Evaluating Semi Additive Process Yield Factors for High Density Substrates
Semi-additive yield depends on seed layer adhesion, lithographic trench verticality, and differential etch undercut control across sequential build-up layers.
Focused Ion Beam Metrology
Nanoscale Measurement
Nanoscale imaging and material removal use a gallium ion beam to examine the internal structures of semiconductor devices and high-density interconnects at the nanometer scale. The application of focused ion beam metrology allows for the precise measurement of cross-sectional features without the mechanical stress of traditional polishing. It provides the high-resolution data needed to verify the integrity of sub-surface vias and metal layers.
Structural Analysis
The process involves milling a small trench into the sample surface to expose the vertical stack-up of a circuit. Using focused ion beam metrology, a lab technician can measure the thickness of a diffusion barrier or identify a microscopic void in a solder joint that would be invisible to x-ray or optical tools. It reveals sub-surface defects.
Process Application
Because the ion beam can both remove and deposit material, it is also used for circuit editing to bypass a faulty connection on a prototype chip. While focused ion beam metrology is a slower and more expensive method than scanning electron microscopy, it offers the unique ability to see through the layers of a package. The data gathered from these measurements informs the design of future fabrication steps by showing exactly how the materials interact at the interface.
This tool is the final authority for verifying dimensions in high-performance electronics.