Development of ALD HfZrOx with TDEAH, TDEAZ and H2O

Abstract

A 300mm ALD HfZrOx process using TDEAH, TDEAZ, and H2O is developed. This process applies a nano-laminate approach to grow a HfZrOx film by intermixing ALD HfO2 and ZrO2 around 250{degree sign}C. It is found that the corresponding Zr content of the film, measured by RBS, increases linearly with the cycle ratio of Zr/(Zr+Hf). In addition, the initial growth behavior of the HfZrOx film of this unique process is insensitive to the starting surface condition and eliminates the long incubation as observed for the halide-based ALD processes. The as-deposited HfZrOx films are amorphous, which can be crystallized with a 950{degree sign}C postdeposition anneal. Depending on the film composition, a different crystalline phase is formed ranging from monoclinic to tetragonal with increasing Zr content. CMOS transistors, using HfZrOx as gate dielectric, are fabricated for the evaluation of the corresponding device performance. Device results show that all splits with HfZrOx as gate dielectric yield not only a similar EOTJg performance but also very low leakage, which demonstrate that ALD HfZrOx is a promising candidate for sub-1nm EOT scaling.