| 主权项 |
1. In a composite structure comprising an oxide bonding layer and a thin film bonded to a support substrate, a method of preventing microcavity formation in the bonding layer due to irreversible transition of the oxide from an elastic mode of deformation to a plastic mode of deformation resulting from creep and thermal expansion due to high temperature exposure of the composite structure, which method comprises:
providing the thin film with a thickness of 5 micrometers or less; providing the bonding layer of oxide with a thickness that is equal to or greater than the thickness of the thin film, with the bonding layer formed between the support substrate and the thin film by low pressure chemical vapor deposition (LPCVD) on either a bonding face of the support substrate or a bonding face of the thin film, or both, to produce the deposited oxide of the bonding layer with a temperature stability that is close to that of an oxide obtained by thermal oxidation; selecting the thin film or support substrate, whichever is to receive the bonding layer, to be of a material having a mean thermal expansion coefficient of 7×10−6 K−1 or more; and bonding the thin film to the support substrate with the bonding layer therebetween, wherein the combination of the thin film, bonding layer and support substrate reduce stress in and plastic deformation of the bonding layer during exposure to high temperatures of more than approximately 900° C. to thus prevent microcavities from appearing in the bonding layer. |
