Patent application number | Description | Published |
20090057847 | Gallium nitride wafer - A gallium nitride wafer | 03-05-2009 |
20090218659 | CHAMFERED FREESTANDING NITRIDE SEMICONDUCTOR WAFER AND METHOD OF CHAMFERING NITRIDE SEMICONDUCTOR WAFER - Technology of making freestanding gallium nitride (GaN) wafers has been matured at length. Gallium nitride is rigid but fragile. Chamfering of a periphery of a GaN wafer is difficult. At present edges are chamfered by a rotary whetstone of gross granules with weak pressure. Minimum roughness of the chamfered edges is still about Ra 10 μm to Ra 6 μm. The large edge roughness causes scratches, cracks, splits or breaks in transferring process or wafer process. A wafer of the present invention is bevelled by fixing the wafer to a chuck of a rotor, bringing an edge of the wafer into contact with an elastic whetting material having a soft matrix and granules implanted on the soft matrix, rotating the wafer and feeding the whetting material. Favorably, several times of chamfering edges by changing the whetting materials of smaller granules are given to the wafer. The chamfering can realize small roughness of Ra 10 nm and Ra 5 μm at edges of wafers. | 09-03-2009 |
20090250790 | NITRIDE SEMICONDUCTOR WAFER AND METHOD OF PROCESSING NITRIDE SEMICONDUCTOR WAFER - Nitride semiconductor wafers which are produced by epitaxially grown nitride films on a foreign undersubstrate in vapor phase have strong inner stress due to misfit between the nitride and the undersubstrate material. A GaN wafer which has made by piling GaN films upon a GaAs undersubstrate in vapor phase and eliminating the GaAs undersubstrate bends upward due to the inner stress owing to the misfit of lattice constants between GaN and GaAs. Ordinary one-surface polishing having the steps of gluing a wafer with a surface on a flat disc, bringing another surface in contact with a lower turntable, pressing the disc, rotating the disc, revolving the turntable and whetting the lower surface, cannot remedy the inherent distortion. The Distortion worsens morphology of epitaxial wafers, lowers yield of via-mask exposure and invites cracks on surfaces. Nitride crystals are rigid but fragile. Chemical/mechanical polishing has been requested in vain. Current GaN wafers have roughened bottom surfaces, which induce contamination of particles and fluctuation of thickness. | 10-08-2009 |
20100279440 | NITRIDE SEMICONDUCTOR WAFER AND METHOD OF PROCESSING NITRIDE SEMICONDUCTOR WAFER - Nitride semiconductor wafers which are produced by epitaxially grown nitride films on a foreign undersubstrate in vapor phase have strong inner stress due to misfit between the nitride and the undersubstrate material. A GaN wafer which has made by piling GaN films upon a GaAs undersubstrate in vapor phase and eliminating the GaAs undersubstrate bends upward due to the inner stress owing to the misfit of lattice constants between GaN and GaAs. Ordinary one-surface polishing having the steps of gluing a wafer with a surface on a flat disc, bringing another surface in contact with a lower turntable, pressing the disc, rotating the disc, revolving the turntable and whetting the lower surface, cannot remedy the inherent distortion. The Distortion worsens morphology of epitaxial wafers, lowers yield of via-mask exposure and invites cracks on surfaces. Nitride crystals are rigid but fragile. Chemical/mechanical polishing has been requested in vain. Current GaN wafers have roughened bottom surfaces, which induce contamination of particles and fluctuation of thickness. | 11-04-2010 |
20130292696 | CHAMFERED FREESTANDING NITRIDE SEMICONDUCTOR WAFER AND METHOD OF CHAMFERING NITRIDE SEMICONDUCTOR WAFER - Technology of making freestanding gallium nitride (GaN) wafers has been matured at length. Gallium nitride is rigid but fragile. Chamfering of a periphery of a GaN wafer is difficult. At present edges are chamfered by a rotary whetstone of gross granules with weak pressure. Minimum roughness of the chamfered edges is still about Ra 10 μm to Ra 6 μm. The large edge roughness causes scratches, cracks, splits or breaks in transferring process or wafer process. A wafer of the present invention is bevelled by fixing the wafer to a chuck of a rotor, bringing an edge of the wafer into contact with an elastic whetting material having a soft matrix and granules implanted on the soft matrix, rotating the wafer and feeding the whetting material. Favorably, several times of chamfering edges by changing the whetting materials of smaller granules are given to the wafer. The chamfering can realize small roughness of Ra10 nm and Ra5 μm at edges of wafers. | 11-07-2013 |
Patent application number | Description | Published |
20080299350 | Method of Polishing Compound Semiconductor Substrate, Compound Semiconductor Substrate, Method of Manufacturing Compound Semiconductor Epitaxial Substrate, and Compound Semiconductor Epitaxial Substrate - Compound-semiconductor-substrate polishing methods, compound semiconductor substrates, compound-semiconductor-epitaxial-substrate manufacturing methods, and compound semiconductor epitaxial substrates whereby oxygen superficially present on the substrates reduced. A compound semiconductor-substrate polishing method includes a preparation step (S | 12-04-2008 |
20100013053 | METHOD FOR MANUFACTURING III-V COMPOUND SEMICONDUCTOR SUBSTRATE, METHOD FOR MANUFACTURING EPITAXIAL WAFER, III-V COMPOUND SEMICONDUCTOR SUBSTRATE, AND EPITAXIAL WAFER - The present invention provides a method for manufacturing a III-V compound semiconductor substrate, a method for manufacturing an epitaxial wafer, a III-V compound semiconductor substrate, and an epitaxial wafer, wherein the thickness of an oxide film formed on the substrate or in the wafer is controlled with high precision, and surface of the epitaxial wafer is prevented from getting rough,. The method for manufacturing a III-V compound semiconductor substrate according to the present invention includes the following steps. Initially, a substrate composed of a III-V compound semiconductor is provided. Thereafter, the resulting substrate is cleaned with an acidic solution. Subsequently, an oxide film is formed on the substrate by a wet method after the cleaning. | 01-21-2010 |
20120135549 | Method of Processing Gallium-Nitride Semiconductor Substrates - Polishing a nitride semiconductor monocrystalline wafer leaves it with a process-transformed layer. The process-transformed layer has to be etched to be removed. The chemical inertness of nitride semiconductor materials has, however, precluded suitable etching. Although potassium hydroxide, for example, or sulfuric acid have been proposed as GaN etchants, their ability to corrosively remove material from the Ga face is weak. Dry etching utilizing a halogen plasma is carried out in order to remove the process-transformed layer. The Ga face can be etched off with the halogen plasma. Nevertheless, owing to the dry etching, a problem arises again—surface contamination due to metal particles. To address the problem, wet etching with, as the etchant, solutions such as HF+H | 05-31-2012 |