Ftir Studies of Silica Surface Passivation and Subsequent Adsorption/Desorption Behavior of Copper Metalorganic Precursors

The passivation of silica surfaces and the subsequent adsorption/desorption of (hfac)Cu(2-butyne) and (hfac)Cu(VTMS) precursors were studied. The goal was to enhance the selective deposition of copper from these compounds during chemical vapor deposition (CVD). The passivation reagents were hexamethyldisilazane (HMDS) and triisobutylaluminum (TIBA). Surface passivation with HMDS shielded the hydrogen-bonded surface hydroxyl groups and the strained siloxane surface sites making them inaccessible to both (hfac)Cu(VTMS) and (hfac)Cu(2-butyne) where hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate and VTMS = vinyltrimethylsilane. The adsorbed copper(I) compounds molecularly desorbed from the HMDS-passivated surface below 125 °C. The surface groups resulting from the reaction of TIBA with the silica surface reacted with the copper compounds subsequently adsorbed at 275 °C. The reaction products were present on the surface above 450 °C. These results demonstrate the utility of SiO2 surface modification using HMDS for control of selective CVD of copper.