Grain-driven zone-melting of silicon films on insulating substrates

Claim 1

The method of forming a single crystal silicon layer on a silicon oxide insulator layer which comprises; forming a silicon oxide insulator layer on a single crystal silicon wafer disc base and forming a slit window in the silicon oxide insulator layer to expose the upper surface of the single crystal silicon wafer disc; forming a polycrystalline silicon layer on the silicon oxide insulator layer; seeding the polycrystalline silicon layer from the single crystal silicon wafer disc base by forming a melt zone with a eutectic alloying agent aligned with said slit window; heating the single crystal silicon wafer disc and the silicon oxide insulator layer and the polycrystalline silicon layer to an isothermal temperature substantially below the melting point of the silicon but above the melting point of the eutectic; maintaining the isothermal temperature at a level to cause the melt zone to advance into the polycrystalline silicon layer, and to cause a single crystal silicon layer to form from the polycrystalline silicon layer at the trailing edge of the melt zone; and cooling the single crystal silicon wafer disc base and the silicon oxide insulator layer and the single crystal silicon layer after the polycrystalline silicon layer has been converted to a single crystal silicon layer.

Claim 2

The method of forming a single crystal silicon layer on a silicon oxide insulator layer which comprises; forming a silicon oxide insulator layer on a single crystal silicon wafer disc base and forming a slit window in the silicon oxide insulator layer to expose the upper surface of the single crystal silicon wafer disc; forming a polycrystalline silicon layer on the silicon oxide insulator layer; seeding the polycrystalline silicon layer from the single crystal silicon wafer disc base by forming a melt zone with a eutectic alloying agent aligned with said slit window; heating the single crystal silicon wafer disc and the silicon oxide insulator layer and the polycrystalline silicon layer to an isothermal temperature substantially below the melting point of the silicon but above the melting point of the eutectic; maintaining the isothermal temperature at a level to cause the melt zone to advance into the polycrystalline silicon layer, and to cause a single crystal silicon layer to form from the polycrystalline silicon layer at the trailing edge of the melt zone; and cooling the single crystal silicon wafer disc base and the silicon oxide insulator layer and the single crystal silicon layer after the polycrystalline silicon layer has been converted to a single crystal silicon layer.

Claim 13

The method of forming a single crystal layer on an insulating substrate which comprises disposing a polycrystalline silicon layer on said insulating substrate, disposing an alloying metal on a portion of said polycrystalline layer and heating said polycrystalline layer and alloying metal to form a eutectic metal zone in contact with said polycrystalline layer, disposing a single crystal silicon seed at one surface of said melt to permit growth of said single crystal from material of said melt, and maintaining the wafer heated to cause the melt to advance into the polycrystalline layer and the deposit of single crystal to follow the melt advance.

Claim 14

The method of forming a single crystal layer on an insulating substrate which comprises disposing a polycrystalline silicon layer on said insulating substrate, disposing an alloying metal on a portion of said polycrystalline layer and heating said polycrystalline layer and alloying metal to form a eutectic metal zone in contact with said polycrystalline layer, disposing a single crystal silicon seed at one surface of said melt to permit growth of said single crystal from material of said melt, and maintaining the wafer heated to cause the melt to advance into the polycrystalline layer and the deposit of single crystal to follow the melt advance.

Claim 25

The method of forming single crystal layers on insulating substrates at high production rates which comprises forming an insulating layer on a single crystal silicon wafer, forming a number of slit windows through said insulating layer to expose said single crystal silicon wafer, depositing a polycrystalline silicon layer on said insulating layer and through the windows thereof, disposing a eutectic forming metal on said polycrystalline layer over said window, heating the resulting structure to melt the polycrystalline silicon occupying said windows into a eutectic composition, and continuing to heat said structure to convert the polycrystalline silicon layer to a single crystal silicon layer.

Claim 26

The method of forming single crystal layers on insulating substrates at high production rates which comprises forming an insulating layer on a single crystal silicon wafer, forming a number of slit windows through said insulating layer to expose said single crystal silicon wafer, depositing a polycrystalline silicon layer on said insulating layer and through the windows thereof, disposing a eutectic forming metal on said polycrystalline layer over said window, heating the resulting structure to melt the polycrystalline silicon occupying said windows into a eutectic composition, and continuing to heat said structure to convert the polycrystalline silicon layer to a single crystal silicon layer.