Recovery of fragile layers produced on substrates by chemical vapor deposition

Claim 1

A method of recovering intact at room temperature a layer of a first material produced by depositing it from the gas phase at a deposition temperature above room temperature on a substrate of a second material having a lower melting point and a different coefficient of thermal expansion than that of the first material, the uncoated side of the substrate being the underside of the substrate and the side of the layer adjacent to the substrate being the underside of the layer, comprising the steps of: supporting the substrate underside around its perimeter along a support plane at a non-orthogonal incline from horizontal; separating the substrate from the layer by heating the substrate to melt the substrate from the layer; receiving the freed layer underside around its perimeter along a plane parallel to the support plane after it displaces in the range of the thickness of the substrate; and cooling the separated layer to room temperature, whereby the separated layer is not subjected to stresses caused by the different thermal expansion of the substrate and layer when they are cooled to room temperature.

Claim 2

A method of recovering intact at room temperature a layer of a first material produced by depositing it from the gas phase at a deposition temperature above room temperature on a substrate of a second material having a lower melting point and a different coefficient of thermal expansion than that of the first material, the uncoated side of the substrate being the underside of the substrate and the side of the layer adjacent to the substrate being the underside of the layer, comprising the steps of: supporting the substrate underside around its perimeter along a support plane at a non-orthogonal incline from horizontal; separating the substrate from the layer by heating the substrate to melt the substrate from the layer; receiving the freed layer underside around its perimeter along a plane parallel to the support plane after it displaces in the range of the thickness of the substrate; and cooling the separated layer to room temperature, whereby the separated layer is not subjected to stresses caused by the different thermal expansion of the substrate and layer when they are cooled to room temperature.

Claim 7

A method of recovering intact at room temperature a layer of a material produced by depositing it from the gas phase at a deposition temperature on a silicon substrate having a lower melting point and a different coefficient of thermal expansion than that of the material, the uncoated side of the substrate being the underside of the substrate and the side of the layer adjacent to the substrate being the underside of the layer, comprising the steps of: supporting the substrate underside around its perimeter along a support plane at an incline from horizontal in the range of 20 degrees; separating the substrate from the layer by heating the substrate to a temperature sufficiently above its melting point to melt the substrate and reduce the viscosity of the melted substrate to favor its separation from the layer, and for a short enough time so that the layer is not dissociated; receiving the freed layer underside around its perimeter along a plane parallel to the support plane after it displaces in the range of the thickness of the substrate; and cooling the separated layer to room temperature, whereby the separated layer is not subjected to stresses caused by the different thermal expansions of the substrate and layer when cooled.

Claim 8

A method of recovering intact at room temperature a layer of a material produced by depositing it from the gas phase at a deposition temperature on a silicon substrate having a lower melting point and a different coefficient of thermal expansion than that of the material, the uncoated side of the substrate being the underside of the substrate and the side of the layer adjacent to the substrate being the underside of the layer, comprising the steps of: supporting the substrate underside around its perimeter along a support plane at an incline from horizontal in the range of 20 degrees; separating the substrate from the layer by heating the substrate to a temperature sufficiently above its melting point to melt the substrate and reduce the viscosity of the melted substrate to favor its separation from the layer, and for a short enough time so that the layer is not dissociated; receiving the freed layer underside around its perimeter along a plane parallel to the support plane after it displaces in the range of the thickness of the substrate; and cooling the separated layer to room temperature, whereby the separated layer is not subjected to stresses caused by the different thermal expansions of the substrate and layer when cooled.

Claim 13

A method of recovering intact at room temperature a layer of silicon carbide produced by depositing it from the gas phase at 1400° C. on a silicon substrate, the uncoated side of the substrate being the underside of the substrate and the side of the layer adjacent to the substrate being the underside of the layer, comprising the steps of: supporting the substrate underside around its perimeter in a hemispherical cavity formed in the upper face of a susceptor positioned with an incline from horizontal in the range of 20° degrees; separating the substrate by heating it to a temperature in the range of 1500° C. to 1550° C. for less than a minute to melt the substrate from the layer; receiving the freed layer underside along its permimeter in the hemispherical cavity after the layer displaces in the range of the thickness of the substrate; and cooling the separated layer to room temperature; whereby the separated layer is not subjected to stresses caused by the different thermal expansions of the substrate and layer when cooled.

Claim 14

A method of recovering intact at room temperature a layer of silicon carbide produced by depositing it from the gas phase at 1400° C. on a silicon substrate, the uncoated side of the substrate being the underside of the substrate and the side of the layer adjacent to the substrate being the underside of the layer, comprising the steps of: supporting the substrate underside around its perimeter in a hemispherical cavity formed in the upper face of a susceptor positioned with an incline from horizontal in the range of 20° degrees; separating the substrate by heating it to a temperature in the range of 1500° C. to 1550° C. for less than a minute to melt the substrate from the layer; receiving the freed layer underside along its permimeter in the hemispherical cavity after the layer displaces in the range of the thickness of the substrate; and cooling the separated layer to room temperature; whereby the separated layer is not subjected to stresses caused by the different thermal expansions of the substrate and layer when cooled.