Method for making a silicon-on-insulator substrate

Claim 1

A method for forming an electrically isolated layer of monocrystalline silicon on a semiconductor substrate, comprising: (a) providing a semiconductor substrate having a major surface; (b) forming a mask of insulating material on the major surface, the mask including an aperture therethrough to the surface; (c) forming a layer of monocrystalline silicon through the aperture and over the mask; (d) forming a first oxidation-barrier layer on the monocrystalline silicon layer and a barrier-protection layer, of a different material, on the first oxidation-barrier layer, the first oxidation-barrier layer and barrier-protection layer including an aperture therethrough in a location corresponding to the aperture in the underlying insulator mask; (e) removing the monocrystalline silicon layer within the aperture in the insulator mask and between that aperture and the aperture in the first oxidation-barrier layer so as to form a cavity that exposes the substrate; (f) forming a second oxidation-barrier layer on the surface of the monocrystalline silicon layer exposed within the cavity; (g) thermally oxidizing the exposed portion of the substrate so as to yield an insulating plug having a surface which is coplanar with the insulator mask; (h) removing the portions of the first and second oxidation-barrier layers that are in contact with the monocrystalline silicon layer; and (i) epitaxially growing silicon from the remaining portions of the monocrystalline silicon layer so as to form a continuous monocrystalline silicon sheet overlying the insulator mask and plug.

Claim 2

A method for forming an electrically isolated layer of monocrystalline silicon on a semiconductor substrate, comprising: (a) providing a semiconductor substrate having a major surface; (b) forming a mask of insulating material on the major surface, the mask including an aperture therethrough to the surface; (c) forming a layer of monocrystalline silicon through the aperture and over the mask; (d) forming a first oxidation-barrier layer on the monocrystalline silicon layer and a barrier-protection layer, of a different material, on the first oxidation-barrier layer, the first oxidation-barrier layer and barrier-protection layer including an aperture therethrough in a location corresponding to the aperture in the underlying insulator mask; (e) removing the monocrystalline silicon layer within the aperture in the insulator mask and between that aperture and the aperture in the first oxidation-barrier layer so as to form a cavity that exposes the substrate; (f) forming a second oxidation-barrier layer on the surface of the monocrystalline silicon layer exposed within the cavity; (g) thermally oxidizing the exposed portion of the substrate so as to yield an insulating plug having a surface which is coplanar with the insulator mask; (h) removing the portions of the first and second oxidation-barrier layers that are in contact with the monocrystalline silicon layer; and (i) epitaxially growing silicon from the remaining portions of the monocrystalline silicon layer so as to form a continuous monocrystalline silicon sheet overlying the insulator mask and plug.