IN-SITU INFRARED SPECTROSCOPIC ELLIPSOMETRY FOR BLANKET ALUMINUM CHEMICAL-VAPOR-DEPOSITION ON TIN AND ON SIO2 SI/

Monitoring of layer growth during metalorganic chemical vapor depositi on (MOCVD) is restricted to optical methods such as reflectance measur ements. We use the high sensitivity of the phase modulated infrared sp ectroscopic ellipsometer (IREL) to observe in situ the properties of g rowing aluminum layers on TiN and SiO2. The spectral range of the IREL is from 930 cm(-1) to 4500 cm(-1), the resolution is 8 cm(-1) and a t ypical measurement takes 30 s. In the case of aluminum deposition on S iO2, after a wetting treatment with TDMAT (tetrakisdimethylaminotitani um), the delta spectra rapidly change from the oxide spectrum to that of an aluminum layer. A time sequence of the delta values (Delta) chos en at a suitable wavenumber (e.g. 2600 cm(-1)) shows the typical growt h behavior of incubation, nucleation, island growth, coalescence and i ncreasing roughness for the aluminum layer on TiN layers. IREL is able to monitor the aluminum layer growth up to complete coalescence with high sensitivity. The maximum of delta Delta(max) is correlated with t he thickness at which complete coalescence occurs. This is connected w ith low surface roughness and a resistivity of 3 mu Omega cm. The thic kness at Delta(max) depends on partial pressure (0.5-60 mu bar) of DMA H (dimethylaluminumhydride) and on the wetting behavior of the bottom layer. Hydrogen remote plasma treatment gives improved wetting of TiN layers for Al MOCVD under our conditions and earlier coalescence durin g Al growth as detected by IREL. (C) 1998 Elsevier Science S.A.