50 results about "Hydrogen etching" patented technology

A process for manufacturing a bipolar type semiconductor device in which at least a part of a region where an electron and a hole are recombined during current flowing is formed with a silicon carbide epitaxial layer that has been grown from the surface of a silicon carbide substrate, is characterized by that the surface of the silicon carbide substrate is treated by hydrogen etching and the epitaxial layer is then formed by the epitaxial growth of silicon carbide from the treated surface. A propagation of a basal plane dislocation to the epitaxial layer can be further reduced by treating the surface of the silicon carbide substrate by using chemical mechanical polishing and hydrogen etching in this order.

The invention discloses a method for preparing thin layer graphene on the surface of a metal catalyst. The method comprises the following steps: 1, putting a metal catalyst matrix in a chemical vapor deposition (CVD) system, and heating and annealing in an H2 and Ar gas mixed atmosphere; 2, carrying out a high temperature carburizing reaction by utilizing different carbon sources; 3, slowly heating samples while etching by introducing a large flow of hydrogen; and 4, completely discharging hydrogen in the CVD system through the Ar gas after the hydrogen etching, and rapidly cooling to room temperature for segregating uniform graphene layers. The number of the graphene layer can be accurately controlled by changing the thickness, the carburizing amount and the hydrogen etching amount of the metal catalyst matrix. The method has the advantages of simple process, easy operation, compatibility with the semiconductor industry, realization of the controllable preparation of graphene, and a graphene material produced through the method has important application prospects in the electronic field, the photoelectric field, the sensing field and the like.

The invention relates to a method for selectable single-side growth of graphene on a SiC substrate. The method comprises the following steps: horizontally placing the SiC substrate in a graphite crucible, allowing the side of C to be downward or the side of Si to be downward, and overlaying a cover sheet on the upward side of the SiC substrate, wherein the cover sheet is a Si atom donor or a C atom absorber; vacuumizing the chamber of a heating furnace for heating, then introducing high-purity H2, and subjecting the surface of the SiC substrate to hydrogen etching so as to form a regular SiC step structure; and closing H2, introducing Ar gas, continuing heating the heating furnace to 1500 to 1800 DEG C, and maintaining the temperature so as to complete the growth of graphene. The graphene grown by using the method provided by the invention has greatly-improved quality and surface morphology, and can be extensively applied in the fields of logic circuits, laser Q modulation, high-frequency nanometer radio frequency devices, etc.

The invention relates to the field of fabrication of a high-quality semiconductor single-walled carbon nanotube, in particular to a method for directly growing the high-quality semiconductor single-walled carbon nanotube through in-situ weak hydrogen etching. A metallic and small-diameter single-walled carbon nanotube can be etched in situ at a certain reaction temperature by regulating and optimizing a flow of carrier gas, namely hydrogen and under the conditions of taking dicyclopentadienyl iron as a catalyst precursor, sulfur powder as a growth promoter and organic low-carbon hydrocarbon as a carbon source; and the high-quality semiconductor-superior single-walled carbon nanotube is finally obtained. The content of the semiconductor single-walled carbon nanotube is greater than or equal to 91wt%, the diameter distribution is between 1.5nm and 2.5nm, and the highest concentrated oxidation temperature reaches 800 DEG. With the adoption of the method, the massive, fast and low-cost controlled growth of the semiconductor single-walled carbon nanotube with the narrower diameter distribution and the high quality is realized, and the problems such as serious damages to a sample due to a strong etching agent, complexity of a fabrication process, low output and high cost during a selective fabrication course of a conduction-superior single-walled carbon nanotube can be effectively solved.

The invention discloses a method for realizing epitaxial growth of wafer level graphene on 4H/6H-SiC carbon surfaces, which aims to realize that when epitaxial growth of wafer level graphene is realized by an existing method, the area of produced graphene is too small and uniformity of the graphene is low. The method includes steps of cleaning and treating the 4H/6H-SiC carbon surfaces to remove organic residues and ion pollutant on the surfaces, filling hydrogen to realize hydrogen etching for the 4H/6H-SiC carbon surfaces to remove scratches of the surfaces, and forming regular step-shaped strips; feeding silane to remove oxide caused by hydrogen etching on the surfaces; feeding argon flow to realize sublimation of silicon atoms under the condition of pressure of 2mbar by the aid of heating, and realizing reconstitution of surfaces of substrate in a sp2 mode by the aid of carbon atoms to form epitaxial graphene. The graphene prepared by the aid of the process method has larger area and fine uniformity, and the method can be applied to preparing wafer level epitaxial graphene materials.

