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XPS, ESCA
X-ray Photoelectron Spectroscopy
In X-ray Photoelectron Spectroscopy, solid state specimen is bombarded with soft X-rays in ultra vacuum condition, to eject electrons from the outermost atomic layers of the surface, allowing us to identify the elements (except for H, He), to quantify the atomic concentrations (with lower limit of approximately 0.1 at%) and to determine chemical bonding between elements present in the layers.
Another term for this technology is “ESCA” (Electron Spectroscopy for Chemical Analysis), since valuable information about the chemistry is also available.
Any material, such as metal, semi-conductor, glass, ceramic, organic substances, or polymer material can be analyzed by means of XPS. On the other hand, the technology is not suitable for analysis on microscopic area (less than 100µm in diameter). However, microscopic analysis around 10µm in diameter comes to be possible by means of system called Micro XPS.
XPS presents excellent analysis capability when it comes to problems related to thin film, junction, solderability, corrosion, discoloration, contamination, cleaning, adhesion, adsorption or surface processing.
Equipment
XPS:S-Probe (SSI)
XPS:PHI Quantera SXMTM (ULVAC-PHI)
Example
Foreign material on Chip surface
What is the foreign material near the solder bump?
SXI (scanning X-ray image) can provide the precise location of the foreign material.
In addition, the system can analyze the minute size foreign material, thanks to it’s fine beam diameter (minimum 9um).
Image on the right shows OK and NG area which are located at the equal distance from solder bump, considering the equivalence of the effect of the solder bump.
Sn detected only in NG area.
Identify the element of the thin foreign material!
A foreign material that contains Sn as its main element adheres on the surface.
Coating peel-off in plastic component
XPS spectrum - Surface analysis result on storage tray (3)
Contaminant Silicon on storage tray adheres to component surface, causing peel off in coating.
Residual resist on Metal spatter film surface
