The present invention addresses the problem of providing novel techniques for manufacturing a SiC substrate that enables reduced material loss when a strained layer is removed. The present invention is a method for manufacturing a SiC substrate 30 which includes a strained layer thinning step S1 for thinning a strained layer 12 of a SiC substrate body 10 by moving the strained layer 12 to a surface side. Including such a strained layer thinning step S1 in which the strain layer is moved to (concentrated toward) the surface side makes it possible to reduce material loss L when removing the strained layer 12.

A drift layer is formed over a semiconductor substrate which is an SiC substrate. The drift layer includes first to third n-type semiconductor layers and a p-type impurity region. Herein, an impurity concentration of the second n-type semiconductor layer is higher than an impurity concentration of the first n-type semiconductor layer and an impurity concentration of the third n-type semiconductor layer. Also, in plan view, the second semiconductor layer located between the p-type impurity regions adjacent to each other overlaps with at least a part of a gate electrode formed in a trench.

A nitride semiconductor device includes: a diamond substrate; a first graphene layer provided on the diamond substrate; a second graphene layer provided on the first graphene layer; a nitride semiconductor layer provided on the second graphene layer; and a nitride semiconductor element having an electrode provided on the nitride semiconductor layer, wherein the first and second graphene layers are provided as an interface layer between the diamond substrate and the nitride semiconductor layer.

A substrate is mounted on a rotator provided in a reaction chamber, while a first process gas containing no source gas is supplied to an upper surface of the substrate from above the substrate and the substrate is rotated at 300 rpm or more, a temperature of a wall surface is changed, and after a temperature of the substrate is allowed to rise, the substrate is controlled to a predetermined film formation temperature and a second process gas containing a source gas is supplied to the upper surface of the substrate from above the substrate to grow an SiC film on the substrate.

In a silicon carbide substrate including: a SiC substrate; and a first semiconductor layer, a second semiconductor layer and a drift layer that are epitaxial layers sequentially formed on the SiC substrate, an impurity concentration of the first semiconductor layer is lower than impurity concentrations of the SiC substrate and the second semiconductor layer, and the second semiconductor layer is formed to have a high impurity concentration or a large thickness.

Provided is a wafer jig including a bottom wall and a ring-shaped side wall. The bottom wall has a supporting surface. The ring-shaped side wall is connected to a periphery of the bottom wall. The ring-shaped side wall includes at least two step portions. The two step portions include a first step portion and a second step portion. The first step portion is connected between the supporting surface and the second step portion, and the first step portion protrudes along a direction toward a center of the bottom wall. The ring-shaped side wall surrounds the center. In addition, a wafer structure and a wafer processing method are also provided.

Provided is a semiconductor substrate with a balance stress. The semiconductor substrate includes a ceramics base, a nucleation layer and a first buffer layer doped with a first dopant. The ceramics base has an off-cut angle other than 0 degree. The nucleation layer is disposed on the ceramics base. The first buffer layer is disposed on the nucleation layer. The first dopant includes C, Fe or a combination thereof. The first buffer layer provides compressive stress to the ceramic base. The concentration of the first dopant in the first buffer layer is increased away from the ceramics base. The curvature of the semiconductor substrate is between 16 km.sup.−1 and −16 km.sup.−1.

A wafer producing apparatus detects a facet area from an upper surface of an SiC ingot, sets X and Y coordinates of plural points lying on a boundary between the facet area and a nonfacet area in an XY plane, and sets a focal point of a laser beam having a transmission wavelength to SiC inside the SiC ingot at a predetermined depth from the upper surface of the SiC ingot. The predetermined depth corresponds to the thickness of the SiC wafer to be produced. A control unit increases the energy of the laser beam and raises a position of the focal point in applying the laser beam to the facet area as compared with the energy of the laser beam and a position of the focal point in applying the laser beam to the nonfacet area, according to the X and Y coordinates.

A semiconductor substrate includes a base portion, an auxiliary layer and a surface layer. The auxiliary layer is formed on the base portion. The surface layer is formed on the auxiliary layer. The surface layer is in contact with a first main surface of the semiconductor substrate. The auxiliary layer has a different electrochemical dissolution efficiency than the base portion and the surface layer. At least a portion of the auxiliary layer and at least a portion of the surface layer are converted into a porous structure. Subsequently, an epitaxial layer is formed on the first main surface.

A SiC epitaxial wafer according to an embodiment includes: a SiC substrate; and a SiC epitaxial layer formed on a first surface of the SiC substrate. The in-plane uniformity of a density of Z.sub.1/2 centers of the SiC epitaxial layer is 5% or less.