The invention relates to a method for preparing single-layer graphene without a buffer layer on a SiC substrate. The method comprises the following steps: performing hydrogen etching on a silicon surface of the SiC substrate to form regular step morphology; introducing argon gas and growing a graphene buffer layer; performing hydrogen annealing on the SiC substrate with only a layer of graphene buffer layer on the surface to insert the hydrogen atom between the graphene buffer layer and the SiC substrate, so that the graphene buffer layer becomes single-layer graphene. According to the method provided by the invention, a problem that the graphene migration rate is influenced by the buffer layer formed when graphene is grown on the silicon surface of the SiC substrate in a SiC pyrolysis method is solved; meanwhile, real single-layer graphene without a buffer layer is obtained and can be directly applied to a radio-frequency device.

The invention discloses a preparation method of graphene on an SiC substrate based on Cu film annealing and chlorine reaction and mainly solves the problem that graphene prepared in the prior art has small area, can not be used for large-scale production and has non-uniform layers, multiple defects and unstable carrier mobility. The preparation method comprises the following steps: cleaning an SiC sample sheet; (2) putting the cleaned SiC sample sheet into graphene growth equipment and carrying out hydrogen etching on the SiC sample sheet; (3) introducing mixed gas of Ar gas and Cl2 into a reaction chamber and reacting SiC with Cl2 for 4-10 minutes at the temperature of 700-1,100 DEG C to generate a carbon film; (4) plating a Cu film on the generated carbon film; (5) putting a carbon film sample sheet plated with the Cu film into Ar gas and annealing for 15-25 minutes at the temperature of 900-1,200 DEG C to generate the graphene; and (6) removing the Cu film from a graphene sample sheet. The graphene prepared by the method has the advantages of smooth surface, good continuity and low porosity and can be used in the fields of biology, micro-electronics, chemicals and the like.

The invention provides a graphene preparation method. The graphene preparation method comprises the steps that hydrogen etching is carried out on a SiC substrate silicon face to form an atom step-shaped surface; a SiC substrate subjected to hydrogen etching is arranged in a reaction chamber, inert gas is fed into the reaction chamber, and a carbon atom buffer layer is prepared on the SiC substratesilicon face; and the SiC substrate on which the carbon atom buffer layer is formed is arranged in a microwave plasma chemical vapor deposition furnace chamber, carbon gas is fed with hydrogen serving as carrier gas, and plasma is stimulated to grow graphene on the buffer layer. The graphene prepared through the method can be directly manufactured into a device without transferring or following treatment, and device preparation is facilitated; by means of the application of the plasma, the thermal stress caused by a reaction temperature and the high temperature is reduced, preparation of thegraphene is more controllable, application of the graphene device is facilitated, the reaction time is effectively shortened, and the reaction rate is accelerated; and the carbon atom buffer layer serves as a middle layer, the defect that in a pyrolysis method, the migration rate of the graphene is reduced by the buffer layer is avoided, and the graphene quality is optimized.

The invention discloses a preparation method of large-area graphene on an Si substrate based on Ni film annealing and mainly solves the problems of small area, poor continuity and non-uniform layers of graphene prepared in the prior art. The preparation method comprises the following implementation steps: growing a carburization layer on the 4-12-inch Si substrate to be used as a transition and growing a 3C-SiC heteroepitaxial film at the temperature of 1200 DEG C to 1350 DEG C by utilizing growth gas sources C3H8 and SiH4; carrying out hydrogen etching on the grown 3C-SiC film and removing a compound generated by etching; reacting 3C-SiC with gaseous CCl4 at a temperature of 800-1,000 DEG C to generate a carbon film; electron beam-depositing an Ni film on the carbon film, putting a sample sheet plated with the Ni film into Ar gas and annealing for 10-20 minutes at a temperature of 1,000-1,250 DEG C to generate a graphene sample sheet; and finally removing the Ni film from the graphene sample sheet. The graphene prepared by the method has the advantage that the area can reach 12 inches, the continuity is good, the surface is smooth, and the porosity is low. The graphene can be used for manufacturing microelectronic devices and biological sensors or sealing gas and liquid.

