CURVATURE COMPENSATED SUBSTRATE AND METHOD OF FORMING SAME

摘要

A curvature-control-material (CCM) is formed on one side of a substrate prior to forming a Group III nitride material on the other side of the substrate. The CCM possess a thermal expansion coefficient (TEC) that is lower than the TEC of the substrate and is stable at elevated growth temperatures required for formation of a Group III nitride material. In some embodiments, the deposition conditions of the CCM enable a flat-wafer condition for the Group III nitride material maximizing the emission wavelength uniformity of the Group III nitride material. Employment of the CCM also reduces the final structure bowing during cool down leading to reduced convex substrate curvatures. In some embodiments, the final structure curvature can further be engineered to be concave by proper selection of CCM properties, and via controlled selective etching of the CCM, this method enables the final structure to be flat.

主权项

1. A method of controlling curvature of a substrate in which a Group III nitride material will be subsequently formed thereon, said method comprising:
depositing a curvature-control-material having a first thermal expansion coefficient directly on a surface of a substrate having a second thermal expansion coefficient at a deposition temperature that is greater than room temperature to provide a first planar structure comprising the substrate and the curvature-control-material, wherein the first thermal expansion coefficient of the curvature-control-material is less than the second thermal expansion coefficient of the substrate; cooling the planar structure from the deposition temperature to room temperature to provide a non-planar structure having a curvature and comprising the substrate and the curvature-control-material; and epitaxially growing a Group III nitride material having a third thermal expansion coefficient on another surface of the substrate that is opposite the surface of the substrate containing the curvature-control-material to provide a second planar structure comprising the Group III nitride material, the substrate and the curvature-control-material, wherein the third thermal coefficient expansion of the Group III nitride material is less than the first thermal coefficient of the substrate.