Application of HfSiON to Deep Trench Capacitors of Sub-45nm Node Embedded DRAM

Abstract

ALD HfSiOx was applied to the node dielectric of deep trench (DT) capacitors of the 65nm node embedded DRAM (eDRAM) for the first time. As a result, capacitance enhancement of 30% from the conventional dielectric (NO) was achieved at the same level of leakage current. The main features of our ALD process are 1) a uniform thickness and depth profile of each component in DT by taking advantage of a catalytic effect of the precursors and 2) a reduced amount of impurities in the film without causing any degradation of step coverage.

Evaluation of Trisilylamine for HfSiOx Atomic Layer Deposition

“…Alkoxyhafniums, especially Hf(OtBu) 4 , tend to decompose after adsorption (8), which is an incompatible phenomenon with a genuine ALD process. The reported process results for ALD HfSiO using amidohafnium and aminosilane have measurable amounts of C incorporated in the film (9). The incorporation of C has been directly linked to changes in the leakage current by Ando et al (9), and as this property is a key parameter for device reliability and performance, means of controlling and minimizing the incorporated Comparing the bond strengths of the hafnium amido ligand and that of silicon amino, it is expected that carbon incorporation in the ALD films may be strongly influenced by the structure of the silicon precursor.…”