A film formation method of forming a film on a surface of a wafer using a vapor growth apparatus is provided. The film formation method includes a film forming process of forming a film on the surface of the wafer. The vapor growth apparatus includes a susceptor that supports the wafer. The susceptor includes a plurality of wafer supports that support the wafer from below and rotates around a rotation axis extending in a vertical direction. The plurality of wafer supports are arranged at intervals in a circumferential direction around the rotation axis. The film forming process includes supporting the wafer using the plurality of wafer supports such that a direction in which the rotation axis and each wafer support are connected when seen in the vertical direction is a direction which is different from a cleaving direction of the wafer.

A silicon carbide epitaxial substrate according to the present disclosure includes: a silicon carbide substrate; a first silicon carbide epitaxial layer disposed on the silicon carbide substrate; and a second silicon carbide epitaxial layer disposed on the first silicon carbide epitaxial layer. When an area density of first particles in the first silicon carbide epitaxial layer is defined as a first area density and an area density of second particles in the second silicon carbide epitaxial layer is defined as a second area density, a value determined by dividing the first area density by the second area density is more than 0.5 and less than 1. The first particles and the second particles each have a maximum diameter of 2 m to 50 m.

A silicon carbide epitaxial layer includes a buffer layer in contact with the silicon carbide substrate, a transition layer disposed on the buffer layer, and a drift layer disposed on the transition layer. An area density of the first defect is a first area density, and an area density of the second defect is a second area density, the first area density is 0.03/cm.sup.2 or more, and a value obtained by dividing the second area density by a sum of the first area density and the second area density is less than 2.91%. The first defect, as viewed perpendicularly to the main surface, is shaped to bifurcate from a first origin. No recessed groove is present on an imaginary line segment connecting both ends of the first defect.

A semiconductor substrate comprising a first epitaxial silicon carbide layer and a second silicon carbide epitaxial layer. At least one semiconductor device is formed in or on the second silicon carbide epitaxial layer. The semiconductor substrate is formed overlying a silicon carbide substrate having a surface comprising silicon carbide and carbon. An exfoliation process is used to remove the semiconductor substrate from the silicon carbide substrate. The carbon on the surface of the silicon carbide substrate supports separation. A portion of the silicon carbide substrate on the semiconductor substrate is removed after the exfoliation process. The surface of the silicon carbide substrate is prepared for reuse in subsequent formation of semiconductor substrates.

An object of the present invention is to provide a high-quality SiC semiconductor device. In order to solve the above problem, the present invention comprises a method for producing a SiC semiconductor device, comprising a growth step of forming a growth layer on a workpiece comprising SiC single crystals, a device formation step of forming at least a portion of a SiC semiconductor device in the growth layer, and a separation step of separating at least a portion of the SiC semiconductor device from the workpiece.

An epitaxial silicon carbide substrate comprises a first epitaxial silicon carbide layer and at least a second silicon carbide epitaxial layer. A plurality of devices are formed in or overlying the second silicon carbide epitaxial layer. The epitaxial silicon carbide substrate is formed overlying a reuseable silicon carbide substrate. An exfoliation layer is at or underlies a surface of the reuseable silicon carbide substrate. The exfoliation layer comprises silicon carbide and carbon. In one embodiment a plurality of trenches is formed in the surface of the reuseable silicon carbide substrate. The layer of carbon is formed in or below the plurality of trenches. An exfoliation process comprises thermal or mechanical processes to separate the reuseable silicon carbide substrate from the epitaxial silicon carbide substrate. The surface of the reuseable silicon carbide substrate is prepared so the reuseable silicon carbide substrate can be reused.

A method of processing a composite structure including a thin layer of single-crystal silicon carbide disposed on a polycrystalline silicon carbide carrier substrate, includes, after formation of electronic component elements on a front face of the composite structure, grinding a rear face of the composite structure and removing a work-hardened layer present on the surface of the rear face as a result of the grinding process.

A silicon carbide (SiC) semiconductor device is proposed. The SiC semiconductor device includes a buffer layer of a first conductivity type and a drift layer of the first conductivity type arranged, along a vertical direction, on the buffer layer. A vertical profile of a doping concentration of the buffer layer includes at least a first valley portion, a first plateau portion and a first transition portion extending from the first valley portion to the first plateau portion. The doping concentration of each of the first valley portion or the first plateau portion varies by less than 20 %. A vertical extent of the first transition portion ranges from 1 % to 30 % of a vertical extent of the first valley portion.

A semiconductor device has a substrate made of a first semiconductor material. The first semiconductor material is silicon carbide. A first semiconductor layer made of the first semiconductor material is disposed over the substrate. A second semiconductor layer made of a second semiconductor material dissimilar from the first semiconductor material is disposed over the first semiconductor layer. The second semiconductor material is silicon. A third semiconductor layer made of the second semiconductor material can be disposed between the first semiconductor layer and second semiconductor layer. A semiconductor device is formed in the second semiconductor layer. The semiconductor device can be a power MOSFET or diode. The second semiconductor layer with the electrical component provides a first portion of a breakdown voltage for the semiconductor device and the first semiconductor layer and substrate provide a second portion of the breakdown voltage for the semiconductor device.

A method for manufacturing an epitaxial substrate includes the steps of: epitaxially growing a group III nitride semiconductor layer on a substrate; removing the substrate from a growth furnace; irradiating a surface of the group III nitride semiconductor layer with ultraviolet light while exposing the surface to an atmosphere containing oxygen; and measuring a sheet resistance value of the group III nitride semiconductor layer.