The invention discloses a method for preparing graphene on an SiC substrate based on Ni film annealing and chlorine reaction and mainly solves the problems of poor continuity and unsmooth surface of graphene prepared in the prior art. The preparation method comprises the following implementation steps: firstly, carrying out RCA cleaning on the SiC substrate; carrying out hydrogen etching on the cleaned SiC substrate and removing etching residues; introducing mixed gas of Ar gas and Cl2 into a quartz tube reaction chamber and reacting SiC with Cl2 for 3-8 minutes at the temperature of 700-1,100 DEG C to generate a carbon film; then electron beam-depositing an Ni film on the carbon film; putting a sample sheet deposited with the Ni film into Ar gas and annealing for 10-30 minutes at the temperature of 950-1,150 DEG C to generate the graphene; and finally removing the Ni film from a graphene sample sheet by utilizing mixed solution of hydrochloric acid and copper sulfate. The graphene generated by the method has the advantages of smooth surface, good continuity and low porosity and can be used for manufacturing microelectronic devices and biological sensors or sealing gas and liquid.

To provide silicon carbide epitaxial wafer in which occurrence of giant step bunchings (GSBs) caused by basal plane dislocations (BPDs) that occur during hydrogen etching is suppressed on low off-angle silicon carbide substrate to decrease surface defect density of epitaxially grown layer to allow formation of silicon carbide semiconductor device having high reliability, method for manufacturing the wafer, and apparatus for manufacturing the wafer, and silicon carbide semiconductor device having the wafer.

A silicon carbide epitaxial wafer of the present invention is such that epitaxially grown layer is disposed on silicon carbide substrate which has α-type crystal structure and in which (0001) Si face is tilted at greater than 0° and less than 5°, wherein surface defect density of the epitaxially grown layer based on giant step bunching caused by basal plane dislocation on substrate surface of the silicon carbide substrate is ≦20/cm².

The invention relates to a method for located growing of big single crystal graphene on a SiC substrate through a point-seed way. The method comprises the following steps: (1) polishing and cleaning SiC; feeding into a growing furnace; pumping vacuum; increasing the temperature to be 1200 to 1300 DEG C; charging argon and hydrogen; increasing the temperature to be 1500-1600 DEG C; performing hydrogen etching; closing hydrogen after etching; decreasing the temperature to be 1400 to 1500 DEG C, and maintaining the temperature; decreasing the temperature to be 800 to 1100 DEG C under argon atmosphere; placing a superfine heat conducting probe on the SiC substrate to form a local undercooling point; charging carbon source gas and hydrogen, wherein an active carbon source obtained by the decomposing of the carbon source gas can preferentially grow into graphene seed crystal at the undercooling point; (2) enabling continuous growing of graphene using the seed crystal on the SiC substrate as the center under the condition that the temperature is 800 to 1100 DEG C, the pressure is 800 to 900mbar, and carbon source gas is supplied, so as to obtain big single crystal graphene; and (3) charging argon after the growth, and decreasing the temperature, thus obtaining the big single crystal graphene. The method is free of a metal substrate, and the grown big single crystal graphene can be directly applied to micro-electronic appliance without being transferred.

The invention discloses a preparation method of large-area graphene on an SiC substrate based on Ni film annealing and mainly solves the problems of poor continuity, unsmooth surface and non-uniform layers of graphene prepared in the prior art. The preparation method comprises the following realization steps: firstly, cleaning the SiC substrate by using mixed solution of ammonia water and hydrogen peroxide and mixed solution of hydrochloric acid and hydrogen peroxide; then carrying out hydrogen etching on the cleaned SiC substrate and removing a generated Si compound; putting the cleaned SiC substrate into reaction equipment, so that SiC reacts with gaseous CCl4 at the temperature of 750-1,150 DEG C to generate a carbon film; then electron beam-depositing an Ni film on the carbon film, putting a sample sheet plated with the Ni film into Ar gas with the temperature of 900-1,200 DEG C and annealing for 10-20 minutes to generate the graphene; and finally removing the Ni film from a graphene sample sheet by using mixed solution of hydrochloric acid and copper sulfate. The graphene prepared by the method has the advantages of large area, good continuity, smooth surface and low porosity and can be produced in a large scale.

