SURFACE MODIFICATION OF BASE MATERIALS FOR TEOS/O3 ATMOSPHERIC-PRESSURE CHEMICAL VAPOR-DEPOSITION

Atmospheric pressure tetraethyloxysilicane (TEOS)/O3 chemically vapor deposited provides excellent step coverage for submicron device structures; however, the properties of the deposited films depend on the surface characteristics of the base materials being used. To illustrate this dependence, the deposition rate of nondoped silicon dioxide obtained on a thermal oxide surface is significantly lower than the deposition rate obtained on a bare silicon surface. A new method to eliminate this base material dependence involving plasma treatment has been investigated. The optimum treatment consists of exposing the base materials to a nitrogen plasma for 1 min while maintaining the base materials at 250-degrees-C. Films deposited on thermal oxide base materials which have first been treated by this new method were found to have the same deposition rate, aqueous HF etch rate, and surface morphology as those films deposited on untreated bare silicon. In addition to a nitrogen plasma, oxygen and argon plasmas were studied and found to produce similar results when the base material temperature was raised to 350-degrees-C. The elimination of base material dependence through the use of this new plasma treatment technique has resulted in higher integrity TEOS/O3 oxides and has also expanded the range of applications for this unique planarizing technology for very large scale integrated device fabrication.