Advanced 3D heterogeneous integration requires precise control of surface topography, material removal and process uniformity. Achieving reliable picometer-scale metrology remains a key challenge, as existing measurement techniques have not yet fully matured to meet the stringent requirements of advanced semiconductor manufacturing. Correlative metrology has therefore become important for simultaneously achieving high throughput and picometer-scale measurement resolution.

Correlative metrology addresses this challenge by combining complementary measurement techniques. In collaborative work, we developed an ultra-fast correlative metrology system that combines high-accuracy phase-shifting interferometry (PSI) with active-probe atomic force microscopy (AP-AFM) with a throughput of 100 s/cm². PSI is a well-established optical metrology technique that measures optical phase related to surface topography, wavefront characteristics, and other optical parameters. Its high accuracy, full-field measurement capability, rapid acquisition, and non-destructive operation make PSI indispensable for semiconductor wafer inspection, particularly in chemical mechanical polishing (CMP) process control, where defects such as dishing must be carefully monitored.

Despite these advantages, PSI is susceptible to several sources of error. These include errors due to phase-step miscalibration, camera nonlinearity, multiple-beam interference, vibration or turbulence-induced phase variations, and image sensor noise. AP-AFM provides quantitative nanoscale topography and can be used to characterize selected regions and individual CMP features in greater detail. The following measurements illustrate how nano analytik’s AP-AFM supports CMP metrology.