Analysis of hydroxyl group controlled atomic layer deposition of hafnium dioxide from hafnium tetrachloride and water
Abstract
Atomic layer deposition (ALD) has recently gained interest because of its suitability for the fabrication of conformal material layers with thicknesses in the nanometer range. Although the principles of ALD were realized 30 to 40 years ago, the description of many physicochemical processes that occur during ALD growth is still under development. “Substrate-inhibited (SI)” ALD growth is one phenomenon not yet well understood. In SI-ALD, the growth-per-cycle (GPC) increases in the beginning of the growth, goes through a maximum, and levels off to a constant value. The origin of SI growth is investigated in this work with two recent models of ALD: Model A of Puurunen [Chem. Vap. Deposition 9, 249 (2003)] and Model B of Alam and Green [J. Appl. Phys. 94, 3403 (2003)]. The hafnium tetrachloride/water ALD process, of interest for gate dielectric applications, is taken to represent typical SI growth. The possible reaction chemistry is evaluated with two models: Model C of Ylilammi [Thin Solid Films, 279, 124 (19...