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What methodology does Versum Materials use to establish thermal stability of CVD and ALD precursors?

In depth understanding of thermal stability of CVD and ALD precursors is critical for their successful commercialization. As a supplier of highly reactive and energetic materials to the semiconductor industry, Versum Materials developed strong capabilities to fully characterize thermal stability of our precursors at all stages of the commercialization process. Initial precursor selection starts from understanding the feasibility of precursor delivery by its evaporation from liquid or solid phase.

Versum Materials also developed methodology to calculate vapor pressure of organosilicon and organo-metallic precursors from TGA analysis. To further understand thermal stability of precursors, Versum Materials is using differential scanning calorimetry (DSC) and a thermal screening unit (TSU). These instruments are used to characterize phase changes and decomposition events during the heating. To ensure safe delivery of highly energetic precursors to the tool, Versum Materials conducts TSU analysis to monitor the pressure and sample temperature as a function of the oven temperature. TSU analysis provides important information about precursor thermal decomposition or phase change events.

To characterize precursor stability on the customer tool, Versum Materials conducts long-term thermal tests, where the precursor is heated for 1-16 weeks at temperatures used on the customer tool. For other applications, accelerated-aging experiments are conducted by heating the precursor at an elevated temperature for 1-4 weeks to estimate the degradation rate at ambient temperature for preliminary shelf-life determination or long-term storage purposes*. The precursor is analyzed before and after heating by a variety of analytical methods to gauge the thermal stability under simulated process or ambient storage conditions. During final precursor production scale up, Versum Materials conducts an accelerated rate calorimetry test, which is an extremely sensitive technique, to detect the onset of precursor thermal decomposition.

These methods are complimentary analytical components that allow Versum Materials to characterize key thermal stability parameters of precursors to ensure optimal performance and safety. The knowledge and expertise of Versum Materials scientists has helped many customers to safely and successfully bring new materials into production.

*ASTM method F1980-07, Standard Guide for Accelerated Aging


Steve Mayorga is a research associate and has been with the company for 26 years. He graduated from the UC Berkeley with a Ph.D. in Inorganic Chemistry.