Si–TiO interface evolution at prolonged annealing in low 2 vacuum or N O ambient

Titanium dioxide layers were obtained by the low-pressure chemical vapour deposition LPCVD.method from a TiCl4, H2 and N2O mixture at 6308C and had rutile modification. The dielectric constant of the titanium dioxide is high, approximately 110, and the breakdown electric field strength more than 1 MVrcm. The fixed charge for the Si–TiO2 structures is negative and has a value in the order of 5=10y8 C cmy2 and the interface state density of these structures is 6=1010 eVy1 cmy2. After annealing in oxidizing ambient, the dielectric constant is found to fall off, and the interface density of states of the Si–TiO2 structures is increased. It is proposed that this is connected with the Si–TiO2 interface evolution by the formation of a superthin silicon dioxide layer. q2000 Elsevier Science B.V. All rights reserved.