Unexpected surface or near-surface contamination can shut down a million dollar manufacturing process so it is invaluable to understand and control any sources of contamination. Extensive characterization time and money is spent identifying contaminants, searching for their sources and also measuring the effectiveness of eliminating costly contaminants.
Deciding which technique(s) to use depends on the suspected nature of the contamination which is where experience and knowledge of processes helps solve the problem faster. The answers to the following questions influence which analytical tool(s) to use to analyze the problem.
- Are your gloves contaminating your products with Silicone Oil, NaCl, hydrocarbons, CaSO4?
- Could contaminant be organic or is it inorganic?
- Could there be a lot of contamination or only a little?
- Is the contamination visible to the eye under a microscope? Or, is it visible under SEM?
- Optical inspection or SEM often reveals if the contamination is widespread, localized, or particulate?
- If the contamination can not be seen on the surface, then it is possibly buried at an interface, or in the bulk?
- If the contamination might be at the parts per million level then the scientist will seek out tools that can measure ppm level concentrations. If you find a pale yellow color using just your eyes, then there is a good chance the contamination is in the PPM range.
Listed below are techniques that might be used. Deciding which technique(s) to use can be resolved if optical inspection reveals irregular patterns, unexpected particles, spots, peeling etc. The XY dimensions of an optically visible contaminant helps us to select which tools to try first. A combination of techniques may be needed, especially when little is known about the contamination or optical inspection gives no clues.
Residues, Continuous Films
Near-Surface Buried Layer
Particles (size affects tool to use)