Abstract
At. layer deposition (ALD) has become an established technique for producing thin films of a wide range of materials. Of particular note is the extensive research on the use of ALD metal oxide films as the replacement for the high-k SiO2 dielec. layer in future semiconductor devices. In much of this work, metal halides or metallorgs. combined with water, peroxide or ozone have served as precursors for the sequential deposition process that forms the basis of ALD. Alternative reaction schemes, such as those in which metal halides are reacted with metal alkoxides, have also been investigated with some success though higher temps. are often required for film deposition. However, the effect of alternative oxidising species in ALD has not been extensively studied in terms of both their efficacy and their influence on the film growth process. Here we describe recent work on the use of t-Bu alc. (tBA) and di-iso-Pr ether (DIPE) for the ALD of titania films from titanium tetrachloride. A quartz crystal microbalance (QCM) was used to monitor film growth in real time. Films were also grown on silicon wafers for post-deposition anal. Spectroscopic ellipsometry, at. force microscopy (AFM), X-ray diffraction (XRD) and secondary ion mass spectrometry (SIMS) were used for this purpose. The results obtained from this combination of surface anal. techniques will be discussed in detail in order to illustrate the strength of this approach for the elucidation of ALD film growth by means of non-hydrolytic reactions.