Deposition of High-k Dielectric Oxide Films by Liquid Injection MOCVD

Abstract

ZrO₂, HfO₂, La₂O₃ and their related silicates are candidates to replace SiO₂ as the gate dielectric material for sub-0.1 μm CMOS technology, and metalorganic chemical vapour deposition (MOCVD) is an attractive technique for the deposition of these materials. However, there are problems associated with many of the existing Zr and Hf oxide precursors. In this paper, we describe the liquid injection MOCVD of ZrO₂ and HfO₂ using the new improved alkoxide precursors [M(OBu^t)₂(OCMe₂CH₂OMe)₂] and [M(OCMe₂CH₂OMe)₄] (M = Zr, Hf). The growth of high quality La₂O₃ or LaSi_xO_y films by MOCVD has also proved difficult due to a lack of suitable precursors, and in this paper we describe the use of [La[N(SiMe₃)₂]₃] for the liquid injection MOCVD of LaSi_xO_y, in the absence of an added Si source. High frequency C-V measurements for MOS-capacitors fabricated from ZrO₂, HfO₂ and LaSi_xO_x demonstrate the feasibility of using liquid injection MOCVD to deposit MOS gate dielectric films at low process temperature.

Keywords:

• MOCVD
• precursors
• zirconium oxide
• hafnium oxide
• lanthanum silicate