Raith

Corresponding 2D SEM imaging information is not sufficient for qualitative process verification. Image credit: Raith

Nanoprofilometric line scans revealing the resulting milling profiles for the respective milling strategy. Image credit: Raith

This information has been sourced, reviewed and adapted from materials provided by Raith.

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