Metrological Step Height Verification for Cluster Processed Amorphous Substrates
Step height verification on cluster-processed amorphous substrates requires guardbanded metrology and tip-force or dispersion compensation to prevent yield loss.
Stylus Profilometry
Contact Metrology
Surface measurement techniques that use a physical probe to track the topography of a sample provide high-resolution data on roughness and feature height. During stylus profilometry, a diamond-tipped needle moves across the substrate with a controlled force to record vertical displacements. This data creates a two-dimensional profile that allows for the calculation of standardized parameters like Ra and Rz. Reliable results emerge because the method remains unaffected by the optical properties of the material, such as transparency or reflectivity, which can confuse laser-based systems.
Physical Interaction
Vertical resolution depends on the sensitivity of the transducer and the noise level of the environment. As the tip moves, it converts mechanical movement into an electrical signal. Modern systems can detect changes as small as one nanometer, making them suitable for inspecting thin films and semiconductor gates.
Surface Limitation
Soft materials like photoresist or uncured polymers can be scratched by the probe if the pressure is too high. The radius of the tip also limits the ability to measure narrow trenches, as a large tip cannot reach the bottom of a deep, thin groove. Choosing the correct tip size and force is therefore a prerequisite for obtaining a valid measurement of a circuit board surface.