A CHEMISTS VIEW OF PRECURSORS AND PROCESSES FOR THE PRODUCTION OF HAFNIUM-BASED HIGH-K DIELECTRICS

The four major Hf precursors used by the industry are reviewed, compared and contrasted. The production of Hf-based chemicals proceeds through HfCl4, the first of the four major Hf precursors used by the industry, and the precursor to all Hf based materials. The synthesis of the other three major Hf precursors (TEMAH, TDEAH and Hf t-butoxide) starting from HfCl4 provides a rational model for the major impurities commonly found in these materials. Analysis of these impurities in Hf-based precursors is reviewed, including the influence that differing sample preparation methods can have on analytical results leading to apparently different analyses of the same chemical batch. Thermal stability of the Hf precursors is also reviewed. Using our knowledge of the chemical reactivity of these precursors with protic reagents we were able to design a CVD method for producing HfSiON films