Physical and Electrical Characterization of Hafnium Silicate Thin Films

Abstract

ABSTRACTEvaluation of physically thicker gate insulator materials with significantly higher dielectric constants (k = 10 – 25) as potential replacements for silicon dioxide, SiO2 (k = 3.9), and silicon oxynitride continues to be a focus of the semiconductor industry. The challenge is to provide a film with lower leakage current and with capacitance equivalent to < 1.0 nm SiO2 [1–4]. One such candidate material; metal-organic chemical vapor deposited (MOCVD) hafnium silicate, has been physically characterized by high resolution transmission electron microscopy (HRTEM) in plan view, as a blanket, uncapped film and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) in cross section following integration into capacitors and complementary metal oxide semiconductor (CMOS) transistors. Changes in the material microstructure associated with phase segregation and crystallization as a function of Hf silicate composition and rapid thermal anneal (RTA) temperature have been observed and a discussion of the segregation mechanisms is presented [5–8]. Also, various methods of incorporating nitrogen into bulk hafnium silicate films have been investigated and resultant transistor electrical performance data has been correlated with physical characterization for NH3 post deposition anneal (PDA) treatments at various temperatures.