Metrology for Airborne
Molecular Contaminants II

Airborne Molecular Contamination (AMC) in the form of chemical vapours or aerosols has an adverse effect on products, processes or instruments. Technological progress is driven by the ability to operate at ever smaller scales and with greater complexity, thus increasing the demand for lower AMC concentration measurement. Real time online monitoring is critical to ensure that corrective action is taken before this impacts on production costs.

Therefore, this project focusses on developing underpinning metrology focused on new ultra-sensitive spectroscopic techniques and high accuracy reference materials at extremely low concentrations for key AMCs. These developments are urgently needed in order to improve manufacturing processes and to control contamination. The aim is to increase industrial competitiveness, reduce down time and remove barriers to efficient manufacturing.

The need

The European semiconductor industry supports ~200,000 European jobs directly and more than 1,000,000 jobs indirectly. The global turnover of the semiconductor sector was ~€230 billion in 2012, with micro and nano electronic components manufacturing having a turnover of around €1,250 billion in 2012. The manufacture of micro and nano electronics is estimated at 10 % of worldwide GDP (European Semiconductor Industry Association (ESIA) data). Europe currently has 9 % of the world share of the semiconductor manufacturing industry, representing $27 billion, with plans, outlined in a European Leaders Group report, to increase this to 20 % by 2025. In this high value business, the need is clearly demonstrated because a small increase in the yield can lead to savings/profits of hundreds of millions of euros.

Progress in advanced technology requires operation at an ever smaller scale with increased complexity. Adverse AMC-related effects can occur in electronics production including, for example, the corrosion of metal surfaces on the wafer, and the formation of contamination layers. These AMCs come from sources including process chemicals, filter breakthrough, building and cleanroom construction materials and operating personnel. Regulations and analytical capabilities in this field are much less well developed than in the field of contamination by particles. AMCs generated as part of the production process need to be detectable at concentrations below 1 nmol/mol as these are detrimental to the product. There is therefore a need to extend the findings of previous studies to other AMCs (e.g. HCl), to improve detection sensitivity, and to increase the range of dynamic reference standards.

Improved real time measurements of AMC are essential in order to enable corrective actions to be taken before production yields are affected and to demonstrate compliance with ISA Standard S71.04. There are currently no NMI realised standards for HCl with which compliance can be verified. Available instrumentation is often not fit-for purpose due to high costs, large size, measurement rate or limited reliability. This is substantiated in the International Technology Roadmap for Semiconductors (ITRS), which states ‘There is clearly a need for better AMC monitoring instrumentation in the cleanroom to measure AMC at the part-per trillion level (by volume) in real time’.