Abstract: 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.

Abstract: A method for manufacturing a silicon carbide epitaxial substrate which has a first surface which is a (000-1) C-face, a silicon carbide epitaxial layer located on the first surface of the silicon carbide substrate, and a line-shaped surface defect density on a top surface of the silicon carbide epitaxial layer is less than 1.0 cm?2 and a stacking fault density is less than 1.2 cm?2.

Abstract: A single-crystal silicon carbide substrate has a main surface having a surface roughness fulfilling Ra?1 nm, and has a ratio of hidden scratches of less than 50%, where, in the case where the main surface is arbitrary observed at 50 or more observation points with a field of view having a diameter of 100 ?m, the ratio of hidden scratches is defined by a value obtained by dividing the number of the observation points at which a striped hidden scratch having a length of at least 50 ?m by the total number of the observation points.

Abstract: A single-crystal silicon carbide substrate has a main surface having a surface roughness fulfilling Ra ?1 nm, and has a ratio of hidden scratches of less than 50%, where, in the case where the main surface is arbitrary observed at 50 or more observation points with a field of view having a diameter of 100 ?m, the ratio of hidden scratches is defined by a value obtained by dividing the number of the observation points at which a striped hidden scratch having a length of at least 50 ?m by the total number of the observation points.

Abstract: A method of manufacturing a SiC substrate which has a first principal surface and a second principal surface, includes the step of removing, by a vapor phase etching process, at least a portion of a work-affected layer which is formed by mechanical flattening or cutting on the first principal surface of the SiC substrate.

Abstract: A thin-film magnetic head substrate according to the present invention includes: a ceramic base with a principal surface; and an undercoat film, which covers the principal surface of the ceramic base. An electrical/magnetic transducer is provided on the undercoat film. The substrate further includes an intermediate layer between the principal surface of the ceramic base and the undercoat film. The intermediate layer is made of a material other than an aluminum oxide and has been patterned so as to make a portion of the principal surface of the ceramic base contact with the undercoat film.

Abstract: A method of manufacturing a SiC substrate which has a first principal surface and a second principal surface, includes the step of removing, by a vapor phase etching process, at least a portion of a work-affected layer which is formed by mechanical flattening or cutting on the first principal surface of the SiC substrate.

Abstract: A method for producing a silicon carbide single crystal substrate according to the present invention includes steps of: (A) preparing a silicon carbide single crystal substrate having a mechanically polished main face; (B) performing chemical mechanical polishing on the main face of the silicon carbide single crystal substrate using a polishing slurry containing abrasive grains dispersed therein to finish the main face as a mirror surface; (C?1) oxidizing at least a part of the main face finished as a mirror surface by a gas phase to form an oxide; and (C?2) removing the oxide.

Abstract: A method of manufacturing an SiC single crystal wafer according to the present invention includes the steps of: (a) preparing an SiC single crystal wafer 10 with a mirror-polished surface; (b) oxidizing the surface of the SiC single crystal wafer 10 with plasma, thereby forming an oxide layer 12 on the surface of the SiC single crystal wafer; and (c) removing at least a portion of the oxide layer 12 by a reactive ion etching process. Preferably, the surface of the wafer is planarized by repeatedly performing the steps (b) and (c) a number of times.

Abstract: A thin-film magnetic head wafer includes a first principal surface and a second principal surface which are substantially parallel to each other. An electrical/magnetic transducer is provided on the first principal surface. Identification information is recorded on the first principal surface of the wafer.

Abstract: A method for producing an alignment mark is performed such that the alignment mark can be removed from the surface of a substrate without leaving any trace thereof after the alignment mark has been used for alignment. After a first photoresist layer has been formed on a substrate, the first photoresist layer is subjected to patterning, and the alignment mark is thereby formed from the first photoresist layer. In the next step, after a second photoresist layer has been formed so as to cover the alignment mark, the second photoresist layer is subjected to patterning on the basis of the alignment mark. After the surface of the substrate has been subjected to etching by use of a resist mask thus formed, the resist mask and the alignment mark are removed, and the region where the alignment mark has been located is made flat.

