3D MEMS Metrology with the Atomic Force Microscope

The AFM creates 3-dimensional images of a surface, covering, typically, an area up to 120µm square and height variations up to 7µm. It enables nanometer-scale in-plane, single-atomic step height, and sub-angstrom (rms) surface roughness measurements. The AFM is a non-destructive technique, ideal for measuring real devices on product wafers. The image analysis software of the AFM includes several methods for single as well as statistical measurements, which can often be automated and streamlined for repeated application. Automated AFMs are used in MEMS production, while highly modular AFMs are making measurements in R&D in MEMS labs. The AFM itself uses a simple MEMS device as its probe: a microfabricated beam and integrated tip. With highly specialized cantilever/tips, the AFM can nondestructively measure some of the most aggressive-geometry devices and smallest dimensions in MEMS and NEMS.