The invention discloses a method for rapidly removing sediments on the back surface of a wafer in an epitaxy process of a silicon carbide . The method comprises the following steps: S1) pretreating a substrate wafer: carrying out cleaning, hydrogen etching and/or polishing pretreatment on the back surface (non-epitaxial growth surface) of a silicon carbide single crystal substrate wafer; S2) forming a metal layer: depositing a metal or alloy on the back surface of the silicon carbide single crystal substrate wafer by adopting a magnetron sputtering method to form the metal layer; S3) forming a silicon carbide epitaxial wafer: growing a silicon carbide epitaxial layer on the epitaxial growth surface of the silicon carbide single crystal substrate wafer through a chemical vapor deposition method to obtain the silicon carbide epitaxial wafer; and S4) removing the metal layer: removing the metal layer on the back surface of the silicon carbide epitaxial wafer and the sediments attached to the surface of the metal layer in a solvent corrosion manner. According to the invention, after the method is adopted, the time of the process for removing the sediments on the back surface of the wafer is greatly shortened, the production efficiency can be effectively improved, and the cost control of the silicon carbide epitaxial wafer is facilitated.

The invention relates to a production method of a silicon carbide inorganic ceramic film, and the method comprises the following steps: (1) carrying out hydrogen etching on the surface of silicon carbide powder; (2) generating a graphene thin layer on the surface of the silicon carbide powder; (3) converting the generated graphene into graphene oxide; (4) swelling the generated graphene oxide; (5)molding the silicon carbide powder; (6) performing reduction and solidification of silicon carbide. The method takes the silicon carbide to epitaxially grow the graphene as a technical basis and provides an innovative silicon carbide inorganic ceramic film production process and method. The silicon carbide inorganic ceramic film prepared by the method has the advantages of small filtering aperture, high aperture distribution precision, good mechanical strength of the film body and high bending strength.

The invention relates to a method for preparing graphene and a graphene device by epitaxy of a pretreated SiC substrate. The method comprises the following steps: performing hydrogen etching on the SiC substrate and then performing oxidation treatment on the SiC substrate after hydrogen etching at a temperature of 800-1300 DEG C for the treatment time of 15-120min; and then rising the temperatureto 1450-1700 DEG C in an inert atmosphere on the pretreated SiC substrate for graphene growth. The SiC surface is passivated through oxidation pretreatment so that nucleation density of the graphene epitaxially grown on the SiC substrate is reduced, the graphene material with larger size and better performance is obtained, and the SiC epitaxial graphene wafer is subjected to deposition, photolithography, doping and integration procedures accordingly so as to prepare the corresponding graphene device.

The invention provides an in-situ etching method for SiC hetero epitaxial growth. The method comprises steps: a processed SiC substrate processed by using ortho-axis 4H or 6H original silicon carbide SiC substrate is subjected to ultrasonic cleaning; an alkaline mixture is used for boiling the processed SiC substrate at a temperature of 85 DEG C for 20 m; an acid mixed solution is used for immersing the processed SiC substrate at a temperature of 85 DEG C for 20 m; an epitaxial furnace is used for carrying out in-situ etching on the processed SiC substrate with a zero deflection angle; at a temperature of 1400 DEG C, inrush of a propane protection gas is carried out to be compared with a pure hydrogen etching condition, and at a temperature of 1500 DEG C, inrush of a silane protection gas is carried out to be compared with a pure hydrogen etching condition; and a well-etched SiC epitaxial layer is taken out from the epitaxial furnace. According to the in-situ etching method for SiC hetero epitaxial growth of the invention, the best substrate surface morphology can be etched, and the SiC hetero epitaxial growth quality is enhanced.