Abstract: A substrate for a thin-film magnetic head includes a ceramic base and an undercoat film of amorphous SiC, which is supported on the ceramic base.

Abstract: A method of manufacturing an SiC single crystal wafer according to the present invention includes the steps of: (a) preparing an SiC single crystal wafer 10 with a mirror-polished surface; (b) oxidizing the surface of the SiC single crystal wafer 10 with plasma, thereby forming an oxide layer 12 on the surface of the SiC single crystal wafer; and (c) removing at least a portion of the oxide layer 12 by a reactive ion etching process. Preferably, the surface of the wafer is planarized by repeatedly performing the steps (b) and (c) a number of times.

Abstract: A method of marking a sintered body includes the step of preparing the sintered body by sintering a mixture of first and second types of powder particles. The first type of powder particles is made of a first material and the second type of powder particles is made of a second material that has a different etch susceptibility from the first material. The method further includes the step of writing ID information on the surface of the sintered body by forming a first concave region to a depth of at least about 10 nm under the surface of the sintered body and a second concave region under the first concave region, respectively. The first concave region is formed by etching away both the first and second types of powder particles, while the second concave region is formed by etching away only the first type of powder particles.

Abstract: A thin-film magnetic head wafer includes a first principal surface and a second principal surface which are substantially parallel to each other. An electrical/magnetic transducer is provided on the first principal surface. Identification information is recorded on the first principal surface of the wafer.

Abstract: A thin-film magnetic head wafer includes a first principal surface and a second principal surface which are substantially parallel to each other. An electrical/magnetic transducer is provided on the first principal surface. Identification information is recorded on the first principal surface of the wafer.

Abstract: A thin-film magnetic head substrate according to the present invention includes: a ceramic base with a principal surface; and an undercoat film, which covers the principal surface of the ceramic base. An electrical/magnetic transducer is provided on the undercoat film. The substrate further includes an intermediate layer between the principal surface of the ceramic base and the undercoat film. The intermediate layer is made of a material other than an aluminum oxide and has been patterned so as to make a portion of the principal surface of the ceramic base contact with the undercoat film.

Abstract: A method of recording different identifiers, each including at least one character, on multiple plate-type members, involves the use of a photomask of a first type and at least two photomasks of a second type. The photomask of the first type has an opaque pattern that defines a blank region to write the identifier thereon. Each of the photomasks of the second type has an opaque pattern defining the at least one character. The method further includes the steps of forming a photoresist layer on the surface of one of the plate-type members, exposing the photoresist layer, except the blank region, to a radiation through the photomask of the first type, and forming a latent image of the at least one character in the blank region through at least one of the photomasks of the second type.

Abstract: A method of marking a sintered body includes the step of preparing the sintered body by sintering a mixture of first and second types of powder particles. The first type of powder particles is made of a first material and the second type of powder particles is made of a second material that has a different etch susceptibility from the first material. The method further includes the step of writing ID information on the surface of the sintered body by forming a first concave region to a depth of at least about 10 nm under the surface of the sintered body and a second concave region under the first concave region, respectively. The first concave region is formed by etching away both the first and second types of powder particles, while the second concave region is formed by etching away only the first type of powder particles.

Abstract: A method of marking a sintered body includes the step of preparing the sintered body by sintering a mixture of first and second types of powder particles. The first type of powder particles is made of a first material and the second type of powder particles is made of a second material that has a different etch susceptibility from the first material. The method further includes the step of writing ID information on the surface of the sintered body by forming a first concave region to a depth of at least about 10 nm under the surface of the sintered body and a second concave region under the first concave region, respectively. The first concave region is formed by etching away both the first and second types of powder particles, while the second concave region is formed by etching away only the first type of powder particles.