CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

esistivity was measured by four point probe and its dependency on plasma power has been
investigated.
3.2 Tetrakis (Dimethylamido) Hafnium (IV) (TDMAH) Adsorption and Reaction on
Hydrogenated Si(100) Surface
3.2.1 Introduction
TDMAH is in the form of colorless to pale yellow crystal at room temperature, which has
a melting point of around 30˚C and a vapor pressure of around 0.1 torr at 48˚C. This material is
moisture sensitive and should be handled in low temperature and/or inert environment. Its
molecular structure is showed in Fig.21.
Fig. 21. Molecular structure of TDMAH.
One of the important concerns for ALD precursors is their thermal stability. If the
precursors decompose in the process of transporting to the substrate surface or on the substrate
surface, it's likely to induce continuous thin film growth and break the rule of self-terminating
adsorption. It's noteworthy that the kinetics of thermal decomposition also has to be considered,
if the degree of decomposition is negligible in the ALD cycle time range, it should not be a big
issue to affect the thin film growth.[8] Another concern for the ALD precursors is the surface
reactivity, i.e., the activation barrier for interfacial bond formation between the precursor and the
surface dangling bonds has to be low enough to allow film growth. In-situ ATR-FTIR is one
efficient way to achieve all of these information through monitoring the surface adsorption and
reaction behavior of precursor molecules. TDMAH has been widely used in ALD of HfO2, but
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