Electron beam heating and atomic surface restructuring of sapphire surface
AssigneeUnited States of America as represented by the Administrator of NASA
InventorsSang H. Choi, Adam J. Duzik
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Abstract
Systems, methods, and devices of the various embodiments may provide a mechanism to enable the growth of a rhombohedral epitaxy at a lower substrate temperature by energizing the atoms in flux, thereby reducing the substrate temperature to a moderate level. In various embodiments, sufficiently energized atoms provide the essential energy needed for the rhombohedral epitaxy process which deforms the original cubic crystalline structure approximately into a rhombohedron by physically aligning the crystal structure of both materials at a lower substrate temperature.
Claims17
A method for heating a wafer to support epitaxy film growth on the wafer, comprising:
- providing the wafer, wherein the wafer is a sapphire wafer;
- heating the wafer with a radiative heating element;
- locally restructuring a crystalline structure of a surface of the wafer by applying irradiation to locally heat the surface of the wafer with an electron beam until the surface of the wafer reaches a selected surface temperature for a selected duration, wherein applying the irradiation includes modifying the atomic crystalline structure of the surface of the wafer by colliding electrons of the electron beam with surface atoms in a top layer of the wafer and therein heating the surface atoms to a temperature that is higher than the temperature of the rest of the wafer and sufficient to provide energy needed for deforming an original cubic crystalline structure of a growing epitaxy film into a rhombohedron;
- and
- growing the epitaxy film on the wafer during or after applying the irradiation, wherein growing the epitaxy film includes using the modified atomic surface crystalline structure to facilitate single-crystal epitaxial layer growth.
A vacuum deposition system, comprising:
- a growth chamber configured to support a sapphire wafer therein, the sapphire wafer having a diameter;
- a radiative heating element configured to heat a back surface of the sapphire wafer;
- a flood electron beam gun rated for providing 40 keV to 50 keV electron beam energy, wherein the flood electron beam gun is configured in the growth chamber to make an expansion angle of an electron beam of the flood electron beam gun illuminate a whole surface area of a front surface of the sapphire wafer opposite the back surface based on the sapphire wafer's diameter and wherein the flood electron beam gun has been configured in the growth chamber such that the electron beam uniformly irradiates and evenly heats the front surface of the sapphire wafer via thermalization losses from colliding electrons of the electron beam with the front surface of the sapphire wafer to modify the crystalline structure of the surface by the collision of the colliding electrons of the electron beam with surface atoms in a top layer of the sapphire wafer and therein heating the surface atoms to a temperature that is sufficient to provide energy needed for deforming an original cubic crystalline structure of a growing epitaxy film into a rhombohedron to facilitate single-crystal epitaxial layer growth.
Dependencies are inferred from the claim text.