The Latest in XRF Coatings Analysis Equipment for Micro-Scale Semiconductor Packaging

Abstract

X-ray fluorescence (XRF) analysis is a widely used technique to measure plating thickness. Its main advantage resides in allowing simultaneous, non-destructive analysis of multilayered plated parts. The miniaturization and increasing complexity of electronic devices proliferated by advancements in smartphone functionality continues with the rise of microelectromechanical systems (MEMS). Consequently, the electronic components and features for these devices are becoming as miniscule as ever. In order to maintain the necessary quality of these components, the measuring and control of the plating thickness and composition is critical. For this application, an XRF plating thickness analyzer capable of high accuracy measurement in small areas is essential. Utilizing the latest X-ray focusing polycapillary technology with a high-sensitivity detector, modern XRF systems deliver high-precision measurements of nanometer-scale plating. The beam diameter of less than $20 \mu \mathrm{m}$ (full width at half maximum, FWHM) not only allows plating thickness measurements, but also composition analysis, useful for solder bumps. This allows for an outstanding measurement repeatability, achieving precision of 1% RSD for gold plating at 100 A. Furthermore, the levels of irradiated energy are lower than those utilized in wavelength dispersive techniques (WDXRF), thus considerably reducing the potential damage to the sample. This paper discusses XRF as an analytical technique for determining the thickness of plated or coated layers applied to a substrate. The effects of layer structure and properties on multilayer XRF thickness measurements are investigated.