Do You Really Have to Break A Wafer to Measure Its Surface Roughness

What does wafer surface roughness stand for? A wafer is required to be flat to ensure quality of pattern layout by later process. It gets even more critical in monitoring roughness to maintain quality after layout etched.

Wafer surface roughness is most likely measured by atomic force microscope (AFM). Conventional AFMs can take sample of dimension smaller than 2cm*2cm. That is, you have to break the wafer before running this measurement and so render it useless for other analyses and tests later.

To address this shortcoming, iST employs a Bruker Dimension ICON AFM (AFM ICON) featuring not only a platform large enough to contain wafers of size up to 12″ but also a vacuum suction to secure better reliability when scanning. In addition, iST is the only lab equipped with a 12″ wafer containable AFM machine unique within Taiwan and mainland industry.

Scanning probes employed by AFMs come in types of contact, non-contact, and tapping with the latter is most used for roughness measurement. Considered customer’s needs in diverse industries, the new AFM ICON of iST features special non-contact measurement mode which profiles the ups and downs of wafer surface with interatomic van der Waals’ force to get surface roughness figures within a margin of error of +/- 10 nm.