Operating Principle
High-resolution surface measurement techniques combine the fine lateral resolution of atomic force microscopy with the extended travel ranges of stylus profilometry to map surface topography. In circuit board fabrication, atomic force profilometry provides non-destructive three-dimensional measurements of sub-micron copper traces and via structures. The technique operates by scanning a sharp probe tip mounted on a flexible cantilever across the specimen surface while maintaining a constant force.
Deflections of the cantilever are monitored by an optical beam deflection system to generate precise height maps.
Inspection Capability
Scanning electron microscopy and optical interferometry often struggle with high-aspect-ratio trenches or suffer from optical artifacts on reflective metallic boundaries. This hybrid profiling system overcomes these limitations by utilizing piezo-actuated stages that coordinate coarse-step and fine-scan motions across millimeters of travel while retaining sub-nanometer vertical precision. Practitioners use this approach to measure the surface roughness of electrodeposited copper foils and build-up films prior to multi-layer lamination.
Defect Capture
Localized variations in lamination layer topography can lead to downstream lithography defects or solder joint weakness. Applying this probe-based analysis after wet etching and chemical mechanical planarization steps allows engineers to verify that line-edge roughness lies within allowable limits. It prevents high-frequency trace failures by quantifying localized structural variations before final copper deposition.
