Patent ID: 8008215

Claim:
A method of forming a stable dielectric stack comprising: providing a substrate, forming a layered structure on said substrate comprising of layers of different materials so as to define the stable dielectric stack having large area buried oxide structures, one of said different materials is selected to be an oxidizable material to form one or more buried low index oxide layers; performing a first sequence of oxidizing steps on said structure by exposing the edges of the said layered structure to a number of controlled succession of temperature linear increases in the presence of steam from an initial temperature to the desired oxidation temperature for a time interval equal to the sum of the time intervals of said succession of linear temperature increases, the linear succession of temperature increases involves a ramping up from the initial temperature to the desired oxidation temperature; performing a second sequential oxidizing step with steam on said layered structure at said specific oxidation temperature for a specific time interval; and performing a final sequence of oxidizing steps on said structure by linearly ramping down in the presence of steam from said desired oxidation temperature to a final temperature when said oxidizing material is oxidized to form said one or more buried low index oxide layers so as to avoid delamination within the stable dielectric stack having large area buried oxide structures.